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Title: Measurement of the charged current muon neutrino differential cross section on scintillator with zero pions in the final state with the T2K on/off-axis near detectors
Creator: Cudd, Andrew Bruce
Date: 2020
Collection: Electronic Theses & Dissertations
Description: The Tokai to Kamioka (T2K) is a long-baseline neutrino oscillation experiment in Japan producing precise measurements of neutrino oscillations and neutrino interactions with nuclear targets. T2K utilizes a muon (anti-)neutrino beam produced at the J-PARC proton accelerator facility which is measured at a suite of near detectors, ND280 and INGRID, and the far detector, Super-Kamiokande. One of the dominant systematic uncertainties for the oscillation analysis is from the uncertainty in...
Show moreThe Tokai to Kamioka (T2K) is a long-baseline neutrino oscillation experiment in Japan producing precise measurements of neutrino oscillations and neutrino interactions with nuclear targets. T2K utilizes a muon (anti-)neutrino beam produced at the J-PARC proton accelerator facility which is measured at a suite of near detectors, ND280 and INGRID, and the far detector, Super-Kamiokande. One of the dominant systematic uncertainties for the oscillation analysis is from the uncertainty in neutrino interaction modeling with complex nuclei, which will eventually become the limiting uncertainty for the next generation of neutrino oscillation experiments. Therefore measurements of neutrino cross sections on nuclear targets is essential for understanding how to model these complicated nuclear interactions. This thesis presents a novel neutrino cross section measurement utilizing both of the T2K near detectors, ND280 and INGRID, in a joint statistical fit. Because the T2K near detectors are exposed to neutrinos from the same beamline, the uncertainties in the neutrino flux prediction will be correlated. This fact combined with the different neutrino energy spectra seen at each detector will allow for some separation of flux and cross section effects, and presents an opportunity to study the neutrino cross section as a function of energy using the same neutrino beam. This analysis is the first cross section measurement on T2K to use samples from multiple detectors in the same beamline. This thesis presents a description of the statistical analysis framework, the event selection, the treatment of systematic uncertainties, and the extracted muon neutrino CC0pi double differential cross section in bins of muon kinematics for ND280 and INGRID, including the correlations between the detectors.
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Title: Use of administative claims data to design and emulate a clinical trial in acute stroke patients comparing rehabilitation at inpatient rehabilitation facilities to skilled nursing facilities
Creator: Simmonds, Kent P.
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Stroke affects nearly 800,000 people every year in the United States and is a leading cause of adult disability. After hospitalization half of stroke patients continue to require medical and rehabilitation services provided at inpatient rehabilitation facilities (IRFs) or skilled nursing facilities (SNFs). In general, IRFs provide time-intensive therapy for two to three weeks, while SNFs provide moderately intensive therapy for four- to five-weeks. There is substantial variation in the...
Show moreStroke affects nearly 800,000 people every year in the United States and is a leading cause of adult disability. After hospitalization half of stroke patients continue to require medical and rehabilitation services provided at inpatient rehabilitation facilities (IRFs) or skilled nursing facilities (SNFs). In general, IRFs provide time-intensive therapy for two to three weeks, while SNFs provide moderately intensive therapy for four- to five-weeks. There is substantial variation in the utilization of these alternative rehabilitation settings, but their relative comparative effectiveness remains uncertain. A randomized controlled trial (RCT) would provide an unbiased comparative effectiveness estimate, but the design of such a trial is complicated by several practical and ethical issues. The overarching purpose of this dissertation was to use Medicare claims data to inform the design and to emulate such a trial. In the first aim, we sought to identify patient and hospital level factors that were associated with IRF or SNF discharge and characterize the heterogeneity of hospital effects that influenced discharge to an IRF (vs. SNF). From a retrospective cohort of 145,894 stroke patients, we used multi-level multivariable models to identify several patient- and hospital- level factors that were independently associated with discharge setting. We also showed that hospitals contributed around a third of the variation in IRF (vs. SNF) discharge, but there was substantial variation in the effect that specific hospitals had on influencing IRF discharge. The second aim, was to identify a target trial population that optimized the explanatory-pragmatic balance of a subsequent RCT. To identify this population, we profiled hospitals based on their propensity to discharge stroke patients to IRFs (vs. SNFs) and inferred IRF and SNF referral networks for each hospital. The final target trial population included 44,950 patients (30.8% of the starting sample) who were treated at 441 hospitals (14.5%) and subsequently discharged to 745 IRFs (64.8%) and 5,974 SNFs (48.2%).The third aim was to emulate three alternate RCTs that compared patient outcomes at IRFs vs. SNFs. Trial #1 used the target trial population identified in Aim 2, while trials #2 and 3 excluded increasingly infrequently used IRFs and SNFs. Comparative effectiveness was estimated using a matched propensity score analysis. Overall, on a relative basis, patients treated at IRFs were between 18-35% more likely to be successfully discharged home (i.e., alive and at home for >30 days) and were between 11-15% less likely to die within one year of acute care discharge. The variation in the effect size estimates across the trials was driven by poorer outcomes among patients treated at infrequently used SNFs. Finally, we identified that a moderate sized unmeasured confounder would nullify the observed differences.In conclusion, we identified that referring hospitals are a major driver of IRF or SNF use, and that patients treated at IRFs had better outcomes (relative to SNF patients). However, our results were limited by the inability to adjust for potentially important unmeasured confounders. A pragmatic RCT would eliminate such biases and provide a more valid comparative effectiveness estimate of these two alternative rehabilitation settings.
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Title: Understanding free-carrier accumulation in semiconductor nanomaterials : plasmonic behavior, charge storage energetics, and quantum confinement resilience of colloidal indium nitride nanocrystals
Creator: Liu, Zhihui
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Heavily doped semiconductor nanocrystals (NCs) are promising materials that can reversibly and substantially store electrical charges. Indium nitride (InN) is a particularly interesting semiconductor material for studying charge storage processes. Colloidal InN NCs are spontaneously degenerately doped with carrier densities large enough to lead to strong localized surface plasmon resonances (LSPR) in the infrared (IR) part of the spectrum. Unfortunately, many fundamental quantities that...
