Physical Sciences and Mathematics Commons^™

Optical Characterization Of Magnetism In Magnetic/Nonmagnetic Heterostructures, Yichun Fan

Dissertations, Theses, and Masters Projects

This thesis focuses on the study of the static and dynamic magnetic interactions in ferromagnetic/nonmagnetic heterostructures using interface-specific and time-resolved optical techniques. The goal of this thesis is to elucidate the interface exchange coupling, magnetic anisotropy, and coherent spin dynamics in these advanced material systems, crucial to the realization of high performance spintronic devices.;First, a pronounced exchange bias (EB) phenomenon is observed in Fe/MgO (001) by magnetic second harmonic generation. The bulk magnetization does not, in marked contrast to typical systems where EB is manifested only in the net magnetization. The magnitude of the exchange bias varies with interface oxygen …

Post-Release Mortality Of School-Size Atlantic Bluefin Tuna (Thunnus Thynnus) In The U.S Recreational Troll Fishery, Benjamin Jon Marcek

Dissertations, Theses, and Masters Projects

Atlantic bluefin tuna Thunnus thynnus (ABFT) support commercial and recreational fisheries throughout the North Atlantic Ocean. Due to heavy fishing pressure over the course of several decades, the eastern and western stocks of ABFT were overfished and the current biomass of the western stock is estimated to be approximately 19% of the biomass necessary for maximum sustainable yield. Despite a variety of management measures, including the implementation of minimum sizes and reductions of the total allowable catch (TAC) and country-specific quotas, little change was observed in the status of the western stock. The U.S. commercial and recreational ABFT fisheries are …

Intelligent Feature Selection Techniques For Pattern Classification Of Time-Domain Signals, Corey Alexander Miller

Dissertations, Theses, and Masters Projects

Time-domain signals form the basis of analysis for a variety of applications, including those involving variable conditions or physical changes that result in degraded signal quality. Typical approaches to signal analysis fail under these conditions, as these types of changes often lie outside the scope of the domain's basic analytic theory and are too complex for modeling. Sophisticated signal processing techniques are required as a result. In this work, we develop a robust signal analysis technique that is suitable for a wide variety of time-domain signal analysis applications. Statistical pattern classification routines are applied to problems of interest involving a …

Applications Of Holographic Dualities, Dylan Judd Albrecht

Dissertations, Theses, and Masters Projects

We introduce and review some of the building blocks to what is known as the AdS/CFT correspondence. We then present, using the framework of the correspondence, two applications: one to QCD (Chapters 2 and 3) and one to superconductivity (Chapter 4). The work presented in these chapters was carried out by the author and collaborators during the author's graduate studies.

Low Energy Tests Of The Standard Model, Benjamin Carl Rislow

Dissertations, Theses, and Masters Projects

The Standard Model describes a wide range of fundamental interactions. Searches are ongoing for experimental results that differ from the Standard Model predictions. Such disagreements would both indicate that the Standard Model is incomplete and constrain the properties of New Physics scenarios. to probe the Standard Model over a wide kinematic range, low energy tests are necessary to complement experiments in the high energy regime. We perform calculations for experiments that are representative of two general types of low energy tests. The Qweak experiment at Jefferson Lab is a low energy measurement of the weak charge of the proton. Since …

The Synthesis Of 2-Pyridones And Louisianin B, Kaila Ashley Margrey

Dissertations, Theses, and Masters Projects

No abstract provided.

Submarine Groundwater Discharge To The York River Estuary: Quantifying Groundwater Flux And Potential For Biogeochemical Cycling, Jenna Lynn Luek

Dissertations, Theses, and Masters Projects

No abstract provided.

A Search For A New Gauge Boson, Eric Lyle Jensen

Dissertations, Theses, and Masters Projects

In the Standard Model, gauge bosons mediate the strong, weak, and electromagnetic forces. New forces could have escaped detection only if their mediators are either heavier than O (TeV) or weakly coupled to charged matter. New vector bosons with small coupling a' arise naturally from a small kinetic mixing with the photon and have received considerable attention as an explanation of various dark matter related anomalies. Such particles could be produced in electron-nucleus fixed-target scattering and then decay to e+ e -- pairs. New light vector bosons and their associated forces are a common feature of Standard Model extensions, but …

Seasonal Nitrogen Uptake And Regeneration In The Water Column And Sea-Ice Of The Western Coastal Arctic, Steven E. Baer

