Physical Sciences and Mathematics Commons^™

Fortnightly Variability In The Transverse Dynamics Of A Coastal Plain Estuary, Arnoldo Valle-Levinson, Kuo-Chuin Wong, Kamazima M. M. Lwiza

CCPO Publications

Current velocity and water density profiles were obtained along two crossestuary transects with the purpose of determining the fortnightly variability of the transverse dynamics in a partially stratified coastal plain estuary. The profiles were measured with a towed acoustic Doppler current profiler and a conductivity-temperaturedepth recorder in the James River estuary, Virginia. The cross-estuary transects were sampled during the spring tides of October 26-27, 1996, and the ensuing neap tides of November 2-3, 1996. The transects were-4 km long, featured a bathymetry that consisted of a channel flanked by shoals, and were sampled repeatedly during two semidiurnal tidal cycles (25 …

Soapbox: The Academic Research Fleet: An Exciting Time For Renewal, Larry Atkinson

CCPO Publications

(First Paragraph) Academic research ships in the United States are the envy of many scientists around the world. A great strength of our system is the diversity of ships and operators: users have a choice, the system can change. A weakness of the system is that very diversity: sometimes it is hard for us to act together. Nevertheless, we now must act together. The vitality of the academic fleet in the coming decades is at stake. The reason is simply because many of our ships, especially in the intermediate size range, will soon reach the end of their useful life.

Measurements Of Salinity In The Coastal Ocean: A Review Of Requirements And Technologies, Catherine Woody, Eddie Shih, Jerry Miller, Thomas Royer, Larry P. Atkinson, Richard S. Moody

CCPO Publications

Salinity, a measure of the dissolved salts in seawater, is a fundamental property of seawater and basic to understanding biological and physical processes in coastal waters. In the open ocean long term salinity measurements are identified as necessary to understand global climate studies, hydrological cycle, and circulation. In the coastal oceans, information on salinity is critical to understanding biological effects on ecosystem function such as disease, nursery grounds, or harmful algal blooms and on physical processes such as freshwater runoff estuarine mixing, and coastal currents. While the importance of salinity is recognized, little attention has been given to making routine …

An Examination Of A Multidimensional Model Of Customer Satisfaction With Internet Purchasing, Kathleen Vanscoyoc

Theses and Dissertations in Business Administration

The World Wide Web and Internet have transformed the competitive business environment and altered the customer-firm relationship by creating a new retailing format and service enterprise. It is rapidly growing as a competitive distribution medium in which customer satisfaction will be a major success factor in the development and maintenance of this new retailing format. Despite its growing importance as a new shopping medium, little empirical research has been conducted that examines the relationship between Internet shopping, customer satisfaction, company image, and future online purchasing. Research is needed to develop theoretical models that will systematically explain and predict behavior related …

Estuarine Relationships Between Zooplankton Community Structure And Trophic Gradients, Gyung Soo Park, Harold G. Marshall

Biological Sciences Faculty Publications

Zooplankton and water quality parameters were investigated at eight mesohaline stations in the lower Chesapeake Bay and Elizabeth River from January through December 1994 to identify the changes of zooplankton community structure with increased eutrophication. The total micro- and mesozooplankton biomass decreased with the increase of eutrophication. However, the relative proportion of microzooplankton increased with increased eutrophication. Within highly eutrophied waters, the small oligotrichs (m) and rotifers dominated the total zooplankton biomass (as carbon). However, tintinnids, copepod nauplii and mesozooplankton significantly decreased with the increase of eutrophication. These patterns were consistent throughout the seasons and had significant relationships statistically. These …

High Energy Effective Action From Scattering Of Shock Waves In Qcd, Ian Balitsky

Physics Faculty Publications

The author demonstrates that the amplitude for high-energy scattering can be factorized as a convolution of the contributions due to fast and slow fields. The fast and slow fields interact by means of Wilson-line operators -- infinite gauge factors ordered along the straight line. The resulting factorization formula gives a starting point for a new approach to the effective action for high-energy scattering in QCD.