Show moreHeavily doped semiconductor nanocrystals (NCs) are promising materials that can reversibly and substantially store electrical charges. Indium nitride (InN) is a particularly interesting semiconductor material for studying charge storage processes. Colloidal InN NCs are spontaneously degenerately doped with carrier densities large enough to lead to strong localized surface plasmon resonances (LSPR) in the infrared (IR) part of the spectrum. Unfortunately, many fundamental quantities that ultimately control the behavior of colloidal InN NCs are currently unknown. In this thesis, we focused on advancing our current understanding of the properties of colloidal InN NCs, with special emphasis on the quantification of free electron density, the LSPR behavior, the charge storage ability, the screening effect on phonon behaviors and few other important fundamental quantities such as the electron effective mass, Fermi level, conduction band (CB) edge potential and IR transition oscillator strength.To understand the LSPR behavior of InN NCs, we first evaluated the free carrier density with a direct, model-independent quantification. We found that the number of free electrons per as-prepared InN NC is directly proportional to the NC volume, such that the free electron density is a size-independent quantity. Furthermore, we demonstrated that free electrons in InN NCs can be reversibly extracted with redox species, which leads to a direct way to manipulate the LSPR. Importantly, the LSPR energy in InN NCs barely shifts with free electron density, a behavior strikingly at odds with what is typically observed in other semiconductor plasmonic systems. These unusual plasmonic signatures are shown to arise from the nonparabolicity of the CB dispersion, which leads to a change in the electron effective mass with the number of free electrons per NC, thus mitigating the shift of LSPR in InN NCs.Consequently, we estimated the charge storage capability of InN NCs by pinning the chemical potential of InN NCs to redox-active molecular species. These studies directly yielded precise information on the Fermi level and on the chemical capacitance of InN NCs, which allowed the CB edge potential of InN NCs to be quantitatively determined for the first time. Surprisingly, the CB edge in InN NCs hardly showed any sign of quantum confinement effects, even for NCs sizes that were clearly smaller than the excitonic Bohr radius of InN. This "resilience to quantum confinement" effect was shown to also arise from the same nonparabolic dispersion effects described above.In addition, the light harvesting ability of free electrons in InN NCs was evaluated by calculating the molar absorptivity per free electron. This value directly yielded the optical oscillator strength of LSPR. We found that optical oscillator strength (per free electron) is independent of NC.Finally, the effects of free electrons on lattice vibrations were also explored. We demonstrated that free electrons weakened the A1(LO) phonon mode by screening the Coulombic restoring force induced by the lattice distortion. The A1(LO) mode frequency red-shifted linearly with the increasing free electron density. This relationship provided a fast way to estimate free electron density of InN NCs by measuring Raman spectroscopy.
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Title: Interfacial challenges of all-solid-state Li-ion batteries : multi-scale computational approach
Creator: Tian, Hong-Kang
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "All-solid-state Li-ion batteries (ASSLB) with solid electrolytes (SEs) have enhanced safety and higher volumetric/gravimetric energy density than conventional Li-ion batteries with liquid electrolytes. However, the applications of ASSLB are still limited by the interfacial issues, such as Li dendrite growth through the SEs and the high SE/electrode interfacial resistance. This thesis developed a multi-scale computational approach, combining Density Functional Theory (DFT) calculation and...
Show more"All-solid-state Li-ion batteries (ASSLB) with solid electrolytes (SEs) have enhanced safety and higher volumetric/gravimetric energy density than conventional Li-ion batteries with liquid electrolytes. However, the applications of ASSLB are still limited by the interfacial issues, such as Li dendrite growth through the SEs and the high SE/electrode interfacial resistance. This thesis developed a multi-scale computational approach, combining Density Functional Theory (DFT) calculation and Finite Element Method (FEM), to investigate the interfacial challenges in ASSLB. The Li dendrite growth through pores in SEs and the resulting short-circuit limit the highest current density in ASSLB. The underlining mechanism of Li dendrite nucleation and growth in SEs is still unclear. A DFT model was developed to evaluate the electronic properties of the bulk and surface structures of different SEs. It was revealed that the reduced bandgap and trapped electrons on the pore and crack surfaces are the main reasons for Li dendrite to form. The DFT computed material properties were compared for different SEs, and it was found that the ranked Li dendrite resistance in these SEs, based on the surface electronic properties instead of mechanical properties, is consistent with a broad range of experimental observations. The DFT results also served as the input to a phase-field model, which predicted the formation of isolated Li dendrite that matched with experimental observations. Furthermore, materials design strategies were proposed based on the critical material properties that can resist Li dendrite growth in SEs.The physically imperfect contact at interfaces is formed during the fabrication process of ASSLB and gets worse during cycling, resulting in high interfacial resistance and damaging to the battery performance. A 1D FEM battery model was constructed to investigate the relationship between the contact area and the discharging performance. Furthermore, the multi-scale Persson's contact theory was applied to predict the necessary pressure to prevent ASSLB capacity degradation due to contact area loss during the cycling of ASSLB. Cracked SE and SE/electrode interfaces also increase the impedance in ASSLB. The mechanical degradation of ASSLB is expected to be more severe than that in traditional Li-ion batteries with liquid electrolytes, as the solid-electrolyte also imposes mechanical constraints on the deformation of electrodes. A coupled electrochemical-mechanical FEM model was developed to evaluate the stress development in ASSLB. Two sources of volume change, namely the expansion/shrinkage of electrodes due to lithium concentration change and the interphase formation at the SE/electrode interface due to the decomposition of SEs, were considered. The favorable SE decomposition reactions and the associated volume change were predicted by DFT calculations. It was found that the SE-decomposition induced stress can be much larger than the electrodes volume changes due to Li concentration change, up to tens of GPa, if there are no voids in ASSLB to release some induced-stress. This model can also be used to design 3D ASSLB architectures to minimize the stress generation in ASSLB."--Pages ii-iii.
