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Articles 1081 - 1110 of 1876
Full-Text Articles in Physical Sciences and Mathematics
Variational Inverse Methods For Transport Problems, Zhaoqing Yang
Variational Inverse Methods For Transport Problems, Zhaoqing Yang
Dissertations, Theses, and Masters Projects
Variational inverse data assimilation schemes are developed for three types of parameter identification problems in transport models: (1) the tracer inverse for the Lagrangian mean transport velocity in a long-term advection-diffusion transport model; (2) determination of inflow salinity open boundary condition in an intra-tidal salinity transport model; and (3) determination of settling velocity and resuspension rate for a cohesive sediment transport model. The gradient of the cost function with respect to the control variables is obtained by the adjoint model. A series of twin experiments are conducted to test the inverse models for the three types of problems. Results show …
The Role Of Epibenthic Predators In Structuring Marine Soft-Bottom Communities Along An Estuarine Gradient, Rochelle D. Seitz
The Role Of Epibenthic Predators In Structuring Marine Soft-Bottom Communities Along An Estuarine Gradient, Rochelle D. Seitz
Dissertations, Theses, and Masters Projects
A unifying theory of community regulation in soft-bottom systems remains elusive, despite extensive field studies on factors controlling community structure. Here, I have (1) reviewed models of community regulation, (2) examined the role of predation in controlling benthic diversity along a salinity gradient, (3) examined effects of predation upon an abundant bivalve, Macoma balthica, and (4) revised a model of community regulation in an estuarine soft-bottom system. The Menge and Sutherland (MS) "consumer stress model" posits that consumers feed ineffectively in harsh environments, and the importance of physical disturbance, competition and predation varies with recruitment, environmental conditions, and trophic position. …
Integrative Analysis Of Ecosystem Processes In The Littoral Zone Of Lower Chesapeake Bay: A Modeling Study Of The Goodwin Islands National Estuarine Research Reserve, Christopher P. Buzzelli
Integrative Analysis Of Ecosystem Processes In The Littoral Zone Of Lower Chesapeake Bay: A Modeling Study Of The Goodwin Islands National Estuarine Research Reserve, Christopher P. Buzzelli
Dissertations, Theses, and Masters Projects
Approximately 40% of the bottom of Chesapeake Bay is less than 2.0 m in depth and many of these broad shoal environments are bordered by wetlands. The vegetated and nonvegetated subtidal and intertidal environment is a dynamic mosaic of highly productive estuarine habitats linked by the exchange of waterborne materials. This study developed simulation models of primary production and material exchange for four littoral zone habitats of the Goodwin Islands National Estuarine Research Reserve (NERR) in lower Chesapeake Bay. Field studies were conducted to determine the sediment biogeochemical and biomass characteristics of sandy shoal, seagrass, silt-mud, and marsh habitats. Ecological …
Expression Of The Xenobiotic Transporter P-Glycoprotein In The Mummichog (Fundulus Heteroclitus), Peter S. Cooper
Expression Of The Xenobiotic Transporter P-Glycoprotein In The Mummichog (Fundulus Heteroclitus), Peter S. Cooper
Dissertations, Theses, and Masters Projects
The mammalian mdr1 P-glycoprotein (Pgp) has been implicated in xenobiotic resistance of drug-resistant cell lines and tumors, and may function in excretion or exclusion of toxic xenobiotics at several sites within the body. Pgp gene family members are expressed in excretory epithelia of several aquatic taxa and may contribute to the survival of pollution-tolerant aquatic animals in contaminated environments. For this reason the expression of Pgp family members was investigated in the livers and liver tumors of creosote-resistant mummichog (Fundulus heteroclitus) inhabiting a creosote-contaminated site (Atlantic Wood) in the Elizabeth River, Virginia. Expression of members of the Pgp gene family …
Potential For Population Regulation Of The Zebra Mussel, Dreissena Polymorpha, In The Hudson River, Larry C. Boles
Potential For Population Regulation Of The Zebra Mussel, Dreissena Polymorpha, In The Hudson River, Larry C. Boles
Dissertations, Theses, and Masters Projects
No abstract provided.
