Digital Commons Network^™

Shining Light On The Storm: Using High-Frequency Optical Water Quality Sensors To Characterize And Interpret Storm Nutrient And Carbon Dynamics Among Contrasting Land Uses, Matthew Ch Vaughan

Graduate College Dissertations and Theses

Elevated nutrient concentrations present significant challenges to surface water quality management globally, and dissolved organic matter mediates several key biogeochemical processes. Storm events often dominate riverine loads of nitrate, phosphorus, and dissolved organic matter, and are expected to increase in frequency and intensity in many regions due to climate change. The recent development of in situ optical sensors has revolutionized water quality monitoring and has highlighted the important role storms play in water quality. This dissertation focuses on improving the application of in situ optical water quality sensors and interpreting the high-frequency data they produce to better understand biogeochemical and …

Ecosystem Function Along An Elevational Gradient In Vermont, Emily Page Piche

Graduate College Dissertations and Theses

Living (biotic) and non-living (abiotic) factors drive the function of ecosystems across a variety of scales from the root-soil interface to the watershed. Biotic and abiotic global change pressures such as increasing temperature and invasive species are shifting how ecosystems function. Thus, exploring and understanding how these factors shape function across the landscape is an important research area. For example, climate change both directly and indirectly affects soil microbial functions – such as carbon mineralization and nitrogen transformations – through increasing activity under warming and altering inputs to the soil through species composition changes. Mountains provide a useful tool for …

Expansion Of The Intramolecular Zwitterionic-1,3-Diaza-Claisen Rearrangement Beyond Bridged-Bicyclic Electron-Deficient Isothioureas To Generate Substituted Cyclic Guanidines, Matthew William Luedtke

Graduate College Dissertations and Theses

Guanidines are ubiquitous in nature and have important applications in biological chemistry and industry, presenting themselves in biomacromolecules and organic materials respectively. The zwitterionic-1,3-diaza-Claisen rearrangement has allowed facile access to a variety of highly-substituted, complex guanidines, which would otherwise require a significant amount of time or resources to synthesize.

Previously, the intramolecular version of the 1,3-diaza-Claisen rearrangement has been used to generate tricyclic guanidines from bridged, bicyclic electron-deficient isothioureas. Extension of this methodology to simpler electron-deficient isothioureas has afforded stable zwitterionic intermediates, which have been isolated via silica gel column chromatography with common organic solvents. Heating the zwitterionic intermediates in …

Measuring Linguistic And Cultural Evolution Using Books And Tweets, Tyler Gray

Graduate College Dissertations and Theses

Written language provides a snapshot of linguistic, cultural, and current events information for a given time period. Aggregating these snapshots by studying many texts over time reveals trends in the evolution of language, culture, and society. The ever-increasing amount of electronic text, both from the digitization of books and other paper documents to the increasing frequency with which electronic text is used as a means of communication, has given us an unprecedented opportunity to study these trends. In this dissertation, we use hundreds of thousands of books spanning two centuries scanned by Google, and over 100 billion messages, or ‘tweets’, …

Higher-Order Runge--Kutta Type Schemes Based On The Method Of Characteristics For Hyperbolic Equations With Crossing Characteristics, Jeffrey Steven Jewell

Graduate College Dissertations and Theses

The Method of Characteristics (MoC) is a well-known procedure used to find the numerical solution of systems of hyperbolic partial differential equations (PDEs). The main idea of the MoC is to integrate a system of ordinary differential equations (ODEs) along the characteristic curves admitted by the PDEs. In principle, this can be done by any appropriate numerical method for ODEs. In this thesis, we will examine the MoC applied to systems of hyperbolic PDEs with straight-line and crossing characteristics. So far, only first- and second-order accurate explicit MoC schemes for these types of systems have been reported. As such, the …

Modeling Agricultural Outcomes In A Warmer, Wetter Vermont, Rachel Mason

Graduate College Dissertations and Theses

This thesis aimed to model agricultural outcomes that are important to Vermont dairy farms and their surrounding communities -- runoff, erosion, nitrogen and phosphorus losses, crop yields, and timeliness of farm operations -- under a set of possible future climates. The Agricultural Policy/Environmental eXtender (APEX) model was used for this work, and the models were calibrated using data from a project that measured most of these outcomes on a set of local farms. The model setup and calibration methodology is thoroughly documented and may be a useful starting point for others who are new to agricultural modeling.

