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Expanding the phosphine source in hydrophosphination: An exploration into phosphine electronics in P–C bond forming reactions
No full textUndergraduateHydrophosphination is an atom–economical way to form phosphorus–carbon bonds. Phosphines have highly tunable steric and electronic properties which makes them ideal for exploratory hydrophosphination. Cu(acac)2 is a general precatalyst for hydrophosphination, aided by photochemical conditions, and is highly active for alkenes. Several diaryl phosphines will be synthesized, with varying substituents in the parasubstituted position. Understanding how adjusting the electronics at phosphorus could tune the chromophore allows for a deeper understanding of phosphorus chemistry. Furthermore, hydrophosphination with a variety of phosphines will yield novel, highly sought after products. These novel phosphines have also shown promise as useful organometallic ligands
The co-evolution of individuals and institutions: a group-based approach
No full textHumans are unique in their ability to cooperate as groups to address large-scale collective action problems. This capacity emerges from the co-evolution of cultural psychology and group-level behaviors, resulting in multiscale dynamics from smallgroups (e.g., households) to large institutions (e.g., countries, firms). This thesis develops a framework for modeling the co-evolution of individuals and institutions from a group-based perspective. Drawing on insights from complex systems, philosophy, and cultural evolution, we show how traditional network dynamics are qualitatively transformed by adopting group-based formalisms that jointly represent institutional dynamics and individual behavior. As a first step, we recount the tumultuous history of group ontology, showing how assumptions about the existence of groups have shaped research methodologies throughout the twentieth century. Building on this foundation, we introduce a typology that maps conceptual views of groups onto modeling assumptions from the physics of higher-order interactions. This typology illustrates how progressively stronger ontological commitments—from momentary multi-way interactions to persistent and potentially misaligned group structures—enable richer representations of group dynamics. To formalize these ideas, we propose a group-based master equation framework that captures both enduring group structures and the co-evolution of cultural group traits. We then present two case studies in group-based modeling that reinterpret diffusion dynamics through a group-level lens. The first integrates institutions into contagion models, revealing a counterintuitive dynamic: higher infection rates can lead to smaller utbreaks due to a call for action–given how a contagion spreads, we might see varying institutional responses. The second examines the emergence of new skills in research groups, using programming in the humanities as a case study. Here, groups face a trade-off between accelerating their computational transition—potentially at the cost of overburdening individuals–or adapting more slowly to accommodate learning curves. Finally, we present preliminary empirical investigations grounded in our framework. One project models the co-evolution of COVID-19 contagion and government policy responses; the other examines the computational turn in the humanities, focus-ing on tensions between group-level incentives and individual costs of acquiring new skills. We conclude by reflecting on the theoretical challenge of integrating collective intentionality–how shared perceptions among individuals shape group behavior–into formal group-based models.Complex Systems and Data ScienceDoctor of Philosophy (PhD
How Does Floodplain Geomorphic Heterogeneity Influence Flood Routing Dynamics?
