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Articles 1 - 30 of 37
Full-Text Articles in Physical Sciences and Mathematics
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 …
Multi-System Analysis Of Nitrogen Use By Phytoplankton And Heterotrophic Bacteria, Paul B. Bradley
Multi-System Analysis Of Nitrogen Use By Phytoplankton And Heterotrophic Bacteria, Paul B. Bradley
Dissertations, Theses, and Masters Projects
Traditional measurements of phytoplankton N uptake have been confounded by bacterial retention on filters used in 15N uptake studies, and such methodological obstacles have limited our understanding of phytoplankton-bacterial interactions regarding N cycling. In this research, uptake of various inorganic and organic N substrates by phytoplankton and bacteria was measured in several marine ecosystems using two distinct approaches: size fractionation into phytoplankton and bacterial size classes, and flow cytometric (FCM) sorting of autotrophic cells. Comprehensive assessments of N uptake dynamics were conducted in Chesapeake Bay, the Mid-Atlantic Bight, and Raunefjord, Norway, with supplementary data collected from the York River, Virginia …
A Numerical Modeling Study On Barotropic And Baroclinic Responses Of The Chesapeake Bay To Hurricane Events, Kyoung-Ho Cho
A Numerical Modeling Study On Barotropic And Baroclinic Responses Of The Chesapeake Bay To Hurricane Events, Kyoung-Ho Cho
Dissertations, Theses, and Masters Projects
The barotropic and baroclinic responses of the Chesapeake Bay to forcings from two hurricanes were investigated by using unstructured-grid three-dimensional hydrodynamic models. The model domain includes Chesapeake Bay proper, the tributaries, and its extended continental shelf in the mid-Atlantic Bight. Two hurricanes were studied: Hurricane Floyd of September, 1999 and Hurricane Isabel of September, 2003, both of which made landfall within 100 km of the Chesapeake Bay mouth. Hurricane Floyd in 1999 passed through the entrance of the Bay from southwest to northeast along the coastlines of Virginia as a Category 1 storm, whereas Hurricane Isabel in 2003 made landfall …
A Privacy Preserving Framework For Cyber-Physical Systems And Its Integration In Real World Applications, Haodong Wang
A Privacy Preserving Framework For Cyber-Physical Systems And Its Integration In Real World Applications, Haodong Wang
Dissertations, Theses, and Masters Projects
A cyber-physical system (CPS) comprises of a network of processing and communication capable sensors and actuators that are pervasively embedded in the physical world. These intelligent computing elements achieve the tight combination and coordination between the logic processing and physical resources. It is envisioned that CPS will have great economic and societal impact, and alter the qualify of life like what Internet has done. This dissertation focuses on the privacy issues in current and future CPS applications. as thousands of the intelligent devices are deeply embedded in human societies, the system operations may potentially disclose the sensitive information if no …
Calculation Of Equilibrants For Semipositive Matrices, Zheng Tong
Calculation Of Equilibrants For Semipositive Matrices, Zheng Tong
Dissertations, Theses, and Masters Projects
No abstract provided.
Identification And Quantification Of Polycyclic Musks And Methyl-Triclosan In Unknown Freshwater Fish Tissue Samples, Elizabeth Mara Jacobs
Identification And Quantification Of Polycyclic Musks And Methyl-Triclosan In Unknown Freshwater Fish Tissue Samples, Elizabeth Mara Jacobs
Dissertations, Theses, and Masters Projects
No abstract provided.
