Physical Sciences and Mathematics Commons^™

Parameter Estimation For Patient Enrollment In Clinical Trials, Junyan Liu

Undergraduate Honors Theses

In this paper, we study the Poisson-gamma model for recruitment time in clinical trials. We proved several properties of this model that match our intuitions from a reliability perspective, did simulations on this model, and used different optimization methods to estimate the parameters. Although the behaviors of the optimization methods were unfavorable and unstable, we identified certain conditions and provided potential explanations for this phenomenon and further insights into the Poisson-gamma model.

A Satellite Imagery Approach To Estimating Migratory Flows In Guatemala Using Convolutional Neural Networks, Sarah Larimer

Undergraduate Honors Theses

Being able to predict migratory flows is important in ensuring political, social, and economic stability. In the wake of violence, unrest, natural disasters, and social pressures, millions of mi- grants have fled Central America in search of a better life. However, due to the infrequent nature and high cost of census data, there is a need for a more remote and up to date approaches. Con- volutional Neural Networks offer a computer vision based approach that is cheaper and with significantly less lag. In this study, we seek to evaluate the effectiveness of different convolu- tional neural networks in predicting …

Considering The Accuracy Of Fiat Boundaries: Ontology And Quantification, Lydia Troup

Undergraduate Honors Theses

Administrative boundaries - i.e., states, counties, or districts - are fiat boundaries; they exist purely as defined by human interpretation. Because of this, and despite their critical importance to government functions, the accuracy of data products claiming to represent such boundaries is difficult to measure. Here, I explore this topic using three boundary data sets: the open source geoBoundaries data set, the humanitarian UN OCHA’s Common Operational Datasets (COD), and Esri’s commercial administrative divisions 0 and 1 data sets in the Living Atlas. The accuracy of each was quantified as the percent overlap between each data set and an authoritative …

Development Of A 780 Nm External Cavity Diode Laser For Rubidium Spectroscopy, Catherine Sturner

Undergraduate Honors Theses

This thesis describes the work done to improve an external cavity diode laser. These improvements consisted of constructing an insulated housing to stabilize the temperature of the laser, tuning the proportional-integral-derivative feedback of the temperature controller, achieving resonance frequencies of rubidium, and implementing and optimizing feed-forward scanning of the frequency of the laser. The laser was then successfully used to measure the linewidth of another laser in the laboratory to better understand how that laser could be best used. The knowledge gained in this thesis can also be used to change the frequency of the laser to achieve other resonances …

Black Hole Entropy In Ads/Cft And The Schwinger-Keldysh Formalism, Luke Mrini

Undergraduate Honors Theses

The Schwinger-Keldysh formalism for non-equilibrium field theory provides valuable tools for studying the black hole information loss paradox. In particular, there exists a Noether-like procedure to obtain the entropy density of a system by a discrete Kubo-Martin-Schwinger (KMS) variation of the action. Here, this Noether-like procedure is applied to the boundary action of an asymptotically anti-de Sitter (aAdS) black hole spacetime in maximally extended Kruskal coordinates. The result is the Kubo formula for shear viscosity, which is known in theories with an Einstein gravity dual to have a universal, constant ratio with the entropy density and is proportional to the …

Automorphisms Of A Generalized Quadrangle Of Order 6, Ryan Pesak

Undergraduate Honors Theses

In this thesis, we study the symmetries of the putative generalized quadrangle of order 6. Although it is unknown whether such a quadrangle Q can exist, we show that if it does, that Q cannot be transitive on either points or lines. We first cover the background necessary for studying this problem. Namely, the theory of groups and group actions, the theory of generalized quadrangles, and automorphisms of GQs. We then prove that a generalized quadrangle Q of order 6 cannot have a point- or line-transitive automorphism group, and we also prove that if a group G acts faithfully on …