No full textThe routing of a flood can influence whether a flood wave is attenuated (i.e., slowed and/or reduced in magnitude) as it moves downstream, which is critical for mitigating flood hazards. Floodplains can influence the routing of floods by reducing flow velocity and providing temporary storage of floodwaters. Existing literature shows how various reach characteristics (e.g., slope, roughness, etc.) and flood wave characteristics influence flood attenuation. However, there has been little focus on how the variability of topographic features, or geomorphic heterogeneity (GH), of floodplains influences flood attenuation by altering unit-scale hydraulic processes. We performed unsteady flow simulations using HEC-RAS 2D models for two study sites in Vermont, United States that had contrasting reach characteristics. The sites also had contrasting floodplain topographic characteristics—different composition (shapes, sizes, etc.) and spatial configurations (distances from channel, orientations, etc.) of meso-scale topographic units (landforms on the order of a few meters to tens of meters in length). We isolated the effect of floodplain topography at each site by comparing flood routing between the natural floodplain and a smoothed floodplain in which the meso-scale topography was removed, leaving no distinct topographic units. Differences in topographic unit variability between the sites were evaluated using unit area, aggregation, distance from channel, elongation, orientation and overall rugosity of the floodplain. We analyzed changes in discharge attenuation, celerity, and stream power at the reach scale and changes in flow velocity and inundation duration at the topographic unit scale. We examined differences between three flood magnitudes at each site and between sites. At the reach scale, we found that the Lemon Fair River with its lower gradient and wider floodplain naturally attenuated >50% of upstream discharge, whereas the Lewis Creek, with a steeper gradient and narrower floodplain, attenuated ~4%. For both sites, we found that floodplain GH had a minimal (though measurable) impact on discharge attenuation but a much more pronounced effect on reducing stream power. Topographic units at Lemon Fair River had more variation in distance from the main channel, concave units were less elongated and had a wider range of orientations relative to those Lewis Creek, which were largely oriented downstream. Removing GH from the floodplain had consistent effects on inundation duration and flow velocity for convex units but different effects for concave and flat units between the two sites. These variations suggest that the potential effects of floodplain GH on flood routing are partly controlled by the specific composition and configuration of floodplain units as well as partly controlled by key reach characteristics (e.g., slope). Findings of this study showed that floodplain GH at our sites has a much stronger potential to mitigate fluvial erosion hazards via stream power reduction than potential to reduce inundation hazards via discharge attenuation. Relationships between topographic unit shapes and flow hydraulics can be applied to alter inundation durations (e.g., to affect biogeochemical processes) or to reduce floodplain flow velocities (e.g., to encourage sediment deposition). This study also demonstrates how hydrodynamic models that represent floodplains as flat and featureless may be missing important changes in routing being induced by floodplain GH.GeologyMaster of Science (MS
Crystallization kinetics of SnO2:Nb2O5 thin films
No full textUndergraduateNiobium oxide (NbOx) thin films have potential in the semiconductor industry as circuit element materials, for applications such as neuromorphic computing. To enable their integration into current fabrication processes, it is important to understand NbOx thin film properties. My project focuses on understanding the impact of alloying NbOx with SnO2 on crystallization kinetics. NbOx-SnO2 thin films are deposited onto silicon wafers using atomic layer deposition (ALD) and then annealed under various conditions. I then characterize these samples using a combination of Raman spectroscopy and optical analysis to evaluate crystallization kinetics and ultimately produce time-temperaturetransition (TTT) diagrams for this materials system
2024 Industrial Hemp Fiber Field Retting Trial
No full textHemp is a non-psychoactive variety of Cannabis sativa L. The crop is one of historical importance in the U.S. and is reemerging in worldwide importance as manufacturers seek hemp as a renewable and sustainable resource for a wide variety of consumer and industrial products. The fiber has high tensile strength and can be used to create a variety of goods. Hemp stalks contain two types of fiber: bast and hurd. The bast fibers are the long fibers found in the bark layer of the hemp stalk and are best suited for applications like textiles, nonwovens, rope, insulation, bio-composites for vehicles, and paper. The hurd fiber comprises the woody core of the stem and is suited for building materials, such as hempcrete and particle boards, animal bedding materials, and absorbents. For decades, U.S. entrepreneurs