Physical Sciences and Mathematics Commons^™

Influence Of Structural Complexity And Location On The Habitat Value Of Restored Oyster Reefs, Melissa Ann Karp

Dissertations, Theses, and Masters Projects

In the Chesapeake Bay, < 1% of the historic oyster population remains, and efforts have been increasing to restore oysters and the services they provide. Building reefs that successfully provide ecosystem services–especially habitat and foraging grounds–may require different restoration techniques than those previously used, and success may depend on reef morphology (complexity), location, and environmental conditions. Salinity and habitat complexity are two important factors that may interact to effect benthic communities and predator-prey interactions on restored reefs. The goals of this project were: (1) Characterize the benthic communities on restored oyster reefs in lower Chesapeake Bay, and (2) examine the effects of structural complexity and salinity on benthic communities and predator-prey interactions. A two-year field survey of restored reefs was carried out in four rivers in lower Chesapeake Bay to characterize faunal communities on restored reefs and to quantify the effect of reef complexity on faunal communities. A laboratory mesocosm experiment was conducted to examine the effect of reef complexity on predator foraging. In total, 61 macrofaunal species were identified among all samples, and restored reefs supported on average, 6,169 org/m2 and 67.88 g-AFDW/m2. There were significant differences in the community composition and diversity among the rivers, and salinity was the environmental factor that best explained the observed differences in species composition across the rivers. Salinity and rugosity (i.e., structural complexity) both positively affected diversity, while salinity negatively affected macrofaunal abundance and biomass. Oyster density and rugosity positively affected macrofaunal biomass, and oyster density positively affected mud crab, polychaete, and mussel densities. In the mesocosm experiment, predator foraging, measured by proportion and number of prey consumed, was significantly reduced in the presence of oyster shell structure. However, predators were able to consume more prey when prey density was increased, even in the presence of oyster shell structure. These results combine to enhance our understanding of the benefits of increased habitat complexity for both prey and predators on restored oyster reefs. Increasing complexity worked to increase the abundance, biomass, and diversity of organisms inhabiting restored reefs, and even though predator consumption was reduced in the presence of structure compared to non-structured habitat, predators were able to consume more prey individuals when prey density was increased. Therefore, increasing the structure of oyster reef habitat may benefit prey species by providing refuge habitat, and benefit predators by providing an increased abundance of available prey items.

Chesapeake Coastal Community Flood Vulnerability--Prediction And Verification, Alexander D. Renaud

Dissertations, Theses, and Masters Projects

Fast moving hurricanes and stationary nor’easters have resulted in significant flood damage in Chesapeake tidewater communities. The Chesapeake Bay region is one of A m erica’s most vulnerable regions with respect to sea-level rise, which will only increase storm surge impacts over upcoming decades. While the general trends are well documented, there is limited information relevant to specific communities’ relative flood risk and response. The dearth o f data is especially troublesome given the lengthy period o f time generally needed for communities to plan and implement adaptive action. This study contributes to the regional understanding of flood and sea-level …

Experimental Apparatus For Quantum Pumping With A Bose-Einstein Condensate., Megan K. Ivory

Dissertations, Theses, and Masters Projects

No abstract provided.

On Shelf-Slope Water Mass Exchanges Near Washington Canyon And Norfolk Canyon In The Mid-Atlantic Bight, Haixing Wang

Dissertations, Theses, and Masters Projects

The physical exchanges between shelf and slope water masses are important drivers of biological productivity in the shelfbreak region of the Mid-Atlantic Bight (MAB). Based on two ocean glider surveys that were conducted in Autumn 2013, and concurrent wind and satellite based sea surface height observations, this study investigates the dynamic mechanisms of wind, surface height variation, water column hydrographic structure, and canyon topography in driving shelf-slope water mass exchanges across the shelfbreak near Norfolk Canyon and Washington Canyon in the MAB. Over the outer shelf, sea surface height variation and wind are important drivers of cross-shelfbreak transport through geostrophic …

Population Dynamics Of Gelatinous Zooplankton In The Chesapeake Bay And Sargasso Sea, And Effects On Carbon Export, Joshua Paul Stone