Applied to two …

I. Contorted Polycyclic Aromatic Hydrocarbons: Attempted Synthesis Of [12]Circulene Derivatives Ii. Synthesis And Characterization Of Novel [1]Benzothieno[3,2-B][1]Benzothiophene Derivatives, Jonathan Hollin

Graduate College Dissertations and Theses

There has been increasing interest in the development of organic materials due to their unique structural and electronic properties. Organic compounds have the advantage of being able to be deposited from solution, leading to low-cost, high-area electronics production. Contorted polycyclic aromatic hydrocarbons have been shown to have potential for use in organic field-effect transistors (OFETs) and organic photovoltaic devices (OPVs) due to their supramolecular properties and charge carrier mobilities. Thiophene-based materials have also shown great promise in OFETs due to their high charge carrier mobilities, stability during device operation, solubility in organic solvents, and structural versatility.

[n]Circulenes are a class …

Rehab Tracker: Framework For Monitoring And Enhancing Nmes Patient Compliance, Timothy Stevens

Graduate College Dissertations and Theses

We describe the development of a cyber-physical system (Rehab Tracker) for improving patient compliance with at-home physical rehabilitation using neuromuscular electrical stimulation (NMES) therapy. Rehab Tracker consists of three components: 1) hardware modifications to sense and store use data from an FDA-approved NMES therapy device and provide Bluetooth communication capability, 2) an iOS-based smartphone/tablet application to receive and transmit NMES use data and serve as a conduit for patient-provider interactions and 3) a back-end server platform to receive device use data, display compliance data for provider review and provide automated positive and remedial push notifications to patients to improve compliance. …

Modeling Electric Vehicle Energy Demand And Regional Electricity Generation Dispatch For New England And New York, Sarah E. Howerter

Graduate College Dissertations and Theses

The transportation sector is a largest emitter of greenhouse gases in the U.S., accounting for 28.6% of all 2016 emissions, the majority of which come from the passenger vehicle fleet [1,2]. One major technology that is being investigated by researchers, planners, and policy makers to help lower the emissions from the transportation sector is the plug-in electric vehicle (PEV). The focus of this work is to investigate and model the impacts of increased levels of PEVs on the regional electric power grid and on the net change in CO2 emissions due to the decrease tailpipe emissions and the increase in …

Multiscale Expression Of Apatite Dissolution, Adele Conde

Graduate College Dissertations and Theses

The weathering of apatite is the foundation of the phosphorus cycle and essential to life, yet little is known about the nanoscale mechanisms driving apatite weathering. Deciphering nanoscale dissolution in apatite is a significant step to understand phosphate weathering behavior, that was key to the development of life. Determining what controls apatite weathering can impact many areas of environmental and medical mineralogy such as dentistry, contaminant scavenging, geochronology, and paleoenvironment studies. The aim of this study was to characterize apatite dissolution across scales with an emphasis on the nanoscale mechanisms. Recent research on the weathering of silicate minerals at the …

Spectroscopic Study Of The Formation And Degradation Of Metalated Tetrapyrroles By The Enzymes Cfba, Isdg, And Mhud, Ariel E. Schuelke-Sanchez

Graduate College Dissertations and Theses

Metal tetrapyrroles represent a large class of earth-abundant catalysts but are limited to naturally-occurring combinations. Chelatase enzymes are responsible for the catalyzed metal insertion into a specific tetrapyrrole. CfbA is a class II chelatase from Archaeaglobis

fulgidus that catalyzes the insertion of nickel into sirohydrochlorin to give rise to Coenzyme F430 required for methanogensis. This archaeal chelatase was used to study the substrate scope of divalent metals and tetrapyrroles to probe various metal tetrapyrrole

combinations. A spectroscopic study established that the CfbA is capable of binding to cobalt and nickel, in addition to various tetrapyrroles. Magnetic circular dichroism (MCD) established …

Residual Soil Phosphorus In Tropical Oxisols: An Opportunity To Enhance Fertilizer Use Efficiency?, Lauren Bomeisl

Graduate College Dissertations and Theses

Phosphorus (P) is essential to life on Earth and often the limiting nutrient in agricultural systems. P fertilizer is thus an essential resource to maintain food security. In the last half century, agricultural intensification has led to an increase in P fertilizer consumption from 4.6 to 17.5 Tg of P/year to meet rising global food demand. Mineral P (i.e., phosphate rock) is a non-renewable resource in the context of the Anthropocene, and its price is vulnerable to global market fluctuations. Increased efficiency of P use on farms is considered the most effective strategy to conserve P. The soybean industry demands …