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Title: Signal processing and machine learning approaches to enabling advanced sensing and networking capabilities in everyday infrastructure and electronics
Creator: Ali, Kamran (Scientist)
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Mainstream commercial off-the-shelf (COTS) electronic devices of daily use are usually designed and manufactured to serve a very specific purpose. For example, the WiFi routers and network interface cards (NICs) are designed for high speed wireless communication, RFID readers and tags are designed to identify and track items in supply chain, and smartphone vibrator motors are designed to provide haptic feedback (e.g. notifications in silent mode) to the users. This dissertation focuses on...
Show moreMainstream commercial off-the-shelf (COTS) electronic devices of daily use are usually designed and manufactured to serve a very specific purpose. For example, the WiFi routers and network interface cards (NICs) are designed for high speed wireless communication, RFID readers and tags are designed to identify and track items in supply chain, and smartphone vibrator motors are designed to provide haptic feedback (e.g. notifications in silent mode) to the users. This dissertation focuses on revisiting the physical-layer of various such everyday COTS electronic devices, either to leverage the signals obtained from their physical layers to develop novel sensing applications, or to modify/improve their PHY/MAC layer protocols to enable even more useful deployment scenarios and networking applications - while keeping their original purpose intact - by introducing mere software/firmware level changes and completely avoiding any hardware level changes. Adding such new usefulness and functionalities to existing everyday infrastructure and electronics has advantages both in terms of cost and convenience of use/deployment, as those devices (and their protocols) are already mainstream, easily available, and often already purchased and in use/deployed to serve their mainstream purpose of use.In our works on WiFi signals based sensing, we propose signal processing and machine learning approaches to enable fine-grained gesture recognition and sleep monitoring using COTS WiFi devices. In our work on gesture recognition, we show for the first time thatWiFi signals can be used to recognize small gestures with high accuracy. In our work on sleep monitoring, we propose for the first time aWiFi CSI based sleep quality monitoring scheme which can robustly track breathing and body/limb activity related vital signs during sleep throughout a night in an individual and environment independent manner.In our work on RFID signals based sensing, we propose signal processing and machine learning approaches to effectively image customer activity in front of display items in places such as retail stores using commercial off-the-shelf (COTS) monostatic RFID devices (i.e. which use a single antenna at a time for both transmitting and receiving RFID signals to and from the tags). The key novelty of this work is on achieving multi-person activity tracking in front of display items by constructing coarse grained images via robust, analytical model-driven deep learning based, RFID imaging. We implemented our scheme using a COTS RFID reader and tags.In our work on smartphone's vibration based sensing, we propose a robust and practical vibration based sensing scheme that works with smartphones with different hardware, can extract fine-grained vibration signatures of different surfaces, and is robust to environmental noise and hardware based irregularities. A useful application of this sensing is symbolic localization/tagging, e.g. figuring out whether a user's device is in their hand, pocket, or at their bedroom table, etc. Such symbolic tagging of locations can provide us with indirect information about user activities and intentions without any dedicated infrastructure, based on which we can enable useful services such as context aware notifications/alarms. To make our scheme easily scalable and compatible with COTS smartphones, we design our signal processing and machine learning pipeline such that it relies only on builtin vibration motors and microphone for sensing, and it is robust to hardware irregularities and background environmental noises. We tested our scheme on two different Android smartphones.In our work on powerline communications (PLCs), we propose a distributed spectrum sharing scheme for enterprise level PLC mesh networks. This work is a major step towards using existing COTS PLC devices to connect different types of Internet of Things (IoT) devices for sensing and control related applications in large campuses such as enterprises. Our work is based on identification of a key weakness of the existing HomePlug AV (HPAV) PLC protocol that it does not support spectrum sharing, i.e., currently each link operates over the whole available spectrum, and therefore, only one link can operate at a time. Our proposed spectrum sharing scheme significantly boosts both aggregated and per-link throughputs, by allowing multiple links to communicate concurrently, while requiring a few modifications to the existing HPAV protocol.
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Title: Intra-household human capital measures and child and maternal health : evidence from Zambia
Creator: Faas, Simone Margaret
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Zambia has one of the highest rates of childhood stunting in the world. Traditional health production functions model that good health quality for young children is dependent on the necessary inputs of parental influences, including parental health, parental education, and household wealth. Using data from a Feed the Future survey from rural Zambia and the Women's Empowerment in Agriculture Index, I examine the relationship between several measures of spousal human capital and the health...
Show moreZambia has one of the highest rates of childhood stunting in the world. Traditional health production functions model that good health quality for young children is dependent on the necessary inputs of parental influences, including parental health, parental education, and household wealth. Using data from a Feed the Future survey from rural Zambia and the Women's Empowerment in Agriculture Index, I examine the relationship between several measures of spousal human capital and the health outcomes of young children and women of child-bearing age. I find the ability to read and write of both spouses is highly correlated with positive changes in children's and women's health outcomes. Literacy and education campaigns which target both boys and girls should be heavily emphasized among rural and disadvantaged communities in southern Africa, as men's literacy and education as well as women's literacy are both important to improving future health outcomes for children and adults.
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Title: Cross-disciplinary integration : through argumentation and for sustainability
Creator: Laursen, Bethany
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Today's sustainability problems require wisdom that can only come by integrating different ways of knowing for each situation. When academic researchers undertake sustainability work, many of these ways of knowing come from different disciplines. However, years of cross-disciplinary research and practice have yielded only metaphorical or abstract understandings of what researchers actually do to integrate disciplinary contributions. Without a clear understanding of the actions researchers...