Monoenergetic Neutrinos From Wimp Annihilations In Jupiter, George French

Undergraduate Honors Theses

Several important lines of evidence point to the existence of dark matter, but it has not yet been experimentally detected. There are several proposed candidates for what dark matter is like, the most popular being weakly interacting massive particles (WIMPs). It has been well-established in the literature that WIMPs would be captured by the Sun after scattering off of atomic nuclei to a velocity lower than the escape velocity. Over time, many WIMPs would be captured and begin to annihilate in the solar core; this would result in the production of kaons that decay at rest into monoenergetic 236 MeV …

Materials Characterization For Microwave Atom Chip Development, Jordan Shields

Undergraduate Honors Theses

This thesis describes research to characterize materials to be implemented on a microwave atom trap chip, which will be able to trap and spatially manipulate atoms using the spin-specific microwave AC Zeeman effect. Potential applications of this research include atom-based interferometry and quantum computing.

Namely, this thesis describes the characterization of the following: (1) the dielectric constant of a well-characterized substrate, Rogers RO4350B, in order to provide proof-of-concept for a method that can be applied to the chip’s substrate, aluminum nitride (AlN), (2) the maximum current that will be able to be applied to the chip, and (3) surface roughness …

Fecal Pellet Production By North Atlantic Zooplankton, Michael Gibson

Undergraduate Honors Theses

Fecal pellet carbon (FPC) production by zooplankton is a significant component of the ocean’s biological carbon pump: the suite of biological processes that mediate export of carbon to the deep ocean, ultimately leading to the sequestration of atmospheric carbon dioxide in the ocean. In this study, mesozooplankton (zooplankton 0.2 mm to ~2 cm) were collected from the epipelagic zone in the temperate North Atlantic Ocean during day and night in May 2021. Zooplankton were live separated into five size fractions and incubated on board ship in natural surface seawater to measure fecal pellet production rate of the mixed mesozooplankton community. …

Seeing What We Can't: Evaluating Implicit Biases In Deep Learning Satellite Imagery Models Trained For Poverty Prediction, Joseph O'Brien

Undergraduate Honors Theses

Previous studies have sought to use Convolutional Neural Networks for regional estimation of poverty levels. However, there is limited research into possible implicit biases in deep neural networks in the context of satellite imagery. In this work, we develop a deep learning model to predict the tertile of per-capita asset consumption, trained on satellite imagery and World Bank Living Standards Measurements Study data. Using satellite imagery collected via survey location data as inputs, we use transfer learning to train a VGG-16 Convolutional Neural Network to classify images based on per-capita consumption. The model achieves an $R^2$ of .74, using thousands …

A Study Of Reciprocal Underwater Motion And Its Use In Algae Harvesting, Marguerite Bright

Undergraduate Honors Theses

In 2009, many research groups at different companies and universities were funded by Statoil to study the use of algae as a potential biofuel. Combined with the Chesapeake Bay TMDL given by the EPA, a team at William & Mary and VIMS studied the growth and harvest of wild algae in the York River. This method also removed harmful nutrients such as nitrogen and phosphorus from the waterways. Other independent research projects stemmed from this. In 2014, a research team sought to commercialize and automate the IWAGS system, and found that a single oscillating blade was the most effective. This …

Identifying Social Media Users That Are Susceptible To Phishing Attacks, Zoe Metzger

Undergraduate Honors Theses

Phishing scams are a billion-dollar problem. According to Threatpost, in 2020, business email compromise phishing attacks cost the US economy $ 1.8 billion. Social media phishing scams are also on the rise with 74% of companies experiencing social media attacks in 2021 according to Proofpoint. Educating users about phishing scams is an effective strategy for reducing phishing attacks. Despite efforts to combat phishing, the number of attacks continues to rise, likely indicative of a reticence of users to change online behaviors. Existing research into predicting vulnerable social media users that are susceptible to phishing mostly focuses on content analysis of …

Examining Factors Using Standard Subspaces And Antiunitary Representations, Paul Anderson

