Physical Sciences and Mathematics Commons^™

Nonlocal Lorentz-Violating Modifications Of Qed, Qian Niu

Undergraduate Honors Theses

We consider nonlocal Lorentz-violating theories, with infinite-derivative quadratic terms. The nonlocal modifications in the form of exponential damping in the propagator lead to a better convergence of amplitudes than in the local theories. Moreover, the nonlocal Lorentz-violating theories are ghost-free and unitary when formulated in Minkowski space. We compute the loop effects assuming one-parameter and two-parameter nonlocal functions. By comparing the lower bound of the nonlocality scale with the Planck scale, we rule out these theories. We then review a more general argument, developed by Collins et al. (2004), that a microscopic theory with Lorentz violation around the Planck scale …

Developing Iron Complexes For Electrocatalytic Hydrogen Generation, Benjamin Travis

Undergraduate Honors Theses

Artificial photosynthesis systems convert solar energy into chemical fuels such as hydrogen gas. Photocatalytic hydrogen generation systems have previously been developed, but reliance on expensive metal catalysts limits the viability of these systems. In order for artificial photosynthesis to be used as a large-scale clean energy solution, it is crucial to discover more active and cost-efficient catalysts.

To this end, several novel iron polypyridyl complexes were synthesized using relatively inexpensive reactants. Electrochemical testing revealed that these complexes are active electrocatalysts for the reduction of protons to generate hydrogen gas. Furthermore, a naphthalene-terminated iron polypyridyl complex was found to be an …

Static And Dynamic Analysis In Cryptographic-Api Misuse Detection Of Mobile Application, Kunyang Li

Undergraduate Honors Theses

With Android devices becoming more advanced and gaining more popularity, the number of cryptographic-API misuses in mobile applications is escalating. Numerous snippets of code in Android are from Stack Overflow and over 90% of them contain several crypto-issues. Various crypto-misuse detectors come out aiming to report vulnerabilities of apps and better secure users’ privacy. These detectors can be broadly classified into two categories based on the analysis strategies employed to catch misuses – static analysis (i.e., by scanning the code base) and dynamic analysis (i.e., by executing the code). However, there are not enough research on comparing their underlying differences, …

Differential Nitrogen Uptake By Aquatic Communities In A Chesapeake Bay Tributary And In The Coastal Alaskan Arctic, Brianna Stanley

Dissertations, Theses, and Masters Projects

Nitrogen (N) is one of the essential building blocks for all life and is available in the form of dissolved N in aquatic ecosystems. It is important to understand how this N can support primary and secondary production mediated by phytoplankton and bacteria, respectively, as it can affect both microbial loop biogeochemistry and the higher trophic levels of food webs. Nitrogen studies have traditionally focused on dissolved inorganic N (DIN) as a labile N source. Dissolved organic N (DON), while still often considered refractory, has been increasingly recognized as an important N source supporting primary and secondary production. However, the …

Polyaromatic-Terminated Iron Polypyridyl Complexes For The Functionalization Of Carbon Surfaces And Electrocatalytic Hydrogen Generation, Caroline Marie Margonis

Dissertations, Theses, and Masters Projects

Artificial Photosynthesis (AP) focuses on developing methods for the conversion of solar energy into chemical fuel in the form of H2 and O2. Heterogeneous photocatalytic systems incorporating carbon nanotubes (CNTs) have shown much promise but are currently limited and expensive due to their reliance on noble metals. To that end, this work focuses on the development and synthesis of cheaper naphthalene- and pyrene-terminated iron polypyridyl complexes for use in the simultaneous functionalization of carbon surfaces, electrocatalytic proton reduction, and eventual incorporation in photocatalytic systems. Cyclic voltammetry was used to characterize the adsorption behavior of each complex on the surface of …

Performance Optimization With An Integrated View Of Compiler And Application Knowledge, Ruiqin Tian

Dissertations, Theses, and Masters Projects

Compiler optimization is a long-standing research field that enhances program performance with a set of rigorous code analyses and transformations. Traditional compiler optimization focuses on general programs or program structures without considering too much high-level application operations or data structure knowledge. In this thesis, we claim that an integrated view of the application and compiler is helpful to further improve program performance. Particularly, we study integrated optimization opportunities for three kinds of applications: irregular tree-based query processing systems such as B+ tree, security enhancement such as buffer overflow protection, and tensor/matrix-based linear algebra computation. The performance of B+ tree query …