Show moreToday's sustainability problems require wisdom that can only come by integrating different ways of knowing for each situation. When academic researchers undertake sustainability work, many of these ways of knowing come from different disciplines. However, years of cross-disciplinary research and practice have yielded only metaphorical or abstract understandings of what researchers actually do to integrate disciplinary contributions. Without a clear understanding of the actions researchers take to accomplish integration, we have been left with confusion, inconsistent proxy measures, or lengthy learning by trial and error. This has left sustainability and other wicked problems either in the hands of veterans with decades of experience or subject to unreliable integrative attempts by newer investigators. To aid practice through clearer understanding, I open the black box of cross-disciplinary integration, explicating one the main processes that investigators use to integrate disciplinary contributions into cross-disciplinary insights: reasoning together.Through three articles, the dissertation shows that (1) as a field, argumentation studies provides valuable, actionable insights into cross-disciplinary integration, (2) one of the main processes of cross-disciplinary integration is reasoning together, and (3) the details of cross-disciplinary reasoning specify and clarify two existing, more abstract models of cross-disciplinary integration. Thus, overall, the dissertation clarifies what has been an urgent but confusing process in sustainability investigations, and, in doing so, it points the way to practical improvements in sustainability research policies, norms, and education.
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Title: Systematic analysis of the signal responsive gene regulatory network governing Myxococcus xanthus development
Creator: Saha, Shreya
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Studies of signal-induced gene expression in bacteria have contributed to understanding of how bacteria cope with environmental stress. As an extensively studied model, Myxococcus xanthus provides fascinating insights into how changes at the level of gene expression enable which bacteria to survive environmental insults such as nutrient limitation. Upon starvation M. xanthus cells glide into aggregates and form mounds that mature into fruiting bodies as some cells form spores. Previously, our...
Show moreStudies of signal-induced gene expression in bacteria have contributed to understanding of how bacteria cope with environmental stress. As an extensively studied model, Myxococcus xanthus provides fascinating insights into how changes at the level of gene expression enable which bacteria to survive environmental insults such as nutrient limitation. Upon starvation M. xanthus cells glide into aggregates and form mounds that mature into fruiting bodies as some cells form spores. Previously, our group defined 24-30 h poststarvation as the critical period for commitment to spore formation, when cells commit to form spores despite perturbation of the starvation signal by nutrient addition. The process of multicellular development that culminates in sporulation is governed by a network of signal-responsive transcription factors that integrate signals for starvation and cellular alignment. In this dissertation I present the first systematic approach to elucidate the network dynamics during the commitment period.In the network, MrpC is a starvation-responsive transcription factor, whereas FruA is a transcription factor that responds to cellular alignment conveyed by C-signaling. Transcription of fruA is dependent on MrpC binding, and FruA activity is proposed to be posttranslationally regulated by C-signaling, although the mechanism is unknown. FruA and MrpC cooperatively regulate transcription of the dev operon. My systematic analysis of the network dynamics supported a model in which posttranslational activation of FruA by C-signaling is critical for dev transcription and for commitment to spore formation. Similar to dev, MrpC and C-signal-activated FruA combinatorially controlled transcription of the late-acting fadIJ operon involved in spore metabolism. Regulation of late-acting operons implicated in spore coat biogenesis (exoA-I, nfsA-H, MXAN_3259-MXAN_3263) was discovered to be under complex control by MrpC and FruA. My evidence suggests that transcription of these operons depends at least in part on a C-signal-dependent switch from negative regulation by unactivated FruA to positive regulation by activated FruA during the period leading up to and including commitment to sporulation. MrpC negatively regulated exo and MXAN_3259 during mound formation, but positively regulated nfs. During commitment to sporulation, MrpC continued to positively regulate nfs, switched to positive regulation of MXAN_3259, and continued to negatively regulate exo. A third transcription factor, Nla6, appeared to be a positive regulator of all the late genes. We propose that in combination with regulation by Nla6, differential regulation by FruA in response to C-signaling and by MrpC controls late gene expression to ensure that spore resistance and surface characteristics meet environmental demands.
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Title: Determinants of eating behaviors of us army ROTC cadets in Midwestern universities
Creator: George, Beatriz G.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Young adults 18-25 years of age, the largest demographic of the military, experience a high burden of obesity and eating disorders (ED) despite an emphasis on physical fitness, body composition, and operational readiness. Etiologic models for obesity and ED suggest body dissatisfaction (BD), dieting, negative affect (NA), and affect regulation represent potentially shared pathways. However, no studies have examined these factors and their shared pathways in military personnel, including ROTC...
