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Humic Substances As Interferences In The Analysis Of Nitrite In Water, Stephanie Ann Tebault

Chemistry & Biochemistry Theses & Dissertations

Humic substances are of current interest because of their roles in environmental processes involving pollutants. It is also becoming recognized that humic substances may interfere in analysis of environmental samples though the possible adverse effects do not appear to be fully appreciated. The present effort focuses on determining whether humic materials interfere in the analysis of nitrite in water using the Griess reaction. This is a well-known reaction using nitrosation to gjve a diazonium salt followed by coupling with an appropriate reagent to form a dye. This colorimetric method continues to be applied in the laboratory and the field for …

A Study Of The Seasonal Composition And Abundance Of Phytoplankton And Autotrophic Picoplankton In A Brackish Water Lake In Portsmouth Virginia, Jennifer Leigh Wolny

Biological Sciences Theses & Dissertations

The phytoplankton and autotrophic picoplankton populations of Hoffler Lake, a brackish-water lake in Portsmouth, Virginia, were monitored from May 1997 through May 1998, Analyses of the phytoplankton community using the Utennohl method showed a dominance of Chlorophytes (61-88% of the total abundance) throughout the year, including a winter bloom of Chlamydomonas snowii (maximum concentration of 2.5 x 101 cells/L). Subdominants were Cyanobacteria (10-33% of the total abundance) whose composition included several species of Anabaena, Lyngbya, and a fall bloom of Microcoleus sp. Diatoms, dinoflagellates, and cryptophytes played a secondary role in the phytoplankton community of Hoffler Lake. …

Three-Dimensional Reconstructions Of Tadpole Chondrocrania From Historical Sections, Gary Radice, Mary K. Boggiano, Mark Desantis, Peter Larson, Joseph Oppong, Matthew Smetanick, Todd Stevens, James Tripp, Rebecca Weber, Michael Kerckhove, Rafael De Sá

Virginia Journal of Science

Reconstructing three dimensional structures (3DR) from histological sections has always been difficult but is becoming more accessible with the assistance of digital imaging. We sought to assemble a low cost system using readily available hardware and software to generate 3DR for a study of tadpole chondrocrania. We found that a combination of RGB can1era, stereomicro­scope, and Apple Macintosh PowerPC computers running NIH Image, Object Image, Rotater, and SURFdriver software provided acceptable reconstruc­tions. These are limited in quality primarily by the distortions arising from histological protocols rather than hardware or software.

Cartilage Regeneration On A Large Articular Surface Facilitated By Stress Shielding, Charles L. Mcdowell, Jennifer S. Wayne, Robert Tuten, Hunter H. Mcguire Jr.

Virginia Journal of Science

An animal model for the study of articular cartilage regeneration in-vivo facilitated by stress-shielding is introduced. The object of the model is to test the hypothesis that some form of cartilaginous tissue will grow upon a large joint surface in vivo with the joint in normal motion. The model utilizes the known capability of immature cells to differentiate. The source of cells is bleeding subchondral bone. In addition, the model provides a mechanically shielded environment in which cell differentiation and maturation can occur. The study showed that a substantial amount of tissue will grow in the animal model only when …

Comparative Taphonomy And Paleoecology Of A Glaciomarine Fauna, Carboniferous (Westphalian- Namurian) La Capilla Fm., Argentina, Rex A. Hanger, Mohutsiwa Gabadirwe

Virginia Journal of Science

The Carboniferous La Capilla Fm. of the Calingasta-Uspallata basin of western Argentina contains a low diversity fauna inhabiting a continental shelf under glacial ice fronts advancing from the east. Distal glaciomarine sediments on these ice-influenced shelves of Gondwana are most commonly interpreted as being deposited under quiet, low-energy conditions. Ta­phonomic and paleoecologic analysis of a sample of the fauna reveals the following: low species richness, yet comparable equitability to coeval, tropi­cal faunas; low articulation ratios and high pedicle valve dominance for brachiopods; diverse corrasion modes, about half relatively high categories; one hundred percent fracturing of brachiopod shells, with carinate fracture …

