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Articles 1441 - 1470 of 1876
Full-Text Articles in Physical Sciences and Mathematics
The Cure Reaction Of An Aromatic Thermosetting Polyimide, Michael Edward Whitham
The Cure Reaction Of An Aromatic Thermosetting Polyimide, Michael Edward Whitham
Dissertations, Theses, and Masters Projects
No abstract provided.
Reproductive Ecology, Population Dynamics And Seasonal Movements Of The Hogchoker (Trinectes Maculatus), In The Elizabeth River, Virginia, Stephen M. Smith
Reproductive Ecology, Population Dynamics And Seasonal Movements Of The Hogchoker (Trinectes Maculatus), In The Elizabeth River, Virginia, Stephen M. Smith
Dissertations, Theses, and Masters Projects
No abstract provided.
Estuary Water Movement, John Dickerson Mitchell
Estuary Water Movement, John Dickerson Mitchell
Dissertations, Theses, and Masters Projects
No abstract provided.
Formation Of Longitudinal Dispersion Coefficient In Partially Mixed Estuaries And Application In A One-Dimensional Real-Time Model, Anne Catherine Wilber
Formation Of Longitudinal Dispersion Coefficient In Partially Mixed Estuaries And Application In A One-Dimensional Real-Time Model, Anne Catherine Wilber
Dissertations, Theses, and Masters Projects
No abstract provided.
Effect Of Strain On Muon Diffusion And Trapping In Metal By Bassam Salim Hitti, Bassam Salim Hitti
Effect Of Strain On Muon Diffusion And Trapping In Metal By Bassam Salim Hitti, Bassam Salim Hitti
Dissertations, Theses, and Masters Projects
Positive muons implanted in metal distort the surrounding lattice; therefore, in addition to electronic interactions, the elastic forces have to be considered in determining the muon state. to explore the elastic and electronic diffusion and trapping mechanisms, we studied AlCu(,420ppm), AlMg(,1000ppm) and AlAg(,1000ppm) alloys. These alloys were selected for the different effects on the host lattice of these impurities; Cu contracts the Al lattice, Mg expands it and Ag has nearly no effect. On the other hand Cu and Ag are monovalent while Mg is divalent. For AlCu between 5K and 14K the temperature exponent (beta) of the two-state-model trapping …
The Sedimentary Processes And Geomorphic History Of Wreck Shoal, An Oyster Reef Of The James River, Virginia, Joseph T. Dealteris
The Sedimentary Processes And Geomorphic History Of Wreck Shoal, An Oyster Reef Of The James River, Virginia, Joseph T. Dealteris
Dissertations, Theses, and Masters Projects
Wreck Shoal is a subtidal oyster reef area located in the James River, Virginia. Two significantly different types of oyster reefs are found in adjacent areas on Wreck Shoal. Hard-rock reefs are characterized by a relatively thick oyster shell layer, higher densities of live oysters, a coarser interstitial sediment, and a negligible sediment cover. In contrast, mud-shell reefs are characterized by a very thin osyter shell layer, considerably lower densities of live oysters, a finer interstitial sediment, and a 1-2 cm layer of very fine sediments covering the reef. The contemporary sedimentation processes operating on the hard-rock and mud-shell oyster …
Lateral Variability In A Coastal Plain Estuary (Fronts, Density, Lateral Circulation), Linda Mary Huzzey
Lateral Variability In A Coastal Plain Estuary (Fronts, Density, Lateral Circulation), Linda Mary Huzzey
Dissertations, Theses, and Masters Projects
A series of observations of the density distribution across the York River estuary documents distinct lateral differences in density and degree of vertical mixing. The magnitude of the density differences varies throughout the tidal cycle; maximum lateral gradients occur at times of minimum current. When the density distribution is sufficiently inhomogeneous, longitudinal estuarine fronts are generated. These fronts are axially aligned, up to several miles in length, and are apparent for less than 2 hours at any given location. Although the density difference across the frontal boundary is often small, horizontal pressure gradients acting over a broad frontal region generate …
Geological History Of A Holocene Drainage System: Hack Creek, Virginia, Robert A. Gammisch
Geological History Of A Holocene Drainage System: Hack Creek, Virginia, Robert A. Gammisch
Dissertations, Theses, and Masters Projects
No abstract provided.