Show moreYoung adults 18-25 years of age, the largest demographic of the military, experience a high burden of obesity and eating disorders (ED) despite an emphasis on physical fitness, body composition, and operational readiness. Etiologic models for obesity and ED suggest body dissatisfaction (BD), dieting, negative affect (NA), and affect regulation represent potentially shared pathways. However, no studies have examined these factors and their shared pathways in military personnel, including ROTC cadets. The overarching aim of this dissertation research was to investigate if ED symptoms were associated with body mass index (BMI), an indicator of obesity, and to describe potential correlates of their development. Three specific aims of this research focus on: 1) the prevalence and correlates of ED risk classification and symptoms in ROTC cadets, 2) the association between ED symptoms and BMI, and their potentially shared mechanisms, psychological inflexibility related to BD and dieting, and 3) the gaps in knowledge about eating behaviors and mediators of eating behaviors within the ROTC context and from perspective of ROTC cadets.In 2018, US Army ROTC cadets (n = 205) were recruited from two Midwestern universities and completed questionnaires about demographics, military-specific eating behaviors and mediators of eating behaviors, ED symptoms, and anthropometric measures. Chi-square, multivariable logistic regression, and multiple linear regression were performed in determining the rate of ED risk classification and correlates of ED risk classification and symptoms (Aim 1). Two measures of psychological inflexibility related to BD and dieting, in addition to the data for Aim 1, were used in mediation path analysis to examine the association of ED symptoms to BMI, and the indirect effects as mediated by psychological inflexibility related to BD and dieting (Aim 2). A purposively selected sample of eighteen cadets participated in one-on-one, semi-structured telephone interviews on eating behaviors and their mediators in the context of ROTC (Aim 3). Interviews were analyzed using thematic analysis to identify the most important themes and determinants related to eating behaviors in ROTC cadets.We found that ED symptoms and ED risk classification are prevalent in a sample of US Army ROTC cadets (10.1% of sample). Correlates associated with greater likelihood of ED risk classification and elevated ED symptoms were: sex, dieting, and military contextual factors such as attempting dieting and weight loss to meet body composition standards, and peers' comments on weight. Total ED symptoms scores were positively associated with BMI and partially mediated by psychological inflexibility related to BD and dieting. Cadets discussed perceived determinants of eating behaviors which included traditional determinants (e.g. time, money, nutrition knowledge) and ROTC-context specific determinants (e.g. preparation for body composition assessments and body image perceptions), which contributed to unhealthy weight control behaviors (dieting) and negative body image perceptions (BD) for some cadets. In conclusion, the prevalent correlates for eating disorder symptoms and risk in the sample of US Army ROTC cadets in this study were factors related to the enforcement of body composition standards and body image perceptions in the military context which may contribute to the development of dieting, BD, and NA. Longitudinal and/or intervention studies on this important topic may benefit our understanding of how ED symptoms and obesity develop over time and how targeting dieting, BD, NA, and affect regulation may be leveraged to mitigate ED and obesity to promote physical fitness, operational readiness and health in military personnel.
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Title: Non-equilibrium phase transformations in charge-density wave and strongly correlated systems studied by coherent femtosecond electron diffraction
Creator: Zhou, Faran
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "By photo-exciting electrons in a material causing subsequent electron-electron and electron-phonon interactions, an energy landscape is created that is very different from that in thermal equilibrium. This distinction sets the baseline that photo-induced phase transitions (PIPT) could go through very different pathways compared with the thermally-induced phase transitions in equilibrium. This opens up a new dimension for complex materials research in non-equilibrium with ultrafast tools. In...
Show more"By photo-exciting electrons in a material causing subsequent electron-electron and electron-phonon interactions, an energy landscape is created that is very different from that in thermal equilibrium. This distinction sets the baseline that photo-induced phase transitions (PIPT) could go through very different pathways compared with the thermally-induced phase transitions in equilibrium. This opens up a new dimension for complex materials research in non-equilibrium with ultrafast tools. In recent years, with the discovery of photo-induced superconductivity (SC) and other hidden quantum states, the study of these metastable and hidden phases in quantum materials has drawn intense interest in the ultrafast community.With femtosecond electron diffraction, we have observed intriguing phenomena in a few charge-density wave (CDW) materials (CeTe3, ErTe3 and 1T-TaS2) and iron chalcogenide systems (FeTe, FeSe0.44Te0.56 and FeSe). We explore the metastable hidden phases and observe universal dynamics in these materials far from equilibrium.CeTe3 exhibits uni-directional stripe CDW order in thermal equilibrium. Bi-directional CDW is thermodynamically forbidden. After femtosecond laser pulse excitation, the system is driven to a bi-directional order as it crosses a nonthermal fixed point. The new state is formed through associated symmetry changes that cause softening/hardening of CDW-related phonons. The CDW wavevector change proves that Fermi surface nesting (FSN)-enhanced electron-phonon coupling plays a central role in driving the CDW instabilities. Based on these results, we propose a nonthermal phase transition pathway in the non-equilibrium phase diagram.The work in ErTe3 is one step further based on the CeTe3 results. ErTe3 is on the opposite side of the rare-earth tritelluride (RETe3) series to host two orthogonal CDW orders at low temperature. Together with CeTe3 data, the ultrafast results at various temperatures in ErTe3 indicate that the system becomes more symmetric after laser excitation. Given the robustness of the data, the conclusion here may be extended to similar systems as well.The generic features of CDW dynamics in 1T-TaS2 are very similar to those in the quench dynamics of isolated quantum systems (e.g. cold atoms). After laser excitation, the system goes to the prethermalization plateau region before the thermalization stage. We find that both regimes follow universal scalings due to the existence of two nonthermal fixed points. Microscopically, we propose a chiral-symmetry-breaking mechanism that mediates the phase transformation. With a 2500 nm excitation laser, we emphasize the photo-doping, instead of the photo-thermal effect, in driving the phase transition. Due to the lack of thermal energy, the phase transition induced by the 2500 nm laser is more first order-like with faster switching speeds than 800 nm excitation. This high-speed switching with little thermal energy deposition holds promise for better future optoelectronic applications.In FeTe, we directly observed the ultrafast structural transition by ultrafast electron diffraction (UED) for the first time. In the studies of optimally-doped compound FeSe0.44Te0.56, we observed the large-amplitude acoustic phonon excitations at right above the transition temperature Tc. While experiments with better spatial-temporal resolutions are needed, the acoustic phonon observed here might be important for SC in iron chalcogenide. In FeSe, we observed the laser-enhanced local stress that is known to be coupled to the nematic phase and superconductivity. Future UED experiments targeted for understanding the local stress would be very helpful."--Pages ii-iii.
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Title: Measuring the half-life of O-26
Creator: Redpath, Thomas
Date: 2019
Collection: Electronic Theses & Dissertations
Description: An interesting property of some neutron-unbound systems is true two-neutron emission where the neutrons are emitted simultaneously as opposed to a sequential decay through an intermediate state. Since neutrons are only affected by the angular momentum barrier, the timescale for this process is much shorter than for two proton emission which is dominated by the Coulomb barrier. One such case is ²2076O where a very low decay energy was measured and the two valence neutrons are expected to...