Enabling Technology For Non-Rigid Registration During Image-Guided Neurosurgery, Andriy Yuri Fedorov
Enabling Technology For Non-Rigid Registration During Image-Guided Neurosurgery, Andriy Yuri Fedorov
Dissertations, Theses, and Masters Projects
In the context of image processing, non-rigid registration is an operation that attempts to align two or more images using spatially varying transformations. Non-rigid registration finds application in medical image processing to account for the deformations in the soft tissues of the imaged organs. During image-guided neurosurgery, non-rigid registration has the potential to assist in locating critical brain structures and improve identification of the tumor boundary. Robust non-rigid registration methods combine estimation of tissue displacement based on image intensities with the spatial regularization using biomechanical models of brain deformation. In practice, the use of such registration methods during neurosurgery is …
Development Of A Storm Surge Model Using A High-Resolution Unstructured Grid Over A Large Domain, Tao Shen
Development Of A Storm Surge Model Using A High-Resolution Unstructured Grid Over A Large Domain, Tao Shen
Dissertations, Theses, and Masters Projects
A quasi-3D storm surge modeling system was developed for forecasting the storm surge and inundation in the Chesapeake Bay. The system was constructed with one large unstructured grid covering the Atlantic Coast from Nova Scotia to Florida and a smaller, limited domain unstructured grid covering the Chesapeake Bay, Virginia Beach, Hampton Roads and the adjacent continental shelf regions. It was demonstrated that, with the large domain grid, the model could simulate the hurricane induced storm surge reasonably well using astronomical tide at the open boundary condition and in turn, provide boundary condition for the limited domain model. Since the difficulty …
Interactions Between Macroalgae And The Sediment Microbial Community: Nutrient Cycling Within Shallow Coastal Bays, Amber Kay Hardison
Interactions Between Macroalgae And The Sediment Microbial Community: Nutrient Cycling Within Shallow Coastal Bays, Amber Kay Hardison
Dissertations, Theses, and Masters Projects
Ephemeral macroalgal blooms are considered a symptom of eutrophication in shallow coastal lagoons, but their influence on nutrient cycling dynamics in these systems is not fully understood. From 2006-2008, I conducted a series of experiments to determine the influence of living and senescent macroalgae on sediment carbon (C) and nitrogen (N) cycling in coastal lagoons along the Delmarva Peninsula, USA. In particular, I focused on how macroalgae affect the microbial community at the sediment-water interface of shallow subtidal sediments because this complex consortium of autotrophic (e.g. benthic microalgae, BMA) and heterotrophic (e.g. bacteria) organisms plays a critical role in nutrient …
Variability In Juvenile Growth, Mortality, Maturity, And Abundance Of American Shad And Blueback Herring In Virginia, Troy D. Tuckey
Variability In Juvenile Growth, Mortality, Maturity, And Abundance Of American Shad And Blueback Herring In Virginia, Troy D. Tuckey
Dissertations, Theses, and Masters Projects
Young-of-year (YOY) population dynamics of American shad and blueback herring in Virginia's rivers were examined with an emphasis on variability in growth and mortality rates. In addition, an analysis was conducted to relate juvenile abundance indices of American shad to adult indices to establish a stock-recruitment relationship. to accomplish the stock recruitment relationship, an additional study that examined maturation schedules and inter-annual variability in maturation schedules among stocks was performed. Results of population dynamics studies found that growth and mortality rates of American shad and blueback herring varied by river and year and that conspecific abundance was an important factor …
Malware Detection And Analysis Via Layered Annotative Execution, Heng Yin
Malware Detection And Analysis Via Layered Annotative Execution, Heng Yin
Dissertations, Theses, and Masters Projects
Malicious software (i.e., malware) has become a severe threat to interconnected computer systems for decades and has caused billions of dollars damages each year. A large volume of new malware samples are discovered daily. Even worse, malware is rapidly evolving to be more sophisticated and evasive to strike against current malware analysis and defense systems. This dissertation takes a root-cause oriented approach to the problem of automatic malware detection and analysis. In this approach, we aim to capture the intrinsic natures of malicious behaviors, rather than the external symptoms of existing attacks. We propose a new architecture for binary code …
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 …
Numerical Modeling Of Eutrophication Dynamics In The Shallow Coastal Ecosystem: A Case Study In The Maryland And Virginia Coastal Bays, Taiping Wang
Dissertations, Theses, and Masters Projects