Age, Growth, And Reproductive Biology Of Blackcheek Tonguefish, Symphurus Plagiusa (Cynoglossidae: Pleuronectiformes), In Chesapeake Bay, Virginia, Mark Richard Terwilliger
Age, Growth, And Reproductive Biology Of Blackcheek Tonguefish, Symphurus Plagiusa (Cynoglossidae: Pleuronectiformes), In Chesapeake Bay, Virginia, Mark Richard Terwilliger
Dissertations, Theses, and Masters Projects
No abstract provided.
Relative Risk Assessment For Cape Hatteras National Seashore, John Cary Buie
Relative Risk Assessment For Cape Hatteras National Seashore, John Cary Buie
Dissertations, Theses, and Masters Projects
No abstract provided.
Field And Laboratory Evidence Of Pheromone Mediated Mating Behavior In The Blue Crab, Callinectes Sapidus, Donald S. Gibbs
Field And Laboratory Evidence Of Pheromone Mediated Mating Behavior In The Blue Crab, Callinectes Sapidus, Donald S. Gibbs
Dissertations, Theses, and Masters Projects
No abstract provided.
The Strong Force: Two Calculations Of Strong Interaction Phenomena, Richard L. Kahler
The Strong Force: Two Calculations Of Strong Interaction Phenomena, Richard L. Kahler
Dissertations, Theses, and Masters Projects
Because the theory of strong interactions is mathematically intractable, it is necessary to make approximations which preserve phenomenological features of the theory in order to get answers to practical questions. This thesis explores two such techniques: (1) the chiral bag model is used to investigate the nucleon-nucleon potential and (2) perturbative QCD is used to investigate the pion form factor. An extensive introduction is presented to make the thesis more understandable to a wider audience of people otherwise unfamiliar with particle physics.
Analysis Of The Electronic Kinetic Energy In Xenon Difluoride, Michael Fiore Amendola
Analysis Of The Electronic Kinetic Energy In Xenon Difluoride, Michael Fiore Amendola
Dissertations, Theses, and Masters Projects
No abstract provided.
The Preparation, Structure And Reactivity Of [([Eta]6-Arene)Mn(Co)3]+And [([Eta]5-Cydlohexadienyl Enone)Mn(Co)3] Complexes, John Derek Jackson
The Preparation, Structure And Reactivity Of [([Eta]6-Arene)Mn(Co)3]+And [([Eta]5-Cydlohexadienyl Enone)Mn(Co)3] Complexes, John Derek Jackson
Dissertations, Theses, and Masters Projects
No abstract provided.
Structured Eigenvectors, Interlacing, And Matrix Completions, Brenda K. Kroschel
Structured Eigenvectors, Interlacing, And Matrix Completions, Brenda K. Kroschel
Dissertations, Theses, and Masters Projects
This dissertation presents results from three areas of applicable matrix analysis: structured eigenvectors, interlacing, and matrix completion problems. Although these are distinct topics, the structured eigenvector results provide connections.;It is a straightforward matrix calculation that if {dollar}\lambda{dollar} is an eigenvalue of A, x an associated structured eigenvector and {dollar}\alpha{dollar} the set of positions in which x has nonzero entries, then {dollar}\lambda{dollar} is also an eigenvalue of the submatrix of A that lies in the rows and columns indexed by {dollar}\alpha{dollar}. We present a converse to this statement and apply the results to interlacing and to matrix completion problems. Several corollaries …
The Projector Basis Method For Electronic Band Structure Calculations, Christopher Haas
The Projector Basis Method For Electronic Band Structure Calculations, Christopher Haas
Dissertations, Theses, and Masters Projects
Over the last several decades, two methods have emerged as the standard tools for the calculation of electronic band structures. These methods, the Car-Parinello plane wave method and the linear augmented plane wave method (LAPW), each have strengths and weaknesses in different regimes of physical problems. The Car-Parinello algorithm is ideal for calculations with soft pseudopotentials and large numbers of atoms. The LAPW method, on the other hand, easily handles all-electron and hard-core pseudopotential calculations with a small number of atoms. The projector basis method, presented here, is a hybrid mixed basis method which allows the calculation of moderately large …
Effects Of Periodic Environmental Hypoxia On Predator Utilization Of Macrobenthic Infauna, Janet A. Nestlerode
Effects Of Periodic Environmental Hypoxia On Predator Utilization Of Macrobenthic Infauna, Janet A. Nestlerode
Dissertations, Theses, and Masters Projects
Hypoxia and anoxia have significant deleterious ecological effects on living resources throughout many estuarine and marine ecosystems worldwide. Brief periods of low oxygen facilitate transfer of benthic production to higher trophic levels as many benthic infaunal species have shallower sediment depth distributions during hypoxic events. A baited time-lapse camera equipped with a water quality datalogger was used to document in situ exploitation of oxygen-stressed benthic invertebrate prey organisms by mobile fish and crustacean predators during alternating normoxia-hypoxia cycles in the York River. Based on photographic and diver observations, this hypoxiainduced benthic-pelagic transfer of production is more likely to occur when …
Habitat Complexity As A Determinant Of Juvenile Blue Crab Survival, Jessica L. Schulman
Habitat Complexity As A Determinant Of Juvenile Blue Crab Survival, Jessica L. Schulman
Dissertations, Theses, and Masters Projects
No abstract provided.