Edge-Of-Field Hydrology And Nutrient Fluxes Within Northeastern Agroecosystems: Evaluation Of Alternative Management Practices And Water Quality Models, Cameron Robert Twombly

Graduate College Dissertations and Theses

Agricultural runoff is one of largest contributors of phosphorus (P), nitrogen (N), and sediment affecting freshwater systems in watersheds across the Northeastern U.S., including the Lake Champlain Basin in Vermont. Agricultural cropping systems, such as corn silage and haylands, used for dairy feed production have been shown to impact watershed hydrology and water quality. Agricultural best management practices (BMPs) have the potential to decrease runoff volumes and flow rates and the associated export of nutrients and sediment from agricultural fields. Many states in the Northeastern U.S., including Vermont, are beginning to require farmers to implement water quality BMPs and further …

Characterizing And Quantifying Vaccine Discourse Patterns On Social Media Amidst Global Pandemics, Amelia Tarren

Graduate College Dissertations and Theses

Globally, the 2019 Coronavirus pandemic (COVID-19) impacted and threatened the everyday lives and wellbeing of humanity. The development of a vaccine resulted in widespread discourse on social media platforms like Twitter, leading to potentially divergent sentiments about the COVID-19 vaccine. Given the novelty and polarity of vaccine sentiment and discourse, critical knowledge gaps exist as to how these factors develop. This study aims to characterize rapidly growing vaccine-specific dis- course by identifying words and phrases connected to the anchor 1-gram "vaccin*", the derivative of "vaccination" and "vaccinate", amongst others. This study draws from a collection of social media posts on …

On The Application Of Computational Modeling To Complex Food Systems Issues, Serge William Wiltshire

Graduate College Dissertations and Theses

Transdisciplinary food systems research aims to merge insights from multiple fields, often revealing confounding, complex interactions. Computational modeling offers a means to discover patterns and formulate novel solutions to such systems-level problems. The best models serve as hubs—or boundary objects—which ground and unify a collaborative, iterative, and transdisciplinary process of stakeholder engagement. This dissertation demonstrates the application of agent-based modeling, network analytics, and evolutionary computational optimization to the pressing food systems problem areas of livestock epidemiology and global food security. It is comprised of a methodological introduction, an executive summary, three journal-article formatted chapters, and an overarching discussion section.

Chapter …

Phosphorus Mobility And Speciation Under Dynamic Redox Conditions In Shallow Eutrophic Freshwater Systems, Austin Wilkes

Graduate College Dissertations and Theses

Internal loading of phosphorus (P) from lake sediments can delay the recovery of lakes from eutrophication for years to decades following decreases in external nutrient inputs. While internal P loading is a pervasive problem in freshwater systems, molecular speciation of P in benthic sediments of these systems remains poorly characterized. As different P species will exhibit different responses to changing sediment-water interface (SWI) geochemistry, quantifying P speciation in sediments is a critical step in understanding P dynamics in sediment-water systems. Here, various synchrotron-based techniques were employed to directly probe the bonding environments of P and iron (Fe) in natural and …

Quadrature-Based Gravity Models For The Homogeneous Polyhedron, Jason Pearl

Graduate College Dissertations and Theses

A number of missions to comets and asteroids have been undertaken by major space organizations driving a need to accurately characterize their gravitational fields. This is complicated however by their irregular shapes. To accurately and safely navigate spacecraft in these environments, a simple point-mass gravity model is insufficient and instead higher-fidelity models are required. Several such models exist for this purpose but all posess drawbacks. Moreover, there are some applications for which the currently available models are not particular well suited.

In this dissertation, numerical quadrature and curvilinear meshing techniques are applied to the small body gravity problem. The goal …

Climate Change And Land Use/Cover Change Impacts On Watershed Hydrology, Nutrient Dynamics – A Case Study In Missisquoi River Watershed, Linyuan Shang

Graduate College Dissertations and Theses

Watershed regulation of water, carbon and nutrient dynamics support food, drinking water and human development. Projected climate changes and land use/cover change (LUCC) have been identified as drivers of watershed nutrient and hydrological processes and are likely to happen jointly in the future decades. Studying climate change and LUCC impacts on watersheds' streamflow and nutrients dynamics is therefore essential for future watershed management.

