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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 …
Comparative Ecology, Morphology, And Population Genetics Of Black Triggerfish, Melichthys Niger, Kathryn D. Kavanagh
Comparative Ecology, Morphology, And Population Genetics Of Black Triggerfish, Melichthys Niger, Kathryn D. Kavanagh
Dissertations, Theses, and Masters Projects
No abstract provided.
Stock Enhancement Of Caribbean Spiny Lobster, Panulirus Argus Latrielle, Using Artificial Shelters: Patterns Of Survival And Dynamics Of Shelter Selection, David Bryan Eggleston
Stock Enhancement Of Caribbean Spiny Lobster, Panulirus Argus Latrielle, Using Artificial Shelters: Patterns Of Survival And Dynamics Of Shelter Selection, David Bryan Eggleston
Dissertations, Theses, and Masters Projects
Field tethering experiments in seagrass beds of Bahia de la Ascension, Mexico examined the impact of different-sized artificial shelters upon survival of three juvenile size-classes of the Caribbean spiny lobster, Panulirus argus. The artificial shelters were concrete structures (casitas) that simulate lobster dens. In the tethering experiments, spiny lobster survival was generally higher in smaller than larger casitas, though the effect depended upon the relationship between lobster and shelter size. Thus, spiny lobster survival depends not only upon the availability of shelter, but also on the scaling between shelter size and lobster size. These results suggest that placement of appropriately-scaled …
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 …
Ecology Of Estuarine Fish Assemblages In Patos Lagoon, Brazil (32 Degrees S), And York River, Usa (37 Degrees N), With Review Of Zoogeography Of Fishes In Western Atlantic Warm-Temperate And Tropical Estuaries, Joao P. Vieira
Dissertations, Theses, and Masters Projects
The first two chapters of this study examine faunal composition and latitudinal patterns in diversity of fishes in warm-temperate and tropical estuarine waters of the western Atlantic from La Plata River (35&\sp\circ&S), Argentina, to Chesapeake Bay (37&\sp\circ&N), USA (33 faunal reports). Species distributions generally corresponded with previously recognized marine zoogeographic regions, and cluster analyses also showed that faunal similarity among estuarine sampling sites was related to the type of sampling gear used and to the type of habitat that was sampled in each estuary. The total number of fish species reported is positively related to the size of the area …
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 …
Food And Feeding Of Northern Bluefin Tuna (Thunnus Thynnus) And Yellowfin Tuna (Thunnus Albarcares): A Comparative Study Of The Food And Feeding Habits Of The Northern Bluefin Tuna Off The Coast Of Virginia, Charles Gilbert Barr
Dissertations, Theses, and Masters Projects
No abstract provided.
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.
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.
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.
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.
Modeling Sediment Resuspension In Lower Chesapeake Bay, Deborah L. Linden
Modeling Sediment Resuspension In Lower Chesapeake Bay, Deborah L. Linden
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.
Preparation And Characterization Of (E)-1-Alkenylboranes And(E)-1-Alkenylboronates An Investigation Of Borane/Nitrone Reactions, Philip Louis Smith
Preparation And Characterization Of (E)-1-Alkenylboranes And(E)-1-Alkenylboronates An Investigation Of Borane/Nitrone Reactions, Philip Louis Smith
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; …
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 …