Pfiesteria Piscicida And Dinoflagellates Similar To Pfiesteria, Harold G. Marshall

Virginia Journal of Science

Pfiesteria pisiccida is a microscopic, unicellular organism that is classified as both a mixotrophic and heterotrophic dinoflagellate, which has been associated with both fish deaths and a cause of human illness (Burkholder et al., 1992; Glasgow et al., 1995; Burkholder and Glasgow, 1997). This species possesses a complex life cycle that includes motile forms (e.g. zoospores, gametes, amoebae) and a cyst stage that may remain dormant in the sediment (Burkholder et al., 1995b). Pfiesteria piscicida is known to have toxin and non-toxin producing populations, where cyst transformation into the toxic motile zoospores may be initiated by the presence of certain …

The Effects Of Task Demand And Knowledge Of Results On Operator Engagement And Vigilance Performance Moderation With A Biocybernetic System, Jamie Lynn Loverde

Psychology Theses & Dissertations

The present study examined whether a biocybernetic system could moderate performance in a vigilance task. The system manipulated critical signal (CS) amplitude based on cybernetic feedback contingencies. Under negative feedback, CS amplitude increased when the index fell below a predetermined level and decreased when the index rose above that level The opposite occurred under positive feedback. The system was expected to initiate more amplitude changes under negative feedback to regulate engagement. Performance feedback (Knowledge of Results; KR) was also provided and was expected to improve performance by motivating participants to pay closer attention to the task.

Forty participants performed a …

The Impact Of Resident And Transient Predators On The Popultation Dynamics Of Juvenile Caribbean Spiny Lobster (Panulirus Argus) In Florida Bay, Florida, Jason Edward Schratwieser

Biological Sciences Theses & Dissertations

There has been a considerable amount of research devoted to exploring the relationship between predators and prey, but many of these studies fail to address how predation can vary over spatial and temporal scales. The tendency of ecologists to model predation as a static entity often masks its capacity for creating distinctive effects in prey populations and communities. Most predation studies also focus on the effect of a single species of predator on a prey population, an unrealistic situation in nature. In the Florida Keys, juvenile spiny lobsters are subjected to two general classes of predators: i) "resident" predators such …

A Study On The Effects Of The N-Terminal Amino Acid Sequence On The Activation Of Human T-Cell Leukemia Virus Type 1 Protease, Hidayah Muhammad Kendall

Chemistry & Biochemistry Theses & Dissertations

Human T-cell leukemia virus type 1 (HTL V-1) is dependent upon the enzymatic activity of its protease for maturation. Maturation of the protease is facilitated by cleavage of specific amino acid residues, followed by dimerization. The effects of the amino acid sequence located N-terminally to the cleavage site on the ability of the protease to become active were the focus of the current study. These amino acid sequences were contributed by the plasmid vector into which the protease gene was inserted.

Surface probability analyses (SPAs) of the vectors, as well as for native sequences which produce the mature protease and …

A Simplified Model Of Wound Healing (With Particular Reference To The Critical Size Defect), J. A. Adam

Mathematics & Statistics Faculty Publications

This paper is an attempt to construct a simple mathematical model of wound healing/tissue regeneration which reproduces some of the known qualitative features of those phenomena. It does not address the time development of the wound in any way, but does examine conditions (e.g., wound size) under which such healing may occur. Two related one-dimensional models are examined here. The first, and simpler of the two corresponds to a "swath" of tissue (or more realistically in this case, bone) removed from an infinite plane of tissue in which only a thin band of tissue at the wound edges takes part …

Use Of Extractable Lipofuscin For Age Determination Of Blue Crab Callinectes Sapidus, Se-Jong Ju, David H. Secor, H. Rodger Harvey

