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Title: ESR studies of alicyclic radicals in adamantane
Creator: Song, John Choo Wang, 1949-
Date: 1977
Collection: Electronic Theses & Dissertations

Title: ESR studies of 1,1-dithiol complexes with niobium (IV)
Creator: Kirksey, Kirby, 1945-
Date: 1975
Collection: Electronic Theses & Dissertations

Title: ESEEM studies of the oxygen evolving complex of photosystem II
Creator: Mac, Michelle
Date: 1993
Collection: Electronic Theses & Dissertations

Title: ER stress sensor IRE1-alpha and its implications in progression of hepatocellular carcinoma
Creator: Oak, Amrita
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "The endoplasmic reticulum (ER) is the site for protein folding and maturation. ER stressors, both physiological and pharmacological, can result in activation of the unfolded protein response (UPR). Palmitate, a saturated fatty acid, is one such ER stressor and leads to induction of the UPR. This is primarily through the activation of Inositol Requiring Enzyme-1 (IRE1) leading to splicing of XBP1 mRNA. However, the mechanism of this activation is unclear. With the aid of a bimolecular...
Show more"The endoplasmic reticulum (ER) is the site for protein folding and maturation. ER stressors, both physiological and pharmacological, can result in activation of the unfolded protein response (UPR). Palmitate, a saturated fatty acid, is one such ER stressor and leads to induction of the UPR. This is primarily through the activation of Inositol Requiring Enzyme-1 (IRE1) leading to splicing of XBP1 mRNA. However, the mechanism of this activation is unclear. With the aid of a bimolecular fluorescence complementation (BiFC) assay, we identified two crucial residues on the transmembrane domain (TM) of IRE1, S450 and W457, that are drivers of palmitate mediated activation. Previous research from our group suggested that IRE1 also has binding sites for palmitate on its cytosolic domain (CD). However, IRE1-CD protein expressed in E. coli was over-phosphorylated which possibly affected its binding to PA. To investigate this, we developed a protocol for expression and purification of wild type and mutant IRE1-CD protein in insect Sf21 cells. A fluorescence polarization based binding assay was performed to determine whether palmitate binds to residues on the IRE1-CD protein. Previously our laboratory demonstrated that palmitate induced the migration of cancer cells as well as transcription factors (TF) involved in epithelial-to-mesenchymal transition (EMT). Here, we investigated the role of IRE1 activation on these processes. Using CRISPR gene editing to generate IRE1 knockouts in liver and breast cancer cell lines, we observed that IRE1 mediates the upregulation in EMT-TFs, a decrease in the expression of the desmoplakin (DSP) protein, and an increase in the migration of liver and breast cancer cells. DSP is a critical component of desmosomes, which function to maintain the structural integrity at adjacent cell-cell contacts.In addition to migration, the effect of XBP1 splicing on metabolism has not been studied. We found the activation of IRE1-XBP1 is accompanied by changes in the metabolic genes involved in glycolysis, fatty acid oxidation, gluconeogenesis, and ceramide metabolism, suggesting that some of the metabolic effects of palmitate are mediated through IRE1. These results could have implications on the development of chemotherapeutic strategies. This study paves the way for further investigations into the far-reaching effects of activation of the UPR on cell survival, metabolism, and chemo-tolerance."--Pages ii-iii.
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Title: EPR studies of electron and proton transfer in cytochrome c oxidase
Creator: Xu, Shujuan
Date: 2008
Collection: Electronic Theses & Dissertations

Title: EPR studies of CS(18C6)e⁻ and Li⁺(C211)e⁻
Creator: Reidy-Cedergren, Kerry Ann
Date: 1992
Collection: Electronic Theses & Dissertations

Title: EPR and ENDOR characterization of model tyrosine and phenol radicals in frozen matrices
Creator: El-Deeb, Mohamed Kamal
Date: 1991
Collection: Electronic Theses & Dissertations

Title: EPIDEMIOLOGY, EVOLUTION, AND DIAGNOSTICS OF TUBERCULOSIS IN HUMANS AND ANIMALS
Creator: Hadi, Syeda Anum
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Tuberculosis control in animals and humans alike requires early detection of Mycobacterium tuberculosis complex as well as current knowledge about the transmission patterns of the disease in the respective populations. These two building blocks provide the foundation on which the disease control programs can build their policies to expediate control efforts. In this thesis we amalgamate molecular epidemiology, genomics, and proteomics. We studied the transmission pattern of M. tuberculosis...