Autoecology Of Paraprionospio Pinnata (Polychaeta: Spionide) Along An Estuarine Gradient, Elizabeth K. Hinchey
Autoecology Of Paraprionospio Pinnata (Polychaeta: Spionide) Along An Estuarine Gradient, Elizabeth K. Hinchey
Dissertations, Theses, and Masters Projects
No abstract provided.
An Analysis Of The Effects Of Sea Level Rise On The Salt Marshes Of Cape Hatteras National Seashore, North Carolina, Christopher Robert Perle
An Analysis Of The Effects Of Sea Level Rise On The Salt Marshes Of Cape Hatteras National Seashore, North Carolina, Christopher Robert Perle
Dissertations, Theses, and Masters Projects
No abstract provided.
A Comparison Of Natural And Laboratory Diets For The Culture Of Marine Invertebrate Larvae American Oyster, Crassostrea Virginica, Queen Conch, Strombus Gigas, And Milk Conch, Strombus Costatus, Sandra Dawn Brooke
Dissertations, Theses, and Masters Projects
No abstract provided.
Effects Of Electron Irradiation And Percent Composition On The Glass Transition Temperature And Damping Of Boron-Epoxy Composites, Ian Ivan Nieves
Effects Of Electron Irradiation And Percent Composition On The Glass Transition Temperature And Damping Of Boron-Epoxy Composites, Ian Ivan Nieves
Dissertations, Theses, and Masters Projects
No abstract provided.
Water Quality Modeling As An Inverse Problem, Jian Shen
Water Quality Modeling As An Inverse Problem, Jian Shen
Dissertations, Theses, and Masters Projects
An inverse mathematical estuarine eutrophication model has been developed. The model provides a framework to estimate unknown parameters by assimilation of the concentration data of those state variables. The inverse model developed is a laterally integrated, two-dimensional, real-time model which consists of a hydrodynamic model, an eutrophication model and an adjoint model. The hydrodynamic model provides the dynamic fields for both the eutrophication model and the adjoint model. The eutrophication model simulates eight water quality state variables which are phytoplankton, organic nitrogen, ammonium nitrogen, nitrite-nitrate nitrogen, organic phosphorus, inorganic (ortho) phosphorus, carbonaceous biochemical oxygen demand and dissolved oxygen. The adjoint …
Perkinsus Marinus Extracellular Proteases: Modulation Of Production By Environmental Factors And Effects On The Host Defense Parameters Of The Eastern Oyster Crassostrea Virginica, Kathleen A. Garreis
Perkinsus Marinus Extracellular Proteases: Modulation Of Production By Environmental Factors And Effects On The Host Defense Parameters Of The Eastern Oyster Crassostrea Virginica, Kathleen A. Garreis
Dissertations, Theses, and Masters Projects
No abstract provided.