Dissertations, Theses, and Masters Projects

Gelatinous zooplankton (GZ; cnidarians, ctenophores, and pelagic tunicates) periodically are the dominant members of the zooplankton throughout the majority of the world’s oceans. their unique body plans and life cycles allow them to rapidly take advantage of favorable environmental conditions, which has far-ranging consequences for food web dynamics and biogeochemical cycles. GZ populations have been speculated to respond to anthropogenic changes, but few long-term studies exist to test this hypothesis and even fewer have examined the consequent effects on carbon export. I analyzed two long-term time series in the Chesapeake Bay and one in the Sargasso Sea for annual and …

Disorder Effects In Dirac Heterostructures, Martin Alexander Rodriguez-Vega

Dissertations, Theses, and Masters Projects

In this dissertation, we study theoretically heterostructures based on Dirac mate- rials, i.e. materials, such as graphene in which the electrons behave as massless Dirac fermions at low energies. We first examine how the presence of long-range disorder affects the electronic ground state of a double layer graphene heterostruc- ture formed by two graphene layers separated by a thin dielectric film. We then identify the necessary conditions for the formation of an interlayer exciton conden- sate in such a system. We also comment on the effect of long-range disorder on the broken symmetry ground state induced by electron-electron interactions in …

Molecular And Performance Properties Of Poly(Amides & Imides) And The Use Of Graphene Oxide Nano-Particles For Improvement, John-Andrew Samuel Hocker

Dissertations, Theses, and Masters Projects

Macroscopic properties of polymers, and in general all types of materials, are innately related to their molecular structure and intermolecular properties. This dissertation offers insight into how the molecular structure, chain properties, and inter-molecular chain interactions within PA11 can be used to explain and predict improved macro level performance properties; and how the addition of graphene oxide nanosheets enhances the performance properties of PA11 and polyimide(ODA-BTDA) through those same intermolecular interactions. Chapter 3 describes the unexpected result that weak small organic acids at low concentrations hydrolyze a polyamide at rates approximately twice that of a water HCl solution of the …

Expanding The Scope Of Terminal Alkynes In Chemical Biology, Johnathan Charles Maza

Dissertations, Theses, and Masters Projects

The terminal alkyne is one of the most widely used chemical moieties in chemical biology. Thanks to the relative absence of this functional group in biology, it has become a widespread functional handle for a plethora of biorthogonal chemistries. Our group has extended the scope of this functionality by developing a biological variant of the Glaser-Hay coupling, which brings together two terminal alkynes to form a diyne linkage. However, our initial findings revealed that the chemistry is plagued by protein degradation due to a deleterious copper(II) hydroxyl intermediate. Herein we extend the scope of the terimanl alkyne be developing a …

Dye-Sensitized Tio2 Modified With Iron Polypyridyl Catalyst For Photocatalytic Hydrogen Evolution, Wanji Zhang

Dissertations, Theses, and Masters Projects

Artificial Photosynthesis (AP) focuses on finding a way to harness solar energy to generate a chemical fuel. TiO2 semiconductors are of interest to AP research due to its relatively low cost and widespread use as an efficient charge-separating support. This research focuses on the development of a device for photocatalytic hydrogen generation. Our approach utilizes the immobilization of iron polypyridyl catalysts and ruthenium chromophores on TiO2 through stable phosphonic acid anchoring groups.

Characterization Of Interfacial Interactions By Functionalized Afm Probes, Laura Rickard Dickinson

Dissertations, Theses, and Masters Projects

Interfacial interactions play a crucial role in many complex materials systems, determining many of their properties. However, characterization of these interactions, especially at the micro- to nanometer length scales is experimentally challenging. Consequently, insufficient knowledge of these systems limits technological advances in important applications. In this work, custom functionalized atomic force microscopy (AFM) probes were developed to measure the interaction forces in two important systems: petroleum reservoirs and nanocomposites. Our work seeks a deeper understanding of the specific interactions that occur in these two systems so that modified approaches can be developed to improve them. Petroleum recovery is concerned with …