Parasite Community Structure In Summer Flounder: Paralichthys Dentatus (Linnaeus), Of The Chesapeake Bay, Maura E. Jansen
Parasite Community Structure In Summer Flounder: Paralichthys Dentatus (Linnaeus), Of The Chesapeake Bay, Maura E. Jansen
Dissertations, Theses, and Masters Projects
No abstract provided.
A Morphological Study Of The Pharyngeal Sac Of Two Species Of Stromateid Fishes: Perrilus Triacanthus And P Paru, Thomas R. Sminkey
A Morphological Study Of The Pharyngeal Sac Of Two Species Of Stromateid Fishes: Perrilus Triacanthus And P Paru, Thomas R. Sminkey
Dissertations, Theses, and Masters Projects
No abstract provided.
Recommendations For Amelioration Of Legal And Environmental Concerns About Mining Of Deepsea Deposits Of Polymetallic Sulfides, Michael P. De Luca
Recommendations For Amelioration Of Legal And Environmental Concerns About Mining Of Deepsea Deposits Of Polymetallic Sulfides, Michael P. De Luca
Dissertations, Theses, and Masters Projects
No abstract provided.
The Role Of Picoplankton In Phytoplankton Dynamics Of A Temperate Coastal Plain Estuary, Robert Triau Ray
The Role Of Picoplankton In Phytoplankton Dynamics Of A Temperate Coastal Plain Estuary, Robert Triau Ray
Dissertations, Theses, and Masters Projects
No abstract provided.
The Role Of Science And Scientists In Marine Environmental Policy And Management, Teny Topalian
The Role Of Science And Scientists In Marine Environmental Policy And Management, Teny Topalian
Dissertations, Theses, and Masters Projects
The role of science and scientists in environmental policy and management is and has been an important, complex, and controversial subject for many years. The objective of this study is to determine how science and scientists interact in environmental policy formation and management and how science is or could be used in the development of policy which can ultimately be used as a basis for effective resource management plans. In the very broad sense this study attempts to evaluate the general hypothesis that "Scientists do not play a role in promoting or encouraging science as a means of changing attitudes …
Carbon Alkylation Of 2-Phenylthio-1,3-Cyclopentanediones, Karol Renee Parham
Carbon Alkylation Of 2-Phenylthio-1,3-Cyclopentanediones, Karol Renee Parham
Dissertations, Theses, and Masters Projects
No abstract provided.
Secondary Isotope Effects Of Nucleophilic Vinylic Substitution, Paul Frederick Drees
Secondary Isotope Effects Of Nucleophilic Vinylic Substitution, Paul Frederick Drees
Dissertations, Theses, and Masters Projects
No abstract provided.
Low-Energy Collisions Of Alkali-Metal Anions, David M. Scott
Low-Energy Collisions Of Alkali-Metal Anions, David M. Scott
Dissertations, Theses, and Masters Projects
Measurements of the total cross section for electron detachment, (sigma)(,e)(E), are presented for low-energy (E(,1ab) < 300 eV) collisions of Na('-), K('-), and Cs('-) with atomic and molecular targets. For many of the atomic (rare-gas) targets, the energy dependence of (sigma)(,e)(E) is striking: virtually no detachment is observed until relatively high collision energies (50 eV in the center-of-mass frame) are reached, in contradistinction to what has been observed for similar collisions involving H('-). The thresholds for alkali anion detachment are approximately equal to the thresholds for excitation observed in collisions of neutral alkali atoms with these same targets. The similarity between the dynamics of the neutral system and that of the negative ion system, together with the observation (at greater energies) of detachment accompanied by excitation of the alkali parent, suggests that electron detachment may be mediated by a two-electron process in some cases. A simple curve-crossing mechanism adequately reproduces the observed (sigma)(,e)(E) for several of these rare-gas targets.;Measurements of both (sigma)(,e)(E) and the cross section for charge transfer (sigma)(,i)(E) have also been completed for H(,2), D(,2), N(,2), O(,2), CO, CO(,2), SO(,2), N(,2)O, CH(,4), and SF(,6) targets. Electron detachment is the dominant process for all of these targets except O(,2), SO(,2), and SF(,6), with thresholds on the order of a few eV. Structure in (sigma)(,e)(E) for the CO(,2) target has been attributed to charge transfer to a metastable state of CO(,2)('-)(('2)A(,1)). Similarly, in the case of N(,2)O, both (sigma)(,e)(E) and (sigma)(,i)(E) exhibit behavior which suggests that a temporary negative ion state is formed during the collision. In the case of the O(,2), SO(,2), and SF(,6) targets, charge transfer is observed to have particularly large cross sections (>100 (ANGSTROM)('2)) at low collision energies.