This research aimed to unveil how climate change and LUCC affect water and nutrient dynamics in the Missisquoi River watershed, Vermont. We used 12 scenarios of future climate data (2021 – 2050) generated by three GCMs (ccsm4, …

Uncovering The Drivers Of Non-Native Plant Invasions Using Ecological Data Synthesis, Marina Golivets

Graduate College Dissertations and Theses

Understanding what promotes invasiveness of species outside their native range and predicting which ecosystems and under which conditions will be invaded is an ultimate goal of the field of invasion ecology. Obtaining general answers to these questions requires synthesis of extensive yet heterogeneous empirical evidence, coupled with a solid theoretical background. In this dissertation, I sought to provide insight into the drivers of non-native plant invasions through combining and synthesizing ecological data from various sources using advanced statistical techniques. The results of this work are presented as three independent research studies.

In the first study, I aimed to understand what …

Quantum Entanglement Of One-Dimensional Spinless Fermions, Emanuel Casiano-Diaz

Graduate College Dissertations and Theses

The constituents of a quantum many-body system can be inextricably linked, a phenomenon known as quantum entanglement. Entanglement can be used as a resource for quantum computing, quantum communication and detecting phase transitions, among others. The amount of entanglement can be quantified via the von Neumann and Rényi entropies, which have their origins in information theory.

In this work, the quantum entanglement between subsystems of a one dimen- sional lattice model of fermions is quantified. The von Neumann and Rényi entropies were calculated for two types of subsystems. In the first study, the subsystems were treated as two subsets of …

Exploring The Modularity And Structure Of Robots Evolved In Multiple Environments, Collin Cappelle

Graduate College Dissertations and Theses

Traditional techniques for the design of robots require human engineers to plan every aspect of the system, from body to controller. In contrast, the field of evolu- tionary robotics uses evolutionary algorithms to create optimized morphologies and neural controllers with minimal human intervention. In order to expand the capability of an evolved agent, it must be exposed to a variety of conditions and environments.

This thesis investigates the design and benefits of virtual robots which can reflect the structure and modularity in the world around them. I show that when a robot’s morphology and controller enable it to perceive each …

An Analysis Of Energy Transitions At Different Scales: Fossil Fuel Divestment In Higher Education And Individual Behavior, Elizabeth Palchak

Graduate College Dissertations and Theses

A sociotechnical energy transition requires both a shift to new technologies and attention to social issues like political movements, policy and human behavior. This dissertation investigates social elements of the renewable energy transition occurring at different scales. The core research questions are: How are universities creating and responding to the shifting language of fossil fuel investments? How and for whom do behavioral interventions work? And finally, do in-home displays (IHDs) change behaviors and attitudes of millennial energy users?

The three studies covered here occurred within higher education and reflect the importance of colleges and universities as dynamic players in energy …

Evaluation Of Mysis Partial Diel Vertical Migration, Brian Patrick O'Malley

Graduate College Dissertations and Theses

Mass animal migrations represent large movements of biomass, energy, and nutrients with predictable patterns and important ecosystem-level consequences. Diel vertical migration (DVM) in aquatic systems, the daily movement of organisms from deeper depths during the day to shallower depths in the water column at night, is widespread in freshwater and marine systems. Recent studies, however, suggest partial migration behavior, whereby only some portion of a population migrates, is the rule rather than the exception in a range of migratory fauna, including those that undergo DVM. Hypotheses to explain why partial migrations occur complicate traditional views on DVM and challenge conventional …

Physicochemical Properties Of Residuals From Anaerobic Digestion Of Dairy Manure And Food Waste: Nutrient Cycling Implications And Opportunities For Edible Mushroom Cultivation, Brendan J. O'Brien

Graduate College Dissertations and Theses

Organics recycling is increasing in New England as multiple states have enacted laws to divert organic materials, including food scraps and food processing residuals, away from landfills. Anaerobic digesters on dairy farms represent an attractive approach to food waste recycling because existing infrastructure is in place and co-digestion of dairy manure with food waste can increase renewable biogas production. In addition, anaerobic digestion results in effluents that can be separated into solid and liquid residual materials, or 'digestates'. Screw-press separated solids consist of lignocellulosic biomass resistant to microbial degradation during anaerobic digestion. These separated solids are typically recycled on farms …