Data-Driven Reflectance Estimation Under Natural Lighting, Victoria Cooper

Dissertations, Theses, and Masters Projects

Bidirectional Reflectance Distribution Functions, (BRDFs), describe how light is reflected off of a material. BRDFs are captured so that the materials can be re-lit under new while maintaining accuracy. BRDF models can approximate the reflectance of a material, but are unable to accurately represent the full BRDF of the material. Acquisition setups for BRDFs trade accuracy for speed with the most accurate methods, gonioreflectometers, being the slowest. Image-based BRDF acquisition approaches range from using complicated controlled lighting setups to uncontrolled known lighting to assuming the lighting is unknown. We propose a data-driven method for recovering BRDFs under known, but uncontrolled …

Ultrafast Optical Control And Characterization Of Carrier And Spin Dynamics In Novel Magnetic Topological Insulator Systems, Peiwen Liu

Dissertations, Theses, and Masters Projects

Magnetic topological insulators (MTIs) are of considerable interest in developing novel spintronics and quantum computing applications. Under the topological protection by time-reversal Z2 invariant number, magnetic topological insulators are provided with robust electronic and magnetic properties against local perturbations. The quantum anomalous Hall effect (QAHE), which harbors dissipationless chiral edge states in MTIs, provides a competitive platform for future low-power consumption and high-speed spintronic devices. Although the present studies on both bulk and surface magnetic properties in MTIs have made significant progress, the in-depth understanding of the exchange couplings and the interaction between the two magnetization sources is far from …

Evaluating Epoxy Cure And Adhesion Strength Through Single-Sided Nmr Measurements Of Molecular Mobility, Kayla Copeman

Dissertations, Theses, and Masters Projects

Commonly used in aerospace, automotive, marine, defense, electronic, and manufacturing industries, epoxy adhesives offer advantages over mechanical joints by providing stronger and/or more flexible bonds, more uniform stress distribution, low shrinkage, and lightweight connections between materials. Determination of curing kinetics and properties of interfaces between epoxy and inorganic substrates provides insight that is useful for quality control and defect detection for such applications. Single-sided NMR provides a nondestructive and inexpensive method for probing epoxy materials and spatially resolving the decay of spin-lattice and spin-spin relaxation times (T1 and T2) during and after curing of epoxy resins onto substrates. In this …

Impact Of Canyon Upwelling And Downwelling In The Mid-Atlantic Bight, Haixing Wang

Dissertations, Theses, and Masters Projects

Submarine canyons can impact regional oceanography and provide a conduit for shelf-slope exchanges via topographically induced processes such as canyon upwelling and downwelling. Between Virginia and New York in the Mid-Atlantic Bight (MAB), there are five major shelf-incising canyons (Norfolk, Washington, Baltimore, Wilmington, and Hudson canyons) and four sizable slope-confined canyons (Accomac, Spencer, Lindenkhol, and Toms canyons). Canyon upwelling and downwelling at these canyons have not been well studied. Consequently, the associated hydrographic variability and dynamics inside the canyons and on the adjacent shelf are largely unknown, and the integrated impact of submarine canyons on MAB shelf hydrography and shelf-slope …

Low-Overhead Techniques For Secure And Reliable Gpu Computing, Gurunath Kadam

Dissertations, Theses, and Masters Projects

In recent years, Graphics Processing Units (GPUs) have become a de facto choice to accelerate the computations in various domains such as machine learning, security, financial and scientific computing. GPUs leverage the inherent data parallelism in the target applications to provide high throughput at superior energy efficiency. Due to the rising usage of GPUs for a large number of applications, they are facing new challenges, especially in the security and reliability domains. From the security side, recently several microarchitectural attacks targeting GPUs have been demonstrated. These attacks leak the secret information stored on GPUs, for example, the parameters of a …