Determination Of The Vacancy Migration Energy Of Aluminum By Nmr, Terry William Gullion
Determination Of The Vacancy Migration Energy Of Aluminum By Nmr, Terry William Gullion
Dissertations, Theses, and Masters Projects
Monovacancy diffusion is a thermally activated process characterized by an activation energy E(,d). The diffusion of atoms requires the formation and migration of vacancies. The concentration of vacancies n/N is given by n/N (DBLTURN) exp(-E(,f)/kT). It can be shown that the activation energy E(,d) is the sum of the energy to form a vacancy E(,f) and the energy required for an atomic jump E(,m): E(,d) = E(,f) + E(,m). Furthermore, the atomic jump rate (omega)(,j) can be shown to be thermally activated and given by (omega)(,j) (DBLTURN) (nu)(,o)(n/N)exp(-E(,m)/kT) ((nu)(,o) is the attempt frequency).;NMR offers many techniques to measure the activation …
Stratigraphy And Heavy Mineral Analysis In The Lower Chesapeake Bay, Virginia, C. R. Berquist Jr
Stratigraphy And Heavy Mineral Analysis In The Lower Chesapeake Bay, Virginia, C. R. Berquist Jr
Dissertations, Theses, and Masters Projects
Spatially continuous patterns of heavy mineral distributions in three dimensions characterized the sandy Holocene sediments of the lower Chesapeake Bay. A pilot study using Q-mode factor analysis on data from an earlier study determined mineral assemblages and mineral composition gradients; the gradients suggested that surficial sediments entered the Bay from offshore and from older deposits to the west. Principal components analysis of the same data indicated that the abundances of only 5 out of 21 minerals were adequate to explain most of the mineral variance. The mineralogy of 87 samples from cores defining two geologic cross-sections was added to the …
The Late Quaternary Evolution Of A Twin Barrier-Island Complex, Cape Charles, Virginia (Stratigraphy, Sedimentology, Wisconsinan, Sea-Level Highstand), Kenneth. Finkelstein
The Late Quaternary Evolution Of A Twin Barrier-Island Complex, Cape Charles, Virginia (Stratigraphy, Sedimentology, Wisconsinan, Sea-Level Highstand), Kenneth. Finkelstein
Dissertations, Theses, and Masters Projects
A total of 68 vibra-cores and 14-box cores in conjunction with high-resolution seismic records are used to describe the late Quaternary development of a twin-barrier island complex. Based on the stratigraphy, radiocarbon dates, and microfossils, a transgressive outer Holocene and inner Pleistocene barrier island complex are recognized. The two subaerial sub-parallel barriers are a result of separate marine transgressions that occurred before and after late Wisconsin glaciation. Pollen assemblages and ten radiocarbon dates from the lagoonal sediments below the older island concur on a date of approximately 30,000 years B.P., hence a probable mid-Wisconsinan age for the overriding barrier island. …
Peroxo Complexes Of Molybdenum (Vi) And Vanadium (V) With Imidazole And Histidine, Jennifer Lisa Gundersen
Peroxo Complexes Of Molybdenum (Vi) And Vanadium (V) With Imidazole And Histidine, Jennifer Lisa Gundersen
Dissertations, Theses, and Masters Projects
No abstract provided.