Convergence Of Lateral Flow Along A Coastal Plain Estuary, Arnoldo Valle-Levinson, Chunyan Li, Kuo-Chuin Wong, Kamazima M. M. Lwiza

CCPO Publications

A set of velocity profiles obtained in the James River estuary with an acoustic Doppler current profiler was used in combination with the results of an analytic tidal model to depict the appearance of surface lateral flow convergences (δv/δy) during both flood and ebb stages of the tidal cycle. The bathymetry of the estuary was characterized by a main channel and a secondary channel separated by relatively narrow shoals. Lateral surface flow convergences appeared over the edges of the channels and were produced by the phase lag of the flow in the channel relative to the …

Series Operation Of Direct Current Xenon Chloride Excimer Sources, Ahmed El-Habachi, Wenhui Shi, Mohamed Moselhy, Robert H. Stark, Karl H. Schoenbach

Bioelectrics Publications

Stable, direct current microhollow cathode discharges in mixtures of hydrochloric acid, hydrogen, xenon, and neon have been generated in a pressure range of 200–1150 Torr. The cathode hole diameter was 250 μm. Sustaining voltages range from 180 to 250 V at current levels of up to 5 mA. The discharges are strong sources of xenon chloride excimer emission at a wavelength of 308 nm. Internal efficiencies of approximately 3% have been reached at a pressure of 1050 Torr. The spectral radiant power at this pressure was measured as 5 mW/nm at 308 nm for a 3 mA discharge. By using …

Microhollow Cathode Discharge Excimer Lamps, Karl H. Schoenbach, Ahmed El-Habachi, Mohamed M. Moselhy, Wenhui Shi, Robert H. Stark

Bioelectrics Publications

Microhollow cathode discharges are high-pressure, nonequilibrium gas discharges between a hollow cathode and a planar or hollow anode with electrode dimensions in the 100 μm range. The large concentration of high-energy electrons, in combination with the high-gas density favors excimer formation. Excimer emission was observed in xenon and argon, at wavelengths of 128 and 172 nm, respectively, and in argon fluoride and xenon chloride, at 193 and 308 nm. The radiant emittance of the excimer radiation was found to increase monotonically with pressure. However, due to the decrease in source size with pressure, the efficiency (ratio of excimer radiant power …

The Effects Of Light And Nitrate Levels On The Relationship Between Nitrate Reductase Activity And (No3-)-N-15 Uptake: Field Observations In The East China Sea, Chin-Chang Hung, George T. F. Wong, Kom-Kee Liu, Fuh-Kwo Shiah, Gwo-Ching Gong

OES Faculty Publications

Nitrate reductase activity (NRA) and ¹⁵NO₃- uptake (NU) were determined in the East China Sea and the adjoining Kuroshio in May 1996, at six stations covering a range of hydrographic conditions: the nutrient-rich and fresher plume of Changjiang Diluted Water along the Chinese coast, the nutrient-rich upwelling Kuroshio Subsurface Water at the shelf edge northeast of Taiwan, the oligotrophic Kuroshio Surface Water and the mixing zones among these water masses on the shelf. The values of NRA in the surface mixed layer ranged between 16 and 0.1 nM-N h^-1, whereas those of NU ranged between …

Intraspecific Variation In The Selenium Requirement Of Different Geographic Strains Of The Toxic Dinoflagellate Gymnodinium Catenatum, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff

OES Faculty Publications

The requirement for selenium (IV) was assessed in five strains of the toxic dinoflagellate Gymnodinium catenatum Graham, representing three populations from Tasmania (Australia), as well as one each from Japan and Spain. Strains were grown in nutrient-enriched sea water medium with 10^-9 M selenium added as selenite (H₂SeO₃), or with no added selenium, and monitored for growth and cell yield. Strains exhibited different selenium (Se) requirements, as evidenced by (i) a decrease in exponential growth rate (10-20%) and cell yield (up to 80%) (Japanese strain); (ii) a decrease in cell yield only (Tasmania Derwent Estuary …

