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Articles 1 - 30 of 39
Full-Text Articles in Physical Sciences and Mathematics
General Methods For Analyzing Machine Learning Sample Complexity, Christoph Cornelius Michael
General Methods For Analyzing Machine Learning Sample Complexity, Christoph Cornelius Michael
Dissertations, Theses, and Masters Projects
During the past decade, there has been a resurgence of interest in applying mathematical methods to problems in artificial intelligence. Much work has been done in the field of machine learning, but it is not always clear how the results of this research should be applied to practical problems. Our aim is to help bridge the gap between theory and practice by addressing the question: "If we are given a machine learning algorithm, how should we go about formally analyzing it?" as opposed to the usual question: "how do we write a learning algorithm we can analyze?".;We will consider algorithms …
Comparative Toxicity Of Creosote And Creosote Contaminated Sediments, Padma T. Venkatraman
Comparative Toxicity Of Creosote And Creosote Contaminated Sediments, Padma T. Venkatraman
Dissertations, Theses, and Masters Projects
No abstract provided.
In Vitro And In Vivo Effects Of Chemotherapeutants On The Oyster Parasite, Perkinsus Marinus, Gustavo W. Calvo
In Vitro And In Vivo Effects Of Chemotherapeutants On The Oyster Parasite, Perkinsus Marinus, Gustavo W. Calvo
Dissertations, Theses, and Masters Projects
To investigate the potential of chemotherapeutants to control the oyster pathogen Perkinsus marinus, anticoccidial and antifungal compounds were tested in vitro on infected hemolymph and cultured P. marinus cells and in vivo on infected oysters. In addition, acute toxicity to oysters was determined for six anticoccidials. In vitro experiments with infected hemolymph consisted of 24 h exposure of 0.2 mL hemolymph aliquots to concentrations ranging from 100 mg/L to 0.01 mg/L of amphotericin-B, amprolium, arprinocid, cycloheximide, lasalocid, malachite green, monensin, sulfadimethoxine, and a potentiated sulfadimethoxine, followed by incubation in fluid thioglycollate medium (FTM) to determine prezoosporangia abundance. Lasalocid, malachite green, …
Deuteron Nuclear Magnetic Resonance Studies Of Molecular Motion In Solids, Tak Yan Tse
Deuteron Nuclear Magnetic Resonance Studies Of Molecular Motion In Solids, Tak Yan Tse
Dissertations, Theses, and Masters Projects
$\sp2$H-NMR is a powerful spectroscopic technique for investigating dynamics in solids. to extend the range of motional rates that can be quantitatively investigated, a new approach for measuring the quadrupolar spin-lattice relaxation time $T\sb{1Q}$ was developed. This uses a Broadband Jeener-Broekaert (BBJB) sequence with echo-detection, which avoids the frequency-discriminated excitation profile and spectral baseline distortion intrinsic to the conventional Jeener-Broekaert (JB) experiment. By combining the BBJB experiment with an Inversion-Recovery sequence with Quadrupole-Echo detection (IRQE), two independent longitudinal relaxation times, $T\sb{1Q}$ and $T\sb{1Z}$, can be measured. Spectral densities of motion $J\sb1(\omega\sb{o}$) and $J\sb2(2\omega\sb{o}$) are extracted from these relaxation times. The …
Inverse Estimation Of Horizontal Pressure Gradients And Vertical Eddy Viscosity Profiles In Shallow Waters, Bohyun Bang
Inverse Estimation Of Horizontal Pressure Gradients And Vertical Eddy Viscosity Profiles In Shallow Waters, Bohyun Bang
Dissertations, Theses, and Masters Projects
A least-squares inverse method was devised to estimate horizontal pressure gradients and vertical eddy-viscosity profiles simultaneously, from current profiles. The method was designed mostly for observations of deterministic or near-deterministic wave currents. Tidal-current observations were chosen for the present study. The inverse system was constructed from a linearized momentum equation. The viscosity was modeled with a time-constant and harmonic function in time, but without its vertical structure predefined. The least-squares problem was solved with the singular value decomposition, by taking current harmonic profiles as input. at first, the method was tested with current profiles simulated by a numerical model employing …
Characterization And Modeling Of Amino Epoxide Resins, Maria Anastasia Argiriadi
Characterization And Modeling Of Amino Epoxide Resins, Maria Anastasia Argiriadi
Dissertations, Theses, and Masters Projects
No abstract provided.
