Physical Sciences and Mathematics Commons^™

A Study Of The Guiding Center Approximation, Qun Yao

Dissertations, Theses, and Masters Projects

A Hamiltonian treatment for the motion of a charged particle in a toroidal magnetic field is given. Assuming the plasma equilibrium, Boozer coordinates are used. The Hamiltonian of the exact trajectory is given in the guiding center coordinates. The higher order corrections to the standard drift Hamiltonian are derived. It is shown that the exact Hamiltonian depends on both the field strength and the shape of the magnetic surfaces (the metric of Boozer coordinates) while the standard drift Hamiltonian depends only on the field strength. The first order correction to the standard drift Hamiltonian, in gyroradius to system size, depends …

Beyond The Standard Model: New Scalars And New Leptons, Yao Yuan

Dissertations, Theses, and Masters Projects

Physics that might lie beyond the standard model is discussed, with special emphasis on two possible extensions of the standard model: multi-Higgs extension, and the fourth generation leptons.;In multi-Higgs-boson extensions of the standard model, tree-level flavor-changing neutral currents exist naturally. It is often believed that the presence of the tree-level FCNC in this model is fatal, unless a discrete symmetry is added, since it requires the exchanged scalar to be extremely heavy. This follows, however, from the assumption that the flavor-changing coupling is quite large. Using a more natural value for the flavor-changing coupling, much smaller bounds were obtained. Unlike …

Hydrodynamical Modeling Of A Multiple‐Inlet Estuary/Barrier System: Insight Into Tidal Inlet Formation And Stability, Carl T. Friedrichs, David G. Aubrey, Graham S. Giese, Paul E. Speer

VIMS Books and Book Chapters

Two specific questions are addressed concerning the role of tidal hydrodynamics in determining the long‐term morphologic evolution of the Nauset Beach‐Monomoy Island barrier system and the Chatham Harbor‐Pleasant Bay tidal estuary, Massachusetts: (1) why do the barrier and estuary exhibit a long‐term (∼150 yr) cycle of new inlet formation, and (2) once a new inlet forms, why is the resulting multiple inlet system unstable? To address these questions, a branched 1‐d numerical model is used to recreate the basic flow patterns in the tidal estuary at ten‐year intervals during the last half century and also to recreate flow conditions shortly …

Nutrient Limitation In The Chesapeake Bay : Nutrient Bioassays In The Virginia Bay System: Final Report, Leonard W. Haas, Richard L. Wetzel

Reports

Nutrient enrichment bioassays were conducted on water samples collected from six stations in the Virginia portion of the Chesapeake Bay system on a monthly basis over a year. Two stations were located in the tidal freshwater portions of the Rappahannock and James Rivers, at the mouths of these rivers and in the mainstem of the Bay. The purpose of the experiments was to determine the spatial and temporal pattern of nutrient limitation of phytoplankton growth.

Distribution Of Aeschynomene Virginica In The Scotland Landing Region Of The Mattaponi River, Virginia, James E. Perry

Reports

The distribution and population densities of a federal listed threatened plant species, the northern joint vetch (Aeschynomene virginica), was determined and mapped in the vicinity of a proposed Mattaponi River water withdrawal structure. The proposed study was intended to determine the size, limits, and density of extant populations of the northern joint vetch in the project area, and to investigate the possible impacts the project may have on the extant populations. Where necessary, . possible mitigation procedures are discussed.

Sediment Processes Monitoring Data Report For Calendar Year 1989, Cheol Mo, Bruce Neilson, Richard L. Wetzel

Reports

Pairs of particle interceptor traps were deployed at three depths - 3, 6, and 9 meters with deployment intervals typically lasting about two weeks. At times of deployment and retrieval, profiles of water temperature, salinity and dissolved oxygen content were made and water samples were collected at trap depths. Bottom sediments also were collected and a sub-sample of the surficial sediments taken. Water samples, bottom sediments, and the materials collected in the traps were returned to the Virginia Institute of Marine Sciences for analysis. The data collected during both 1988 and 1989 are presented in the appendices. Both 1988 and …

Effects Of Nutrient Enrichment On Natural And Transplanted Salt Marshes In Virginia : A Literature Review With Management Recommendations - Final Report, R. D. Rheinhardt, J. D. Perry

Reports

This study was initlated in response to a request by SEAS to review their technical recommendations concerning the fertilization of tidal salt marshes and determine whether those recommendations are sound in light of current scientific knowledge. The intention of this analysis was to determine whether benefits are derived from applying nutrients to marshes, and if so, whether those benefits outweigh the costs associated with the potential pollution of Chesapeake Bay's tidal waters.

To provide insight into the effects of adding fertilizers to salt marshes, the scientific literature was examined from four perspectives:

1) the dynamics of ·nutrient cycling in natural …

A Feasibility Study Of Detached Breakwater Designs Using A Combined Refraction/Diffraction Wave Model, Virginia Beach, Virginia, John D. Boon

Reports

The Virginia Institute of Marine Science, together with management agencies in the commonwealth, has a continuing interest in the matter of beach preserva~ion along Virginia's Atlantic coastline. This interest is particularly acute along the coastline fronting the resort city of Virginia Beach, Virginia, where some 225,000 cubic meters of artificial sand nourishment are required each year to maintain recreational beaches. Wright et al.(1987), in their detailed report on beach dynamics from Cape Henry to False Cape, have stated that offshore loss of sand is a major cause of shoreline erosion in the Virginia Beach sector. Because of the narrowness and …

Marine Aquaculture In The Commonwealth Of Virginia, Michael Oesterling

Reports

No abstract provided.

