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Polish Immigration to America: The Complicated History of Poland that Led to Mass Exodus
No full textPopulation estimates of shorebirds on the Atlantic Coast of southern South America generated from large-scale, simultaneous, volunteer-led surveys
No full textPopulation abundance and trend estimates are crucial to science, management, and conservation. Shorebirds, which are abundant in many coastal habitats and play important roles in coastal ecosystems, are facing some of the most dramatic population declines of any group of birds globally. However, accurate and up-to-date population estimates are lacking for most shorebird species. We thus conducted large-scale, simultaneous, and community scientist-led surveys of the Atlantic Coast of southern South America, stretching from central Brazil to Tierra del Fuego, to gather counts of shorebirds stratified by habitat that we combined with remote sensing analyses and two-step hurdle models that accounted for presence and abundance. Our objectives were to estimate shorebird densities by habitat, identify high-concentration areas, understand the environmental factors affecting their distributions, and provide population estimates for both Nearctic and Neotropical species. We counted a total of 37,207 shorebirds of 17 species and, from those counts, estimated that nearly 1.1 million shorebirds use the region’s coastline. We found that the northern portion of the region was important for sandy beach specialists, while southern portions supported higher abundances of species that rely on intertidal mudflat and rocky habitats. We also found that shorebirds occurred in the highest densities in wetland habitats and that fewer shorebirds occupied areas that were further away from estuaries. Although not directly comparable, our results suggest the population sizes of the Nearctic species whose nonbreeding ranges are predominantly in southern South America may have declined substantially since previous estimates. At the same time, our study represents the first empirically derived population estimates for Neotropical breeding shorebird species and indicates that they are far more abundant than previously thought. Taken together, our results highlight the power of community scientists to carry out structured protocols at continental scales and generate critical data for a group of at-risk species
GENOME-WIDE ANALYSES OF RESISTANCE TO DMI AND FLUAZINAM FUNGICIDES IN DOLLAR SPOT, CAUSED BY CLARIREEDIA JACKSONII
No full textDollar spot, caused by the newly renamed ascomycete fungus Clarireedia jacksonii, is the most prevalent and economically important turfgrass disease worldwide. Despite fungicides remaining the primary tool for managing the disease, the rise of fungicide resistance-especially to demethylation inhibitors (DMIs)-poses a growing challenge to effective control. This study provides a comprehensive investigation into the mechanisms of DMI resistance in C. jacksonii, focusing on a highly propiconazole-resistant isolate (HRI11) and a sensitive isolate (HRS10). Through whole-genome sequencing and hybrid assembly, we discovered that HRI11 harbors genetic variants in transcription factors, transporters, and fungicide target genes, contributing to its baseline resistance. Additionally, the adaptive upregulation of efflux pumps in response to fungicide stress enhances energy efficiency, further strengthening the isolate’s resistance. A novel mutation was also identified in the sterol-sensing domain (SSD) of the HMG-CoA reductase gene (hmg1) in HRI11. However, this mutation alone did not fully account for the observed resistance, suggesting that multiple factors contribute to the high-level azole resistance in HRI11.
Fluazinam resistance was detected in field isolates collected from New England golf courses, marking the first documented case of reduced fluazinam sensitivity in Clarireedia isolates in the United States. Both in vitro and field-inoculated trials demonstrated that the fluazinam insensitivity observed in the lab was associated with reduced field efficacy, particularly under high disease pressure and when applied at half-label rates. Historical data showed that isolates collected after 2017, following several years of fluazinam use, exhibited significantly higher EC50 values, further confirming that prolonged exposure might contribute to reduced sensitivity.