Selection Of Curricular Topics Using Extensions Of Quality Function Deployment, Paul Kauffmann, Abel Fernandez, Charles Keating, Derya Jacobs, Resit Unal

Engineering Management & Systems Engineering Faculty Publications

Decision science can be an effective tool for enhancing organizational participation during strategic and complex decision making. This involvement develops a group consensus for relating organizational goals and the methods to achieve them. This paper describes an application of Quality Function Deployment (QFD) to define curricular topics that meet program objectives. Based on the ability of QFD to establish relationships, the model identifies the most important topics and quantifies their impact on meeting program goals. The model was developed to support restructuring of a Masters of Engineering Management degree program. The model supported decisions in selecting and prioritizing the required …

Iron And Manganese In The Ross Sea, Antarctica: Seasonal Iron Limitation In Antarctic Shelf Waters, Peter N. Sedwick, Giacomo R. Ditullio, Denis J. Mackey

OES Faculty Publications

Dissolved iron and manganese and total dissolvable iron were measured in water column samples from the Polynya Region of the southern Ross Sea in cruises in Nov.-Dec. 1994 (spring 1994) and Dec. 1995 to Jan. 1996 (summer 1995). Iron and manganese addition bottle incubation experiments were also performed on these cruises to assess the nutritional sufficiency of ambient iron and manganese concentrations for phytoplankton growth. Generally high dissolved iron concentrations (>0.5 nM) and relatively complex iron and manganese vertical profiles were obtained in spring 1994 vs. summer 1995. Dissolved iron concentrations in the upper water column averaged 1.0 nM …

The Linkage Between Upper Circumpolar Deep Water (Ucdw) And Phytoplankton Assemblages On The West Antarctic Peninsula Continental Shelf, Barbara B. Prézelin, Eileen E. Hofmann, Claudia Mengelt, John M. Klinck

OES Faculty Publications

Intrusion of Upper Circumpolar Deep Water (UCDW), which was derived from the Antarctic Circumpolar Current (ACC), onto the western Antarctic Peninsula (WAP) shelf region in January 1993 provided a reservoir of nutrient-rich, warmer water below 150 m that subsequently upwelled into the upper water column. Four sites, at which topographically-induced upwelling of UCDW occurred, were identified in a 50 km by 400 km band along the outer WAP continental shelf. One additional site at which wind-driven upwelling occurred was also identified. Diatom-dominated phytoplankton assemblages were always associated with a topographically-induced upwelling site. Such phytoplankton communities were not detected at any …

Biochemical Composition Of Particles And Dissolved Organic Matter Slong An Estuarine Gradient: Sources And Implications For Dom Reactivity, Antonio Mannino, H. Rodger Harvey

OES Faculty Publications

The chemical composition of high molecular weight dissolved organic matter (DOM) and particulate organic matter (POM) was examined along the salinity gradient of the Delaware Estuary. DOM was collected and fractionated by tangential-flow ultrafiltration into 1-30 kDa (HDOM; high molecular weight) and 30 kDa to 0.2 μm (VHDOM; very high molecular weight) and compared to particles collected in parallel. Polysaccharides comprised 12-43% of particulate organic carbon (POC), 30-56% of VHDOM carbon, and 7.5-19% of HDOM carbon. Hydrolyzable amino acids comprised 17-38% of POC, 5.4-12% of VHDOM carbon, and 1.5-4.2% of HDOM carbon. Only 7-43% of dissolved organic nitrogen in VHDOM …

The Ups Prototype: An Experimental End-User Service Across E-Print Archives, Herbert Van De Sompel, Thomas Krichel, Michael L. Nelson, Patrick Hochstenbach, Victor Lyapunov, Kurt Maly, Mohammad Zubair, Mohamed Kholief, Xiaoming Liu, Heath O'Connell

