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Articles 541 - 570 of 1876
Full-Text Articles in Physical Sciences and Mathematics
Alternative Substrates As A Native Oyster (Crassostrea Virginica) Reef Restoration Strategy In Chesapeake Bay, Russell Paul Burke
Alternative Substrates As A Native Oyster (Crassostrea Virginica) Reef Restoration Strategy In Chesapeake Bay, Russell Paul Burke
Dissertations, Theses, and Masters Projects
Oyster shell for native oyster reef restoration is scarce in Chesapeake Bay and other estuaries (Chapter 1). Consequently, alternative substrates merit consideration in oyster restoration. This dissertation examines the suitability of shell alternatives, including granite, concrete, limestone marl, concrete modules and reefballs with reef surveys and experiments in the Rappahannock and Lynnhaven Rivers of Chesapeake Bay. Oyster recruitment, growth, survival, density, biomass, condition, and disease stress, as well as reef accretion and persistence, were measured. In the Lynnhaven River, intertidal riprap had a mean density of 978 oysters m-2 (165 g AFDM m-2) and peak densities > 2000 oysters m-2 (Chapter …
Copepod Carcasses, Mortality And Population Dynamics In The Tributaries Of The Lower Chesapeake Bay, David Thomas. Elliott
Copepod Carcasses, Mortality And Population Dynamics In The Tributaries Of The Lower Chesapeake Bay, David Thomas. Elliott
Dissertations, Theses, and Masters Projects
Several studies have documented the occurrence of substantial numbers of zooplankton carcasses in marine field samples. However, the potential effect of carcasses on conclusions resting on zooplankton abundance estimates, and the reasons for carcass occurrence have been largely disregarded. Many field studies do not account for the presence of carcasses in their sampling methodology. Zooplankton carcasses in situ are significant for several reasons. as concentrated particles of organic matter in the water column, zooplankton carcasses can be important vehicles for organic matter transport and hotspots of microbial abundance and activity. If dead animals are treated alive, carcasses could bias the …
Bioavailability Of Biosolids- And Consumer Product-Associated Polybrominated Diphenyl Ether (Pbde) Flame Retardants To Terrestrial Invertebrates, Michael O. Gaylor
Bioavailability Of Biosolids- And Consumer Product-Associated Polybrominated Diphenyl Ether (Pbde) Flame Retardants To Terrestrial Invertebrates, Michael O. Gaylor
Dissertations, Theses, and Masters Projects
The primary objectives of this research were therefore to evaluate polybrominated diphenyl ether (PBDE) bioavailability to ecologically distinct soil invertebrates exposed to Penta-BDE-treated consumer polyurethane foam (PUF) products and biosolid products with incurred PBDEs. In laboratory bioassays, earthworms (Eisenia fetida) bioaccumulated SigmaPBDEs (47+99+100+183) up to 11,000 mug/kg lipid after 28 days from a mixture of artificial soil and anaerobically-digested sludge biosolid (ADB). Earthworms also bioaccumulated SigmaPBDEs (47+99+100+153+154+183) up to 13,500 and 838,000 mug/kg lipid after 28 d from a mixture of artificial soil and composted sludge biosolid (CB) and Penta-BDE-spiked artificial soil (SAS), respectively. No previous lab studies on bioaccumulation …
Persistent Organic Pollutants(Pops) As Tracers Of Environmental Change And Antarctic Seabird Ecology, Heidi N. C. Geisz
Persistent Organic Pollutants(Pops) As Tracers Of Environmental Change And Antarctic Seabird Ecology, Heidi N. C. Geisz
Dissertations, Theses, and Masters Projects
Antarctic seabirds including Adelie penguins (Pygoscelis adeliae), south polar skuas (Catharacta maccormicki), southern giant petrels (Macronectes gigantus) are high trophic level predators that accumulate persistent organic pollutants (POPs) present in the food webs in which they forage. Little is known about the levels of POPs in some Antarctic organisms (e.g. southern giant petrels), as well as the long-term trends of POPs in the Antarctic ecosystem. Samples from all three seabird species were collected post mortem, including eggs, from the Western Antarctic Peninsula (WAP) and in the Ross Sea throughout the austral summer breeding seasons of 2004--2006. The samples were analyzed …
Effects Of Habitat Quality On Secondary Production In Shallow Estuarine Waters And The Consequences For The Benthic-Pelagic Food Web, David James Gillett
Effects Of Habitat Quality On Secondary Production In Shallow Estuarine Waters And The Consequences For The Benthic-Pelagic Food Web, David James Gillett
