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Articles 1 - 30 of 39
Full-Text Articles in Physical Sciences and Mathematics
Gender Roles And Home Computer Use By Children, Trelles Whitfield D'Alemberte
Gender Roles And Home Computer Use By Children, Trelles Whitfield D'Alemberte
Dissertations, Theses, and Masters Projects
No abstract provided.
A Superconducting Compact Hydrogen Maser Resonator, David B. Opie
A Superconducting Compact Hydrogen Maser Resonator, David B. Opie
Dissertations, Theses, and Masters Projects
The discovery of high critical temperature superconductors (HTSC) has raised the temperature at which the greatly reduced surface resistance, characteristic of superconducting materials, may be exploited. For microwave frequencies below 100 GHz, the surface resistance, R{dollar}\sb{lcub}s{rcub}{dollar}, at liquid nitrogen temperatures (77K) of the new HTSC materials is found to be better than copper measured at the same temperature and frequency. Consequently, the miniaturization of passive microwave components will be among the first applications of these new materials. This dissertation details the development, testing and evaluation of a superconducting compact hydrogen maser resonator made from electrophoretic Y{dollar}\sb1Ba\sb2Cu\sb3{dollar}O{dollar}\sb{lcub}7-\delta{rcub}{dollar} (YBCO). Such a resonator …
Factors Affecting Survival Of Early Life Stages Of Striped Bass, John Clarke Mcgovern
Factors Affecting Survival Of Early Life Stages Of Striped Bass, John Clarke Mcgovern
Dissertations, Theses, and Masters Projects
In 1988 laboratory presentations, bay anchovy, and Atlantic menhaden tested positive as potential predators. Consumption of striped bass larvae by bay anchovy increased at higher prey densities to a maximum of 42 larvae/h at prey densities of 1,650/m&\sp3&. Examination of 229 stomachs of bay anchovy collected during peak spawning in 1988 and 1989 provided direct evidence of predation on striped bass eggs and larvae. The relationship between patterns of survival inferred from the back-calculation of juvenile hatchdates were compared with data sets describing predator and prey fields, egg production, food abundance, and changing environmental conditions during the 1988 and 1989 …
Vegetation Ecology Of Tidal Freshwater Swamps Of The Lower Chesapeake Bay, United States Of America, Richard D. Rheinhardt
Vegetation Ecology Of Tidal Freshwater Swamps Of The Lower Chesapeake Bay, United States Of America, Richard D. Rheinhardt
Dissertations, Theses, and Masters Projects
Woody and herbaceous vegetation were sampled in 23 tidal swamps along a tidal freshwater tributary of lower Chesapeake Bay. Four vegetative categories were ordinated with Detrended Correspondence Analysis (DECORANA). Species distribution patterns of each strata were compared with respect to edaphic factors, a wetness index, and mean water table depth. Woody species are restricted to hummocks (topographic highs). Hummocks drain as quickly as the tide drops and so are partially inundated for only short periods each day. Although low in canopy diversity, tidal swamps are floristically rich in herbaceous and woody understory species, ranking them among the most speciose in …
The Investigation Of Organoboron Compounds And Organoboron/Nitrone Reactions, David Kent Hood
The Investigation Of Organoboron Compounds And Organoboron/Nitrone Reactions, David Kent Hood
Dissertations, Theses, and Masters Projects
No abstract provided.
The Effects Of The Exposure Of Atomic Oxygen On Polymeric Material: I Siloxane Modified Epoxy Resins Ii Polyetherimide Films With Additives, Eugene Canlas Aquino
The Effects Of The Exposure Of Atomic Oxygen On Polymeric Material: I Siloxane Modified Epoxy Resins Ii Polyetherimide Films With Additives, Eugene Canlas Aquino
Dissertations, Theses, and Masters Projects
No abstract provided.
The Hydraulic Sorting Of Light And Heavy Minerals, Heavy-Mineral Concentrations, And Grain Size, Sara M. Dydak
The Hydraulic Sorting Of Light And Heavy Minerals, Heavy-Mineral Concentrations, And Grain Size, Sara M. Dydak
Dissertations, Theses, and Masters Projects
No abstract provided.
The Effect Of Low Salinity On Established Infections Of Perkinsus Marinus (Apicomplexa: Perkinsasida) In The Eastern Oyster, Crassostrea Virginica, Lisa M. Ragone
Dissertations, Theses, and Masters Projects
No abstract provided.