Water Clarity And Suspended Particle Dynamics In The Chesapeake Bay: Local Effects Of Oyster Aquaculture, Regional Effects Of Reduced Shoreline Erosion, And Long-Term Trends In Remotely Sensed Reflectance, Jessica Turner

Dissertations, Theses, and Masters Projects

Water clarity is a key indicator of the ecosystem health in the Chesapeake Bay. Estuarine water clarity fluctuates due to external inputs from the watershed as well as processes occurring within the estuary itself, such as sediment resuspension and organic matter production. Therefore, water clarity requires study at multiple spatial and temporal scales and with multiple metrics. One local-scale process potentially influencing water clarity is shellfish aquaculture. One part of this dissertation examined how water quality and hydrodynamics varied among oyster farms as well as inside versus outside the extent of caged areas located in southern Chesapeake Bay. Current speed …

Estuarine Microbiomes And Biogeochemistry: Impacts Of Spatiotemporal Variation, Algal Blooms, And Microplastics, Samantha Grace Fortin

Dissertations, Theses, and Masters Projects

Estuaries are biogeochemical hotspots connecting terrestrial and coastal ecosystems. Anthropogenic disturbances, including increased nitrogen loading and plastic pollution, may have significant impacts on estuarine carbon and nitrogen cycling by altering microbiome structure and functions. The overarching goal of this dissertation was to examine how microbiomes and their associated biogeochemical processes are influenced by natural variation and anthropogenic disturbances in the York River Estuary (YRE). In chapter 2, spatial and temporal variation in benthic microbiomes and the rates of denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were examined to determine biotic and abiotic drivers of nitrogen …

Sediment Transport And Trapping On The Ayeyarwady-Martaban Continental Shelf, Matthew Joshua Fair

Dissertations, Theses, and Masters Projects

The Ayeyarwady and Thanlwin Rivers, which primarily drain Myanmar, are together one of the largest point sources of freshwater and sediment to the global ocean. Much of the estimated 600 Mt of river sediment annually carried by the combined Ayeyarwady and Thanlwin River system is delivered to a wide continental shelf in the northern Andaman Sea. Called here the Ayeyarwady-Martaban continental shelf, this area is influenced by strong tides, monsoon conditions, and periodic cyclones; however, the processes that dominate dispersal of fluvial material in the coastal ocean of this system remain poorly understood. The shelf exhibits a dramatic asymmetry of …

A Pain Free Nociceptor: Predicting Football Injuries With Machine Learning, Andrew Lyubovsky

Undergraduate Honors Theses

Injuries are a significant aspect of every sport, with the ability to impact a player’s career and the success of a team in their season. As sensor data is able to pick up on a player’s physical state, recently it has been analyzed for its ability to predict player injuries. We inspect the predictive power of player stats, subjective player responses, GPS data, and training load data in forecasting game injuries from an NCAA American football team during the 2019 season. Data processing techniques are used to remove noise and decrease correlated data, and as large portions of the data …

Progress Towards Electromagnetic Manipulation And Trapping Of Micro-Particles, Andrew John Beling

Undergraduate Honors Theses

This thesis describes research to investigate the electromagnetic manipulation of microspheres and microrings. The work consists of three main thrusts: 1) the use of an electric field gradient to move dielectric microspheres, 2) the use of an AC magnetic field to move a conducting ring, and 3) the preparation of substrates for a microwave atom chip. The electrostatic movement of dielectric polyethylene microspheres was observed and recorded with a CCD imaging system. The microspheres were suspended in various liquids and placed on top of a microstrip transmission line, which consists of a conducting copper trace separated from a ground plate …

Investigating Charge Transfer Complexes In Brown Carbon Aerosols, Brianna Peterson

Undergraduate Honors Theses

Aerosols are suspensions of particles in the air, commonly seen as dust or fog in the atmosphere. Brown carbon is a particular classification of carbonaceous atmospheric aerosol that increases in absorption from the visible to ultraviolet region, making it important for radiative forcing models. Elucidating the structures of brown carbon chromophores has been difficult as brown carbon is a broad category and the chromophore type can change depending on emission source, temperature, humidity, and season. Twisted intramolecular charge transfer (TICT) molecules have been identified as potential brown carbon chromophores. TICT molecules are those that allow charge transfer to occur between …