Dissertations, Theses, and Masters Projects
Anthropogenic degradation of coastal and estuarine habitats is an ongoing problem facing scientists, natural resource mangers, and the general public. Decreases in habitat quality produce relatively predictable changes in the structure and composition of macrobenthic communities and it has traditionally been assumed that the ecosystem functions of the community change as well. In Chesapeake Bay, the most pervasive cause for the degradation of benthic habitats is the excessive inputs of nutrients that lead to eutrophication and the accumulation of organic matter in the system. Working within this framework, a study was conducted investigating changes in macrobenthic (i.e., secondary) production along …
Integrating Space-And Time-Scales Of Sediment-Transport For Poverty Bay, New Zealand, Aaron J. Bever
Integrating Space-And Time-Scales Of Sediment-Transport For Poverty Bay, New Zealand, Aaron J. Bever
Dissertations, Theses, and Masters Projects
Poverty Bay is a small embayment located in the middle of the Waipaoa River Sedimentary Dispersal System (WSS) on the eastern coast of the north island of New Zealand. Within this dispersal system, a large multidisciplinary study was focused on determining the sediment routing from the source within the headwaters to the locations of sediment accumulation on the continental shelf and slope. Poverty Bay acts as the land to sea transition area in the WSS, and as such significantly modifies the fluvial sedimentary signal before it is exported to the continental shelf. Until this study, little hydrodynamic or sediment-transport work …
Characterization And Deposition Of Aerosol Organic Matter In The Eastern United States, Andrew S. Wozniak
Characterization And Deposition Of Aerosol Organic Matter In The Eastern United States, Andrew S. Wozniak
Dissertations, Theses, and Masters Projects
Aerosol organic carbon (OC) was characterized in two eastern United States watersheds to investigate the potential importance of aerosol OC in watershed OC budgets and cycling. Fluxes of 1.7 and 2.1 mg aerosol OC m-2 d-1 were measured for aerosol samples in Harcum, VA and Millbrook, NY, respectively. Scaled to the area of nearby watersheds (York River watershed, VA and Hudson River watershed, NY) these fluxes are similar in magnitude or greater than the magnitude of riverine OC exported by corresponding rivers indicating that aerosols must be taken into account when thinking about biogeochemical exchanges between the atmospheric, terrestrial, and …
Electron Scattering From An Almost Free Neutron In Deuterium, Nathan Kidd Baillie
Electron Scattering From An Almost Free Neutron In Deuterium, Nathan Kidd Baillie
Dissertations, Theses, and Masters Projects
The Barely off-Shell Nucleon Structure (BoNuS) experiment measured electron scattering from neutrons bound in deuterium nuclei at Jefferson Lab's Hall B with the intent of obtaining the ratio Fn2/Fp2 at high Bjorken x. The Fn2 structure function is difficult to obtain due to nature's lack of a free neutron target. Previous experiments have measured inclusive scattering from atomic nuclei, but extracting Fn2 from these data requires knowledge of inclusive scattering from the proton and corrections for nucleon binding and Fermi motion. In BoNuS we restrict our analysis to neutron scattering events tagged by a backward-going low-energy recoil proton. This selects …
Application Of Information Theory And Statistical Learning To Anomaly Detection, Steven Gianvecchio
Application Of Information Theory And Statistical Learning To Anomaly Detection, Steven Gianvecchio
Dissertations, Theses, and Masters Projects
In today's highly networked world, computer intrusions and other attacks area constant threat. The detection of such attacks, especially attacks that are new or previously unknown, is important to secure networks and computers. A major focus of current research efforts in this area is on anomaly detection.;In this dissertation, we explore applications of information theory and statistical learning to anomaly detection. Specifically, we look at two difficult detection problems in network and system security, (1) detecting covert channels, and (2) determining if a user is a human or bot. We link both of these problems to entropy, a measure of …
Optical Control Of Ultrafast Spin -Wave Relaxation By Magnetic Anisotropy In A Ferromagnet, Kevin James Smith
Optical Control Of Ultrafast Spin -Wave Relaxation By Magnetic Anisotropy In A Ferromagnet, Kevin James Smith