Estimating Abundance And Annual Production Of Striped Bass Eggs With In Situ Silhouette Photography, John Douglas Field
Estimating Abundance And Annual Production Of Striped Bass Eggs With In Situ Silhouette Photography, John Douglas Field
Dissertations, Theses, and Masters Projects
No abstract provided.
Temporal And Spatial Response Of Two Tidal Marsh Species To Salinity Changes In The Pamunkey River, Laura R. Mitchell
Temporal And Spatial Response Of Two Tidal Marsh Species To Salinity Changes In The Pamunkey River, Laura R. Mitchell
Dissertations, Theses, and Masters Projects
No abstract provided.
The Relationship Of Habitat And Spatial Scale Upon The Developmental State And Settlement Of Blue Crab Postlarvae In Chesapeake Bay, Karen S. Metcalf
The Relationship Of Habitat And Spatial Scale Upon The Developmental State And Settlement Of Blue Crab Postlarvae In Chesapeake Bay, Karen S. Metcalf
Dissertations, Theses, and Masters Projects
No abstract provided.
Low-Energy Collisions Of Negative Ions With Atomic Hydrogen, Michael A. Huels
Low-Energy Collisions Of Negative Ions With Atomic Hydrogen, Michael A. Huels
Dissertations, Theses, and Masters Projects
Total cross sections for charge transfer and electron detachment for collisions of a variety of negative ions with atomic hydrogen have been separately determined for laboratory collision energies ranging from about 5 eV to 500 eV. The experiments are performed with an apparatus that utilizes a crossed-beam configuration with a radio-frequency discharge as the source of atomic hydrogen.;For collisions of H{dollar}\sp-{dollar}(D{dollar}\sp-{dollar}) with H the charge transfer cross sections increase monotonically with decreasing energy and display an isotope effect. at the lowest collision energies, the electron detachment cross sections are about one order of magnitude smaller than those for charge transfer; …
Population Biology Of The Polychaete Loimia Medusa (Savigny) On A Tidal Sand Flat Of The York River, Chesapeake Bay, Rochelle D. Seitz
Population Biology Of The Polychaete Loimia Medusa (Savigny) On A Tidal Sand Flat Of The York River, Chesapeake Bay, Rochelle D. Seitz
Dissertations, Theses, and Masters Projects
No abstract provided.
Photodetachment Of Hydride Ion In Perpendicular Electric And Magnetic Fields, Aaron David Peters
Photodetachment Of Hydride Ion In Perpendicular Electric And Magnetic Fields, Aaron David Peters
Dissertations, Theses, and Masters Projects
A simple analytic formula for the photodetachment cross section of H$\sp{-}$ in perpendicular electric and magnetic fields is obtained. Oscillations in the spectrum are predicted by the formula, and these oscillations are correlated with closed classical orbits. We point out that the quantum mechanical derivation, using a stationary phase approximation, is in complete agreement with the three-dimensional semiclassical solution to the problem.
Evaluation Of A Technique To Quantify Lipids In Bivalve Larvae Crassostrea Virginica Gmelin, Using Nile Red And Epiflourescence Microscopy, Laura Liliana Castell Perez
Evaluation Of A Technique To Quantify Lipids In Bivalve Larvae Crassostrea Virginica Gmelin, Using Nile Red And Epiflourescence Microscopy, Laura Liliana Castell Perez
Dissertations, Theses, and Masters Projects
No abstract provided.
Sediment Inorganic Nitrogen Stocks And Root-Rhizome Ammonium Uptake By Eelgrass (Zostera Marina L) In The Lower Chesapeake Bay, Christopher P. Buzzelli
Sediment Inorganic Nitrogen Stocks And Root-Rhizome Ammonium Uptake By Eelgrass (Zostera Marina L) In The Lower Chesapeake Bay, Christopher P. Buzzelli
Dissertations, Theses, and Masters Projects
No abstract provided.