OES Faculty Publications

The blue crab Callinectes sapidus is an economically and ecologically important species in many temperate estuaries, yet stock assessments have been limited to length-based methods for demographic analyses. We evaluated the potential of age pigments (lipofuscins) sequestered in neural tissue of eye-stalks and brains to estimate the age of blue crabs collected from Chesapeake Bay and Chincoteague Bay. The rate of lipofuscin accumulation was determined using crabs of known age reared in the laboratory. Age pigments were extracted from neural tissues (eye-stalk or brain), quantified, and normalized to protein content to allow comparisons across tissue types and crab sizes. Field-collected …

Identification And Characterization Of Determinants Of Head And Neck Tumor Cell Invasion, Yangguan Wu

Theses and Dissertations in Biomedical Sciences

Head and neck squamous cell carcinoma (HNSCC) is a common malignant disease with poor prognosis. The majority of patients die from local invasion or lymphatic metastasis. The mechanism(s) underlining the invasiveness of HNSCC are poorly understood. Utilizing a panel of HNSCC cell lines previously established in our laboratory, we tested the application and relevance of the three-step hypothesis of tumor invasion to HNSCC and investigated the mechanism(s) pertaining to the regulation of each step in the invasive process. Data presented in this thesis demonstrated that tumor cell invasion in HNSCC is a complex process involving three repeated sequential steps: adhesion, …

Generation Of Human Chorionic Gonadotropin Beta Subunit Specific Monoclonal Antibody Using A Synthetic Peptide, Zhe Huang

Chemistry & Biochemistry Theses & Dissertations

Human chorionic gonadotropin (hCG) is well known for early immunological and bioassay tests for early detection of pregnancy. Since the hormone specific beta subunit confers unique biological and immunological specificity to hCG, immunochemical measurement of hCG has achieved greater specificity and sensitivity in recent years by using either the beta subunit as an immunogen or a partially reduced beta subunit polypeptide chain. However, antiserum raised against the entire hCG beta subunit usually cross-reacts to some extent with human luteinizing hormone (hLH). hCG has been found to be present in the extract of tumors and minute quantities of hCG are synthesized …

Attention Deficit Hyperactivity Disorder: Considering The Impact Of Educational Institutions And Teacher Perceptions, Cynthia S. Glass

Sociology & Criminal Justice Theses & Dissertations

This research examines teacher perceptions about the nature of Attention Deficit Hyperactivity Disorder ("ADHD") and the teaching strategies used to work with students who display ADHD behaviors. It also examines the relationship between classroom size and perception of incidence of ADHD within the classroom.

Results indicate that older and more experienced teachers are more flexible than younger, less experienced teachers in their teaching strategies when working with students who display ADHD behaviors. Teachers who received information about ADHD from their school administration utilized flexible methods more often than those who did not receive information. The proportion of students identified as …

An Exploratory Study Of The Correlates Of Drug Use Among Juveniles: Analysis Of Regional Variations In The United States, Denise D. Nation

Sociology & Criminal Justice Theses & Dissertations

Research on substance use and abuse has increased exponentially over the past twenty-five years. However, research focusing on regional differences in drug use seems to be very limited. The purpose of this study is to examine the correlates of drug use among juveniles in the four major geographic regions of the United States: the Northeast, the North Central, the South and the West. Here, drug use is defined in terms of alcohol and marijuana use for the age group 12-19. Four research hypotheses are proposed. The 1996 National Household Survey on Drug Abuse data was used to assess and analyze …

Gender Roles Presented In Children's Literature: A Random Selection And Analysis Of Non-Award Winning Books, Renae M. Poarch

Sociology & Criminal Justice Theses & Dissertations

The purpose of this study was to examine the gender role stereotyping that occurs in children's non-award winning literature. This vast selection of non-award winning books has been neglected by researchers when selecting a sample to study. Past research has concentrated on the Caldecott and Newbery Award Winning books, which are not the majority of those owned by public libraries, hence not the majority being read by young readers. The purpose of this study was not to provide a list of appropriate reading material for parents and educators to select from, but rather provide an awareness of the issues so …

Virginia Junior Academy Of Science Awards, 1999 Annual Meeting

Virginia Journal of Science

List of award winning student papers by section from the 1999 Annual Meeting of the Virginia Junior Academy of Science

Virginia Journal Of Science Research Awards

Virginia Journal of Science

List of awards granted by the Virginia Academy of Science in summer 1999.