Dissertations, Theses, and Masters Projects
This thesis presents an investigation of the damping of spin waves in ferromagnetic Au(3 nm)/Ni(10 nm)/MgO(001) thin films using the time-resolved Magneto-optical Kerr Effect (TR-MOKE) and ferromagnetic resonance (FMR) techniques. In the optical measurements, a 150 fs, 800 nm laser beam pulse is split into pump and probe components. The pump pulse, containing most of the beam energy, thermally excites coherent spin precession. The weaker probe pulse, time-delayed by a variable beam path, captures the magnetization dynamics via the polar MOKE effect, and oscillations are observed as a function of external field amplitude and direction. The extracted precession frequency is …
Quantum Information Dynamics, Jeffrey Yepez
Quantum Information Dynamics, Jeffrey Yepez
Dissertations, Theses, and Masters Projects
Presented is a study of quantum entanglement from the perspective of the theory of quantum information dynamics. We consider pairwise entanglement and present an analytical development using joint ladder operators, the sum of two single-particle fermionic ladder operators. This approach allows us to write down analytical representations of quantum algorithms and to explore quantum entanglement as it is manifested in a system of qubits.;We present a topological representation of quantum logic that views entangled qubit spacetime histories (or qubit world lines) as a generalized braid, referred to as a super-braid. The crossing of world lines may be either classical or …
Enhancing Web Browsing Security, Chuan Yue
Enhancing Web Browsing Security, Chuan Yue
Dissertations, Theses, and Masters Projects
Web browsing has become an integral part of our lives, and we use browsers to perform many important activities almost everyday and everywhere. However, due to the vulnerabilities in Web browsers and Web applications and also due to Web users' lack of security knowledge, browser-based attacks are rampant over the Internet and have caused substantial damage to both Web users and service providers. Enhancing Web browsing security is therefore of great need and importance.;This dissertation concentrates on enhancing the Web browsing security through exploring and experimenting with new approaches and software systems. Specifically, we have systematically studied four challenging Web …
Advancements In Dual-Pump Broadband Cars For Supersonic Combustion Measurements, Sarah Augusta. Tedder
Advancements In Dual-Pump Broadband Cars For Supersonic Combustion Measurements, Sarah Augusta. Tedder
Dissertations, Theses, and Masters Projects
Space- and time-resolved measurements of temperature and species mole fractions of nitrogen, oxygen, and hydrogen were obtained with a dual-pump coherent anti-Stokes Raman spectroscopy (CARS) system in hydrogen-fueled supersonic combustion free jet flows. These measurements were taken to provide time-resolved fluid properties of turbulent supersonic combustion for use in the creation and verification of computational fluid dynamic (CFD) models. CFD models of turbulent supersonic combustion flow currently facilitate the design of air- breathing supersonic combustion ramjet (scramjet) engines. Measurements were made in supersonic axi-symmetric free jets of two scales. First, the measurement system was tested in a laboratory environment using …
Assessing The Functional Status Of Created Wetlands In Eastern Virginia Via A Soil And Vegetative Developmental Trajectory, Sara Elizabeth Kreisel
Assessing The Functional Status Of Created Wetlands In Eastern Virginia Via A Soil And Vegetative Developmental Trajectory, Sara Elizabeth Kreisel
Dissertations, Theses, and Masters Projects
No abstract provided.
Survival In An Urbanized Landscape: Radio-Tracking Fledgling Eastern Bluebirds (Sialia Sialis) On Golf Courses, Allyson Kathleen Jackson
Survival In An Urbanized Landscape: Radio-Tracking Fledgling Eastern Bluebirds (Sialia Sialis) On Golf Courses, Allyson Kathleen Jackson
Dissertations, Theses, and Masters Projects
No abstract provided.
Multifunctional Polymer Synthesis And Incorporation Of Gadolinium Compounds And Modified Tungsten Nanoparticles For Improvement Of Radiation Shielding For Use In Outer Space, Emily Grace Harbert
Multifunctional Polymer Synthesis And Incorporation Of Gadolinium Compounds And Modified Tungsten Nanoparticles For Improvement Of Radiation Shielding For Use In Outer Space, Emily Grace Harbert
Dissertations, Theses, and Masters Projects
No abstract provided.