Wetlands Guidelines, Department Of Wetlands Ecology, Virginia Institute Of Marine Science, Habitat Management Division, Virginia Marine Resources Commission

Reports

No abstract provided.

End-To-End Analysis Of Hexagonal Vs Rectangular Sampling In Digital Imaging Systems, John Clifton Burton Ii

Dissertations, Theses, and Masters Projects

The purpose of this study was to compare two common methods for image sampling in digital image processing: hexagonal sampling and rectangular sampling. The two methods differ primarily in the arrangement of the sample points on the image focal plane. In order to quantitatively compare the two sampling methods, a mathematical model of an idealized digital imaging system was used to develop a set of mean-squared-error fidelity loss metrics. The noiseless continuous/discrete/continuous end-to-end digital imaging system model consisted of four independent components: an input scene, an image formation point spread function, a sampling function, and a reconstruction function. The metrics …

A Study Of Molecular Order And Motion In Nematic Liquid Crystal Mixtures, Jon Michael Goetz

Dissertations, Theses, and Masters Projects

Materials which flow like fluids, but possess anisotropic properties like molecular crystals, are called 'liquid crystals'. Studies of liquid crystals contribute to our understanding of how molecular orientation influences macroscopic properties. This thesis presents experimental and theoretical investigations of molecular order and dynamics in nematic liquid crystal systems. First, deuterium nuclear magnetic resonance is used to determine the degree of orientational order of both components of a liquid crystal mixture simultaneously. The temperature dependence of the four order parameters is interpreted using a newly developed mean field theory of nematic binary mixtures composed of biaxial molecules. Next, mean field theory …

Photoabsorption Spectra Of Hydrogen In Magnetic Fields, John A. Shaw

Dissertations, Theses, and Masters Projects

Measurements of the absorption spectrum of atomic H in strong magnetic fields have been analyzed. The measurements, performed by the Bielefeld, Germany experimental group, investigated the photoabsorption to levels near the ionization threshold in magnetic fields ranging from 2.7 to 6 Tesla. Taking advantage of a classical scaling law, the photon energy and the magnetic field strength were varied simultaneously in the experiment and the absorption rate vs. B{dollar}\sp{lcub}-1/3{rcub}{dollar} at fixed scaled-energy, {dollar}\varepsilon{dollar} = E/(B/B{dollar}\sb{lcub}\rm o{rcub})\sp{lcub}2/3{rcub}{dollar} was measured. The absorption rate was observed to exhibit sinusoidal fluctuations which we correlate with closed classical orbit of the electron. A Fourier transformation …

Flush Communication Channels: Effective Implementation And Verification, Tracy Kay Camp

Dissertations, Theses, and Masters Projects

Flush communication channels, or F-channels, generalize more conventional asynchronous communication paradigms. A distributed system which uses an F-channel allows a programmer to define the delivery order of each message in relation to other messages transmitted on the channel. Unreliable datagrams and FIFO (first-in-first-out) communication channels have strictly defined delivery semantics. No restrictions are allowed on message delivery order with unreliable datagrams--message delivery is completely unordered. FIFO channels, on the other hand, insist messages are delivered in the order of their transmission. Flush channels can provide either of these delivery order semantics; in addition, F-channels allow the user to define the …

Responses Of Cytochrome P450ia In Freshwater Fish Exposed To Pulp Mill Effluents In Experimental Stream Channels, Laura Anne Bankey

Dissertations, Theses, and Masters Projects

No abstract provided.

Participation Of Alkenylboronate Esters In [2+2] Enone-Olefin Photocycloadditions, William Charles Lappenbusch

Dissertations, Theses, and Masters Projects

No abstract provided.

Synthesis Of Boron-Substituted Isoxazolidines By Reaction Of Nitrones With Alkenyl Boronate Esters, Kevin P. Gwaltney

Dissertations, Theses, and Masters Projects

No abstract provided.

The Synthesis Of N,N-Disubstituted Hydroxylamines Via Rearrangement Reactions Between Trialkylboranes And Nitrones, Stacie M. Cook

Dissertations, Theses, and Masters Projects

No abstract provided.

Interspecific And Intraspecific Variability In Placoid Scale Morphology In Relation To Body Form Variability In Squaliformes, Christopher R. Tabit

Dissertations, Theses, and Masters Projects

An ontogenetic series of nine species; Centrophorus granulosus, Centroscymnus coelolepis, Dalatias licha, Deania calcea, Echinorhinus cookei, Isistius brasiliensis, Oxynotus centrina and Squalus acanthias were studied to determine swimming capabilities, boundary-layer flow conditions and placoid scale functional morphologies. Body morphometric variables included the girth and the distance from snout to the orbitals, origin of the median and paired fins, and the caudal peduncle, body and fin surface area, fin aspect ratios and caudal fin angles. Placoid scales were sampled from sixteen regions across the body. Morphometric variables included the number of scales per area of integument, scale crown width, length and …