Contribution To The Hydrobiology Of The York River: Predicting Surface Mixed Layer Depth (Destratification, Tidal, Semilunar, Virginia), Donald Max Hayward
Contribution To The Hydrobiology Of The York River: Predicting Surface Mixed Layer Depth (Destratification, Tidal, Semilunar, Virginia), Donald Max Hayward
Dissertations, Theses, and Masters Projects
Destratification in the York River, USA, during high spring tides is the result of the interruption of normal two-layer estuarine flow by advection of relatively fresh water in to the River mouth from the Chesapeake Bay. This is due to the presence of a longitudinal salinity gradient in the Bay and a difference of tidal current phase between the River and the Bay. Similar behavior is seen in other subestuaries of the Chesapeake Bay and may be common in subestuary-estuary interactions. Correlation and regression analysis are used to examine relationships between stratification variation in the lower York River and a …
Seasonal Immune Response In Juvenile Summer Flounder Paralichthys Dentatus To The Hemoflagellate Trypanoplasma Bullocki In The Lower Chesapeake Bay, Linda Jane Frizzell
Seasonal Immune Response In Juvenile Summer Flounder Paralichthys Dentatus To The Hemoflagellate Trypanoplasma Bullocki In The Lower Chesapeake Bay, Linda Jane Frizzell
Dissertations, Theses, and Masters Projects
No abstract provided.
Abundance, Seasonality And Community Structure Of Fishes On The Mid-Atlantic Bight Continental Shelf, James Alden Colvocoresses
Abundance, Seasonality And Community Structure Of Fishes On The Mid-Atlantic Bight Continental Shelf, James Alden Colvocoresses
Dissertations, Theses, and Masters Projects
Cluster analyses of seasonal (spring and fall) National Marine Fisheries Service Groundfish Survey bottom trawl catches on the Middle Atlantic Bight continental shelf revealed consistent species associations and faunal zones over a nine year period during. Boundaries between faunal zones tended to follow isotherms on the inner portions of the shelf and isobaths along the outer shelf. During the late winter/early spring, four faunal zones were identified: a northern inner and middle shelf zone extending from Cape Cod southward to about Delaware Bay, a northern middle and outer shelf zone offshore of the first zone, a southern middle and outer …
A Systematic Revision Of The South American Freshwater Stingrays (Chondrichthyes: Potamotrygonidae) (Batoidei, Myliobatiformes, Phylogeny, Biogeography), Ricardo De Souza Rosa
A Systematic Revision Of The South American Freshwater Stingrays (Chondrichthyes: Potamotrygonidae) (Batoidei, Myliobatiformes, Phylogeny, Biogeography), Ricardo De Souza Rosa
Dissertations, Theses, and Masters Projects
Three genera are recognized in the family Potamotrygonidae of neotropical freshwater stingrays: Potamotrygon, Paratrygon, and Plesiotrygon, the latter being described as a new genus. Potamotrygon is polytypic, and both Paratrygon and Plesiotrygon are monotypic, as far as known. The family name Potamotrygonidae has priority over Paratrygonidae Gill. Nineteen previously described species of Potamotrygonidae are recognized: Paratrygon aiereba, Potamotrygon brachyura, P. castexi, P. constellata, P. dumerilii, P. falkneri, P. henlei, P. histrix, P. humerosa, P. leopoldi, P. magdalenae, P. motoro, P. ocellata, P. orbignyi, P. schroederi, P. schuemacheri, P. scobina, P. signata, and P. yepezi. One additional specific name is established …
Preparation Of Methyl-Substituted Dienols By The Hydromethylation Of Ene-Yn-Ol Substrates With Titanium Tetrachloride And Trimethylaluminum, Terry James Zitzelberger
Preparation Of Methyl-Substituted Dienols By The Hydromethylation Of Ene-Yn-Ol Substrates With Titanium Tetrachloride And Trimethylaluminum, Terry James Zitzelberger
Dissertations, Theses, and Masters Projects
No abstract provided.