Show moreTuberculosis control in animals and humans alike requires early detection of Mycobacterium tuberculosis complex as well as current knowledge about the transmission patterns of the disease in the respective populations. These two building blocks provide the foundation on which the disease control programs can build their policies to expediate control efforts. In this thesis we amalgamate molecular epidemiology, genomics, and proteomics. We studied the transmission pattern of M. tuberculosis and its evolution within a marginalized population. The patterns led to the identification of gaps in TB control policies in marginalized populations with little access to healthcare. Similarly, we studied the genomewide polymorphisms in a naturally attenuated strain - M. bovis strain Ravenel to elucidate possible mechanisms for its reduced virulence and pathogenicity. Insights gained from genome sequence analysis in conjunction with pathogenesis study for M. bovis Ravenel paved the pathway to defining the complex and multi-faceted reasons for attenuation of the oldest bacteria of the world. Next, pathogen-specific biomarkers were evaluated to assist in unambiguous disease detection across multiple host species. Discovery and validation of biomarkers work facilitated the field diagnostic applications for TB in animals and humans. This three-pronged approach developed in this study, understanding the genomic basis of attenuation, and enhanced field TB diagnostics in the animal-human interface.
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Title: EPIDEMIOLOGY OF ANTIBIOTIC RESISTANT SHIGA TOXIN-PRODUCING ESCHERICHIA COLI (STEC) AND NON-TYPHOIDAL SALMONELLA (NTS) IN MICHIGAN
Creator: Mukherjee, Sanjana
Date: 2018
Collection: Electronic Theses & Dissertations
Description: The enteric pathogens, Shiga toxin-producing E. coli (STEC) and non-typhoidal Salmonella (NTS), are leading causes of foodborne infections in the US, resulting in 265,000 and 1.2 million illnesses every year, respectively. The emergence of antibiotic resistance in these pathogens has been documented and is of great concern due to negative patient health outcomes and the possibility of transfer of resistance genes to other clinically relevant pathogens. However, there is a scarcity in...
Show moreThe enteric pathogens, Shiga toxin-producing E. coli (STEC) and non-typhoidal Salmonella (NTS), are leading causes of foodborne infections in the US, resulting in 265,000 and 1.2 million illnesses every year, respectively. The emergence of antibiotic resistance in these pathogens has been documented and is of great concern due to negative patient health outcomes and the possibility of transfer of resistance genes to other clinically relevant pathogens. However, there is a scarcity in information about frequencies of antibiotic resistant and factors associated with resistant STEC and NTS infections in Michigan. It is necessary to have a complete understanding about the of emerging antibiotic resistance and factors driving the rise of resistance in STEC and NTS to help develop effective control strategies. In this dissertation, 980 STEC isolates collected from patients in Michigan between 2001 and 2014 were examined for resistance to clinically relevant antibiotics. The examination of STEC strains for resistance, revealed high frequencies of resistance to ampicillin and trimethoprim-sulfamethoxazole, with significant increases in antibiotic resistance rates observed over this 14-year period. Multivariate logistic regression analysis identified non-O157 serotypes to be independently associated with antibiotic resistance. The recent increase in incidence of non-O157 serotypes observed in the US, coupled with the high frequencies of antibiotic resistance observed in this study, suggest the emergence of antibiotic resistant non-O157s as important human pathogens. Additionally, antibiotic resistant STEC isolates from patients in recent years (2010-2014) were more likely to cause hospitalizations than pansusceptible STEC isolates, suggesting that resistant STEC infections may result in adverse patient outcomes. Using whole genome sequencing, we also identified chromosomal mutations and 33 horizontally acquired genes present in the genomes of non-O157 STEC, likely conferring resistance. Importantly, by creating a co-occurrence network of these genes, we identified the co-occurrence of certain resistance genes, which are possibly present on the same mobile genetic element, thus resulting in multi-drug resistance. In addition to examining resistance in STEC, a total of 198 clinical NTS isolates collected between 2011 and 2014 were also examined for antibiotic resistance in this dissertation. Resistance to tetracycline, trimethoprim-sulfamethoxazole and ampicillin were commonly observed. Concerningly, high frequencies of multidrug resistant NTS were also observed with significant increases in their prevalence observed between 2011 and 2014. These high multidrug resistant rates have important implications on patient care as the efficacy of multiple antibiotics is reduced. Antibiotic resistant NTS isolates were also found to result in significantly longer mean hospital stays compared to pansusceptible NTS. Serovar specific differences in frequencies of antibiotic resistance were observed; S. Enteritidis were observed to have lower resistance frequencies than other serovars. Lastly, to better understand the role that cattle reservoirs play in harbouring antibiotic resistant STEC strains, we examined 121 STEC isolates collected in 2012 from six cattle farms in Michigan for antibiotic resistance. While high resistance frequencies to tetracycline and trimethoprim-sulfamethoxazole were observed in certain herds, no resistance to ampicillin was observed, unlike what was observed in STEC isolates collected from patients. While different populations of resistant STEC may be circulating in the clinical and agricultural environments, continuous monitoring of resistance in the cattle reservoir is warranted to determine if animal reservoirs can serve as potential sources of resistant infections in humans.
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Title: EPIDEMIC MODELS UNDER MOBILITY ON MULTI-LAYER NETWORKS
Creator: Abhishek, Vishal
Date: 2021
Collection: Electronic Theses & Dissertations
Description: We study epidemic spreading models namely, SIS and SIR models, under mobility on multilayer networks. In particular, we consider a patchy environment in which each patch comprises individuals belonging the different classes, e.g., individuals in different socio-economic strata. We model the mobility of individuals of each class across different patches through an associated Continuous Time Markov Chain (CTMC). The topology of these multiple CTMCs constitute the multi-layer network of mobility...
