Physical Sciences and Mathematics Commons^™

Variate Generation For Nonhomogeneous Poisson Processes With Time Dependent Covariates, Li-Hsing Shih, Lawrence Leemis

Arts & Sciences Articles

Algorithms are developed for generating a sequence of event times from a nonhomogeneous Poisson process that is influenced by the values of covariates that vary with time. Closed form expressions for random variate generation are shown for several baseline intensity and link functions. Two specific models linking the baseline process to the general model are considered: the accelerated time model and the proportional intensity model. In the accelerated time model, the cumulative intensity function of a nonhomogeneous Poisson process under covariate effects is [formula], where z is a covariate vector, ⋀0(t) is the baseline cumulative intensity function and …

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 …

Sediment Characterization Of Southern New England Systems, The Hudson And Delaware Estuaries, Virginian Province, Maynard M. Nichols, Caroline Brouwer-Riel, Et Al

Reports

The estuarine systems selected are from the NOAA National Estuarine Inventory in the EMAP Virginian Province (Figure 1). The principal spatial unit of each system is the estuarine drainage area (EDA) defined in the NEI data atlas (U.S. NOAA, 1985). The sediment and contaminant distributions embrace the estuarine bottom area, i.e. from the head of tides to the mouth where the estuary meets the ocean, bay or sound as determined by physiographic features (U.S. NOAA, 1985). Data coverage embraces whole estuaries and farfield distributions. Chart scales are smaller than 1:80,000 and the minimum mappable unit is 1.0 km2 or larger …

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 …

Identification Of Historic Locations Of Aeschynomene Virginica Within The Tidal Freshwater Zone Of The Pamunkey River, Virginia : Final Report, James E. Perry

Reports

The historical distribution and population densities of a federal listed threatened plant species, the northern joint vetch (Aeschynomene virginica), was determined and mapped in the tidal regions of the Pamunkey River, Virginia, where a potential water withdrawal structure is being evaluated.

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.

Investigation Of Potential Distribution Of Aeschynomene Virginica In The Tidal Wetlands Of Ware Creek, Virginia : Final Report, James E. Perry

Reports

The distribution and population densities of a federal listed threatened plant species, the northern joint vetch (Aeschynomene virginica), was determined in the vicinity of the proposed Ware Creek Reservoir site in James City County and New Kent County, Virginia. 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.

Criteria For Predicting Zebra Mussel Invasions In The Mid-Atlantic Region, Patrick Baker, Shirley Baker, Roger Mann

Reports

What is the probability that zebra mussels will invade specific bodies of water within a given state? If they do invade, will they become economic and ecological pests as they have in portions of the Great Lakes? These and similar questions are addressed, with the expectation that management strategies can be developed to delay, mitigate, or possibly even prevent zebra mussel invasions, in some areas.

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 …

The Structure Of The Holocephalan Head And The Relationships Of The Chondrichthyes, Eileen D. Grogan

Dissertations, Theses, and Masters Projects

The interrelationship of the chondrichthyan subclasses is evaluated based on divergence in the nature of the suspensorium, the preorbital cranial anatomy, the distribution of major venous sinuses and localization of hematopoietic tissue. The anatomy of representative extant taxa was examined by radiography and/or dissection. Fossil selachians, paraselachians, and holocephalans of the Bear Gulch of Montana, U.S.A. (Mississippian, Namurian E2B) were studied for evidence of vascular pigmentation, suspensorium, and cranial, branchial, and pectoral anatomy. These studies validate the suspensorial condition of autodiastyly and suggest autodiastyly is a fundamental condition involved in the basic radiation of Chondrichthyes. The plesiomorphous condition of all …

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 …

Marine Aquaculture In The Commonwealth Of Virginia, Michael Oesterling

Reports

No abstract provided.