Undergraduate Honors Theses

In an effort to provide an axiomization of quantum mechanics, John von Neumann and Francis Joseph Murray developed many tools in the theory of operator algebras. One of the many objects developed during the course of their work was the von Neumann algebra, originally called a ring of operators. The purpose of this thesis is to give an overview of the classification of elementary objects, called factors, and explore connections with other mathematical objects, namely standard subspaces in Hilbert spaces and antiunitary representations. The main results presented here illustrate instances of these interconnections that are relevant in Algebraic Quantum Field …

Spatial Variability Of Alkali-Metal Polarization, Lauren Vannell

Undergraduate Honors Theses

An experiment was conducted at William & Mary to study how alkali polarization varies spatially in a spherical cell during the process of optical pumping. Similar cells are used to study the neutron via electron scattering from polarized 3He nuclei, and those experiments could be improved if alkali polarization is maximized and uniformly distributed throughout the cell. The results of this experiment indicate that the alkali polarization is non-uniform and more heavily concentrated on the side of the cell facing the pump laser.

Kfactorvae: Self-Supervised Regularization For Better A.I. Disentanglement, Joseph S. Lee

Undergraduate Honors Theses

Obtaining disentangled representations is a goal sought after to make A.I. models more interpretable. Studies have proven the impossibility of obtaining these kinds of representations with just unsupervised learning, or in other words, without strong inductive biases. One strong inductive bias is a regularization term that encourages the invariance of factors of variations across an image and a carefully selected augmentation. In this thesis, we build upon the existing Variational Autoencoder (VAE)-based disentanglement literature by utilizing the aforementioned inductive bias. We evaluate our method on the dSprites dataset, a well-known benchmark, and demonstrate its ability to achieve comparable or higher …

Pion Detection For The Moller Parity-Violating Electron Scattering Experiment, Michael Tristan Hurst

Undergraduate Honors Theses

The MOLLER Experiment at Jefferson Lab intends to make a precise measurement of the weak charge of the electron through parity-violating electron scattering. To achieve the level of precision required for the experiment, background rates of events other than electron-electron scattering must be known. Working with data from Monte-Carlo simulations created using a GEANT4 simulation package, I show that the combined signal from two existing detector subsystems of the MOLLER experiment allow for particle identification between electron and pion events. I worked to optimize an additional ‘Pion Exit Scintillator’ which improves the ability to distinguish particle identity at the cost …

Ecosystem Transitions And State Changes Rapidly Alter The Coastal Carbon Landscape: Evidence From The Chesapeake Bay Region, Alexander Jason Smith

Dissertations, Theses, and Masters Projects

The coastal landscape is a naturally shifting mosaic of distinct ecosystems that are rapidly migrating with climate change. While directional changes in climate, such as warming and sea level rise, are fundamentally reorganizing the coastal landscape, ecosystem function, especially carbon storage, is affected to an unknown degree. This dissertation presents four chapters that examine the role of ecosystem transitions in coastal carbon dynamics across a range of spatial scales – within individual ecosystems, between two ecosystems, and at the landscape between an array of ecosystems. Ghost forests, or the marsh-forest ecotone, serves as an ideal example of a migratory ecotone. …

A Reevaluation Of Why Crypto-Detectors Fail: A Systematic Revaluation Of Cryptographic Misuse Detection Techniques, Scott Marsden

Dissertations, Theses, and Masters Projects

The correct use of cryptography is central to ensuring data security in modern software systems. Hence, several academic and commercial static analysis tools have been developed for detecting and mitigating crypto-API misuse. While developers are optimistically adopting these crypto-API misuse detectors (or crypto-detectors) in their software development cycles, this momentum must be accompanied by a rigorous understanding of their effectiveness at finding crypto-API misuse in practice. The original paper presents the MASC framework, which enables a systematic and data-driven evaluation of crypto-detectors using mutation testing. MASC was grounded in a comprehensive view of the problem space by developing a data-driven …

Domain-Specific Optimization For Machine Learning System, Yu Chen

Dissertations, Theses, and Masters Projects

The machine learning (ML) system has been an indispensable part of the ML ecosystem in recent years. The rapid growth of ML brings new system challenges such as the need of handling more large-scale data and computation, the requirements for higher execution performance, and lower resource usage, stimulating the demand for improving ML system. General-purpose system optimization is widely used but brings limited benefits because ML applications vary in execution behaviors based on their algorithms, input data, and configurations. It's difficult to perform comprehensive ML system optimizations without application specific information. Therefore, domain-specific optimization, a method that optimizes particular types …