Global Phylogeography Of Yellowfin Tuna, Thunnus Albacares, And Mackerels Of The Genus Scomber, Daniel R. Scoles
Global Phylogeography Of Yellowfin Tuna, Thunnus Albacares, And Mackerels Of The Genus Scomber, Daniel R. Scoles
Dissertations, Theses, and Masters Projects
Intraspecific genetic relationships within yellowfin tuna, Thunnus albacares, and three mackerels of the genus Scomber were studied by restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA). The comparison of these scombrids, with different larval distributions, adult distributions, and vagilities, served to investigate the hypothesis that population structure in marine fishes results from geographic and physical oceanographic processes that limit dispersal of early life history stages. Samples of 20 yellowfin tuna were examined from each of five Pacific locations and one Atlantic location. MtDNA analysis with 12 informative restriction endonucleases demonstrated considerable genetic variation, as evidenced by overall nucleon …
Food, Feeding, And Length-Weight Relationships Of Young-Of-The-Year Striped Bass, Morone Saxatilis And Young-Of-The-Year White Perch, Morone Americana, Paul J. Rudershausen
Food, Feeding, And Length-Weight Relationships Of Young-Of-The-Year Striped Bass, Morone Saxatilis And Young-Of-The-Year White Perch, Morone Americana, Paul J. Rudershausen
Dissertations, Theses, and Masters Projects
No abstract provided.
The Role Of Predation On Zostera Marina L (Eelgrass) Seed Abundance, James Fishman
The Role Of Predation On Zostera Marina L (Eelgrass) Seed Abundance, James Fishman
Dissertations, Theses, and Masters Projects
No abstract provided.
Toxicity Resistance In Mummichog (Fundulus Heteroclitus) From A Chemically Contaminated Environment, Cynthia A. H. Williams
Toxicity Resistance In Mummichog (Fundulus Heteroclitus) From A Chemically Contaminated Environment, Cynthia A. H. Williams
Dissertations, Theses, and Masters Projects
No abstract provided.
A Gis Spatial Analysis Of The Potential Conflict Between Submerged Aquatic Vegetation Management And The Development Of Shellfish Aquaculture In The Lower Chesapeake Bay, Laura Ann Grignano
A Gis Spatial Analysis Of The Potential Conflict Between Submerged Aquatic Vegetation Management And The Development Of Shellfish Aquaculture In The Lower Chesapeake Bay, Laura Ann Grignano
Dissertations, Theses, and Masters Projects
No abstract provided.