Show moreWe study epidemic spreading models namely, SIS and SIR models, under mobility on multilayer networks. In particular, we consider a patchy environment in which each patch comprises individuals belonging the different classes, e.g., individuals in different socio-economic strata. We model the mobility of individuals of each class across different patches through an associated Continuous Time Markov Chain (CTMC). The topology of these multiple CTMCs constitute the multi-layer network of mobility. At each time, individuals in the multi-layer network of spatially-distributed patches move according to their CTMC and subsequently interact with the local individuals in the patch according to SIS or SIR models. We establish the existence of various equilibria under different parameter regimes and establish their (almost) global asymptotic stability using Lyapunov techniques. We also derive simple conditions that highlight the influence of the multi layer network on the stability of these equilibria. We numerically illustrate that the derived model provides a good approximation to the stochastic model with a finite population and also demonstrate the influence of the multi-layer network structure.Next, we extend some of the results to the case of weakly connected networks. Here, we use the notion of strongly connected components and input to state stability to study the stability of equilibria. Finally, we consider a resource allocation problem to maximize the rate of convergence to an equilibrium. We show that under certain assumptions the problem can be formulated as a geometric program. We provide numerical illustrations to corroborate the results.
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Title: ENVIRONMENTAL IMPACTS OF MANUFACTURING CRYSTALLINE SILICON AND ORGANIC PHOTOVOLTAICS
Creator: Heidari, Seyed Mohammadreza
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Photovoltaics (PV) should provide about 25% of the global electricity production by 2050, which will require large-scale manufacturing. PV is expected to be a clean technology that can reduce the carbon footprint of electricity production. To maximize carbon reduction and maximize the environmental benefit, we must reduce the environmental impact of the manufacturing stage. This work evaluates the life cycle environmental impact of manufacturing mature (silicon) and emerging (organic) PV and...
Show morePhotovoltaics (PV) should provide about 25% of the global electricity production by 2050, which will require large-scale manufacturing. PV is expected to be a clean technology that can reduce the carbon footprint of electricity production. To maximize carbon reduction and maximize the environmental benefit, we must reduce the environmental impact of the manufacturing stage. This work evaluates the life cycle environmental impact of manufacturing mature (silicon) and emerging (organic) PV and evaluates alternative processes.For organic PV, C60 is often used as an acceptor material in OPV. Existing C60 purification methods are energy-intensive and require a large quantity of hazardous solvents. Therefore, it is desirable to modify existing C60 purification methods before OPV large-scale production to mitigate the potential environmental, cost, and chemical hazards of the manufacturing process. We used life-cycle assessment (LCA) to identify the environmental hotspots of the purification process. In addition to LCA, green chemistry, toxicity assessment, and analytical chemistry were employed to identify greener replacements. The alternative C60 purification has lower environmental (59%), cost (85%), and chemical hazard (42%) impacts compared to the existing C60 purification process. For mature technologies such as silicon PV (Si PV), it is necessary to evaluate the amount of materials needed to meet the expected PV capacity additions. Si PV is 95% of the current PV market and is expected to remain the leading technology until 2040 (>50%). We estimated the amount of material necessary for Si PV manufacturing based on PV installation in the US and the rest of the world in the next ten years. A bottom-up approach was used to evaluate the required materials for each sub-Si PV technology (e.g., aluminum back surface field, PERC, heterojunction, mono facial, bifacial, and perovskite/silicon tandem). Solar glass with 74 million metric tons and metallurgical-grade silicon (MG-Si) with three million metric tons have the highest material demand in the next decade. MG-Si production requires silica sand extracted from high-quality quartz (>98% purity). This study identified the purity and availability of potential quartz deposits globally. The country-specific carbon footprint of silica sand production was evaluated for quartz with various purity. The carbon footprint of producing silica sand was about 36% higher for low-quality quartz (65% purity) than high-quality deposits. We also quantified the carbon footprint and the cumulative energy demand of silica sand production from legal and illegal mines. The lower cost of silica sand production from illegal mines could result in using illegal quartz in the Si PV supply chain. Therefore, it is essential to have third-party certifications to ensure that the PV supply chain is free from illegal quartz and PV consumers buy ethical products.
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Title: ENVIRONMENTAL IMPACT OF CIVIL ENGINEERING INFRASTRUCTURES : FLEXIBLE PAVEMENTS USING END-OF-LIFE TIRES AND MATERIAL INTENSITY FOR WIND TURBINES
Creator: Farina, Angela
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Construction projects that involve flexible pavements and wind turbines typically utilize and handle large volumes of materials. Polymer modifications can improve the durability of flexible pavements and reduce the amount of virgin materials used over the service life. Crumb rubber (CR) from end-of-life tires might substitute the synthetic polymer in the asphalt mixtures, which would reduce the use of virgin materials and the number of tires deposited in landfills. Wind power contribution to...