Show moreAn interesting property of some neutron-unbound systems is true two-neutron emission where the neutrons are emitted simultaneously as opposed to a sequential decay through an intermediate state. Since neutrons are only affected by the angular momentum barrier, the timescale for this process is much shorter than for two proton emission which is dominated by the Coulomb barrier. One such case is ²2076O where a very low decay energy was measured and the two valence neutrons are expected to occupy d-wave orbitals. Also, the ground state of ²2075O is located 700 keV higher. Using the data from a previous measurement of the decay energy, the MoNA collaboration extracted a lifetime of 4:5+1:1-1:5(stat) ± 3(syst) ps with a confidence level of 82% (1). Results from a recent measurement give T1/2 = 5:0+2:0-1:6 (stat) ±1:7 (syst) ps and support the previous finding.Measurements of neutron-unbound systems using invariant mass spectroscopy are often performed using low-intensity radioactive ion beams. Low reaction yields can be countered by using a thicker target but at the expense of larger uncertainties in the reconstructed invariant mass. A new segmented target was designed to address this trade-off, and it was first used in this experiment to re-measure the ground state half-life of ²2076O.
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Title: Analysis of drinking water quality and sanitation in a peri-urban area of Dar es Salaam, Tanzania
Creator: Ngasala, Tulakemelwa Mhamilawa
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "While the Sustainable Development Goal 6 called for universal access to water and sanitation by 2030, the challenge of achieving this goal seems daunting in the context of the bourgeoning peri- urban communities of the developing world. These areas are often in a regulatory grey area, receiving municipal water on an irregular basis and lacking sanitation and other basic services. And yet, SDG 6 recognizes that improving global health and wellbeing is critically linked to addressing this...
Show more"While the Sustainable Development Goal 6 called for universal access to water and sanitation by 2030, the challenge of achieving this goal seems daunting in the context of the bourgeoning peri- urban communities of the developing world. These areas are often in a regulatory grey area, receiving municipal water on an irregular basis and lacking sanitation and other basic services. And yet, SDG 6 recognizes that improving global health and wellbeing is critically linked to addressing this problem. A multi-method study of the peri-urban area of Dar es Salaam was conducted to determine the extent of the problem and to make recommendations for system-wide approaches to alleviate the risk of waterborne disease. Existing water sources in the area were identified. Water collection and storage practices were assessed at the household level to determine how water from relatively clean sources becomes contaminated. Escherichia coli (E. coli), nitrate, and total dissolved solid (TDS) were analyzed as indicators for the sewage contamination. Bivariate correlation and univariate regression analyses were used to identify the sources of contamination. The assessment focused on the relationship and association of water contamination with site-specific variables. The variable that had the highest negative impact to the water source was analyzed by using a groundwater flow and contaminant transport model as a tool to make recommendations for proper site-specific sanitation practices. Of the three water sources identified (city water, vendors, and domestic wells), water quality analysis showed that city water at the point of collection (POC) was deemed excellent, whereas it diminished at the point of use (POU) for all three water sources. Reasons for change in water quality at POU and POC were due to mixing of water from different water sources at homes during storage. Using a multinomial regression model, the main reason for mixing water was determined to be the dilution of the salty taste of well water (p < 0.05) and insufficient storage containers (p < 0.05). Of the three water sources identified, domestic wells were found to be the most contaminated. Further analysis on the domestic wells showed a significant contamination, where 80% of wells tested contained E. coli. Also, 58% and 81% of wells tested had concentrations of nitrate and TDS, respectively, that exceeded the WHO guidelines. Univariate regression analysis confirmed the association of contaminants with distance of a well from a sanitation system and well depth (p < 0.05). Groundwater transport modeling showed a strong correlation between the tracer and contaminants and the tracer and distance and helped identify the safe well setback distance that is specific to site conditions, soil type, and aquifer properties. Groundwater modeling was shown to be a good assessment tool for contamination within an aquifer system in urban overpopulated areas of developing countries. Our findings also indicate that the risk of exposure to waterborne disease comes from a combination of factors that involve multiple actors, from improved awareness and sanitation practices to improved regulatory oversight, supply practices, and sanitation technologies."--Pages ii-iii.
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Title: On designing biological nanoscale organization
Creator: Young, Eric J.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "Life at the nanoscale creates a dazzling array machines and structures. Studying these nanoscale creations often requires inter-disciplinary efforts of scientists, along with the support of other personnel. This thesis serves to communicate some personal insights and data captured in studying nanoscale organization of biologically-driven components, as part of such a team. The first chapter addresses spatiotemporal organization of material inside cells, with a focus on scaffolding-type...
Show more"Life at the nanoscale creates a dazzling array machines and structures. Studying these nanoscale creations often requires inter-disciplinary efforts of scientists, along with the support of other personnel. This thesis serves to communicate some personal insights and data captured in studying nanoscale organization of biologically-driven components, as part of such a team. The first chapter addresses spatiotemporal organization of material inside cells, with a focus on scaffolding-type strategies. The second chapter offers a literature perspective on constructing scaffolds with a structurally-characterized protein-domain. The third chapter surveyed functionality of an in vivo designer nanoscaffolding system. The fourth chapter, alongside the appendix materials, forms a collection of future-steps and comments on projects I have encountered while working on my thesis project."--Page ii.
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Title: Deciphering the genetic basis for complex trait variation : utilizing alternative genome-wide association metrics and molecular phenotypes
Creator: Funkhouser, Scott A.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Within any population, complex trait variation can be attributed to an impressive number of genetic factors. Identification of such factors has been made possible, in part, by large biomedical datasets comprised of genotypes and phenotypes for hundreds of thousands of individuals. Furthermore, understanding the biological mechanisms through which genetic variation creates complex trait variation has been facilitated by high-throughput sequencing technology, used to quantify molecular,...