A Bipartite Model Of Distributed Systems: Possibilities And Implications, Anna Karin Brunstrom
A Bipartite Model Of Distributed Systems: Possibilities And Implications, Anna Karin Brunstrom
Dissertations, Theses, and Masters Projects
Networking software is generally designed in layers. User processes exist at the application layer. They rely on the transport layer to provide them with end-to-end communication. In the distributed systems literature communication is traditionally viewed from the application layer. at the application layer we have no knowledge of the whereabouts of a message once a send operation is completed. at the transport layer, on the other hand, information about the delivery of a message to the transport layer in the receiving host is often available. We believe transport layer information can be better utilized in distributed systems design. This dissertation …
Transport In Chaotic Systems, Xian Zhu Tang
Transport In Chaotic Systems, Xian Zhu Tang
Dissertations, Theses, and Masters Projects
This dissertation addresses the general problem of transport in chaotic systems. Typical fluid problem of the kind is the advection and diffusion of a passive scalar. The magnetic field evolution in a chaotic conducting media is an example of the chaotic transport of a vector field. In kinetic theory, the collisional relaxation of a distribution function in phase space is also an advection-diffusion problem, but in a higher dimensional space.;In a chaotic flow neighboring points tend to separate exponentially in time, exp({dollar}\omega t{dollar}) with {dollar}\omega{dollar} the Liapunov exponent. The characteristic parameter for the transport of a scalar in a chaotic …
Selective Inversion In Solid-State Deuteron Nmr, Marco J. Brown
Selective Inversion In Solid-State Deuteron Nmr, Marco J. Brown
Dissertations, Theses, and Masters Projects
Deuteron NMR selective inversion (SI) is developed to study slow molecular motions in solids. Theoretical and practical aspects of selective inversion of spin-1 nuclei in solids are presented. Differences between powdered solids and liquids are considered. Double sideband modulated (DSBM) shaped pulses are shown to improve the performance of SI pulses. DSBM and DANTE selective pulses are compared for off-resonance SI applications. Common spin-{dollar}{lcub}1{rcub}\over{lcub}2{rcub}{dollar} shaped pulses are tested for suitability to solid state deuteron NMR. Simple, short pulses are shown to be most effective due to fast spin-spin relaxation and large underlying homogeneous linewidths in solids.;The power and utility of …
The Role Of Microbial Food Webs In Benthic-Pelagic Coupling In Freshwater And Marine Ecosystems, Adele J. Pile
The Role Of Microbial Food Webs In Benthic-Pelagic Coupling In Freshwater And Marine Ecosystems, Adele J. Pile
Dissertations, Theses, and Masters Projects
A majority of carbon in freshwater and marine ecosystems is in the form of ultraplankton, heterotrophic and autotrophic plankton &<&5 &\mu&m including heterotrophic bacteria, Prochlorococcus, cyanobacteria, and autotrophic eucaryotes. However, ultraplankton and subsequently microbial food webs have yet to be incorporated into models of benthic-pelagic coupling despite the preponderance of macroinvertebrates with the capacity to feed on ultraplankton. I have examined the role of microbial food webs in benthic-pelagic coupling in three ecosystems: Lake Baikal, Siberia, Russia; Gulf of Maine, Northwest Atlantic Ocean; and Conch Reef, Florida Keys, USA. Using sponges as a model organism and in situ measurements, I have quantified (1) suspension feeding on ultraplankton and (2) release of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) resulting in direct evidence that benthic macroinvertebrates do occupy the level of primary consumer within the microbial food web. Dual-beam flow cytometry was employed to quantified sponge suspension feeding on five types of ultraplankton: heterotrophic bacteria, Synechococcus-type cyanobacteria, autotrophic picoplankton &<&3 &\mu&m, autotrophic eucaryotes 3-10 &\mu&m, and in marine ecosystems Prochlorococcus. Grazing by the freshwater sponges Baikalospongia intermedia and B. bacilliferia and the boreal marine sponge, Mycale lingua, was unselective for all types of ultraplankton with efficiencies ranging from 63-99%. This is the first time that grazing on Synechococcus-type cyanobacteria and Prochlorococcus by macroinvertebrates has been quantified in freshwater and marine ecosystems. Conversely, the coral reef sponges Ircinia felix and I. strobilina release significant amounts of DIN and DIP as a result of grazing on procaryotic plankton. Using a general model for organism-mediated fluxes, it is conservatively estimated that through active suspension feeding sponges in Lake Baikal retain 1.97 g C day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& and M. lingua retains 29 mg C day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& while at Conch Reef sponges released 204 &\mu&mol DIN day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& and 48 &\mu&mol DIP day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}&. A majority of the carbon retained at all three locations was from procaryotic cell types suggesting that ultraplankton are an important overlooked component of benthic-pelagic coupling.