Predation On Juvenile Blue Crabs, Callinectes Sapidus Rathbun, In Lower Chesapeake Bay: Patterns, Predators, And Potential Impacts, Kirt E. Moody
Predation On Juvenile Blue Crabs, Callinectes Sapidus Rathbun, In Lower Chesapeake Bay: Patterns, Predators, And Potential Impacts, Kirt E. Moody
Dissertations, Theses, and Masters Projects
Various investigations of the population dynamics of blue crabs in Chesapeake Bay indicate that predator-induced mortality in the juvenile phase may determine year-class strength. In a tethering study, which spanned three seasons in shallow-water habitats of the lower York River, daily mortality rates of juvenile crabs were measured across three variables: crab size (30-70 mm carapace width), habitat type (seagrass, mud, and sand), and month (May-November). Vulnerability to predation was consistently lower for larger crabs, approaching a size refuge from predation at approximately 90 mm carapace width. Predation was most intense in unvegetated sand habitats, and significantly lower in seagrass …
Investigations Into Cataract Formation In Sciaenid Fish Species From The Elizabeth River, Chesapeake Bay, Virginia, Christopher D. Williams
Investigations Into Cataract Formation In Sciaenid Fish Species From The Elizabeth River, Chesapeake Bay, Virginia, Christopher D. Williams
Dissertations, Theses, and Masters Projects
Cataract formation in the Elizabeth River (ER) has been reported since 1986. Previous studies have concentrated on describing cataract as a function of exposure to polluted sediments, especially polycyclic aromatic hydrocarbons (PAH). These studies, however, have not examined what processes might be involved in fish cataractogenesis. The overall objective of this research was to identify important processes associated with the early development of cataract in feral fish populations. Field studies were used to systematically examine cataract development. Cataract in sciaenids was not associated with previously described cataractogenic factors, but could be linked to contaminated sediments of the ER. Cataract was …
Directional Wave Spectra Using An Acoustic Doppler Current Profiler, William T. Stockhausen
Directional Wave Spectra Using An Acoustic Doppler Current Profiler, William T. Stockhausen
Dissertations, Theses, and Masters Projects
No abstract provided.
Collisions Of Atomic Hydrogen With Oxygen, Sulfur, Sodium And Halogen Anions At Low Energies, James Anthony Fedchak
Collisions Of Atomic Hydrogen With Oxygen, Sulfur, Sodium And Halogen Anions At Low Energies, James Anthony Fedchak
Dissertations, Theses, and Masters Projects
Total electron detachment and charge transfer cross sections, $\sigma\sb{\rm e}$(E) and $\sigma\sb{\rm ct}$(E), have been measured for collisions of the negative ions O$\sp{-}$, S$\sp{-}$, F$\sp{-}$, Cl$\sp{-}$, Br$\sp{-}$, I$\sp{-}$, Na$\sp{-}$, and K$\sp{-}$ with atomic hydrogen for laboratory energies ranging from 2 to 500 eV. For the systems F$\sp{-}$, Cl$\sp{-}$, Br$\sp{-}$, O$\sp{-}$ and S$\sp{-}$ + H, $\sigma\sb{\rm e}$(E) displays no barrier for associative detachment; the results are found to be adequately described by simple curve-crossing models based upon available intermolecular potentials, or by classical orbiting models which assume that the anion interacts with the H atom via an attractive potential of the …
Photoabsorption Spectra Of Hydrogen And Alkali Atoms In Electric Fields, Jing Gao
Photoabsorption Spectra Of Hydrogen And Alkali Atoms In Electric Fields, Jing Gao
Dissertations, Theses, and Masters Projects
A systematic study of the photoabsorption spectra of highly excited hydrogen and alkali atoms in electric fields is presented, based on the semiclassical closed-orbit theory. In most respects, hydrogen and alkali atoms behave similarly, because the excited alkali atoms have a single electron outside of a small ionic core, and the core only produces small shifts of energy levels and small phase shifts of scattered wave functions.;For hydrogen, the classical motion of the excited electron is regular and closed orbits can be enumerated. Above the zero-field ionization threshold, the system is rather simple. There is only one closed orbit, called …