Show moreConstruction projects that involve flexible pavements and wind turbines typically utilize and handle large volumes of materials. Polymer modifications can improve the durability of flexible pavements and reduce the amount of virgin materials used over the service life. Crumb rubber (CR) from end-of-life tires might substitute the synthetic polymer in the asphalt mixtures, which would reduce the use of virgin materials and the number of tires deposited in landfills. Wind power contribution to global electricity generation is expected to increase from 5 to 30% by 2050. This growing capacity will lead to increasing construction of wind farms globally. The scope of the study presented in this dissertation includes evaluating the mechanical, environmental, and toxic impact of different asphalt mixtures containing CR and the material demand for wind turbines in the USA and globally until 2050.Polymer coated rubber (PCR) and devulcanized rubber (DVR) are enhanced CR products used as recycled modifiers in asphalt mixtures. However, a comprehensive evaluation of the mechanical, environmental, and toxic impact of asphalt mixtures containing enhanced CR is still missing and necessary to evaluate whether the replacement of synthetic polymers with recycled modifiers is viable. In this study, life cycle assessment (LCA) and mechanistic-empirical pavement design (MEPDG) were used to compare the environmental impact of enhanced CR (PCR, dry and wet technology, and DVR) used in pavement materials with reference mixes (Control, unmodified, and SBS, modified with the synthetic polymer styrene-butadiene-styrene). Moreover, the potential leaching of metals from the same mixtures was assessed through the mass transfer rate of constituents, the 1315 EPA method. PCR dry mixture performed mechanically and environmentally as well as the SBS mix. Over the service life of road pavement, it was observed that the use of PCR dry and SBS mixtures leads to material savings up to 2.4 times compared to the control mixture. Leaching tests revealed that zinc was present in all asphalt mixtures, with a concentration greater than the drinking water standard limit. The number of wind turbines that are expected to be built by 2050 to meet the renewable energy targets will require a large amount of material mining and transformation. The material demand for wind turbines installed in the USA and the rest of the world were estimated and compared to the expected production until 2050. In addition, the carbon footprint and the cumulative energy demand associated with the material production were quantified based on the annual addition capacity using three different outlooks for the USA and one for the rest of the world. The material demand in the USA and globally was lower than the expected material production. The carbon footprint for material manufacturing for all wind turbines built in 2050 will be eight times lower than the CO2 equivalent emitted by coal power plants in the USA in that year. Lowering the environmental impact of wind turbine manufacturing will increase the competitiveness of wind energy compared to non-renewable sources.
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Title: ENVIRONMENTAL FATE AND PLANT UPTAKE OF CHEMICALS OF EMERGING CONCERN IN AGRICULTURAL SYSTEMS
Creator: Rhodes, Geoffrey Ryan
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Chemicals of emerging concern (CECs), such as pharmaceuticals and per- and polyfluoroalkyl substances (PFAS), have been frequently detected in agricultural systems, resulting from crop irrigation with contaminated water and land application of biosolids and animal manures. Crops can take up CECs from soil and water, leading to their accumulation in human and animal foodstuffs. The long-term consumption of contaminated foodstuffs and the resulting potential human and animal health impacts is...
Show moreChemicals of emerging concern (CECs), such as pharmaceuticals and per- and polyfluoroalkyl substances (PFAS), have been frequently detected in agricultural systems, resulting from crop irrigation with contaminated water and land application of biosolids and animal manures. Crops can take up CECs from soil and water, leading to their accumulation in human and animal foodstuffs. The long-term consumption of contaminated foodstuffs and the resulting potential human and animal health impacts is of particular concern. Currently, the mechanism(s) controlling the uptake and accumulation of CECs in crops is not well understood. Additionally, agricultural lands contaminated by CECs can serve as a source that spread pollutants to the surrounding environment. The first study of this dissertation examined the accumulation and distribution of a commonly prescribed pharmaceutical (cephalexin) in lettuce, celery, and radish. Cephalexin did not accumulate in the shoots of all three vegetables but accumulated in the roots in the order of lettuce > celery > radish. Sorption of cephalexin to vegetable roots ranked in the order of lettuce > celery > radish, and the transformation of cephalexin by root enzyme extracts in the order of lettuce < radish < celery. Therefore, the sorption of cephalexin to plant roots and its transformation by plant enzymes could collectively determine the uptake and accumulation of cephalexin in vegetables. The second study examined the mechanisms controlling the transport of PFAS, from roots to shoots, using Arabidopsis thaliana Columbia-0 (wild type) and a mutant of this ecotype with a compromised Casparian strip (a potential barrier root-to-shoot transport). A. thaliana wild type and mutant plants were exposed to a mixture of PFAS and the pharmaceutical carbamazepine. Biomasses at harvest, amount of water transpired, carbamazepine concentration in shoots, and PFAS and carbamazepine concentration in roots were not significantly different between wild type and mutant plants. Significantly higher concentrations of PFAS were observed in the shoots of the mutant plants than in the wild type plant shoots suggesting that the Casparian strip plays a role in reducing the translocation of PFAS from roots to shoots. Translocation factors for PFAS with a molecular weight <450 g/mol and PFAS with a molecular weight of >450 g/mol were 3.4 times and 1.5 times higher in mutant plants than in wild type plants, respectively. This suggests that the translocation of PFAS with molecular weight < 450 g/mol could be more impacted by the Casparian strip. The final study investigated the concentrations and compositional profiles of PFAS in surface water and sediment samples collected near an agricultural field which received biosolids likely containing PFAS in the early 1980’s. The total PFAS concentrations downstream of the biosolids-applied field ranged from 596 ng/L to 12,530 ng/L in surface water samples, with the highest concentration occurring immediately downstream of the biosolids-applied field. The total PFAS concentrations decreased with increasing distance away from the biosolids-applied field. The total PFAS concentrations in surface water samples upstream of the biosolids-applied field ranged from 40 to 173 ng/L. The highest concentration of total PFAS in the sediment samples (15,220 ng/kg) was found at an intermediate distance downstream of the biosolids-applied field, suggesting the transport of PFAS-contaminated sediments. These results indicate that the application of PFAS-containing biosolids to agricultural lands could have a long-term impact on the downstream environments.