Shallow coastal bays and lagoons (mean depths <2-3 meters) are important buffer zones and links between terrestrial and deep marine ecosystems. They are inherently vulnerable to eutrophication, and are normally dominated by benthic primary producers such as seagrass, benthic micro- and macroalgae. There is an urgent need for quantitative models that are specifically designed for studying eutrophication dynamics in shallow coastal ecosystems. In this study, a hydrodynamic and water quality modeling system consisting of the hydrodynamic model UnTRIM and the water quality model CE-QUAL-ICM was applied to a representative shallow coastal bay ecosystem, the Maryland and Virginia Coastal Bays (MVCBs). A high-resolution unstructured model grid was generated to resolve the complex geometry. to address the important role played by benthic macroalgae, a benthic macroalgal module, which assimilated macroalgal kinetics from literature and recent laboratory studies, was incorporated into the water quality model framework. The module includes two representative macroalgal species, Ulva lactuca and Gracilaria vermiculophylla , common in the MVCBs, and employs the internal nutrient-limited growth kinetics proposed by Droop. The numerical modeling system has been calibrated against a comprehensive field monitoring data collected by the Maryland Department of Natural Resources in the MVCBs. The data include water level, current velocity, salinity, and major water quality variables, such as chlorophyll a, dissolved oxygen, and nutrients. The calibrated hydrodynamic model was used to calculate the physical transport time scales. The model estimated flushing time for the entire system is on the order of 2-3 months, which are much longer than typical time scales required by most biological processes. In addition, the local residence time is found to be extremely variable throughout the system. Depending on locations, the local residence time can vary from 0 to more than 200 days. The calculated transport time scales were further compared with spatial water quality distributions in the system. The comparisons demonstrate that physical circulations could substantially modulate biological processes in the system. By using the Droop equation, the benthic macroalgae's unique property, the so-called luxury uptake, was satisfactorily captured. Furthermore, the characteristic boom-and-bust life cycle of benthic macroalgae was qualitatively simulated using a box model. The expanded water quality model that includes the benthic macroalgal module reproduced both temporal and spatial distributions of observed benthic macroalgae and major water quality variables reasonably well in the MVCBs. The model results indicate that benthic macroalgae are highly important in regulating ecosystem metabolism in areas where they are abundant. Moreover, spring phytoplankton bloom was substantially suppressed when benthic macroalgae were present. The incorporation of a benthic macroalgal module also improved the model's predictive capability in simulating dissolved oxygen in shallow ecosystems affected by benthic macroalgae. In terms of nutrient budget, the model estimated that benthic macroalgae retain approximately 10% of annual nonpoint source nitrogen inputs from the watershed based on the simulation of year 2004. This is lower than that contributed by benthic microalgae reported in other shallow coastal bays such as the Lynnhaven Bay. It is suspected that the restricted distribution of benthic macroalgae in the MVCBs limited their role from the whole bay perspective. With the incorporation of a benthic macroalgae module, the overall water quality model prediction capability is improved.
Assessing Genetic Variation Within And Among Native Populations And Hatchery Stocks Of Crassostrea Ariakensis Using Microsatellite Markers, Jie Xiao
Dissertations, Theses, and Masters Projects
Assessing genetic variation within and among native populations and hatchery stocks of Crassostrea ariakensis using microsatellite markers In response to the dramatic decline of eastern oyster (Crassostrea virginica) populations in the Chesapeake Bay, introduction of the non-native Asian oyster Crassostrea ariakensis has been proposed. Currently several hatchery stocks of C. ariakensis, derived from a few wild populations along the coast of Japan and China, are being maintained in U.S. hatcheries in the Pacific northwest and on the east coast. In recent years, as the risks of the proposed introduction are being assessed, these hatchery animals have been widely used for …
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 …
Chaotic Scattering In An Open Vase-Shaped Cavity: Topological, Numerical, And Experimental Results, Jaison Allen Novick
Chaotic Scattering In An Open Vase-Shaped Cavity: Topological, Numerical, And Experimental Results, Jaison Allen Novick
Dissertations, Theses, and Masters Projects
We present a study of trajectories in a two-dimensional, open, vase-shaped cavity in the absence of forces The classical trajectories freely propagate between elastic collisions. Bound trajectories, regular scattering trajectories, and chaotic scattering trajectories are present in the vase. Most importantly, we find that classical trajectories passing through the vase's mouth escape without return. In our simulations, we propagate bursts of trajectories from point sources located along the vase walls. We record the time for escaping trajectories to pass through the vase's neck. Constructing a plot of escape time versus the initial launch angle for the chaotic trajectories reveals a …
Water Quality In Headwater Streams: A Test Of Best Management Practices, Jonathan Worth Holley
Water Quality In Headwater Streams: A Test Of Best Management Practices, Jonathan Worth Holley
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.