Effects Of Methyl Parathion On The Cellular Immune Responses In Giant Black Tiger Shrimp, Penaeus Monodon, Nantarika. Bodhipaksha
Effects Of Methyl Parathion On The Cellular Immune Responses In Giant Black Tiger Shrimp, Penaeus Monodon, Nantarika. Bodhipaksha
Dissertations, Theses, and Masters Projects
The effects of an organophosphorus pesticide, methyl parathion, on cellular immune defense mechanisms of the giant black tiger shrimp (Penaeus monodon) were studied. Animals were exposed for 96 hours at concentrations equal to, above and below the LC&\sb{lcub}50{rcub}& (3 ppb). Phagocytes were obtained from the heart and circulating hemolymph. Cellular immune responses, including chemotaxis, phagocytosis and the respiratory burst were examined. Chemotactic activity was determined by means of a modified Boyden double chamber technique. There was a dose-dependent decrease in the chemotactic activities of both circulating hemocytes and cardiac phagocytes. Phagocytic activity (percent phagocytosis) was examined by the microscopic enumeration …
Mechanisms Of Larval Spot Transport And Recruitment To The Chesapeake Bay, Deborah A. Bodolus
Mechanisms Of Larval Spot Transport And Recruitment To The Chesapeake Bay, Deborah A. Bodolus
Dissertations, Theses, and Masters Projects
The spot (Leiostomus xanthurus) is an important commercial and recreational species in Virginia. Recruitment of juveniles to the Bay is characterized by large interannual fluctuations, that can be explained by the sequence and direction of wind during various phases of the early life history. An environmentally-modified Ricker stock-recruitment curve was developed incorporating the southeasterly winds in November-December, the southerly winds in January-March, and the westerly winds in April-May. This model explained 81% of the variation and closely paralleled the VIMS Juvenile Spot Index. Spot from the Chesapeake Bay migrate south in fall to spawn near or south of Cape Hatteras. …
Size-Specific Fecundity Of The Sea Scallop, Placopecten Magellanicus, During One Spawning Period In The Mid-Atlantic Resource Area, Ryan B. Carnegie
Size-Specific Fecundity Of The Sea Scallop, Placopecten Magellanicus, During One Spawning Period In The Mid-Atlantic Resource Area, Ryan B. Carnegie
Dissertations, Theses, and Masters Projects
No abstract provided.
Mitochondrial Dna Variation In Natural And Cultured Populations Of The Bay Scallop, Argopecten Irradians (Lamarck) And The Calico Scallop, Argopecten Gibbus (Dall), Sandra Grace Blake
Mitochondrial Dna Variation In Natural And Cultured Populations Of The Bay Scallop, Argopecten Irradians (Lamarck) And The Calico Scallop, Argopecten Gibbus (Dall), Sandra Grace Blake
Dissertations, Theses, and Masters Projects
No abstract provided.
Use Of A Landscape-Level Approach To Determine The Habitat Requirements Of The Yellow-Crowned Night-Heron, Nycticorax Violaceus, In The Lower Chesapeake Bay, Ellen L. Bentley
Use Of A Landscape-Level Approach To Determine The Habitat Requirements Of The Yellow-Crowned Night-Heron, Nycticorax Violaceus, In The Lower Chesapeake Bay, Ellen L. Bentley
Dissertations, Theses, and Masters Projects
No abstract provided.
An Investigation Of The Late Quaternary Morphology Of Mobjack Bay, Va And Application Of A Facies Model, Donna Angela Milligan
An Investigation Of The Late Quaternary Morphology Of Mobjack Bay, Va And Application Of A Facies Model, Donna Angela Milligan
Dissertations, Theses, and Masters Projects
No abstract provided.
Great Blue Herons And River Otters: The Changing Perceptions Of All Things Wild In The Seventeenth And Eighteenth-Century Chesapeake, Elise Helene Manning-Sterling
Great Blue Herons And River Otters: The Changing Perceptions Of All Things Wild In The Seventeenth And Eighteenth-Century Chesapeake, Elise Helene Manning-Sterling
Dissertations, Theses, and Masters Projects
No abstract provided.
Direct Determination Of Trace Metals In Saline Water Samples Using Gfaas, Michael Joseph Wassell
Direct Determination Of Trace Metals In Saline Water Samples Using Gfaas, Michael Joseph Wassell
Dissertations, Theses, and Masters Projects
No abstract provided.