Monooxygenase Induction And Lethality As Endpoints In Aquatic Toxicology, Daniel W. Sved
Monooxygenase Induction And Lethality As Endpoints In Aquatic Toxicology, Daniel W. Sved
Dissertations, Theses, and Masters Projects
Spot, Leiostomus xanthurus, were exposed to suspended sediments (&\approx&20 mg/L) contaminated with polycyclic aromatic hydrocarbons (PAH) in a laboratory flow-through system to evaluate the applicability of hepatic ethoxyresorufin O-deethylase (EROD) induction as an indicator of PAH exposure. PAH sources tested were coal-tar creosote (CTC), a low molecular weight fraction of creosote (LMWF), and a high molecular weight fraction of creosote (HMWF). A standard 96-h acute toxicity test was conducted to ensure that PAH concentrations tested in induction studies were sub-acutely toxic. The 96-h LC50 for spot was 1740 &\mu&g PAH/L (95% confidence interval = 1480-2060 &\mu&g PAH/L). The lowest concentration …
Life History Of The Bay Anchovy, Anchoa Mitchilli, In Chesapeake Bay, Jiangang Luo
Life History Of The Bay Anchovy, Anchoa Mitchilli, In Chesapeake Bay, Jiangang Luo
Dissertations, Theses, and Masters Projects
In lower Chesapeake Bay, the spawning season of the bay anchovy Anchoa mitchilli in 1988 was from early May to mid-September. Spawning was temporally synchronized and lasted for about 1.5 h each night. Spawning frequency per individual was every 4 d in early June and 1.3-1.9 d in other months. Batch fecundity was a linear function of fork length and body weight; regression slopes on 6 July and 4 August were significantly higher than those on 6 June and 31 August. Estimated mean total spawnings per female in 1988 was 54. Total egg production for a fish of average size …
Contaminant Accumulation In Hard And Soft Shell Blue Crabs From An Urban Subestuary, Robert F. Mothershead
Contaminant Accumulation In Hard And Soft Shell Blue Crabs From An Urban Subestuary, Robert F. Mothershead
Dissertations, Theses, and Masters Projects
Muscle and hepatopancreas of blue crabs (Callinectes sapidus), collected from the Elizabeth River, Virginia, contained residues of polycyclic aromatic hydrocarbon (PAHs}, polychlorinated biphenyls (PCBs) and organochlorine pesticides. Analytical procedures involved dichloromethane extraction of lyophilized tissue, followed by molecular size and polarity-based purification of the extract. capillary gas chromatography with flame ionization detection and electrolytic conductivity detection was used for quantitation and tentative identification of the xenobiotic compounds. Mass spectrometry was used for confirmation of these identities. Contaminant concentrations were greater in hepatopancreas than in muscle in crabs from every site examined. Hepatopancreas PAH burdens were as high as 11 mg/kg …
Contrasts Between Tidal Freshwater And Estuarine Phytoplankton Growth On Intracellular And Recycled Nutrient Pools Over A Summer-Winter Seasonal Transition, Dean Douglas Kindler
Contrasts Between Tidal Freshwater And Estuarine Phytoplankton Growth On Intracellular And Recycled Nutrient Pools Over A Summer-Winter Seasonal Transition, Dean Douglas Kindler
Dissertations, Theses, and Masters Projects
No abstract provided.
A Comparison Of Meristics And Morphometrics Between Two Strains Of Pond Cultured Striped Bass (Morone Saxatilis), Steven Gornak
A Comparison Of Meristics And Morphometrics Between Two Strains Of Pond Cultured Striped Bass (Morone Saxatilis), Steven Gornak
Dissertations, Theses, and Masters Projects
No abstract provided.
Interactions Between Temperature And Tributlytin (Tbt) Toxicity To The Estuarine Mysid, Mysidopsis Bahia, Prentiss H. Balcom
Interactions Between Temperature And Tributlytin (Tbt) Toxicity To The Estuarine Mysid, Mysidopsis Bahia, Prentiss H. Balcom
Dissertations, Theses, and Masters Projects
No abstract provided.
Nucleon Axial Vector Form Factors And Electromagnetic Transition Amplitudes In Perturbative Qcd, Jennifer L. Poor
Nucleon Axial Vector Form Factors And Electromagnetic Transition Amplitudes In Perturbative Qcd, Jennifer L. Poor
Dissertations, Theses, and Masters Projects
Values for the normal isovector axial vector form factor g$\sb{\rm A}$(Q$\sp2$) are calculated from the leading order perturbative QCD hard scattering amplitude and some previously reported models for the nucleon distribution amplitude, some of which have been derived from QCD sum rules. The values obtained from each of the distribution amplitudes gives a result that is consistent with the data extrapolated to high momentum transfer. The axial vector form factor is around one and one half times the proton's magnetic form factor in all the models which is also in accord with the data. We also calculate the isoscalar axial …
U(1) String Tension, Arthur F. Griesser
U(1) String Tension, Arthur F. Griesser
Dissertations, Theses, and Masters Projects
The long distance force between quarks in the U(1) approximation to quantum chromodynamics is calculated on a home made reduced instruction set computer optimized for that purpose. It is found that previous calculations were in error by as much as 85% due to contamination by the Coulomb interaction. The Coulomb constant, measured for the first time in this work, agrees with analytically obtained values.