Show moreWithin any population, complex trait variation can be attributed to an impressive number of genetic factors. Identification of such factors has been made possible, in part, by large biomedical datasets comprised of genotypes and phenotypes for hundreds of thousands of individuals. Furthermore, understanding the biological mechanisms through which genetic variation creates complex trait variation has been facilitated by high-throughput sequencing technology, used to quantify molecular, intermediate phenotypes. Despite such datasets being widely available, we lack understanding of the full spectrum of genetic effects, including gene-by-sex (GxS) interactions. We also have yet to uncover various molecular phenotypes that may "link" genetic variation to complex trait variation. To address these gaps in knowledge, the following chapters will 1) develop and utilize statistical methodology for mapping GxS interactions among human traits, and 2) utilize a pig model to characterize RNA editing-a relatively understudied form of transcriptional regulation- and evaluate its potential to link genetic variation with complex trait variation.Growing evidence from genome-wide parameter estimates suggest males and females from human populations possess differing genetic architectures. Despite this, mapping GxS interactions remains challenging, suggesting that the magnitude of a typical GxS interaction is exceedingly small. We have developed a local Bayesian regression (LBR) approach to estimate sex-specific single nucleotide polymorphism (SNP) marker effects after fully accounting for local linkage-disequilibrium (LD) patterns. This provided means to infer GxS interactions either at the SNP level, or by aggregating multiple sex-specific SNP effects to make inferences at the level of small, LD-based regions. In simulations, LBR provided greater power and resolution to detect GxS interactions than the traditional approach to genome-wide association (GWA), single-marker regression (SMR).When using LBR to analyze human traits from the UK Biobank (N 223C 250,000) including height, BMI, bone-mineral density, and waist-to-hip ratio, we find evidence of novel GxS interactions where sex-specific effects explain a very small proportion of phenotypic variance (R2 < 1x10-4) but are enriched in expression quantitative trait loci (eQTL). By leveraging large datasets and powerful metrics, we are providing evidence that GxS interactions may influence phenotypic variance for a variety of human complex traits.Adenosine to inosine (A-to-I) RNA editing impacts gene function by converting adenosine to inosine molecules within specific regions of the transcriptome and is catalyzed by adenosine deaminase acting on RNA (ADAR). High-throughput sequencing studies, most of which utilizing human models, have found thousands of A-to-I edited loci commonly located within repetitive elements such as the primate-specific Alu element. Here, we utilized matched whole-genome sequencing and RNA sequencing from the same animal to demonstrate that widespread RNA editing occurs within pig transcriptomes, largely within pig-specific repetitive elements known as PRE-1.The degree that sites in the transcriptome are edited by ADAR-the "editing level"-has been observed to vary within populations but it is largely unknown how genetic variation as whole influences editing level variation. Using 168 F2 pigs with SNP genotyping data and RNA sequencing from skeletal muscle, we identified five RNA editing sites across four genes whose editing level variation was significantly attributed to the additive effects of all observed SNP markers (estimated genomic heritability = 0.31-0.56; p-value = 8.2E-5-8.8E-4). We then used bivariate models to estimate how genetics influences covariance between site-specific RNA editing levels and complex traits in pigs. We found modest evidence that SNPs near ADAR contribute to covariance in RNA editing activity and numerous growth traits such as average daily gain (local genetic correlation [SE] = -0.87 [0.16]; p-value = 0.029). These results suggest potential pleiotropic effects between RNA editing activity and complex traits and encourages further use of multi-variate mixed models determine if RNA editing can "link" genetic variation with complex trait variation.
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Title: Investigating emergency medical service (EMS) providers' behaviors with packaging in a prehospital context
Creator: Lee, Jiyon
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "Little is known about how packages perform in emergency contexts and the behaviors that Emergency Medical Service (EMS) responders use to deal with any shortcomings in package designs in these environments. Our years of work with healthcare providers in varied care settings yields anecdotal evidence that emergency personnel interact differently with healthcare packaging than providers in perioperative environments (e.g. one-handed use and use of teeth/tools for opening). It is not...
Show more"Little is known about how packages perform in emergency contexts and the behaviors that Emergency Medical Service (EMS) responders use to deal with any shortcomings in package designs in these environments. Our years of work with healthcare providers in varied care settings yields anecdotal evidence that emergency personnel interact differently with healthcare packaging than providers in perioperative environments (e.g. one-handed use and use of teeth/tools for opening). It is not unreasonable to purport that these behaviors have the potential to play a role in patient outcomes. As such, investigation into difficulties with packaging, the designs, and conditions that induce them, is warranted.The overarching goal of this work is to develop packages optimized for prehospital settings and austere use contexts. In support of this overarching goal, work presented here was directed by four specific aims;2022Aim 1-Verify the presence of difficulties with packaging in prehospital contexts, coping strategies employed to overcome difficulties and begin to characterize prevalence.2022Aim 2- Identify factors (both package design and context) that induce unintended behaviors (e.g. use of teeth and scissors) in prehospital settings.2022Aim 3-Create simulation scenarios (contexts) that induce the unintended behaviors/coping strategies studied previously.2022Aim 4- Develop an understanding of affordance behaviors EMS personnel use to deal with packaging (i.e. coping strategies) during tasks (opening, identifying and using) and characterize design cues and contextual factors that induce them.In support of Aim 1, a survey was distributed to 12,000 paramedics. Of the 1,912 responses (16% response rate), 1,702 were usable for analysis. Survey results reinforced anecdotal observations that EMS providers have difficulty with packaging, namely, identifying, opening, and using. Over 20% of respondents included in the analysis reported that they had experienced difficulties identifying (21.1 %) or opening (20.0%) medications and identifying (17.1 %) or opening (23.5%) medical supplies within the past year. This was reported to negatively impact patient care for between 1.2% (identifying a medication) and 3.0% (opening supplies) of total responses. The results suggested difficulties associated with packaging use (identify, open, and use) induced coping strategies and negative patient outcomes and supports our anecdotal observation that paramedics use coping strategies (e.g. one hand use and use of teeth/tools, etc.) to deal with shortcomings of package design.In support of Aims 2 and 3, we created a collective case study gathered using a series of semi-structured interviews for the purpose of designing the final study, a formative usability study employing simulation scenarios for two patients. Findings suggested patient demographics (namely infants and obese patients); condition (those requiring care on multiple systems-e.g. pulmonary and cardiac) and behavior (e.g. drunk, belligerent, intoxicated, non-responsive patients) formed "worst case" scenarios. Sudden stops, bumps and potholes were all reported as further impacting difficulties. These findings coupled with a thorough review of ISO 2631 and the literature regarding whole body vibration and human ability informed decisions regarding the creation of a vibration profile intended to present realistic, but extreme, conditions likely to induce difficulties.Leveraging learnings from Aims 1 and 2, simulation scripts were drafted and conducted in our ambulance simulator that incorporated motion with licensed paramedics. Video collected from varied angles was analyzed post-hoc to conduct a formative usability analysis. Usability metrics included in analysis were informed by ISO 9241-11; namely, 1) efficiency (time task analysis), 2) error (identification of designs that induced unintended behaviors, and 3) self-reported satisfaction (informed by ISO 9241-11 (2018 International Organization for Standardization [ISO], 2018)."--Pages ii-iii.