A Measurement Of The Branching Ratio Of Long-Lived Neutral Kaon Going To Positive Muon Negative Muon, Michael Thomas Witkowski

Dissertations, Theses, and Masters Projects

The branching ratio $B(K\sbsp{L}{0} \to \mu\sp+\mu\sp-)$ has been measured using data obtained during running periods in 1988, 1989 and 1990. The data obtained in the 1990 running period are the latest and last from BNL experiment E791. During the three running periods, 87, 274 and 346 respective candidate events were observed, forming an overall sample of 707 $\mu\sp+\mu\sp-$ events. This number represents the largest sample to-date of $K\sbsp{L}{0} \to \mu\sp+\mu\sp-$ events. The result for the branching fraction using the total data set is $B(K\sbsp{L}{0} \to \mu\sp+\mu\sp-)$ = (6.86 $\pm$ 0.37) $\times$ 10$\sp{-9}$. This result is very near the unitarity bound …

The Dynamics Of An Oligohaline, Macrofaunal, Fouling Community, Michelle Lynne Thompson Neubauer

Dissertations, Theses, and Masters Projects

No abstract provided.

Boundary Layer Structure In Homogeneous Tidal Flows: A Theoretical And Numerical Study, Jian Shen

Dissertations, Theses, and Masters Projects

No abstract provided.

In Situ Dielectric Monitoring And Kinetic Analysis Of Phase Separation, Theodore Joon Kim

Dissertations, Theses, and Masters Projects

No abstract provided.

Dielectric Relaxation In Controlled Pore Glass, David Brian Faddis

Dissertations, Theses, and Masters Projects

No abstract provided.

Cross-Linking Additives As Smoke Suppressants For Poly(Vinyl Chloride), Steven Alfred Terranova

Dissertations, Theses, and Masters Projects

No abstract provided.

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.

Growth Response Of Eelgrass (Zostera Marina L) To Root-Rhizome And Whole Plant Exposure To Atrazine, Arthur C. Schwarzschild

Dissertations, Theses, and Masters Projects

No abstract provided.

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 …

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 …

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 …

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 …

Sediment Characterization Of North Atlantic Systems, New England, Maynard M. Nichols, Caroline Brouwer-Riel

Reports

The estuarine systems selected are from the NOAA National Estuarine Inventory in the North Atlantic region (Figure 1). The principal spatial unit of each system is the estuarine drainage area (EDA) defined in the NEI data atlas (U.S. NOAA, 1985). The sediment distributions embrace the estuarine bottom area, i.e. from the head of tides to the mouth where the estuary meets the ocean, bay or sound as determined by physiographic features (U.S. NOAA, 1985). Data coverage embraces whole estuaries and far-field distributions. Chart scales are smaller than 1:80,000 and chart units larger than 0.06 square kilometer.

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.

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

Reports

No abstract provided.

The Metompkin Islands: A Case Study In Ownership And Management Of A Dynamic Barrier System, David Harold Niebuhr

Dissertations, Theses, and Masters Projects

No abstract provided.

Gill Surface Area In Relation To Growth Rates And Maximum Size In Sharks, David Noboru Hata

Dissertations, Theses, and Masters Projects

The most commonly used equation to describe size at age in fishes is the von Bertalanffy equation (VBE), which assumes that growth rate is based on the balance of anabolic and catabolic processes: dW/dt = HW&\sp{lcub}\rm d{rcub}&-kW&\sp{lcub}\rm m{rcub}&. Anabolism, HW&\sp{lcub}\rm d{rcub}&, is considered proportional to gill surface area (A = rW&\sp{lcub}\rm d{rcub}&), and a "generalized" VBE (GVBE) has been previously determined: L&\sb{lcub}\rm t{rcub}& = L&\sb\infty&(1-exp(-KD(t-t&\sb{lcub}\rm O{rcub})))\sp{lcub}\rm 1/D{rcub}&, where D = b-bd and b is from W = qL&\sp{lcub}\rm b{rcub}&. The growth rate may be rewritten in terms of gill area, A, as dW/dt = kA/(A&\sb\infty&/W&\sb\infty\sp{lcub}\rm m{rcub}&)-kW&\sp{lcub}\rm m{rcub}&. Gill areas were …