Magnetic Field Strength Of Toroidal Plasma Equilibria, David Alan Garren
Magnetic Field Strength Of Toroidal Plasma Equilibria, David Alan Garren
Dissertations, Theses, and Masters Projects
The goal of nuclear fusion research is to confine a deuterium-tritium plasma at a sufficiently high temperature (15 keV) and density (3 $\times$ 10$\sp{20}$ m$\sp{-3}$) for a sufficient length of time (1 sec) to produce net fusion power. One means to attain the required plasma confinement is to embed the plasma within a magnetic field. The global structure of this magnetic field determines the variation of magnetic field strength within the surfaces of constant plasma pressure. This field strength variation in turn determines many of the stability and confinement properties of the plasma. This dissertation gives the first detailed exposition …
Completely Bootstrapped Tokamak, Richard Henry Weening
Completely Bootstrapped Tokamak, Richard Henry Weening
Dissertations, Theses, and Masters Projects
A fundamental requirement for the successful operation of a tokamak is the maintenance of a toroidal electric current within the tokamak plasma itself. Maintaining this internal plasma current can be a very difficult technological problem. In this work, a well-known but non-standard method for maintaining the tokamak current called the bootstrap effect is discussed. The bootstrap effect occurs when a fusion plasma is near thermonuclear conditions, and allows the tokamak to greatly amplify its electric current.;Because the bootstrap effect amplifies but does not create a plasma current, it has long been argued that a completely bootstrapped tokamak is not possible. …
Nuclear Magnetic Resonance Studies Of Amorphous Nickel-Zirconium Hydrides, Harris Clarence Hoke Jr.
Nuclear Magnetic Resonance Studies Of Amorphous Nickel-Zirconium Hydrides, Harris Clarence Hoke Jr.
Dissertations, Theses, and Masters Projects
This research deals with one aspect of the scientific field of hydrogen in metals. The study of hydrogen in metals is technologically important for many reasons, among them is the use of hydrogen in metals to store energy. Hydrogen related energy technology is particularly attractive because hydrogen can be extracted from water, our most abundant resource, and can be used without any pollution. Metal hydrides may one day be widely used for automotive propulsion in cars, in batteries, and many other energy conversion devices. Amorphous NiZr is particularly interesting for hydrogen storage because high concentrations of hydrogen can be sorbed …
Causal Reasoning About Distributed Programs, William Samuel Lloyd
Causal Reasoning About Distributed Programs, William Samuel Lloyd
Dissertations, Theses, and Masters Projects
We present an integrated approach to the specification, verification and testing of distributed programs. We show how "global" properties defined by transition axiom specifications can be interpreted as definitions of causal relationships between process states. We explain why reasoning about causal rather than global relationships yields a clearer picture of distributed processing.;We present a proof system for showing the partial correctness of CSP programs that places strict restrictions on assertions. It admits no global assertions. A process annotation may reference only local state. Glue predicates relate pairs of process states at points of interprocess communication. No assertion references auxiliary variables; …
Nutrient Standing Stocks And Partitioning In A Forested Coastal Plain Watershed: Groundwater, Stream And Marsh Creek, Sandra A. Hartenstine
Nutrient Standing Stocks And Partitioning In A Forested Coastal Plain Watershed: Groundwater, Stream And Marsh Creek, Sandra A. Hartenstine
Dissertations, Theses, and Masters Projects
No abstract provided.
Dielectric Monitoring Of The Chemical, Rheological, And Morphological Changes Incurred During Cure Of Epoxide-Amine Systems, Dara Elyn Levy
Dielectric Monitoring Of The Chemical, Rheological, And Morphological Changes Incurred During Cure Of Epoxide-Amine Systems, Dara Elyn Levy
Dissertations, Theses, and Masters Projects
No abstract provided.