Together, these findings underscore the urgent need for proactive resistance monitoring and the implementation of integrated management strategies to preserve fungicide efficacy against dollar spot. The identification of hmg1 mutations as a novel genetic determinant of azole resistance, coupled with the emerging evidence of fluazinam resistance, highlights the critical need for diversified fungicide programs and responsible stewardship practices to delay resistance development and protect turfgrass health.Doctor of Philosophy (Ph.D.)2026-05-1
CONTROLLING PRESENCE AND TOXICITY OF DISINFECTION BYPRODUCTS BY PRE- AND POST- TREATMENT APPROACHES
No full textDisinfection by-products (DBPs) are a group of regulated and unregulated compounds produced as unintended consequences of water disinfection. Toxicological studies revealed that the unregulated species possess 2-4 magnitude of toxicity higher than the currently regulated DBPs. To protect public health from the DBP-related health risks, USEPA is considering expanding the current haloacetic acid rule (HAA5) to HAA9 to include four more brominated HAAs. However, the regulatory shift might cause burdens to utilities and may not achieve the desired health goals. Questions need to be answered to support the regulatory decision such as whether an HAA9 based maximum contaminant level (MCL) controls DBP toxicity better than the current HAA5 MCL. Chapter 1 of this dissertation investigated the effectiveness of two HAA9 MCLs and the current HAA5 rule to control DBP total toxicity on three separate utilities. The performance of five precursor removal strategies on three types of raw surface water were tested to achieve the MCLs. The effectiveness of MCLs and the treatment performance was water dependent. Results indicated that HAA9-based MCLs are more effective in controlling DBP toxicity for raw water with high bromide levels, while for low bromide water, there was no significant difference in the DBP toxicity control between HAA9-based MCLs and the current HAA5 MCL.
Impact of treatments on toxicity control varies across water, since the effectiveness of those treatments on DBP precursor removal is different. Chapter 2 dived into the mechanisms of DBP precursor removal by those five treatment scenarios. Results showed that coagulation controlled the formation of various DBP groups to differing extents. Oxidation processes, such as ozonation and chlorine dioxide application, modified the chemical characteristics of DBP precursors, thereby influencing their subsequent removal efficiency by coagulation. Both oxidants were observed to shift natural organic matter (NOM) toward more hydrophilic and lower molecular weight fractions, which are inherently more difficult to remove through conventional coagulation. The combination of coagulation with granular activated carbon (GAC) or ion exchange (IX) has proven effective in reducing precursor levels across multiple DBP classes. However, these approaches may be less effective in controlling brominated DBPs (Br-DBPs), as bromide removal by both media types is typically less efficient than NOM removal. This discrepancy results in an elevated Br:DOC ratio, thereby enhancing the formation potential of Br-DBPs. Notably, when media doses are sufficiently high, NOM removal becomes dominant, and the formation of Br-DBPs is limited. These findings highlight the critical importance of optimizing media dosage to achieve effective control of both DBP formation and associated toxicity.
As discussed in the first 2 chapters, water treatment measures can only limit the formation of DBPs to a certain level. Some DBPs, especially Br-DBPs which are recalcitrant to precursor removal strategies, are formed and reached to consumers tap. Multiple methods are applied at point-of-use (POU) to remove DBPs, including oxidation, adsorption and filtration, which all have limitations. Such as replacement of absorbents and filters are needed to maintain removal efficiency, which can be costly. There are safety concerns about chemical handling. Adding strong oxidants into water might form other hazardous compounds. UVLED, however, does not have these concerns. Furthermore, according to the molar absorptivity, Br- and I-DBPs are more photosensitive than Cl-DBPs, meaning that the more toxic the DBP compound is, the more degradable it is by UV. Therefore, we can target the toxic compounds by UV photolysis. Chapter 3 explored in batch system the capability of DBP photolysis in real water matrix by UV LED under four wavelengths: 255, 265, 280 and 295nm. The calculated additive toxicity (CAT) decrease was calculated under each wavelength to indicate the impact of UV LED on DBP total toxicity. Time-based and fluent-based decay rate constant of each species was analyzed. Electrical energy per order (EEO) was calculated to indicate energy consumption. Results illustrate that UV LED is effective in degrading the Br-DBPs in real water and controlling DBP posed total toxicity. With more bromide in the compound, the photolysis is faster and more energy efficient. The decay rate constant increased while the EEO decreased as the number of halogens or molecular weight of the brominated compound increased. For example, the decay rate constants of HAAs followed the order of tri- > di- > mono-HAAs. Rate constant of DBAA was higher than BCAA. EEO ranked as MBAA > BCAA > DBAA > BDCAA > CDBAA. Toxicity decreased to the highest extent under 265nm. 255nm is the most energy effective wavelength to degrade most of the compounds, followed by 265nm, 280nm and 295 nm. Top four toxicity driving species were MBAA, DCAN, BCAN and TCAA. Toxicity decrease was due to the removal of toxicity driving brominated DBPs, MBAA and BCAN. Removals of the 2 chlorinated toxicity drivers were not as much. The dose required to achieve Br-DBP removal and toxicity decrease was higher than typical disinfection dose (40mJ/cm2). As the cleavage energy to break halogen-carbon bond is higher than pathogen inactivation.Water Research Foundation
WRRC USGSDoctor of Philosophy (Ph.D.