Dissertations, Theses, and Masters Projects

The logistical difficulties of research in extremely low temperatures and lack of access to the Arctic have meant that there is a historic dearth of knowledge of coastal Arctic biogeochemistry, especially during winter when sea ice is present. Recent observations, however, indicate that the Arctic is changing rapidly. Changes include increased temperatures, decreased extent and volume of sea ice, and increased freshwater inputs. How these changes influence biogeochemical cycles is an open question, especially in the highly productive coastal regions of the Chukchi Sea. Here I present nitrogen (N) uptake and regeneration rates for phytoplankton and bacteria measured in the …

Experimental Generation And Manipulation Of Quantum Squeezed Vacuum Via Polarization Self-Rotation In Rb Vapor, Travis Scott Horrom

Dissertations, Theses, and Masters Projects

Nonclassical states of light are of increasing interest due to their applications in the emerging field of quantum information processing and communication. Squeezed light is such a state of the electromagnetic field in which the quantum noise properties are altered compared with those of coherent light. Squeezed light and squeezed vacuum states are potentially useful for quantum information protocols as well as optical measurements, where sensitivities can be limited by quantum noise. We experimentally study a source of squeezed vacuum resulting from the interaction of near-resonant light with both cold and hot Rb atoms via the nonlinear polarization self-rotation effect …

Improving Energy Efficiency And Security For Pervasive Computing Systems, Fengyuan Xu

Dissertations, Theses, and Masters Projects

Pervasive computing systems are comprised of various personal mobile devices connected by the wireless networks. Pervasive computing systems have gained soaring popularity because of the rapid proliferation of the personal mobile devices. The number of personal mobile devices increased steeply over years and will surpass world population by 2016.;However, the fast development of pervasive computing systems is facing two critical issues, energy efficiency and security assurance. Power consumption of personal mobile devices keeps increasing while the battery capacity has been hardly improved over years. at the same time, a lot of private information is stored on and transmitted from personal …

Methylmercury Exposure Affects Risk-Taking Behaviors In Zebra Finches: Tradeoffs Between Eating And Being Eaten, Megan Elizabeth Kobiela

Dissertations, Theses, and Masters Projects

No abstract provided.

Ecologically-Framed Mercury Database, Exposure Modeling And Risk/Benefit Communication To Lower Chesapeake Bay Fish Consumers, Xiaoyu Xu

Dissertations, Theses, and Masters Projects

Mercury concentrations and determinants of mercury accumulation were examined for ten finfish species from the lower Chesapeake Bay and its tributaries. None of the sampled fish had total mercury concentrations approaching the U.S. EPA human health screening value. Mercury concentrations in different fish species generally increased with increasing delta 15N, but not delta 13C, suggesting that trophic position, but not dietary carbon source was a dominant determinant. A methylmercury biomagnification model was built to estimate a food web magnification factor of approximately 10-fold increase per trophic level in Chesapeake Bay. Based on otolith strontium-calcium ratios, Atlantic croaker inhabiting less saline …

Application Of Acoustics And Optics For The Characterization Of Suspended Particulate Matter Within An Estuarine Observing System, Grace M. Cartwright

Dissertations, Theses, and Masters Projects

As part of this dissertation work, a long term observing station at Clay Bank on the York River in Virginia has been established and maintained since 2006, and was used to gain a better understanding of sediment processes in a muddy estuary and in muddy coastal environments in general. While data from this NSF-funded Multi-Disciplinary Benthic Exchange Dynamic (MUDBED) observing system has and will be used by other students for this general purpose, this dissertation focuses specifically on better understanding and interpretation of the data collected by key instrumentation regularly deployed at the observing station, especially the acoustic Doppler velocimeter …

Acoustic And Sedimentological Investigations Of Seabed Conditions And Related Bio-Geological Parameters In A Tidally Energetic, Fine-Grained Environment: York River Estuary, Virginia, Lindsey M. Kraatz

Dissertations, Theses, and Masters Projects

The transport and fate of fine-grained sediments is a critical factor affecting the physical, chemical, and biological health of estuaries, coastal embayments, riverine, lacustrine, and continental shelf environments. A geophysical and sedimentological study of the York River as a part of the NSF Multi-disciplinary Benthic Exchange Dynamics (MUDBED) project was conducted to determine: 1) the primary drivers of sediment erodibility within a fine-grained system, 2) if these drivers can be accurately measured through sedimentological and acoustic information, and 3) the spatial and seasonal variability of erosion within the estuary. Previous studies indicate that increased erodibility within the York River Estuary …