Appearance Driven Reflectance Modeling, James Christopher Bieron

Dissertations, Theses, and Masters Projects

Creating realistic computer generated imagery is essential for modern movies and video games. Recreating the appearance of materials is integral to generating such photo-realistic images. While the problem of how to model materials is well studied, here we will focus on the question of how to recreate the appearance of specific materials found in the real world. In this dissertation we will begin with a short introduction to rendering, followed by a discussion of various material models, techniques for measuring reflectance, and strategies for fitting these models to reflectance data. We will then introduce a novel two-stage process for fitting, …

Emerging Red Sore Disease Of American Eel (Anguilla Rostrata) In Chesapeake Bay: Etiology, Epidemiology, And Impacts In Aquaculture And The Wild, Amanpreet Kaur Kohli

Dissertations, Theses, and Masters Projects

Emerging infectious diseases in aquatic systems, both in aquaculture and in the wild, are a global concern. Many have proposed an uptick in marine diseases as a result of environmental changes including a warming climate, habitat modifications, trade and transfer of wildlife and aquaculture products, pollution, overharvesting of resources, and other anthropogenic impacts. These perturbations can disturb the delicate host-pathogen relationships and result in new diseases or exacerbate the existing diseases in a population. Diseases can lead to several direct and indirect effects in the ecosystem such as population declines and extinctions, and thereby a change in population dynamics, as …

Exploring Software Licensing Issues Faced By Legal Practitioners, Nathan James Wintersgill

Dissertations, Theses, and Masters Projects

Most modern software products incorporate open source components, which requires compliance with each component’s licenses. As noncompliance can lead to significant repercussions, organizations often seek advice from legal practitioners to maintain license compliance, address licensing issues, and manage the risks of noncompliance. While legal practitioners play a critical role in the process, little is known in the software engineering community about their experiences within the open source license compliance ecosystem. To fill this knowledge gap, a joint team of software engineering and legal researchers designed and conducted a survey with 30 legal practitioners and related occupations and then held 16 …

Program Analysis For Software Engineers And Students, Jialiang Tan

Dissertations, Theses, and Masters Projects

Software inefficiencies are inevitable in computer systems. At the code level, software packages have become increasingly complex, they are comprised of a large amount of source code, sophisticated control and data flow, and growing levels of abstraction. This complexity often introduces inefficiencies across software stacks, leading to performance degradation. At the resource level, the evolution of hardware outpaces the performance optimization of software, leading to resource wastage and energy dissipation in emerging architecture. To better understand program behaviors, software developers take advantage of performance profiling tools. Existing profiling techniques, whether fine-grained profilers or coarse-grained profilers focus on identifying hotspots, which …

Artificial Illumination Of Trawl Gear Components To Reduce Pacific Halibut (Hippoglossus Stenolepis) Bycatch In The U.S. West Coast Groundfish Bottom Trawl Fishery, Derek Jackson

Dissertations, Theses, and Masters Projects

Pacific halibut (Hippoglossus stenolepis) is a prohibited species for the U.S. West Coast Bottom Trawl Fishery and in the last decade, there has been a concentrated interest in the use of artificial illumination serving as a potential bycatch reduction device. Previous studies conducted off the coast of Oregon have found that the addition of green light-emitting diodes to the bridles of low-rise, cutback trawls greatly reduced the number of Pacific halibut caught. However, recent regulation changes now permit high-rise trawls, a gear configuration that fishes a very different volume of water than the previously permissible gear profile, in areas where …

Environmental Education In The Classroom: Selected Early-Career Teachers' Experiences Navigating Pre-Service And In-Service Activity Systems, Sarah Mcguire Nuss