Computer Science Faculty Publications

A meeting was held in Santa Fe, New Mexico, October 21-22, 1999, to generate discussion and consensus about interoperability of publicly available scholarly information archives. The invitees represented several well known e-print and report archive initiatives, as well as organizations with interests in digital libraries and the transformation of scholarly communication. The central goal of the meeting was to agree on recommendations that would make the creation of end-user services -- such as scientific search engines and linking systems -- for data originating from distributed and dissimilar archives easier. The Universal Preprint Service (UPS) Prototype was developed in preparation for …

Upper Bounds To The Clique Width Of Graphs, Bruno Courcelle, Stephan Olariu

Computer Science Faculty Publications

Hierarchical decompositions of graphs are interesting for algorithmic purposes. Many NP complete problems have linear complexity on graphs with tree-decompositions of bounded width. We investigate alternate hierarchical decompositions that apply to wider classes of graphs and still enjoy good algorithmic properties. These decompositions are motivated and inspired by the study of vertex-replacement context-free graph grammars. The complexity measure of graphs associated with these decompositions is called clique width. In this paper we bound the clique width of a graph in terms of its tree width on the one hand, and of the clique width of its edge complement on …

On The Sources Of Weddell Gyre Antarctic Bottom Water, Michael P. Meredith, Ricardo A. Locarnini, Kim A. Van Scoy, Andrew J. Watson, Karen J. Heywood, Brian A. King

CCPO Publications

In March-April 1995, as part of the World Ocean Circulation Experiment section A23, we completed 49 hydrographic stations across the Weddell Gyre and southern Antarctic Circumpolar Current, from the Antarctic continental shelf (72.5°S, 16.5°W) to South Georgia (55°S, 34.5°W). Chlorofiuorocarbon (CFC11, CFC-12, and CFC-113) data collected at these stations reveal that distinct sources renew the Antarctic Bottom Water (defined as waters with potential temperatures less than 0°C) of the Weddell Gyre. Weddell Sea Bottom Water (defined as waters with potential temperatures less than- 0.7°C) formed in the western Weddell Sea has CFC concentrations about 5 to 6 times higher in …

Textured Mos 2 Thin Films Obtained On Tungsten: Electrical Properties Of The W/Mos 2 Contact, E. Gourmelon, J. C. Bernède, J. Pouzet, S. Marsillac

Electrical & Computer Engineering Faculty Publications

Textured films of molybdenum disulfide have been obtained by solid state reaction between the constituents in thin films form when a (200) oriented tungsten sheet is used as substrate. The crystallites have their c axis perpendicular to the plane of the substrate. The annealing conditions are T=1073K and t=30 min. The films are stoichoimetric and p type. Such highly textured films are achieved without foreign atom addition (Ni, Co...). It appears, as shown by x-ray photoelectron spectroscopy, that a thin WS₂ layer is present at the interface W/MoS₂. The crystallization process is discussed by a …

An Architectural Framework For Performance Analysis: Supporting The Design, Configuration, And Control Of Dis /Hla Simulations, David B. Cavitt

Computer Science Theses & Dissertations

Technology advances are providing greater capabilities for most distributed computing environments. However, the advances in capabilities are paralleled by progressively increasing amounts of system complexity. In many instances, this complexity can lead to a lack of understanding regarding bottlenecks in run-time performance of distributed applications. This is especially true in the domain of distributed simulations where a myriad of enabling technologies are used as building blocks to provide large-scale, geographically disperse, dynamic virtual worlds. Persons responsible for the design, configuration, and control of distributed simulations need to understand the impact of decisions made regarding the allocation and use of the …

Virtual Compton Scattering In The Nucleon Resonance Region, Luminita Anca Todor

Physics Theses & Dissertations

This thesis is a study of virtual Compton scattering reaction in which a virtual photon is elastically scattered off a proton γv p → γp. The p( e,e′p)γ reaction was measured in the nucleon resonance region for the first time in the experiment E93-050 in Hall A at Thomas Jefferson National Accelerator Facility. To lowest order in ^αQED, this reaction is a coherent superposition of radiation from the incident or scattered electron in elastic ep scattering (Bethe-Heitler) and exclusive production of a photon on the proton, by absorption of a virtual photon …