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Title: ENVIRONMENTAL DRIVERS AND EVOLUTIONARY CONSEQUENCES OF HORIZONTAL GENE TRANSFER IN SOIL BACTERIA
Creator: Kittredge, Heather
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Horizontal gene transfer (HGT) is a driving force in bacterial evolution and could drive rapid adaptation in bacterial communities. Natural transformation is one mechanism of HGT that allows bacteria to pick up extracellular DNA (eDNA) from the environment and integrate it into their genome. But the rate of HGT in natural environments, and the role this process plays in facilitating rapid adaptation remains unknown. As climate change threatens the stability of environments worldwide,...
Show moreHorizontal gene transfer (HGT) is a driving force in bacterial evolution and could drive rapid adaptation in bacterial communities. Natural transformation is one mechanism of HGT that allows bacteria to pick up extracellular DNA (eDNA) from the environment and integrate it into their genome. But the rate of HGT in natural environments, and the role this process plays in facilitating rapid adaptation remains unknown. As climate change threatens the stability of environments worldwide, understanding how quickly bacteria can adapt to novel environments is essential. My dissertation research characterizes the environmental drivers and evolutionary consequences of natural transformation in a highly transformable model soil bacterium Pseudomonas stutzeri.Despite decades of research on understanding HGT at the molecular level, less is known about the ecological drivers of HGT. To understand the soil conditions relevant for transformation, I first measured eDNA in the field over a short-term drying rewetting disturbance (Ch. 2). I found that eDNA increased in response to the rewetting disturbance but quickly disappeared from soil, suggesting a small portion of this eDNA could be transformed by bacterial cells recovering from the disturbance. To test the efficiency of transformation under the conditions in which eDNA disappeared, I created a novel microcosm system for quantifying transformation in soil (Ch. 3). Here, I inoculated soil with live antibiotic-susceptible, and dead antibiotic-resistant P. stutzeri. I then tracked the evolution of antibiotic resistance over a range of soil conditions and eDNA concentrations. Transformation drove the evolution of antibiotic resistance across a wide range of soil moistures and increased in response to larger inputs of dead cells (eDNA source), with antibiotic resistance repeatedly appearing in antibiotic free soil. Despite the prevalence of transformation across bacterial species, the evolutionary origins and consequences of transformation are still largely unknown. Transformation presumably provides a fitness benefit in stressful or continuously changing environments, but few studies have quantified changes in transformation in response to adaptive evolution. Here, I evolved P. stutzeri at different salinities and tested how the growth rate and transformation efficiency changed in response to salt adaptation (Ch. 4). Overall, the growth rate increased in response to adaptation, but the transformation efficiency declined, with only ~50% of the evolved populations transforming eDNA at the end of experiment – as opposed to 100% of ancestral populations transforming eDNA. Overall, my dissertation research elucidates the factors driving transformation in soil, setting the stage for future experiments to scale up estimates of transformation to the whole community level. I find that transformation occurs under most soil conditions and allows genetic variants to arise at low frequencies in the absence of selection. I also report novel experimental evidence that transformation efficiency can change dramatically, and in a highly variable manner, over just ~330 generations. Taken together, this body of research highlights a role for transformation in many natural systems of ecological significance, and points to dead cells as an important but often overlooked source of genetic diversity.
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Title: ENSO, IOD, SST : impact study on NEMR in Tamil Nadu, South India
Creator: Govindasamy Thulasi, Mahalakshmi Bargavi
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Rainfall variability in Tamil Nadu, a southeastern state in India, is gaining importance for its associations with ocean-atmosphere coupled phenomena such as the El-Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) mode. A complete documentation of the rainfall pattern in this region is necessary to understand its behavior with respect to other climate factors related to moisture transport. These rainfall patterns are also driven by surface latent heat flux (SLHF) observed...