The Development Of Ecological Functions In Created Forested Wetlands, Sean P. Charles

Dissertations, Theses, and Masters Projects

Wetland mitigation has become a 2.4 billion dollar per year industry in the U.S. and in Virginia it leads to the replacement of 77 ha of palustrine forested wetlands (PFWs) per year with mitigation wetlands, including created forested wetlands (CFWs). Mitigation hinges on the idea that compensation wetlands lead to “no net loss of wetland function” when compared to impacted wetlands. We assessed the functions of provision of habitat and biogeochemical functions associated with production of biomass, the retention and removal of nutrients and the accumulation of soil C over 8 years in seven CFWs of approximately 11 and 20 …

Investigations Of The Life Cycle Of The Peritrich Ciliate Zoothamnium Intermedium In Chesapeake Bay, Sikai Peng

Dissertations, Theses, and Masters Projects

Epibiosis is a common phenomenon in aquatic environments. The chitinous exoskeletons of crustaceans provide stable surfaces for attachment and growth of epibiotic microorganisms. Epibiont ciliate colonization on copepods is commonly recorded but has rarely been studied in Chesapeake Bay; also, little is known about the life cycles of epibiont ciliates in the bay.

The present work focuses on the life cycle of Zoothamnium intermedium in Chesapeake Bay. A peritrich ciliate belonging to the genus Zoothamnium was found as an epibiont on the calanoid copepods Acartia tonsa and Pseudodiaptomus pelagicus during the summer in the York River, a tributary of the …

Distribution And Impacts Of Invasive Bivalve Corbicula Fluminea In Tidal Freshwater York River Tributaries, Matthew Ryan Freedman

Dissertations, Theses, and Masters Projects

The Asian clam, Corbicula fluminea, is one of the most invasive bivalves in the world but there is limited research on its presence in tidal freshwater systems. Despite its introduction into Chesapeake Bay tributaries in the 1970s, the initial colonization and subsequent development of populations of C. fluminea in the Mattaponi and Pamunkey sub-tributaries of the York River, Virginia, is mostly undocumented. This study assessed the spatial distribution and population structure of C. fluminea in tidal freshwater sections of these rivers (~45km) with benthic surveys during summer 2011 – 2012. Benthic grabs (2.4L, 0.023m2) taken at 40 sites in each …

Electroless Gold Deposition With Self-Assembled Monolayers For Gas Chromatography Stationary Phases, Jessica Lynn Belton

Dissertations, Theses, and Masters Projects

No abstract provided.

Multi-Meson Systems From Lattice Quantum Chromodynamics, Zhifeng Shi

Dissertations, Theses, and Masters Projects

Systems of non-zero isospin chemical potential ( muI), where the chemical potential for up and down quarks is equal in magnitude but of opposite sign, do not suffer from the sign problem, and normal LQCD techniques can be successfully adapted to study such systems. From chiral perturbation theory (chiPT), in addition to the deconfined phase transition at high temperature at zero chemical potential, another phase transition from ordinary hadronic states to a Bose Einstein Condensate (BEC) state has been conjectured [1] at non-zero isospin chemical potential. Such a BEC phase is of phenomenological relevance in the interior of neutron stars.;In …

Synthesis And Fluorescence Studies Of Ph-Responsive Rhodamine B Derivatives, William Lawrence Czaplyski

Dissertations, Theses, and Masters Projects

No abstract provided.

Studies Of Molecular Dynamics Of Fmoc-Alanine-D3 Through Solid State Deuteron Nuclear Magnetic Resonance, Jianhua Sun

Dissertations, Theses, and Masters Projects

No abstract provided.

Surface Modifications For Gas Chromatography Micro Columns, Daniel Andre Hirtenstein

Dissertations, Theses, and Masters Projects

No abstract provided.