Understanding Security Threats In Cloud, Zhang Xu

Dissertations, Theses, and Masters Projects

As cloud computing has become a trend in the computing world, understanding its security concerns becomes essential for improving service quality and expanding business scale. This dissertation studies the security issues in a public cloud from three aspects. First, we investigate a new threat called power attack in the cloud. Second, we perform a systematical measurement on the public cloud to understand how cloud vendors react to existing security threats. Finally, we propose a novel technique to perform data reduction on audit data to improve system capacity, and hence helping to enhance security in cloud. In the power attack, we …

Influence Of Perkinsus Marinus Infection And Oyster Health On Levels Of Human-Pathogenic Vibrios In Oysters, Lydia M. Bienlien

Dissertations, Theses, and Masters Projects

The eastern oyster Crassostrea virginica is an ecologically and commercially important species whose natural populations have been devastated by overharvesting, habitat destruction, and disease, but the rapid growth of oyster aquaculture has shown potential to restore the economic significance of this species. A key threat to the growth and sustainability of oyster aquaculture is the association of human-pathogenic Vibrio bacteria with product marketed for raw consumption. Two Vibrio species, Vibrio vulnificus and Vibrio parahaemolyticus, are the causes of the highest rates of seafood consumption-related mortality and gastrointestinal illness, respectively. Identification of the factors influencing V. vulnificus and V. parahaemolyticus prevalence …

The Effects Of Drifting Fish Aggregating Devices On Bycatch In The Tropical Tuna Purse Seine Fisheries In The Atlantic And Indian Oceans, Julia Snouck-Hurgronje

Dissertations, Theses, and Masters Projects

Thousands of floating objects, known as drifting fish aggregating devices (dFADs), are released every year by commercial tropical tuna purse seine vessels in the three equatorial oceans to aggregate tuna and increase catch. The escalation in the number of dFADs deployed over the last three decades has caused changes in fishing effort that are poorly reflected in traditional indices of purse seine effort and catch per unit of effort (CPUE). In addition, concerns have been raised regarding the impacts of such high numbers of dFADs being deployed on both catch and bycatch species. I studied two aspects of dFAD deployments …

Gas-Phase Thermochemical Properties Of Proline-Containing Dipeptides And Fluorinated Alcohols Using The Extended Kinetic Method, Kathy Tang Huynh

Dissertations, Theses, and Masters Projects

No abstract provided.

Electronic Properties Of Chiral Two-Dimensional Materials, Christopher Lawrence Charles Triola

Dissertations, Theses, and Masters Projects

In this dissertation we study the electronic properties of certain two-dimensional chiral electron systems. We study the static and dynamic screening of gapped bilayer graphene and find important qualitative differences between the dielectric screening function obtained using a simplified 2-band model and that obtained using a more sophisticated 4-band model. We also formulate a continuum model to study the low-energy electronic properties of heterostructures formed by graphene on a strong three-dimensional topological insulator (TI) both for the case of commensurate and incommensurate stacking. We find that the proximity of the TI induces a strong enhancement of the spin-orbit coupling in …

Advancing Feedback-Driven Optimization For Modern Computing., Mingzhou Zhou

Dissertations, Theses, and Masters Projects

No abstract provided.

Noble Metal Free Catalysts For Hydrogen Generation From Aqueous Solutions, Dan Liu

Dissertations, Theses, and Masters Projects

The current energy crisis is becoming more and more serious due to the industrial development and increasing population. Mimicking photosynthesis in plants provides a new way to solve this crisis. The goal is to harness solar energy and convert it into energy stored in chemical bonds such as methanol or hydrogen gas. Currently, most catalysts for proton reduction contain precious metals, such as palladium, platinum and ruthenium. The main goal of our research is to develop catalysts made of earth abundant metals. By incorporating organic ligands in our complexes, we can make catalysts that have similar catalytic activity as those …

Internally Hydrogen-Bonded Prodan Derivatives, Douglas William Cheek

Dissertations, Theses, and Masters Projects

No abstract provided.

Development Of A Three Step Cascade Synthesis Of 2,4-Dihydro-1h-Benzo[F]Isochromenes, Shane E. Lewis

Dissertations, Theses, and Masters Projects

No abstract provided.