Virginia Academy Of Science 1999 Best Student Paper Awards

Virginia Journal of Science

List of award winning student papers by section from the Virginia Academy of Science, 1999

Abstracts Of Papers, 77th Annual Meeting Of The Virginia Academy Of Science, May 26-28, 1999, Old Dominion University, Norfolk, Virginia

Virginia Journal of Science

This document is a list of abstracts presented at the 77th annual meeting of the Virginia Academy of Science, between May 26 and May 28th, 1999, at Old Dominion University.

An Extracellular Protein Produced By Staphylococcus Hominis Strain Αm With Antimicrobial Activity Against Mycobacterium Spp, Sandra May Jacobsen

Biological Sciences Theses & Dissertations

The inhibitory activity exhibited by Staphylococcus hominis strain αM toward Mycobacterium species was examined. These studies included determining the conditions that maximized inhibitory agent production, analyzing characteristics of the agent, determining the time of agent production, ascertaining plasmid possession and the role of plasmids in the production of this inhibitory agent, and ascertaining the antimicrobial activity of other strains of S. hominis. On solid and in liquid media, S. hominis strain αM exhibits a unique inhibitory activity toward Mycobacterium species that is not demonstrated by Staphylococcus epidermidis or other S. hominis strains. Maximum agent production and recovery was …

The Virginia Conservative Party, 1965-1969, Gerald Paul Gaidmore Iii

History Theses & Dissertations

This study examines the Virginia Conservative Party of the 1960's. The party was founded in 1965 as a protest against the increasing liberalism in Virginia and national politics. Dedicated to providing voters an alternative to the two major parties, the Conservative Party participated in every major state election from 1965 to 1969. Although failing to win any statewide election, the Conservatives played a significant role in Virginia politics during the 1960's. Paradoxically, the Virginia Conservative Party contributed to the demise of the conservative Democratic Byrd Organization by refusing to support conservative Democrats. Subsequent internal disputes over the party's action in …

Henri Iv As Military Commander, Terence W. Loveridge

History Theses & Dissertations

Henri IV won the throne of France as a feat of arms in a time of great social, religious, economic and military transformation. Militarily, Henri has generally been regarded as a gallant, opportunistic and lucky cavalry commander whose remarkable sense of timing and flexible personal principles enabled him to play a major role in the ending of the Wars of Religion in France. Current debate over the "Military Revolution" of the sixteenth century and the "Revolution in Military Affairs" of the twentieth has renewed interest in both the characters and the techniques of warfare in transformation.

New approaches to military …

Factors Which Affect Post-Hospital Resource Use And Patient Health Outcomes Among Taiwanese Older Adults, Chouh-Jiaun Lin

Health Services Research Dissertations

The purpose of this study was to explore relationships among population characteristics, patient post-hospital resource use and patient health outcomes in terms of the Andersen health behavioral model. An additional purpose of this study was to examine a discharge planning screening instrument used in a large urban hospital in Taiwan to determine if it predicts resource use and patient outcomes. A longitudinal research design was adopted for this study. Data were collected from the general medicine departments of an 800-bed university teaching hospital. Out of 109 patients who were interviewed, 78 participants qualified (participation rate = 71.6%).

The majority of …

Perceptions Of Childhood Relation With Parents Related To Current Functioning, Peter O. Lielbriedis

Psychology Theses & Dissertations

This study investigated the relationships between perceptions of childhood relationships with parents, certain current self-conscious emotions, current religious orientation, and current risk-taking behaviors. The study also sought to develop models that would predict risk-taking behavior based on the other variables.

At an eastern university, 174 students (79 males) completed the Test of Self-Conscious Affect, Religious Life Inventory, Clark-Parent Child Relations Questionnaire, and the Past Frequency scale of the Cognitive Appraisal of Risky Events Questionnaire. Of these, 30 students were solicited from on-campus, religious organizations.