The Lateral Extent And Spatial Variation Of Mercury Exposure In Birds And Their Prey Near A Polluted River, Mikaela Gioia Selene Howie
The Lateral Extent And Spatial Variation Of Mercury Exposure In Birds And Their Prey Near A Polluted River, Mikaela Gioia Selene Howie
Dissertations, Theses, and Masters Projects
No abstract provided.
Multimodal Non-Rigid Registration For Image-Guided Head And Neck Surgery, Michael Lawrence Weissberger
Multimodal Non-Rigid Registration For Image-Guided Head And Neck Surgery, Michael Lawrence Weissberger
Dissertations, Theses, and Masters Projects
No abstract provided.
"You Have No Boss Here To Work For": Women And Labor In Chesapeake Bay Fishing Communities, Elizabeth Marie O'Grady
"You Have No Boss Here To Work For": Women And Labor In Chesapeake Bay Fishing Communities, Elizabeth Marie O'Grady
Dissertations, Theses, and Masters Projects
No abstract provided.
Adaptive Learning And Cryptography, David Goldenberg
Adaptive Learning And Cryptography, David Goldenberg
Dissertations, Theses, and Masters Projects
Significant links exist between cryptography and computational learning theory. Cryptographic functions are the usual method of demonstrating significant intractability results in computational learning theory as they can demonstrate that certain problems are hard in a representation independent sense. On the other hand, hard learning problems have been used to create efficient cryptographic protocols such as authentication schemes, pseudo-random permutations and functions, and even public key encryption schemes.;Learning theory / coding theory also impacts cryptography in that it enables cryptographic primitives to deal with the issues of noise or bias in their inputs. Several different constructions of "fuzzy" primitives exist, a …
Silver-Polyimide Nanocomposite Films: Single-Stage Synthesis And Analysis Of Metalized Partially-Fluorinated Polyimide Btda/4-Bdaf Prepared From Silver(I) Complexes, Joshua Erold Robert Abelard
Silver-Polyimide Nanocomposite Films: Single-Stage Synthesis And Analysis Of Metalized Partially-Fluorinated Polyimide Btda/4-Bdaf Prepared From Silver(I) Complexes, Joshua Erold Robert Abelard
Dissertations, Theses, and Masters Projects
No abstract provided.
Acoustics Of Anthropogenic Habitats: The Impact Of Noise Pollution On Eastern Bluebirds, Caitlin Rebecca Kight
Acoustics Of Anthropogenic Habitats: The Impact Of Noise Pollution On Eastern Bluebirds, Caitlin Rebecca Kight
Dissertations, Theses, and Masters Projects
An increasing number of habitats are affected by anthropogenic noise pollution, which is often louder, has a different frequency emphasis, and may occur over a different temporal scale, than natural noise. An increasing number of studies indicate that acoustically-communicating animals in such areas can modify their vocalizations in order to make themselves heard over the noise, but many questions still remain, including: How taxonomically widespread is vocal flexibility in response to anthropogenic noise, and do all vocally flexible species employ the same mechanisms to escape acoustic masking? Are there fitness repercussions for living, communicating, and breeding in noisy habitats? and, …
Anthropogenic Causes Of Copepod Mortality And Bacterial Decomposition Of Copepod Carcasses, Samantha L. Bickel
Anthropogenic Causes Of Copepod Mortality And Bacterial Decomposition Of Copepod Carcasses, Samantha L. Bickel
Dissertations, Theses, and Masters Projects
Although zooplankton carcasses can be quite prevalent within aquatic systems, they have largely been overlooked in most zooplankton population studies. Anthropogenic stressors can potentially increase the overall abundance of carcasses on a local scale. Once a carcass is present within a system, the fate of its biomass is of considerable interest as it may be remineralized within the water column or transported to depth. Through the collection of field samples I assessed the possibility of an anthropogenic stressor (boat-generated turbulence) as a potential source of nonconsumptive mortality. I also conducted a series of laboratory experiments to monitor the decomposition of …
Environmental Analysis Of Selected Estrogens And Androgens: Applying Ultra-Performance Liquid Chromatography And Combating Matrix Interference, Stacie L. Rice