Physical And Mechanical Behavior Of Amorphous Poly(Arylene Ether-Co-Imidazole)S And Poly(Arylene Ether-Co-Imidazole) Modified Epoxies, Patricia D. Roberts-Mcdaniel
Physical And Mechanical Behavior Of Amorphous Poly(Arylene Ether-Co-Imidazole)S And Poly(Arylene Ether-Co-Imidazole) Modified Epoxies, Patricia D. Roberts-Mcdaniel
Dissertations, Theses, and Masters Projects
Due to the high crosslink density of cured epoxy resins they generally lack damage tolerance. A significant amount of research has been expended to improve the toughness of epoxies. Research into the area of thermoplastic epoxy modifiers has begun to overcome some of the limitations of early methods of epoxy toughening (i.e. lower modulus and thermal stability).;This study examines the physical and mechanical properties of random poly(arylene ether-co-imidazole) (PAE-co-Is) and the characterization of epoxies modified with poly(arylene ether-co-imidazole)s.;Poly(arylene ether-co-imidazole)s exhibited the highest solubility in N,N,N{dollar}\rm\sp\prime,N\sp\prime,{dollar}-tetraglycidyl- 4,4{dollar}\sp\prime{dollar} diaminodiphenyl methane (TGMDA) based resins. The high molecular weight polymers caused significant decreases in …
Models For Water Outgassing From Metal Surfaces, Minxu Li
Models For Water Outgassing From Metal Surfaces, Minxu Li
Dissertations, Theses, and Masters Projects
In this study, the outgassing rate from an electropolished stainless steel surface following exposures to H{dollar}\sb2{dollar}O vapor under various conditions was measured. The results of the experiments showed that the outgassing rate is proportional to {dollar}p\sb0\sp{lcub}n{rcub}{dollar}, where {dollar}p\sb0{dollar} is the H{dollar}\sb2{dollar}O exposure pressure and n is about 0.25. The outgassing rate is not as strongly dependent on the system temperature as one would expect if the temperature is kept the same during exposure and pump-down. The outgassing rate is also a function of the exposure time for the first several hours of exposure, indicating that the adsorption saturation time is …
The Effects Of Contaminated Sediment On The Epidermal Goblet Cells Of The Mummichog, Fundulus Heteroclitus, Laurent C. Mézin
The Effects Of Contaminated Sediment On The Epidermal Goblet Cells Of The Mummichog, Fundulus Heteroclitus, Laurent C. Mézin
Dissertations, Theses, and Masters Projects
Secretion of mucus by epidermal goblet cells is an important first line of defense for teleosts. It protects them against many of the biological, physical and chemical insults they encounter in their environment. This project monitored changes in hemoglobin concentration in epidermal mucus and in the density, diameter and mucus quality of epidermal goblet cells in the mummichog, Fundulus heteroclitus, following exposure to creosote-contaminated sediment. Male fish (200) were exposed for 13 days in flowthough aquaria to either an uncontaminated reference sediment or contaminated sediment containing 30% Elizabeth River sediment. Fish were sampled on Days 0, 3, 7 and 13. …
Alternative Management Programs Within The Atlantic Sea Scallop Placopecten Magellanicus Fishery: Property Rights, Transferable Quotas And Fishing Effort, Niels E. Moore
Dissertations, Theses, and Masters Projects
No abstract provided.
Measurement Of In Situ Eelgrass Community Metabolism In Standing And Flowing Waters: Methods And Models, William James Seufzer
Measurement Of In Situ Eelgrass Community Metabolism In Standing And Flowing Waters: Methods And Models, William James Seufzer
Dissertations, Theses, and Masters Projects
No abstract provided.
Glueball Wave Functions And Production Cross Sections, Anthony B. Wakely
Glueball Wave Functions And Production Cross Sections, Anthony B. Wakely
Dissertations, Theses, and Masters Projects
Three topics are studied in this dissertation.;Using QCD sum rules, I first calculate the first few moments of the distribution amplitude of the pseudoscalar glueball, a bound state of gluons. The distribution amplitude is the momentum wave function integrated over the transverse momentum. QCD sum rules are a method of finding hadronic parameters using perturbative QCD. I use an approximation in which the glueball is treated as a narrow resonance. The moments of the distribution amplitude then give the corresponding first few coefficients of the distribution amplitude for the glueball expanded in Gegenbauer polynomials. The distribution amplitude is rather close …