Experimental Investigation Of Long-Lived "Zeke" Rydberg States In Ultracold Argon, Gambhir Ranjit

Physics Theses & Dissertations

There is considerable interest in the dynamics of ultracold plasmas and ultracold Rydberg gases. Ultracold plasmas are typically formed by photo-excitation of ultracold atoms to an energy region near (both above and below) an ionization threshold. Excitation to bound, highly-excited Rydberg states can lead to formation of a plasma via several processes, including collisions between Rydberg atoms. Three-body recombination in an ultracold plasma can also result in the production of ultracold Rydberg atoms. Understanding the dynamics of ultracold Rydberg gases is therefore important for understanding the dynamics of ultracold plasmas. In this dissertation, we have investigated the formation and survival …

Multicast Services For Multimedia Collaborative Applications, Emad Eldin Mohamed Mohamed

Computer Science Theses & Dissertations

This work aims at providing multicast services for multimedia collaborative applications over large inter-networks such as the Internet. Multimedia collaborative applications are typically of small group size, slow group membership dynamics, and awareness of participants' identities and locations. Moreover, they usually consist of several components such as audio, video, shared whiteboard, and single user application sharing engines that collectively help make the collaboration session successful. Each of these components has its demands from the communication layer that may differ from one component to another. This dissertation identifies the overall characteristics of multimedia collaborative applications and their individual components. It also …

Extending Traditional Static Analysis Techniques To Support Development, Testing And Maintenance Of Component-Based Solutions, Robert David Cherinka

Computer Science Theses & Dissertations

Traditional static code analysis encompasses a mature set of techniques for helping understand and optimize programs, such as dead code elimination, program slicing, and partial evaluation (code specialization). It is well understood that compared to other program analysis techniques (e.g., dynamic analysis), static analysis techniques do a reasonable job for the cost associated with implementing them. Industry and government are moving away from more ‘traditional’ development approaches towards component-based approaches as ‘the norm.’ Component-based applications most often comprise a collection of distributed object-oriented components such as forms, code snippets, reports, modules, databases, objects, containers, and the like. These components are …

A Simplified Model Of Wound Healing - Ii: The Critical Size Defect In Two Dimensions, J. S. Arnold, John A. Adam

Mathematics & Statistics Faculty Publications

Recently, a one-dimensional model was developed which gives a reasonable explanation for the existence of a Critical Size Defect (CSD) in certain animals [1]. In this paper, we examine the more realistic two-dimensional model of a circular wound of uniform depth to see what modifications are to be found, as compared with the one-dimensional model, in studying the CSD phenomenon. It transpires that the range of CSD sizes for a reasonable estimate of parameter values is 1 mm-1 cm. More realistic estimates await the appropriate experimental data.

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.

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 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 …

Newton Parameter Update Algorithm For Recurrent Neural Networks Applied To Adaptive System Identification And Control, Donald Allen Gates

Electrical & Computer Engineering Theses & Dissertations

This paper shows that the combination of a second-order neural network parameter update algorithm and internal network feedback can be effectively used for adaptive, nonlinear, dynamical system identification and control. Adaptive neural identification and control algorithms are typically utilized for real-time applications where the rate of adaptation is often critical. A fast, adaptive network parameter update algorithm is presented.

Simulation results show that this algorithm is capable of quickly identifying and adapting to changes in system parameters, making it feasible to use for real-time control and fault accommodation applications.

A Family Of Hierarchical Encoding Techniques For Image And Video Communications, Samah A. Senbel

Computer Science Theses & Dissertations

As the demand for image and video transmission and interactive multimedia applications continues to grow, scalable image and video compression that has robust behavior over unreliable channels are of increasing interest. These desktop applications require scalability as a main feature due to its heterogeneous nature, since participants in an interactive multimedia application have different needs and processing power. Also, the encoding and decoding algorithm complexity must be low due to the practical considerations of low-cost low-power receiver terminals. This requires image and video encoding techniques that jointly considers compression, scalability, robustness, and simplicity.

In this dissertation, we present a family …