Role of Charge Patterning and Hydrophobicity in Peptide-Based Complex Coacervates
No full textComplex coacervation has emerged as a powerful model for studying the self-assembly of intrinsically disordered proteins (IDPs) in biological condensates in cells. We characterized the phase behavior and rheology of coacervates formed from peptides with regular repeating sequences to examine the effects of charge patterning and hydrophobicity on coacervate stability and material properties. Our results show that increasing the size of charged blocks enhances salt resistance via electrostatic cooperativity, while incorporating small hydrophobic segments further stabilizes coacervates and increases viscosity through hydrophobic clustering. Interestingly, our results involving alanine as the neutral residue suggest that structural conformations present for peptides with shorter block sizes may contribute to increased viscosity within the coacervate phase. Overall, these findings underscore the potential of sequence-controlled materials as versatile platforms for engineering self-assembling materials with tunable mechanical and phase properties
Work in the Digital Era: The Economic, Social, and Political facets of Popular Computer-centered Automation Technologies in the US Labor Environment
No full textI study the way that beliefs about the purpose of technology, as well as its design by management and developers, impact the day-to-day opportunities and roles of wage workers. I define opportunities widely to include personal development, autonomy, and economic wellbeing. I conceptualize processes of automation, and the technology involved in them as sites of struggle, and there are struggles. Despite the US recent economic success, an impressive rebound from the 2007 recession and a similar if muted struggle through the covid-19 pandemic, inequality and wage stagnation are still significant problems. Thus, the main questions of the overall project are ‘Can we create a more just set of social relations given that contemporary capitalist labor is increasingly based on managerial software?’, and ‘What role can a refreshed, and newly nuanced, understanding of computing, automation, and the ostensible “objectivity” of those technologies bring to our pursuit of that aim?’ I figure computer-centered automation systems as sociotechnical phenomena relevant to multiple registers of concern including: contemporary forms of inequity, prevailing understandings of technology, contemporary social relations of labor and capital, and the relational features and material effects of specific sociotechnical systems whose creation and deployment rely on and promote the existence of epistemic features such as the false binary of bias vs objectivity in the functioning of sociotechnical phenomena. Rather than simply dichotomizing technology and automation processes as either the cause of, or solution to, worker inequality I figure them as potential sources of opportunity for equality and democratic participation if their development is democratized. In our increasingly mechanized and automated world, the time and space for critical participation is shrinking. We have become reliant on moments of democratic participation, and even these are few and far between. By conceptualizing the development of technology and processes of automation as sites of struggle I am also positing them as important moments for democratic participation. Moments when more than just upper management should have a voice as to the purposes and uses of our shared intellectual projectsSummer 2024 Graduate School Dissertation Completion Fellowship
Sawyer Seminar Dissertation FellowshipDoctor of Philosophy (Ph.D.)2026-05-1
Biomarkers in postmenopausal breast cancer etiology and risk prediction
No full textBiomarkers are important tools in epidemiologic research. They can be used to elucidate the etiology of a disease and in risk prediction modeling. However, the large study population, long follow-up time for sufficient case accrual, expense and logistics of sample collection and biomarker measurement are substantial hurdles to overcome in biomarker studies. Collaborations with multiple large cohort studies allow for pooling data to increase analytic sample size and statistical power. Thus we have established a collaboration between four prospective cohort studies: the Nurses’ Health Study, the Generations Study, the Mayo Mammography Health Study, and the Melbourne Collaborative Cohort Study in order to pool data and resources to establish a large dataset with questionnaire, plasma hormone, mammographic density, and genotype data.