The Functionalization Of Carbon Nanosheets, Ronald A. Quinlan
The Functionalization Of Carbon Nanosheets, Ronald A. Quinlan
Dissertations, Theses, and Masters Projects
Carbon nanosheets are a novel two-dimensional nanostructure made up of 2-20 graphene atomic planes oriented with their in-plane axis perpendicular to the growth substrate. Previous efforts in developing nanosheet technology have focused on the characterization of the system and their development as an electron source due to the high atomic enhancement factor (beta) and low turn on field. Further investigation of nanosheets as high surface area electrodes revealed poor wetting by polymeric material and extreme hydrophobic behavior.;Because nanosheet technology has promise as a high surface area electrode material, this thesis research has focused on three areas of interest: the enhancement …
The Effect Of Realistic Focal Conditions On Strong -Field Double Ionization, Jay Paul Paquette
The Effect Of Realistic Focal Conditions On Strong -Field Double Ionization, Jay Paul Paquette
Dissertations, Theses, and Masters Projects
In recent years, a great deal of progress has been made in understanding the ionization processes that result from the interaction of an intense laser pulse with multielectron atoms. However, due to experimental limitations, the effect of the laser field's spatial dependence on strong-field processes has rarely been investigated. Presented in this work is a theoretical analysis of this spatial dependence including a proposal for an experimentally observable result of the phenomenon. We begin by outlining the elements of the laser field that will vary as a function of position and show their effects on simple free electron trajectories. We …
Dependence-Driven Techniques In System Design, Ningfang Mi
Dependence-Driven Techniques In System Design, Ningfang Mi
Dissertations, Theses, and Masters Projects
Burstiness in workloads is often found in multi-tier architectures, storage systems, and communication networks. This feature is extremely important in system design because it can significantly degrade system performance and availability. This dissertation focuses on how to use knowledge of burstiness to develop new techniques and tools for performance prediction, scheduling, and resource allocation under bursty workload conditions.;For multi-tier enterprise systems, burstiness in the service times is catastrophic for performance. Via detailed experimentation, we identify the cause of performance degradation on the persistent bottleneck switch among various servers. This results in an unstable behavior that cannot be captured by existing …
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 …
Topics In Particle Physics Beyond The Standard Model, Brian Audley Glover
Topics In Particle Physics Beyond The Standard Model, Brian Audley Glover
Dissertations, Theses, and Masters Projects
We present new models of particle physics beyond the Standard Model. These models include extensions to the ideas of extra dimensions, deconstruction, supersymmetry, and Higgsless electroweak symmetry breaking. Besides introducing new models and discussing their consequences, we also discuss how galaxy cluster surveys can be used to constrain new physics beyond the Standard Model.;We find that an ultraviolet completion of gauge theories in the Randall-Sundrum model can be found in a deconstructed theory. The warping of the extra dimension is reproduced in the low energy theory by considering a general potential for the link fields with translational invariance broken only …
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.
Using An Occupancy Modeling Framework To Test The Effects Of Habitat Variables On Pond Occupancy Of Mabee's Salamander (A Mabeei) And Marbled Salamander (A Opacum), Christy Michelle Fairman
Using An Occupancy Modeling Framework To Test The Effects Of Habitat Variables On Pond Occupancy Of Mabee's Salamander (A Mabeei) And Marbled Salamander (A Opacum), Christy Michelle Fairman
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.
New Developments In Xanthate Ester Chemistry And The Potential For Protecting Group Applications, Matthew Hobson Jones
New Developments In Xanthate Ester Chemistry And The Potential For Protecting Group Applications, Matthew Hobson Jones
Dissertations, Theses, and Masters Projects
No abstract provided.
A Bayesian Network Approach To Feature Selection In Mass Spectrometry Data, Karl W. Kuschner
A Bayesian Network Approach To Feature Selection In Mass Spectrometry Data, Karl W. Kuschner
Dissertations, Theses, and Masters Projects
One of the key goals of current cancer research is the identification of biologic molecules that allow non-invasive detection of existing cancers or cancer precursors. One way to begin this process of biomarker discovery is by using time-of-flight mass spectroscopy to identify proteins or other molecules in tissue or serum that correlate to certain cancers. However, there are many difficulties associated with the output of such experiments. The distribution of protein abundances in a population is unknown, the mass spectroscopy measurements have high variability, and high correlations between variables cause problems with popular methods of data mining. to mitigate these …
Songbirds, Pesticides, And Golf Courses: Exposure And Effects, Ryan Brennan Burdge
Songbirds, Pesticides, And Golf Courses: Exposure And Effects, Ryan Brennan Burdge
Dissertations, Theses, and Masters Projects
No abstract provided.
Measurement Of The Strange Quark Contribution To The Vector Structure Of The Proton, Sarah Katherine Phillips
Measurement Of The Strange Quark Contribution To The Vector Structure Of The Proton, Sarah Katherine Phillips
Dissertations, Theses, and Masters Projects
The goal of the G0 experiment is to determine the contribution of the strange quarks in the quark-antiquark sea to the structure of the nucleon. to this end, the experiment measured parity-violating asymmetries from elastic electron-proton scattering from 0.12 ≤ Q2 ≤ 1.0 (GeV/ c)2 at Thomas Jefferson National Accelerator Facility. These asymmetries come from the interference of the electromagnetic and neutral weak interactions, and are sensitive to the strange quark contributions in the proton. The results from the forward angle measurement, the linear combination of the strange electric and magnetic form factors GsE + etaGsM, suggest possible non-zero, Q …