The Effects Of A Regulatory Gear Restriction On The Harvest Of The Recruiting Year Class In The Offshore Sea Scallop, Placopecten Magellanicus, Fishery, Jeffrey C. Brust
The Effects Of A Regulatory Gear Restriction On The Harvest Of The Recruiting Year Class In The Offshore Sea Scallop, Placopecten Magellanicus, Fishery, Jeffrey C. Brust
Dissertations, Theses, and Masters Projects
No abstract provided.
Contributions To The Life History Of Juvenile Blueback Herring (Alosa Aestivalis): Phototactic Behavior And Population Dynamics, Douglas A. Dixon
Contributions To The Life History Of Juvenile Blueback Herring (Alosa Aestivalis): Phototactic Behavior And Population Dynamics, Douglas A. Dixon
Dissertations, Theses, and Masters Projects
This research investigated the relationship between juvenile abundance indexes (JAIs) for anadromous blueback herring (Alosa aestivalis) and abiotic factors (river flow and temperature) during the spawning and nursery period in the tidal freshwater areas of James, Pamunkey, Mattaponi, and Rappahannock Rivers in Virginia. Accomplishing this objective required the evaluation of the JAI methodology, specifically the effect of phototactic behavior on diel changes in the surface availability to the pushnet sampling gear, and obtaining population dynamics information (hatch dates, growth, natural mortality) during early life history from otolith microstructure of samples collected in 1991 and 1992. Mean catch-per-unit effort (CPUE) at …
Temporal Variablity Of The Pycnocline In The Mid-Chesapeake Bay, Linda Jane Frizzell-Makowski
Temporal Variablity Of The Pycnocline In The Mid-Chesapeake Bay, Linda Jane Frizzell-Makowski
Dissertations, Theses, and Masters Projects
Mixing and dispersion in a partially mixed estuary are driven by, among other processes, the gravitational circulation, wind-events and tides. These processes are important in the vertical and horizontal distribution and exchange of salinity, oxygen, nutrients, and organisms. The objective of this research was to examine the temporal variability of the pycnocline in the mid-Chesapeake Bay in response to forcing at subtidal and higher frequencies as observed in the spring of 1993. The largest change in the pycnocline was associated with meteorological forcing. Up-Bay wind stress and subsequent abatement of the wind stress produced a 5 meter displacement of the …
Gaseous Flux And Distribution Of Polycyclic Aromatic Hydrocarbons Across The Air-Water Interface Of Southern Chesapeake Bay, Kurt E. Gustafson
Gaseous Flux And Distribution Of Polycyclic Aromatic Hydrocarbons Across The Air-Water Interface Of Southern Chesapeake Bay, Kurt E. Gustafson
Dissertations, Theses, and Masters Projects
Gaseous fluxes of polycyclic aromatic hydrocarbons (PAHs) across the air-water interface of Southern Chesapeake Bay were calculated for the period January 1994 through May 1995 using a modified two-film model. Additionally, the distributions of PAHs between the vapor and aerosol phase in the atmosphere, and between the freely dissolved and suspended particulate phase in the water column were investigated. Net instantaneous gaseous fluxes of PAHs were determined to vary in direction and magnitude both spatially and temporally across the air-water interface of Southern Chesapeake Bay at four sites ranging from remote to urban and highly industrialized. The magnitude of gas …
Modeling Storm-Induced Sediment Transport On The Inner Shelf: Effects Of Bed Microstratigraphy, Baeck Oon Kim
Modeling Storm-Induced Sediment Transport On The Inner Shelf: Effects Of Bed Microstratigraphy, Baeck Oon Kim
Dissertations, Theses, and Masters Projects
Sediment transport during a storm event on the inner continental shelf was detailed through the development of models based on field experiments conducted at Duck, North Carolina in October 1994. A vertical one-dimensional model (1DV model) was developed by coupling the Grant and Madsen (1986) model with bed stratigraphy to consider real seabeds. Sediment was divided into seven size classes and fractional transport was estimated. Mixing depth and total depth from a simplified sediment conservation equation provided the basis for changing bottom sediment, sediment availability for transport, and armoring processes. These processes involve a feedback between hydrodynamics and bed stratigraphy. …