In Chapter 1, we conducted an analysis on the association between plasma c-peptide and postmenopausal invasive breast cancer using data from the B2RISK consortium. Our study provides, to our knowledge, the largest prospective assessment of this association including 3557 cases and 4825 non-cases.
In Chapter 2, we assessed the performance of three existing breast cancer risk prediction models, the Gail model, the Rosner-Colditz model, and the simplified Rosner-Colditz model. We extended these models using biomarker data collected as part of the B2RISK consortium including: a polygenic risk score, percent mammographic density, and plasma hormones. In conclusion, our findings suggest apositive association between plasma c-peptide and postmenopausal breast cancer. This association did not vary by standard breast cancer risk factors of tumor molecular characteristics, nor was this association fully accounted for by the correlation of c-peptide and other hormonal risk factors. We also confirmed and validated, in independent populations, previous analyses that showed large improvements that mammographic density and polygenic risk scores offer to breast cancer risk models. We further determined that plasma estradiol significantly improves the performance of breast cancer risk prediction models in postmenopausal women not taking exogenous hormones.R01 CA207369Doctor of Philosophy (Ph.D.)2026-05-1
AI-Driven Misinformation: A Comparative Legislation Analysis
No full textArtificial intelligence (AI) plays a growing role in the creation and spread of misinformation, which raises urgent policy challenges. This paper uses a six-dimensional framework to compare how China, the European Union, and the United States regulate AI-driven misinformation. Through analysis of policy documents since 2020, we identify distinct approaches: China emphasizes centralized oversight; the EU adopts a risk-based regulatory model; and the US takes a fragmented, proposal-focused stance. These findings highlight the diverse ways governments are framing and addressing AI-related misinformation and suggest areas for future research and policy development
Controlling Selectivity Toward Dehydration or Fission in Acid-Catalyzed Aldol Reactions
No full textAldol reactions are important carbon-carbon bond-forming processes crucial to bulk and fine chemical synthesis, with growing interest in their use for converting bio-derived feedstocks into chemicals and fuels. Despite their versatility and wide-ranging applications, controlling selectivity in aldol reactions remains a significant challenge because of the formation of multiple products, including primary self- and cross-condensation derivatives and secondary aldol condensation products. Moreover, the fission reaction, a competing carbon-carbon bond-cleavage event to olefins and carboxylic acids, has garnered interest as a sustainable route for producing industrially relevant compounds such as isobutene from acetone self-condensation. Conventional strategies for selectivity control often rely on soluble catalysts and specialized reagents; however, these methods often involve expensive separations, generate significant wastes, and pose environmental concerns. This dissertation investigates the factors governing selectivity in acid-catalyzed aldol reactions, aiming to develop sustainable, selective pathways for the aldol chemistry.
Key reaction pathways in aldol reactions—dehydration and fission—are revealed to proceed as parallel reactions of a shared aldol intermediate. The catalyst type exerts a strong influence on selectivity. While soluble Brønsted acids favor the dehydration pathway, solid Brønsted acids preferentially promote the fission pathway. Poisoning experiments with base probes of varying pore accessibilities underscore the role of void size and Brønsted acid site in driving fission, with larger void sizes in microporous solids correlating with enhanced fission selectivity.
The role of acid strength in influencing reaction rates and selectivity is also elucidated using zeolites with varying trivalent heteroatoms. For soluble acids, stronger acid sites accelerate condensation reactions without altering product distribution. For microporous solid acids, both pore topology and Brønsted acid strength influence selectivity and reaction rates toward the fission pathway.
Reactant electronic properties are also shown to significantly impact selectivity. Hammett analysis reveals that electron-donating substituents enhance reaction rates, with solid acids exhibiting greater sensitivity to electronic effects than their soluble counterparts. Furthermore, cross-aldol reactions using diverse substrates produce olefins and carboxylic acids of industrial relevance through the fission pathway, although at varying yields.
Overall, this work demonstrates that selectivity in aldol reactions can be strategically modulated through careful selection of catalysts and substrates. These findings provide a foundation for advancing selective and sustainable aldol chemistries, offering significant potential for industrial applications.National Science Foundation. Grant Number 1804041
U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Catalysis Science. Award Number DE-SC0021041Doctor of Philosophy (Ph.D.)2026-05-1