Dissertations, Theses, and Masters Projects

Recent publications argue that to prepare teachers of all grade levels to be confident and competent in incorporating environmental education into their classrooms, pre-service teacher training is effective (e.g., J. T. McDonald & Dominguez, 2010). But the systems in which teachers learn and work are complex, making professional learning about, and implementation of, environmental education both disparate and limited (Franzen, 2017). This study sought to understand the nature of participants’ experiences within and between teacher preparation and in-service learning systems as they relate to environmental education. Cultural historical activity theory (CHAT) provided a framework to allow for deeper understanding of …

From Field To Shore: Policy Improvements To Better Protect Ecosystem And Human Health From Poultry Wastes In Virginia, Rachael A. King

Dissertations, Theses, and Masters Projects

Commercial poultry production is a large industry with economic importance in Virginia. However, mismanagement of manures and wastes generated from the poultry industry can be a serious threat to ecosystem and human health. Primarily, there is a concern about nutrient pollution related to runoff and infiltration of poultry wastes. High nutrient loading can cause groundwater contamination, eutrophication, and harmful algal blooms (HABs). Additional concerns include metals, antibiotics, and pesticides that can be found in poultry wastes. To determine existing threats to ecosystem and human health from the poultry industry, Virginia policies regulating the industry are reviewed and their strengths and …

Learning-Based Ubiquitous Sensing For Solving Real-World Problems, Woosub Jung

Dissertations, Theses, and Masters Projects

Recently, as the Internet of Things (IoT) technology has become smaller and cheaper, ubiquitous sensing ability within these devices has become increasingly accessible. Learning methods have also become more complex in the field of computer science ac- cordingly. However, there remains a gap between these learning approaches and many problems in other disciplinary fields. In this dissertation, I investigate four different learning-based studies via ubiquitous sensing for solving real-world problems, such as in IoT security, athletics, and healthcare. First, I designed an online intrusion detection system for IoT devices via power auditing. To realize the real-time system, I created a …

Tracing Atlantic Sea Scallops Using Radio Frequency Identification (Rfid) Technology, Will Shoup

Dissertations, Theses, and Masters Projects

Traceable seafood can be linked back to its origin and method of catch. Improving the traceability of marine organisms involves establishing a transparent Chain of Custody (CoC) by collecting data at checkpoints throughout the supply chain, from ship to shore to store. This report explores the feasibility of integrating Radio Frequency Identification (RFID) technology into the United States Atlantic sea scallop (Placopecten magellanicus) fishery in order to improve traceability. This report serves as a forward-looking evaluation of RFID technology that is intended to inform interested stakeholders of its functionality and capabilities. It is not intended to serve as a management …

Constraining Of The Minerνa Medium Energy Neutrino Flux Using Neutrino-Electron Scattering, Luis Zazueta

Dissertations, Theses, and Masters Projects

Long baseline neutrino oscillation experiments rely on the flux from accelerator-based neutrino beams. As experimental neutrino physics moves to the next generation of experiments a precise characterization of the neutrino flux on a given experiment becomes crucial to the goals of the experiments: to precisely determine the neutrino oscillation parameters.This work takes advantage of neutrino-electron scattering processes for their precisely predicted cross section. The observed number of scattering events can be used as a benchmark to constrain the neutrino flux. A measurement was made of the energy spectrum of neutrino-electron elastic scattering (νe-→νe-), using data from the antineutrino-enhanced run period …

Chesapeake Bay Carbonate Cycle: Past, Present, And Future, Fei Da

Dissertations, Theses, and Masters Projects

Multiple natural and anthropogenic drivers are expanding the variability of the estuarine carbonate system (CO2 system). These changes in the CO2 system are threatening the health of ecologically and economically important bivalve species. This dissertation investigates the Chesapeake Bay CO2 system by using numerical models and historical water quality data, focusing on the past three decades, the contemporary period, and the late 2060s. In Chapter 2, sensitivity experiments are conducted with a 3-D Chesapeake Bay hydrodynamic-biogeochemical model and reveal that the magnitude of decadal trends in the CO2 system over the past 30 years is much greater than that observed …