Show moreRainfall variability in Tamil Nadu, a southeastern state in India, is gaining importance for its associations with ocean-atmosphere coupled phenomena such as the El-Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) mode. A complete documentation of the rainfall pattern in this region is necessary to understand its behavior with respect to other climate factors related to moisture transport. These rainfall patterns are also driven by surface latent heat flux (SLHF) observed over the Indian Ocean, especially coincident with the 2004 earthquake in Indonesia. This study analyzes rainfall characteristics for Tamil Nadu during the north-east monsoon rainfall (NEMR) period starting from October through December over the period of 1982 - 2005. In particular, this study examines a relationship between the Sea Surface Temperature (SST) change in the Nino regions, Saji regions and the 2004 Earthquake epicenter region and rainfall variations in both the quake vicinity and Tamil Nadu. This can improve understanding of global remotely sensed variables (e.g. precipitation, SST) and in applications such as climate modeling.
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Title: ENHANCING CORPORATE CRIME ENFORCEMENT WITH MACHINE LEARNING—A MULTIDISCIPLINARY RISK FACTOR APPROACH
Creator: Chan, Fiona
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Despite its severe and lasting social and financial ramifications, corporate financial crime remains one of the most understudied crime types, as it is often hindered by two challenges. First, its multidisciplinary nature requires both financial and criminological expertise among others to conduct proper investigations. Second, corporate crime data is fraught with constraints such as high dimensionality, complex interactions, and nonlinear functional forms that are ill-suited for classical...
Show moreDespite its severe and lasting social and financial ramifications, corporate financial crime remains one of the most understudied crime types, as it is often hindered by two challenges. First, its multidisciplinary nature requires both financial and criminological expertise among others to conduct proper investigations. Second, corporate crime data is fraught with constraints such as high dimensionality, complex interactions, and nonlinear functional forms that are ill-suited for classical statistical modeling. The lack of research coupled with the limited resources in corporate crime enforcement represent a great impediment to the advancement of fraud interventions. This dissertation seeks to overcome these specific challenges by unifying cross-disciplinary financial fraud research under a risk factor framework, and by leveraging recent advancements in artificial intelligence. The goal is to examine whether two machine learning algorithms—random forest and neural network—can be used to enhance corporate fraud risk detection/prediction beyond more commonly employed analytical techniques. Findings from the analysis showed that the random forest algorithm outperformed logistic regression and a naïve classifier in a 1:1 matched sample. The neural network performed better than a naïve classifier but slightly worse than logistic regression. Feature selection improved the algorithms’ predictive accuracy and ability to distinguish between classes even further. Despite promising results from the 1:1 matched sample, both machine learning algorithms struggled with a heavily imbalanced 1: many dataset, which represents a more realistic setting. With the implementation of an oversampling strategy and feature selection, the algorithms improved substantially in identifying the rare fraud cases, and showed promise of improvement with further research on imbalanced classification. Feature importance from the random forest classifier identified risk factors that are consistent with findings from prior studies. Measures of financial distress ranked lower in importance than measures of financial health, suggesting future research can build on prior findings on corporate strain to examine specific mechanisms. The analysis also identified auditor independence as a key concept of guardianship and opportunity structure that warrants further study. Findings from this research also have important methodological implications for corporate crime studies—namely, the need to improve measurements of organizational-level fraud risk factors.
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Title: ENGINEERING STUDIES IN ADVANCED PLA MATERIALS – STEREOCHEMISTRY, STEREOCOMPLEXATION, AND THERMAL RECYCLING OF PLA
Creator: Alhaj, Mohammed A.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Polylactide (PLA) polymers are the world’s foremost 100% biobased resin with both composting and recycling end-of-life options in harmony with Ellen MacArthur Foundation “Circularity Model.” It is commercially manufactured by converting lactic acid to lactide, which is then polymerized to PLA. These molecules present unique and intriguing stereochemistry that dictate manufacturing, performance properties, and processability. However, it is seldom discussed and not well understood in the role...