have been importing hemp fiber from China and Eastern Europe. Therefore, industrial hemp is poised to be a “new” cash crop and potential market opportunity for Vermont farms. It is also versatile and suitable for rotation with cereal grains, corn, and other grasses. To help farmers succeed, agronomic research on hemp is needed, as much of the historical production knowledge for the region has been lost. Once hemp is mowed it must “ret” or rot in the field. This microbial process decomposes the glues that bind the outside bast fiber to the internal hurd core. The goal of this trial is to document the retting process to create guidance for farmers on when the retting process should be complete. If the hemp fiber is allowed to ret too long, the fiber may be too low quality for most applications. During this trial, we evaluated duration of retting on hemp fiber yield and quality
Identifying Perceived Barriers to Postpartum Healthcare Among Patients and Healthcare Professionals in Vermont
No full textBackground Social Determinants of Health (SDOH) uniquely impact those seeking out women’s healthcare, as women and minority groups are more vulnerable to the poor health outcomes SDOH create. SDOH ultimately result in unequal distribution of healthcare services to individuals accessing postpartum care, consequently increasing the risk of illness for the postpartum population. Objective The purpose of this study is to identify the most significant barriers to accessing postpartum healthcare in Vermont. Methods This study employed a descriptive observational research design with use of online surveys for data collection. Patient and healthcare professional participant groups completed anonymous surveys on the Qualtrics platform regarding their experiences giving and/or receiving postpartum care. The 18-item survey consisted of multiple-choice, Likert scale, and short answer questions. Descriptive statistics were calculated for frequency distribution of both patient and healthcare professional self-perceived barriers to postpartum care. Categorical observations were made using the Stats iQ feature on Qualtrics. Results Participants (n=12) identified a new theme that has not been previously addressed in postpartum SDOH research; difficulty prioritizing postpartum care amidst other postpartum responsibilities. Both the healthcare professional and patient populations expressed that new parents have low prioritization of their own healthcare needs in relation to other responsibilities – newborn healthcare, transportation needs, food insecurity, housing insecurity, and work. The SDOH identified as having the most significant impact on access to postpartum care across participant population groupings were low health literacy, lack of transportation, low income, social biases/stereotypes, poor English proficiency, and lack of social support. Conclusions Healthcare professionals indicate that a lack of supportive resources result in difficulty accessing and prioritizing one’s own healthcare over other needs. The development and implementation of advanced education regarding community resources for new parents may increase social support and help to alleviate transportation, food, and housing insecurities.Nursin
Biofilms: The Latest ‘blockbuster’ In Preweaned Holstein Calf Management
Full text linkMany bacteria form biofilms, an extracellular polysaccharide (EPS) that allows adherence to surfaces and protection from environmental assaults. The molecular and cellular characteristics of certain biofilm-forming bacteria demonstrate inhibitory effects against pathogenic agents and interact positively with commensal gastrointestinal bacteria to promote growth and development. There is opportunity to expand understanding of their functionality as promoters of growth and development, complements to cleaning and disinfection procedures, and alternatives to antimicrobials, which is a relatively new area of research in intensive animal-rearing systems. More evidence is needed to elucidate the interplay of beneficial biofilms with other environmental factors and relationships to animal health and development, and current knowledge and gaps in the literature are discussed. This dissertation will examine application of beneficial biofilm-forming bacteria as 1) a complement to a cleaning procedure, and 2) direct-fed microbial interventions to influence gastrointestinal health, feed intake, and rumen development in the pre-weaned calf. In Chapter 2, we first develop an on-farm method to evaluate a multi-species, beneficial biofilm-forming cocktail of Bacillus spp. and Pediococcus spp. for adherence to naïve polyethylene calf hutch material, and second, to determine if application in situ to individual calf hutches post-cleaning (n=30) influenced surface recolonization by enteric pathogens. To our knowledge, this study is the first use in individual pre-weaned calf housing. Applying the beneficial biofilm-forming solution to calf hutches 24 h after cleaning influenced the microbial population on the surfaces and potentially reduced the presence of certain pathogenic bacteria on high-contact interior surfaces. We next explore, in Chapter 3, the use of the fermented cows’ milk beverage