Environmental Analysis Of Selected Estrogens And Androgens: Applying Ultra-Performance Liquid Chromatography And Combating Matrix Interference, Stacie L. Rice
Dissertations, Theses, and Masters Projects
Investigations of environmental hormone contamination commonly utilize solidphase extraction (SPE) followed by high-performance liquid chromatography / (electrospray ionization) tandem mass spectrometry (HPLC/(ESI)MS2) in the detection of estrogens. Matrix interference is widely reported. In this study, androgens were targeted alongside estrogens as environmentally co-introduced endocrine disrupting chemicals. Analytical methods were developed in parallel for detection of several hormones from each class, with comparison of protocols and instrumental parameters. Ultraperformance LC (UPLC®), an emerging technology advertised for reduced retention times, was used in place of HPLC for hormone separation. Applicability to diverse aqueous samples was tested. Matrix interference was combated with two …
Continental Shelf Sediment Transport And Depositional Processes On An Energetic, Active Margin: The Waiapu River Shelf, New Zealand, Yanxia Ma
Dissertations, Theses, and Masters Projects
The Waiapu River drains a small mountainous basin, characterized by steep terrain, heavy rainfall, and unconsolidated soft Tertiary mudstone and siltstone. These factors, combined with heavy deforestation over the past 100 years have created one of the world's highest sediment yields. Water discharge of the Waiapu River is very episodic over both inter- and intra-annual timescales, and almost all of the discharge is associated with floods brought by cyclonic storms. The Waiapu River drains an active margin that has a narrow shelf and steep slope. Marine conditions on the Waiapu continental shelf are very energetic, with strong waves as well …
Laser Desorption From A Room Temperature Ionic Liquid, Peter Ronald Harris
Laser Desorption From A Room Temperature Ionic Liquid, Peter Ronald Harris
Dissertations, Theses, and Masters Projects
We report laser desorption from a Room Temperature Ionic Liquid (RTIL) as a novel source for time of flight mass spectrometry. We use the 2nd harmonic of an Nd:YAG laser to deposit intensities of 1-50 MW/cm2 via backside illumination onto our RTIL desorption sample. A microstructured metal grid situated on top of a glass microscope slide coated with RTIL serves as our desorption sample. The RTIL we use, 1-Butyl, 3-Methylimidazolium Hexafluorophosphate, remains liquid at pressures below 10-8 torr. The use of liquid desorption sample allows for improved surface conditions, homogeneity and sample life as compared to Matrix Assisted Laser Desorption …
Polybrominated Diphenyl Ether Flame Retardants In Birds Of Prey From The U.S. And China, Da Chen
Polybrominated Diphenyl Ether Flame Retardants In Birds Of Prey From The U.S. And China, Da Chen
Dissertations, Theses, and Masters Projects
Polybrominated diphenyl ether (PBDE) flame retardants are widely used as non-reactive additives in textiles, polyurethane foams, plastics, furnishings, and electronic products. as a result of substantial, long-term usages, PBDEs have contaminated humans, wildlife, air, water, soil, and sediment, even in remote areas. Although the North American and Asian (particularly Chinese) markets have consumed the majority of global PBDE production, knowledge about PBDE contamination is limited in these two regions. Therefore, this research aimed to investigate PBDE contamination in some Chinese and North American areas by examining the birds of prey that have been considered as sensitive monitoring species for organochlorine …
Mortality Of Diamondback Terrapins In Blue Crab Traps: Population Changes And Conservation In Southeastern Virginia, Megan Ann Rook
Mortality Of Diamondback Terrapins In Blue Crab Traps: Population Changes And Conservation In Southeastern Virginia, Megan Ann Rook
Dissertations, Theses, and Masters Projects
No abstract provided.
The Synthesis And Spectroscopic Study Of A Spirooxazine-Functionalized Poly(Phenylenevinylene), Jordan Thomas Walk
The Synthesis And Spectroscopic Study Of A Spirooxazine-Functionalized Poly(Phenylenevinylene), Jordan Thomas Walk
Dissertations, Theses, and Masters Projects
No abstract provided.
Cyclization Reactions Catalyzed By Bi(Iii) Compounds, Jia Liu
Cyclization Reactions Catalyzed By Bi(Iii) Compounds, Jia Liu
Dissertations, Theses, and Masters Projects
No abstract provided.