Show morePolylactide (PLA) polymers are the world’s foremost 100% biobased resin with both composting and recycling end-of-life options in harmony with Ellen MacArthur Foundation “Circularity Model.” It is commercially manufactured by converting lactic acid to lactide, which is then polymerized to PLA. These molecules present unique and intriguing stereochemistry that dictate manufacturing, performance properties, and processability. However, it is seldom discussed and not well understood in the role stereochemistry can play and impact product performance and use. In the current work, we critically review and discuss the stereochemical implications for PLA through studies on different PLA compositions.To-date, it is unclear the origin of D-content present in commercial grade PLA, although it is assumed to originate from D-lactide. In this work, we validate that manufacture of lactide monomer from (L)- lactic acid predominantly results in a mixture of L and meso (DL), not L- and D- lactide. Optical rotation and 1H NMR studies are used to elucidate this stereochemistry. Copolymers of L-lactide and meso-lactide and copolymers of L-lactide and D-lactide are synthesized via bulk polymerization at various compositions. The optical rotation, tacticity, crystallinity, and thermal properties of synthesized copolymers are characterized. The optical rotation of poly(meso-lactide) has also been reported for the first time in this text. Differential scanning calorimetry (DSC) and 1H NMR studies confirm that PLA transitions from a predominantly isotactic, semi-crystalline polymer to a predominantly atactic, amorphous polymer when one copolymerizes greater than 10% meso-lactide with L-lactide. The stereochemical composition, mechanical and rheological properties of commercial grade PLA are measured to elucidate the effect of stereochemistry on the tensile and rheological behavior of PLA. We conclude this section with studies on PLA stereochemistry and its influence on immune cellular response. Hydrolytic degradation of semi-crystalline and amorphous PLA is analyzed via molecular weight characterization and lactic acid abundance. Semi-crystalline and amorphous PLA are then studied as potential carriers for glycolytic inhibitors. The stereochemistry of PLA and its implication on performance properties are further explored in studies on stereocomplex PLA. A pilot-scale continuous manufacturing process of stereocomplex PLA is developed and optimized by melt-blending a 1:1 blend of high molecular weight poly(L-lactide) (PLLA) and high molecular weight poly(D-lactide) (PDLA) in a co-rotating twin screw extruder. Stereocomplexation is first characterized via DSC at different temperatures and times. The optimal reaction temperature and reaction time are found and used to process >95% stereocomplex PLA conversion (melting peak temperature Tpm = 240°C). Stereocomplex PLA is used as an additive to produce 70% PLLA/30% stereocomplex PLA composites. The crystallinity, thermal properties, and tensile properties of composites are then characterized. A study on stereocomplex PLA and its effect on the crystallization kinetics of PLLA is conducted. 5% stereocomplex PLA is blended with 95% PLLA to analyze its use as a nucleating agent. The final section discusses a pilot-scale end-of-life method for PLA via thermal recycling. This study continues previous studies on PLA thermodepolymerization by scaling up the reversible reaction in a pilot-scale batch reactor. PLA is run at various temperatures and times to elucidate the processing conditions that yield the highest lactide conversion. The chemical purity, optical purity, lactide yield and stereoisomeric composition of the final lactide product are characterized by DSC, optical rotation, mass balance, and 1H NMR, respectively.
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Title: ENGINEERING B. SUBTILIS TRANSCRIPTIONAL CONTROL AND PHYSIOLOGY FOR THE ADVANCEMENT OF BACTERIOTHERAPIES
Creator: Greeson, Emily Marilynn
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation explores to avenues of improvement for current bacteriotherapy approaches. Cody Madsen and I worked closely to advance engineered B. subtilis as a modular platform technology and Dr. Ashley Makela was instrumental in the in vivo studies (Chapter 2). In Chapter 2, transcriptional control of B. subtilis will demonstrate the ability to use magnetothermal energy generated by superparamagnetic iron oxide nanoparticles (SPIONs) and alternating magnetic fields (AMF) to induce...
Show moreThis dissertation explores to avenues of improvement for current bacteriotherapy approaches. Cody Madsen and I worked closely to advance engineered B. subtilis as a modular platform technology and Dr. Ashley Makela was instrumental in the in vivo studies (Chapter 2). In Chapter 2, transcriptional control of B. subtilis will demonstrate the ability to use magnetothermal energy generated by superparamagnetic iron oxide nanoparticles (SPIONs) and alternating magnetic fields (AMF) to induce temperature-sensitive repressors. Chapter 3 demonstrates how synthetic biology techniques can allow engineered B. subtilis to invade epithelial cells with the “zipper” mechanism. This was a collaborative effort as it was a multidisciplinary study and the contributions of Cody Madsen, Evran Ural, Dr. Ashley Makela, Dr. Bige Unluturk, and Victoria Toomajian were important and have been specifically noted in author contributions at the end of Chapter 3.Most patients on organ transplant waitlists will need alternative therapeutics due to a deficit of organ donations. Regenerative medicine approaches, including cellular reprogramming are being used to help address the deficit, but there are limitations. Bacteriotherapies aim to better deliver the therapeutics to a variety of targets, however, most approaches do so externally to the target cells. B. subtilis, a generally recognized as safe organism, engineered to express listeriolysin O (LLO) has been shown to replicate in the cytoplasm of macrophages and deliver transcription factors and modulate cell surface markers, cytokines, and chemokines. This mechanism of uptake only works with phagocytic cells creating an opportunity for the engineering of B. subtilis that targets internalization into non-phagocytic cells. When introducing known virulence factors into non-native organisms it is important to consider controlling the gene expression while trying to remain as minimally invasive as possible. Alternating magnetic fields (AMF) cause local temperature increases in regions with Superparamagnetic iron oxide nanoparticles (SPIONs), and we investigated the ability of this magnetic hyperthermia approach to regulate temperature-sensitive repressors (TSRs) in bacteria. Magnetic hyperthermia-based control of bacterial gene expression would advance development of bacteriotherapies and expand options of regulated bacterial transcription. TSRs block transcription in a temperature-dependent manner. B. subtilis was coated with three SPION variations, plain-dextran, amine- or carboxyl-coated and the interactions and AMF responses were characterized and induction of the TSRs was demonstrated using AMF. Murine intramuscular injections revealed continual association of SPIONs with B. subtilis. While there was no induction via AMF in vivo, pairing TSRs with magnetothermal energy using SPIONs for localized heating with AMF can lead to regional bacterial transcriptional control, a minimally invasive method that could be used with virulence factors and therapeutics. To delivery therapeutics to epithelial cells, B. subtilis llo was engineered to express internalin A (InlA), a protein native to Listeria monocytogenes. Internalin A is an adhesin that binds to the E-cadherin host cell receptor found in epithelial cells and mediates a “zipper” mechanism of invasion. B. subtilis llo inlA demonstrated cytosolic persistence and B. subtilis llo remained extracellular. Ultimately, the engineering of B. subtilis transcriptional control and physiology creates a new modular approach to regenerative medicine, cellular reprogramming, and cancer therapy that can be used in human health applications.