Phytoplankton Growth Rates In The Ross Sea, Antarctica, Anna Ford Mosby

Dissertations, Theses, and Masters Projects

The Ross Sea is a highly productive region of the Southern Ocean characterized by spatially variable distribution of phytoplankton, primarily Phaeocystis antarctica, but phytoplankton growth rates in the region have not been thoroughly investigated. Variability in growth rates was investigated from January to February 2012 on a cruise to the Ross Sea using two methods: 14C-isotopic tracer incubations and dilution experiments. Because all methods of measuring growth rates may not be appropriate in all systems due to errors inherent to each method, I assessed and compared the two methods for possible sources of error by examining the effect of extended …

Effects Of Episodic Turbulence On Diatoms: With Comments On The Use Of Evans Blue Stain For Live-Dead Determinations, Haley S. Garrison

Dissertations, Theses, and Masters Projects

Episodic turbulence is a short-lived, high-intensity phenomenon in marine environments produced by both anthropogenic and natural causes, such as boat propellers, strong winds, and breaking waves. Episodic turbulence has been shown to cause mortality in zooplankton, but its effects on marine phytoplankton have rarely been investigated. This study focused on two diatoms: Thalassiosira weissflogii and Skeletonema costatum. I found that exposure for 45 s to turbulence intensities above 2.5 cm2 s-3 caused 24-32% reduction in diatom abundance and increased the amount of intact dead cells to 22%. Turbulence also caused extracellular release of optically reactive DOM. At a turbulence level …

Composition, Sources, And Age Of Dissolved And Particulate Organic Matter In The Delaware River And Estuary, Hadley Allaben Mcintosh

Dissertations, Theses, and Masters Projects

Estuaries are important sites of organic matter (OM) transformation, exchange, and burial but remain one of the least understood regions in the global carbon cycle. The carbon cycle within these regions is complex due to strong gradients in biological and physical processes, and increasing anthropogenic impacts. This is further complicated by the many sources of particulate and dissolved organic matter (OM) in estuaries, including materials derived from terrestrial and anthropogenic sources as well as aquatic and marine primary production. This study combined lipid biomarker analyses with stable and radiocarbon signatures of lipids and source-specific biomarkers to better understand the sources …

Improvements In Triploid Crassostrea Virginica Production: Characterizing The Diploid Parent, Brian R. Callam

Dissertations, Theses, and Masters Projects

The effect of triploidy to effect faster growth and increased survival compared to diploid oysters is called the ‘triploid advantage’ and this advantage in the Chesapeake Bay for Crassostrea virginica is the principal reason for the value of triploid C. virginica in the Chesapeake Bay, USA. The triploid advantage is hypothesized to be the result of genetic effects, physiological changes, or a combination of both. The causative genetic mechanisms at play may include additive genetic effects and heterosis while the physiological changes obtain from triploid sterility. The triploid advantage was examined by comparing 13 diploid and 13 triploid crosses across …

Habitat And Fish Population Dynamics: Advancing Stock Assessments Of Highly Migratory Species, Patrick D. Lynch

Dissertations, Theses, and Masters Projects

Fisheries sustainability is inherently linked to an understanding of the population-level effects of fishing. With an accurate characterization of historical fish and fishery dynamics, management agencies are more equipped to create regulations that sustain fishery resources over the long term. The overarching goal of this dissertation is to contribute to the advancement of fisheries stock assessment and promote resource sustainability. My research focused on highly migratory species (HMS), particularly fishes that reside in the open ocean. These species constitute some of the highest valued global fisheries; however, numerous factors compromise HMS stock assessment and management. These challenges are fully described …

Foraging Ecology And Habitat Use Of The Northern Diamondback Terrapin (Malaclemys Terrapin Terrapin) In Southern Chesapeake Bay, Diane C. Tulipani

Dissertations, Theses, and Masters Projects

The northern diamondback terrapin (Malaclemys terrapin ) is the only estuarine turtle residing along western Atlantic and Gulf of Mexico coasts of North America. Through predation, terrapins may be a key species in coastal marine habitats by exerting top-down control on marsh invertebrates, and thereby help to maintain healthy marshes. Despite the terrapin's ecological importance, there has not been a thorough study of terrapin foraging ecology and movements in lower Chesapeake Bay. In this dissertation, the research focused on the foraging habits of diamondback terrapins and their effects within salt marsh and seagrass habitats of lower Chesapeake Bay. I provided …

Network Traffic Aware Smartphone Energy Savings, Andrew Joseph Pyles

Dissertations, Theses, and Masters Projects

In today's world of ubiquitous Smartphone use, extending the battery life has become an important issue. A significant contributor to battery drain is wireless networking. Common usage patterns expect Smartphones to maintain a constant Internet connection which exacerbates the problem.;Our research entitled A Network Traffic Approach to Smartphone Energy Savings focuses on extending Smartphone battery life by investigating how network traffic impacts power management of wireless devices. We explore 1) Real-time VoIP application energy savings by exploiting silence periods in conversation. WiFi is opportunistically placed into low power mode during Silence periods. 2.) The priority of Smartphone Application network traffic …