Molecular Cluster Fragment Machine Learning Training Techniques To Predict Energetics Of Brown Carbon Aerosol Clusters, Emily E. Chappie

Undergraduate Honors Theses

Density functional theory (DFT) has become a popular method for computational work involving larger molecular systems as it provides accuracy that rivals ab initio methods while lowering computational cost. Nevertheless, computational cost is still high for systems greater than ten atoms in size, preventing their application in modeling realistic atmospheric systems at the molecular level. Machine learning techniques, however, show promise as cost-effective tools in predicting chemical properties when properly trained. In the interest of furthering chemical machine learning in the field of atmospheric science, I have developed a training method for predicting cluster energetics of newly characterized nitrogen-based brown …

Topology Of The O(3) Non-Linear Sigma Model Under The Gradient Flow, Stuart Thomas, Christopher Monahan

Undergraduate Honors Theses

Quantum field theory is an extraordinarily successful framework that describes phenomena in particle physics and condensed matter. The O(3) non-linear sigma model (NLSM) is a specific theory used in both of these fields, describing ferromagnets and acting as a prototype for the strong nuclear force. It features topologically stable configurations known as instantons which cannot continuously evolve to the ground state. The topological susceptibility is a parameter that describes this stability and is predicted to vanish in physical theories, however numerical simulations find that the topological susceptibility diverges in the continuum limit. This issue has motivated the application of the …

Determining Quantum Symmetry In Graphs Using Planar Algebras, Akshata Pisharody

Undergraduate Honors Theses

A graph has quantum symmetry if the algebra associated with its quantum automorphism group is non-commutative. We study what quantum symmetry means and outline one specific method for determining whether a graph has quantum symmetry, a method that involves studying planar algebras and manipulating planar tangles. Modifying a previously used method, we prove that the 5-cycle has no quantum symmetry by showing it has the generating property.

The Minimum Number Of Multiplicity 1 Eigenvalues Among Real Symmetric Matrices Whose Graph Is A Tree, Wenxuan Ding

Undergraduate Honors Theses

For a tree T, U(T) denotes the minimum number of eigenvalues of multiplicity 1 among all real symmetric matrices whose graph is T. It is known that U(T) >= 2. A tree is linear if all its vertices of degree at least 3 lie on a single induced path, and k-linear if there are k of these high degree vertices. If T′ is a linear tree resulting from the addition of 1 vertex to T, we show that |U(T′)−U(T)|

Simulation And Optimization Of Kinematics Measurements For The Moller Parity-Violating Electron-Electron Scattering Experiment, Lauren Carver

Undergraduate Honors Theses

This report describes the optimization of the sieve collimator that will be used for the MOLLER experiment at Jefferson Laboratory. The MOLLER experiment seeks to study the parity-violating asymmetry in electron-electron elastic scattering. For this project, Monte Carlo simulations were run using a GEANT4 simulation package, which includes the main geometry of the proposed experiment, and the essential physics reaction processes. A sieve collimator was added to the simulated geometry. This collimator has pin-hole openings to select scattered electrons at certain locations (radial and azimuthal positions) corresponding to specific scattering angles (theta, and phi). Analysis of the simulated data were …

Three Centuries Of Vegetation Change In The William & Mary College Woods Reconstructed Using Phytoliths, Timothy Terlizzi

Undergraduate Honors Theses

The College Woods, west of William & Mary’s campus, consists of ~900 acres of protected southern mixed hardwood forest. The woods surround Lake Matoaka, a former millpond established in ~1700. Despite the rich history of the area, little is known about how the dominant vegetative landcover has shifted over the last 300 years. This study set out to quantify the modern vegetation within the College Woods via the phytolith assemblages within the soil and identify shifts in the assemblages since the creation of Lake Matoaka and whether these changes are distinct from the vegetation that existed in the area before …

Performance Implications Of Memory Affinity On Filesystem Caches In A Non-Uniform Memory Access Environment, Jacob Adams