Signature Of Recent Sediment Accumulating In Prince William Sound, Alaska: A Record Of Storms, Earthquakes, And Seasonal Inputs, Nicole R. Marshall

Dissertations, Theses, and Masters Projects

This study focuses on the development o f provenance signatures for sediments accumulating in Prince William Sound, with an emphasis on interpreting mechanisms of sediment deposition using historical earthquake, wave, river discharge, and glacial outburst flood records. A highresolution sedimentary sequence in Prince William Sound, Alaska contains sediments sourced from local watersheds as a result of seasonal and event-driven sedimentation. This study contributes to the development of paleo-proxies for sediment provenance, earthquakes, shelf sediment resuspension, and Copper River discharge. Geochemical studies of sediment cores and end-member samples using X-ray fluorescence and inductively coupled plasma mass spectrometry allows for the development …

Assessing The Impact Of Climate Change On Proposed Restoration Of The Lynnhaven River Ecosystem, Emily E. Skeehan

Dissertations, Theses, and Masters Projects

Environmental degradation of the Chesapeake Bay (CB) and its sub-estuaries has been linked to population growth in the surrounding coastal zone, rapid development in the watershed and resultant nutrient loading into the Bay. Consequently, the federal government and its partners have developed restoration plans to mitigate the effects of eutrophication and improve essential ecosystem functions, though few restoration plans have considered the interactive effects of climate change. Climate change and other anthropogenic drivers are causing changes in ecosystem structure and function, thereby impacting the beneficial services ecosystems provide. While some studies have attempted to quantitatively predict the benefits of ecosystem …

Development Of Boron-Containing Polyimide Materials And Poly(Arylene Ether)S For Radiation Shielding, Brittani May Collins

Dissertations, Theses, and Masters Projects

No abstract provided.

Enhancing Bug Reports For Mobile Apps, Kevin Patrick Moran

Dissertations, Theses, and Masters Projects

No abstract provided.

Heavy Flavor Interactions And Spectroscopy From Lattice Quantum Chromodynamics, Zachary S. Brown

Dissertations, Theses, and Masters Projects

In the present work, spectroscopy and interactions of hadrons containing heavy quarks is investigated. In particular, a focus is placed on properties of exotic heavy hadronic states, including doubly and triply heavy baryons and doubly heavy tetraquark states. The framework in which these calculations are carried out is provided by lattice quantum chromodynamics, a discrete formulation of the modern theory of the strong interaction. The main body of the thesis had two main project focuses. For the first project, an extensive calculation of the mass spectrum of doubly and triply heavy baryons including both charm and bottom quarks is carried …

Human Induced Cyclical Erosion Due To Altered Sediment Bypassing Mechanisms Of A Barrier Island And The Resultant Impact On The Housing Market, Andrew R. Fallon

Dissertations, Theses, and Masters Projects

No abstract provided.

Enabling Parallel Execution Via Principled Speculation., Zhijia Zhao

Dissertations, Theses, and Masters Projects

No abstract provided.

Sterile Neutrino Search With Minos., Alena V. Devan

Dissertations, Theses, and Masters Projects

No abstract provided.

Configuring And Assembling Information Retrieval Based Solutions For Software Engineering Tasks., Bogdan Dit

Dissertations, Theses, and Masters Projects

No abstract provided.

Determination Of The Proton's Weak Charge Via Parity Violating E-P Scattering., Joshua Russell Hoskins

Dissertations, Theses, and Masters Projects

No abstract provided.

The Influence Of Environmental Factors And Resource Availability On Zostera Marina Flowering Intensity, Andrew J. Johnson

Dissertations, Theses, and Masters Projects

Sexual reproduction and the production of seeds are important for the resilience of all angiosperm species. For clonal species, such as the seagrass Zostera marina, resource allocation is complicated because these species reproduce both asexually and sexually, and the factors contributing to allocation to these two processes remains unknown. The goal of this study was, therefore, to investigate the importance of critical light, nutrient, and rhizome resources on Z.

marina sexual reproduction and flowering intensity. To evaluate the importance of sediment nutrients on Z. marina flowering intensity two distinct field manipulative experiments and one field survey were initiated: 1. Sediments …