Local Farmer Knowledge Of Adaptive Management On Diversified Vegetable And Berry Farms In The Northeastern Us, Alissa White

Graduate College Dissertations and Theses

Agricultural adaptation to climate change is notoriously context specific. Recently updated projections for the Northeastern US forecast increasingly severe and erratic precipitation events which pose significant risks to every sector of agricultural production in the region. Vegetable and berry farmers are among the most vulnerable to the risks of severe precipitation and drought due to the intensive soil and crop management strategies which characterize of this kind of production. To successfully adapt to a changing climate, these farmers need information which is tailored for the unique challenges of vegetable and berry production, framed at the level of climate impacts, and …

Applications In Sentiment Analysis And Machine Learning For Identifying Public Health Variables Across Social Media, Eric Michael Clark

Graduate College Dissertations and Theses

Twitter, a popular social media outlet, has evolved into a vast source of linguistic data, rich with opinion, sentiment, and discussion. We mined data from several public Twitter endpoints to identify content relevant to healthcare providers and public health regulatory professionals. We began by compiling content related to electronic nicotine delivery systems (or e-cigarettes) as these had become popular alternatives to tobacco products. There was an apparent need to remove high frequency tweeting entities, called bots, that would spam messages, advertisements, and fabricate testimonials. Algorithms were constructed using natural language processing and machine learning to sift human responses from automated …

Metal Catalyzed Group 14 And 15 Bond Forming Reactions: Heterodehydrocoupling And Hydrophosphination, Michael Cibuzar

Graduate College Dissertations and Theses

Investigation of catalytic main-group bond forming reactions is the basis of this dissertation. Coupling of group 14 and 15 elements by several different methods has been achieved. The influence of Si–N heterodehydrocoupling on the promotion of α-silylene elimination was realized. Efficient Si–N heterodehydrocoupling by a simple, earth abundant lanthanide catalyst was demonstrated. Significant advances in hydrophosphination by commercially available catalysts was achieved by photo-activation of a precious metal catalyst.

Exploration of (N3N)ZrNMe2 (N3N = N(CH2CH2NSiMe3)33–) as a catalyst for the cross-dehydrocoupling or heterodehydrocoupling of silanes and amines suggested silylene reactivity. Further studies of the catalysis and stoichiometric modeling reactions hint …

Increasing Private Contributions To Environmental Goods With Behavioral Insights, Hilary Byerly Flint

Graduate College Dissertations and Theses

Privately owned lands often undersupply environmental benefits and oversupply environmental costs through land use and management decisions. Insights into human behavior suggest a range of cognitive biases and nonstandard preferences that offer alternative explanations for and, perhaps, strategies to influence landowner behavior. People respond to simple changes in context and framing, make inconsistent choices over time, and respond to social influence—the opinions and behavior of peers.

This dissertation applies insights from behavioral science to strategies that seek to influence individual decisions that impact the environment, especially related to land management. First, I review existing experimental research on behavioral insights to …

Mathematical Analysis Of Some Partial Differential Equations With Applications, Kewang Chen

Graduate College Dissertations and Theses

In the first part of this dissertation, we produce and study a generalized mathematical model of solid combustion. Our generalized model encompasses two special cases from the literature: a case of negligible heat diffusion in the product, for example, when the burnt product is a foam-like substance; and another case in which diffusivities in the reactant and product are assumed equal. In addition to that, our model pinpoints the dynamics in a range of settings, in which the diffusivity ratio between the burned and unburned materials varies between 0 and 1. The dynamics of temperature distribution and interfacial front propagation …

Consumer Support For Renewable Energy Systems: A Case Study Of Community Biodigesters In Vermont, Katelynn Maria Conedera

Graduate College Dissertations and Theses

From the steady rise in dairy farm closures to concerns over algae blooms in Lake Champlain, Vermont’s dairy industry is facing a multitude of challenges. While many potential solutions have been proposed, this study focuses specifically on community anaerobic digester systems (CADS) to aid in manure management, help to mitigate runoff, produce renew energy, and even provide an alternative revenue source to participating farms. CADS technology converts the gas emissions from manure and other organic substances into biogas through a process called anaerobic digestion. Unlike traditional on-farm biodigesters, which are often only financially viable for the largest dairy farms, CADS …