Undergraduate Honors Theses

Non-Uniform Memory Access imposes unique challenges on every component of an operating system and the applications that run on it. One such component is the filesystem which, while not directly impacted by NUMA in most cases, typically has some form of cache whose performance is constrained by the latency and bandwidth of the memory that it is stored in. One such filesystem is ZFS, which contains its own custom caching system, known as the Adaptive Replacement Cache. This work looks at the impact of NUMA on this cache via sequential read operations, shows how current solutions intended to reduce this …

A Survey Of Methods To Determine Quantum Symmetry Of Graphs, Samantha Phillips

Undergraduate Honors Theses

We introduce the theory of quantum symmetry of a graph by starting with quantum permutation groups and classical automorphism groups. We study graphs with and without quantum symmetry to provide a comprehensive view of current techniques used to determine whether a graph has quantum symmetry. Methods provided include specific tools to show commutativity of generators of algebras of quantum automorphism groups of distance-transitive graphs; a theorem that describes why nontrivial, disjoint automorphisms in the automorphism group implies quantum symmetry; and a planar algebra approach to studying symmetry.

“Garden-Magic”: Conceptions Of Nature In Edith Wharton’S Fiction, Jonathan Malks

Undergraduate Honors Theses

I situate Edith Wharton’s guiding idea of “garden-magic” at the center of my thesis because Wharton’s fiction shows how a garden space could naturalize otherwise inadmissible behaviors within upper-class society while helping a character tie such behavior to a greater possibility for escape. To this end, Wharton situates gardens as idealized touchstones within the built environment of New York City, spaces where characters believe they can reach self-actualization within a version of nature that is man-made. Actualization, in this sense, stems from a character’s imaginative escape that is enabled by a perception of the garden as a kind of natural …

Proteomic Analysis Of Mycobacteriophage Crimd, William Moeller

Undergraduate Honors Theses

Bacteriophages represent a large portion of the biomatter on our planet, and many of them have yet to be fully characterized. Here we discuss the proteomic analysis of a particular Bacteriophage, Mycobacteriophage CrimD. This phage was discovered on the Campus of William & Mary and has had its genome characterized. We took the next logical step of proteomic analysis.

In our analyses we made use high pressure liquid chromatography paired with linear ion trap mass spectrometry to analyze the proteome of CrimD at specific time points after the infection of its host, Mycobacterium smegmatis. Additionally, we used nanospray ionization with …

Using Machine Learning To Track The Location Of The Shock Train In Hypersonic Engines, Alison Reynolds

Undergraduate Honors Theses

Proposed hypersonic vehicles would be able to travel at five to ten times the speed of sound, but there are still many problems that need to be solved to construct a functioning vehicle. One such problem involves shocks created in the engine isolator when the vehicle reaches high speeds. These shocks must be contained to the isolator to maximize performance and avoid potential failure. This project attempts to track the location of the leading shock given images of airflow from ground tests of engines using random forests and convolutional neural networks. When the models are trained and tested on data …

Scope: Building And Testing An Integrated Manual-Automated Event Extraction Tool For Online Text-Based Media Sources, Matthew Crittenden

Undergraduate Honors Theses

Building on insights from two years of manually extracting events information from online news media, an interactive information extraction environment (IIEE) was developed. SCOPE, the Scientific Collection of Open-source Policy Evidence, is a Python Django-based tool divided across specialized modules for extracting structured events data from unstructured text. These modules are grouped into a flexible framework which enables the user to tailor the tool to meet their needs. Following principles of user-oriented learning for information extraction (IE), SCOPE offers an alternative approach to developing AI-assisted IE systems. In this piece, we detail the ongoing development of the SCOPE tool, present …

Contentious Vulnerability: Infrastructure, Assemblages, And Environmental Justice Communities, Mads Emmett

Undergraduate Honors Theses

Charles City County, Virginia has been the target of several large developmental proposals in recent years. Two of these proposed projects, the C4GT and Chickahominy natural gas power stations, have faced opposition from residents of Charles City County and people across the state who are concerned about the environmental impacts and health risks associated with fossil fuel infrastructure. These proposed power plants are part of an extensive assemblage of infrastructure: an uneven built network of physical and affective relationships brought together through contingencies which involves human and non-human parts and facilitates the distribution of resources and people around the world …