kefir as a practical and efficient on-farm probiotic supplement under different management conditions in. Holstein heifer calves (n=148) on three Northern New York farms were randomized at 3 d of age to receive either a control of 60 mL salable whole milk (or nothing) or 60 mL kefir 1x/d in liquid diet until 21 d of life. Although kefir was only supplemented until 21 d of life, increases in feed intake in supplemented calves on one farm suggests there may be residual metabolic or physiological benefit that merits further investigation. Production of EPS in kefir may be enhanced by co-fermenting with Saccharomyces cerevisiae. Chapter 4 outlines a practical laboratory methodology for evaluating four different concentrations of commercially available dried, activated distiller’s yeast or autolyzed yeast powder for EPS optimization in kefir. An inclusion rate of 1% autolyzed yeast powder achieved this objective. Chapter 5 discusses the effects of supplementing kefir fermented with or without 1% autolyzed yeast powder on dry matter intake, intestinal permeability, and rumen fermentation profile of Holstein calves. Holstein heifers (n=81) were randomized at 3 d of age to receive either 125 mL of salable whole milk (CON), 125 mL kefir (KEF), or 125 mL of kefir fermented with 1% autolyzed yeast powder (YAK) until 28 d of life. Rumen fermentation profile, starter intake, and body weight gain were improved in YAK calves compared with KEF and CON. This work provides more data to support the use of kefir as a practical probiotic supplement in calves and the implementation of beneficial EPS in calf-rearing environments.Animal BiosciencesDoctor of Philosophy (PhD
Pilot Study of Antimicrobial-Resistant Enteric Bacteria Identifies Shared Strain Types on a Vermont Dairy Farm
No full textWe explored the potential transmission of enteric pathogens and antibiotic resistance genes between birds and cattle on the UVM Miller farm. We hypothesized we would isolate the same enteric bacterial strain types from birds and cattle living on the same farm, and that these bacteria carry the same antibiotic resistance genes. We collected cow, calf, and bird fecal samples and cattle feed samples, isolated bacteria using MacConkey’s agar with and without cefotaxime, a third-generation cephalosporin, and ciprofloxacin, a second-generation fluoroquinolone, and determined species identity and antibiotic resistance genes using whole genome sequencing.Animal Scienc
Flames and Roots: Exploring Wildfires and Place Attachment in Trinity County, California
No full textThis research explores the importance of place attachment in choosing to stay in a fire-prone region of the United States. Drawing on a qualitative research approach including semi-structured interviews and a mixed-method online questionnaire, this research explores how rural geographies and wildfire inform attachments to Trinity County, California. The findings suggest that residents of Trinity County perceive fire as a natural part of their lives and choose to live there in part due to a strong sense of place attachment. The research found that residents’ engagement in the landscape through wildfire mitigation work allows for the development of a sense of agency in the face of natural hazards, thus, empowering them as active agents in shaping their relationship to fire. The study brings attention to the unique challenges and experiences faced by rural communities such as Trinity County, contributing to a more comprehensive understanding of wildfire impacts beyond well-studied urban areas. Further, it calls for rethinking wildfire resilience to include conceptions of place attachment.Environmental Studie
Characterizing the effect of genetic diversity on temperature-dependent behaviors in Drosophila melanogaster
No full textEnvironmental conditions shape behavioral decisions critical for survival and reproduction, yet individuals within a species often respond differently to the same conditions. While previous research has demonstrated that Drosophila melanogaster shift their feeding behavior in response to temperature, these studies do not account for genetic diversity in natural populations, limiting our understanding of how genetic variation influences this response. In this study, I used the Drosophila Genetics Reference Panel (DGRP) to examine genotype-dependent variation in feeding preference and egg-laying behavior at different temperatures. I found that while some genotypes shifted their feeding preferences from yeast-based to plant-based diets in cold environments, others maintained consistent feeding behavior or exhibited a response in the opposite direction. Egg-laying behavior in a cold environment also varied by genotype, with some flies conserving energy by not laying eggs, while others showed significant investment in eggs. These results suggest that the proposed adaptive shift in diet and reproductive investment under cold conditions is not a universal strategy but rather one influenced by genetic background. By highlighting genetic variation in these behaviors, this study underscores the importance of incorporating genetic diversity when investigating how organisms respond to environmental challenges.Biolog