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Title: ENERGY TRENDS IN IRRIGATION : A METHOD FOR ESTIMATING LOCAL AND LARGE-SCALE ENERGY USE IN AGRICULTURE
Creator: McCarthy, Benjamin Michael
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Agricultural Intensification has presented various opportunities for study in the field of water use, crop trends and energy consumption. In the United States alone, 70% of water consumed is used for the agricultural sector. Whether sources from surface bodies or groundwater, the energy required to irrigate fields has changed over the last three decades. The advent of efficient irrigation systems has created new avenues for farmers to grow crops, through new planting practices, increased...
Show moreAgricultural Intensification has presented various opportunities for study in the field of water use, crop trends and energy consumption. In the United States alone, 70% of water consumed is used for the agricultural sector. Whether sources from surface bodies or groundwater, the energy required to irrigate fields has changed over the last three decades. The advent of efficient irrigation systems has created new avenues for farmers to grow crops, through new planting practices, increased water extractions and varied on-farm practices. In this thesis, I evaluate the impact that shifting technologies have had on the FEW nexus, with a strong emphasis on the Energy consumption from irrigation. In Chapter 1, I developed an energy model for Kansas, one of the states with the highest data availability for farm practices. I used a combination of state and federal datasets to estimate the impact of shifting irrigation technologies on energy consumption. The results of this study are then investigated by energy source and a life cycle assessment model is applied to understand the role of shifting energy sources on the agricultural system. For Chapter 2, I expanded my energy model to encompass the continental United States. I estimate county level aggregates of direct energy consumed for irrigation. The results are then leveraged by agricultural region, and the crop types are evaluated spatially. Understanding how energy consumption in the agricultural sector is distributed both spatially and temporally can become a key asset when determining how to improve water practices, which regions need further study, and develop spatial relationships.
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Title: ENABLING REAL-TIME COMMUNICATION FOR HUMAN AUGMENTATION SYSTEMS VIA UNOBTRUSIVE HIGH BANDWIDTH MACHINE TO HUMAN ELECTROTACTILE PERIPHERAL NERVE STIMULATION
Creator: Parsnejad, Sina
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The advent of sensor technologies and the resulting abundance of information together with modern advanced processing capabilities makes improving human lives via human augmentation technologies ever more appealing. To establish a new effective form of human-machine-communication (M2HC) for augmentation, this dissertation explores non-invasive peripheral nerve stimulation via electrotactile waveforms. This dissertation conducts extensive convergence research between the fields of psychology,...
Show moreThe advent of sensor technologies and the resulting abundance of information together with modern advanced processing capabilities makes improving human lives via human augmentation technologies ever more appealing. To establish a new effective form of human-machine-communication (M2HC) for augmentation, this dissertation explores non-invasive peripheral nerve stimulation via electrotactile waveforms. This dissertation conducts extensive convergence research between the fields of psychology, electrical engineering, neuroscience and human augmentation and established innovations to create distinct sensations that can be utilized as iconic electrotactile M2HC. Existing electrotactile stimulation models deliver a limited range of distinct sensations, making iconic communication challenging. To address this issue, we created a software/hardware infrastructure, including novel electrotactile electrode arrays and improved stimulation circuitry, that allows for rapid prototyping and testing various electrotactile innovations. We created a model for electrotactile waveform generation (MEWS) wherein a train of high-frequency electrotactile pulses is shaped into electrotactile waveforms through a multi-layer on-off-keying modulation forgoing the need for constant frequency recalibration and making painful sensations less likely to happen. Using MEWS, we conducted multiple human trials on 15 volunteering participants stimulating a total of ~6000 electrotactile sensations which led us to create 13 distinct electrotactile waveform with an accuracy of 85.4%. To increase the number of messages that can be delivered by electrotactile stimulation, a model for creating varying electrotactile waveforms (MOVES) was created based on linguistic concept of phonemes and taking a semi-heuristic approach to creating electrotactile waveforms. Using MOVES we conducted multiple human trials on 21 volunteering participants stimulating a total of ~5000 electrotactile sensations. Our human trials proved that MOVES was able to create 24 distinct sensations with an accuracy of 89% that can be used to convey messages through iconic communication and has the potential to expand further beyond the 24 messages. The number of messages delivered by MOVES pentuples the best recorded number of distinct electrotactile sensations in literature.
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