The data did not show an inverse relationship between “positive parenting” and shame proneness or risk-taking …

Zinc Speculation And Ligand Fluxes In Chesapeake Bay And Elizabeth River Pore Waters, Duncan Glover Byers

Chemistry & Biochemistry Theses & Dissertations

Presented here are the first data on the vertical concentrations, complexation, speciation, and fluxes of total dissolved zinc and zinc complexing ligands, and zinc speciation in sediment pore waters in the Chesapeake Bay and Elizabeth River, Virginia.

Sediment pore waters were collected in mid and southern Chesapeake Bay in November 1997 and in the Elizabeth River (Pinner's Point) in March, April, and July 1998. Flux experiments were conducted in Elizabeth River sediment cores in April and July 1998. [TDZn] and zinc complexation were determined using differential pulse anodic stripping voltammetry at a hanging mercury drop electrode (DPASV-HMDE).

[TDZn] in the …

Nitrate Reductase Activity, Nitrate Uptake And Iodine Speciation In The Marine Environment, Chin-Chang Hung

OES Theses and Dissertations

The present method for the determination of new production (NP) by measuring the uptake of added ¹⁵NO₃^– suffers from a number of limitations. In an attempt to improve this situation, this research examined the possibility of estimating ¹⁵NO₃– uptake by measuring the activity of nitrate reductase (NRA). In addition, because it has long been suspected that the biological reduction of IO₃^– to I^– may be mediated by nitrate reductase (NR), this research investigated the ability of NR to catalyze the reduction of iodate to iodide.

An improved method for the determination …

A Comparison Of Cognitive Development Between Whites And African Americans Based On William Perry's Scheme Of Intellectual And Ethical Development, Joan Johnson

Theses and Dissertations in Urban Services - Urban Education

This study compared cognitive complexity between student groups based on cultural background and academic class utilizing William Perry's (1970) cognitive theory of intellectual and ethical development. In addition, the study examined the influence of gender and socioeconomic status (SES) on cognitive development. The goal was to ascertain whether Perry's theory, developed from his research on a relatively homogeneous college student population without consideration of the impact of a culturally diverse environment, would be valid for culturally diverse students.

The research design employed to investigate cognitive development used a cross-sectional sample of entering freshmen and graduating seniors attending a predominantly White, …

Tissue-Specific Expression And Steroid Hormone Regulation Of Human Gonadotropin -Releasing Hormone (Hgnrh) Gene In Placental Cells (Jeg -3 Cells), Zhengguang Chen

Theses and Dissertations in Biomedical Sciences

Using JEG-3 cells as an in vitro model, I investigated the mechanisms behind the tissue-specific expression and steroid hormone regulation of the hGnRH gene in the human placenta. The hGnRH upstream promoter was found to be functionally active in JEG-3 cells. The DNA sequence responsible for functioning of the upstream promoter in JEG-3 cells is narrowed to a region between –1048 bp and –730 bp. This DNA fragment contains four elements, which can bind with nuclear extract from JEG-3 cells (but not from GT1-7 cells).

Estradiol (E2) represses the hGnRH upstream promoter activity in JEG-3 cells. This inhibition is receptor-mediated, …

Encystment, Excystment And Photosynthetic Activity In The Temporary Cysts Of Amphidinium Carterae, Steven R. Kibler

OES Theses and Dissertations

Although the formation of temporary cysts has been documented in several papers, the physiology of these stages has remained obscure. Research dealing with dinoflagellate resting stages has primarily targeted sexual cysts. Accordingly, formation, germination and photosynthetic activity in the temporary cysts of Amphidinium carterae have been investigated in the present study. The effect of light intensity upon cyst germination was tested by incubating temporary cysts at three different light intensities. In order to assess the potential for photosynthesis in cysts, cellular chlorophyll-a concentrations and cellular fluorescence were quantified during encystment. Photosynthetic carbon uptake of H¹⁴CO₃^- was …