Energy Utilization Model For Silver Perch, Bairdiella Chrysoura (Bioenergetics, Sciaenidae, Growth, Eelgrass, Chesapeake Bay), Hugh Anthony Brooks
Energy Utilization Model For Silver Perch, Bairdiella Chrysoura (Bioenergetics, Sciaenidae, Growth, Eelgrass, Chesapeake Bay), Hugh Anthony Brooks
Dissertations, Theses, and Masters Projects
An energetics model was constructed as an alternative method to length frequency analysis for the estimation of growth for juvenile silver perch, Bairdiella chrysoura. The model approach was adopted since estimation of juvenile estuarine fish growth by only collecting length or weight frequency data is difficult due to the large bodies of water and variety of microhabitats that must be regularly sampled over short time intervals. Field and laboratory data was included in analysis of model compartments for growth, metabolism, food intake and energy loss in waste products. Food habit studies indicated that silver perch is a planktivore that feeds …
Turbulent Disruptions From The Strauss Equations, Jill Potkalitsky Dahlburg
Turbulent Disruptions From The Strauss Equations, Jill Potkalitsky Dahlburg
Dissertations, Theses, and Masters Projects
The subject of this thesis is an analysis of results from pseudospectral simulation of the Strauss equations of reduced three-dimensional magnetohydrodynamics. We have solved these equations in a rigid cylinder of square cross section, a cylinder with perfectly conducting side walls, and periodic ends. We assume that the uniform-density magnetofluid which fills the cylinder is resistive, but inviscid. Situations which we are considering are in several essential ways similar to a tokamak-like plasma; an external magnetic field is imposed, and the plasma carries a net current which produces a poloidal magnetic field of sufficient strength to induce current disruptions. These …
Stability And Transition Of The Driven Magnetohydrodynamic Sheet Pinch, Russell B. Dahlburg
Stability And Transition Of The Driven Magnetohydrodynamic Sheet Pinch, Russell B. Dahlburg
Dissertations, Theses, and Masters Projects
The stability and transition properties of a bounded, current carrying magnetofluid are explored, using the hydrodynamic theory developed for plane shear flows as a guide. A driven magnetohydrodynamic sheet pinch equilibrium is employed. A sixth order, complex eigenvalue equation which governs the normal modes of small oscillations is derived, and solved numerically by the Chebyshev tau method. Eigenfunctions are shown, as well as the curve of neutral stability. The locus of critical Lundquist numbers has the form of a hyperbola. The nonlinear stability of a primary disturbance of the system is considered. For regions in parameter space close to criticality, …
Community Structure Of Demersal Fishes On The Inshore U.S. Atlantic Continental Shelf: Cape Ann, Ma. To Cape Fear, N.C. (United States, Cluster Analysis, Massachusetts, North Carolina), William C. Phoel
Dissertations, Theses, and Masters Projects
Numerical classification analyses (clustering) of spring, summer and fall National Marine Fisheries Service bottom trawl catches on the inshore continental shelf between Cape Ann, Ma. and Cape Fear, N.C., showed consistent species associations and faunal zones over a three year period. Analysis of a data set created by combining all nine survey cruises also produced consistent species associations, however sites clustered by seasons as well as by geographic area. The three faunal provinces of the U.S. east coast (Gulf of Maine, Middle Atlantic Bight and South Atlantic Bight) were represented in the study area, as were the seasonal faunal barriers …
Thermodynamics And Kinetics Of Aqueous Solution Of Liquid Hydrocarbon Mixtures (Solutes, Petroleum), David Robert. Burris
Thermodynamics And Kinetics Of Aqueous Solution Of Liquid Hydrocarbon Mixtures (Solutes, Petroleum), David Robert. Burris
Dissertations, Theses, and Masters Projects
Two-phase systems of a liquid hydrocarbon mixture, containing medium molecular weight (C(,7)-C(,12)) aromatic and aliphatic hydrocarbons, and water were examined in both equilibrium and kinetic experiments. Knowledge of the aqueous solution behavior of liquid hydrocarbon mixtures is of importance in determining the fate of hydrocarbon components in such systems of an environmental or geologic nature. Solute concentrations were determined by solvent extraction followed by gas chromatography. The equilibrium solute concentration for a given component i (C(,i)) is related to the pure compound solubility (C(,i)('o)), mole fraction of component i in the hydrocarbon phase (x(,i(h))) and the activity coefficient of component …