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Title: Natural language addition via degrees, events, and focus
Creator: Feldscher, Cara
Date: 2019
Collection: Electronic Theses & Dissertations
Description: This dissertation began asking where do we see addition in natural language? This began by reframing comparatives, it extended to other types of addition, looking at list environments and opening up questions about the nature of the language that enables "adding to lists", which in turn effected a cross-categorical research project, building on work on degree semantics, event semantics, focus, and discourse structure.Work on comparatives is foundational in degree semantics and comparatives...
Show moreThis dissertation began asking where do we see addition in natural language? This began by reframing comparatives, it extended to other types of addition, looking at list environments and opening up questions about the nature of the language that enables "adding to lists", which in turn effected a cross-categorical research project, building on work on degree semantics, event semantics, focus, and discourse structure.Work on comparatives is foundational in degree semantics and comparatives continue to be the source of ongoing research in the field (Cresswell, 1976; VonStechow, 1984; Kennedy & Levin, 2008; Schwarzschild, 2008). Here I work on an understudied ambiguity that can be analyzed as more creating an event summing reading instead of the typically studied reading. I contribute novel data showing a class of expressions participates in this ambiguity, supporting a compositional analysis. Event semantics typically analyzes adjectival constructions as stative constructions, in lieu of incorporating degrees (Davidson, 1967; Parsons, 1990). This research works in the interface between these two subfields, and provides an argument for studying their interactions, as well as a compositional account of one way we see degree constructions build to event constructions.From there, I follow morphological link to discover a class of data that impressionistically adds propositions to lists, including data with the focus sensitive particle also. Following Rooth (1992), I provide an analysis of this list effect via the semantics of focus and focus sensitivity. This requires assuming that propositions as a whole can be focused, which in turn requires precise assumptions about how the discourse context is framed formally. I follow both the Table theory from Farkas and Bruce (2010) and the conversational scoreboard model of Roberts (2004), showing that pieces of both models can function as contextual restrictions on the focus semantic value for focus sensitive expressions. Further investigation showed that other focus sensitive expressions can have similar restrictions, so major contributions of this include not only this revised notion of how to view "context", but also the ability to use focus sensitivity to investigate the nature of the discourse and what objects it contains.The final section of this dissertation focuses on data linking these two previous sections. The appearance of aspectual particles like still in comparatives has been noted in the literature (Ippolito 2007). This pretheoretically looks like an event related expression contributing to a degree construction, which is the opposite direction from the data analyzed earlier in this dissertation. However, following Ippolito's lead in analyzing still here as a focus sensitive particle, I implement the analysis of focus and contextual restrictions I laid out in the previous chapter. The result is that no evidence is found for treating this case as an event construction building to a degree construction, but also further evidence is given for my theory in which objects in the discourse are the contextual limitations on focus semantic values.The major contributions of this dissertation thus fall into two main categories or topics. On the subject of degrees and events, novel data solidified a previously observed link. Then the analysis I proposed supports a compositional and directional analysis where degree constructions can be built into event constructions. This highlights the importance of research on the interface between topics and theories within the same subfield, like degree and event semantics. On the subject of focus and the discourse, again I contribute novel data showing a class of expressions, which supports an analysis involving focusing whole propositions. This analysis gives evidence that objects in the discourse are the "context" that restricts the focus alternatives. These restrictions are lexical, showing that research in this area, looking at other focus sensitive expressions, gives us a new tool to investigate the structure of the discourse with.
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Title: Contemporary liberalism and the nation
Creator: Fram, Daniel
Date: 2019
Collection: Electronic Theses & Dissertations
Description: What is the status and legitimacy of the nation within the horizon of liberalism today? Surveying three representative, contrasting, recent works in contemporary political philosophy, I argue that the nation loses its status and legitimacy from every side. John Rawls's allegedly status-quo preserving theory in The Law of Peoples (Rawls 1999) defends only the shell of sovereignty and in fact points toward cosmopolitan aspirations. Cosmopolitan liberals, and conservative nationalists, therefore...
Show moreWhat is the status and legitimacy of the nation within the horizon of liberalism today? Surveying three representative, contrasting, recent works in contemporary political philosophy, I argue that the nation loses its status and legitimacy from every side. John Rawls's allegedly status-quo preserving theory in The Law of Peoples (Rawls 1999) defends only the shell of sovereignty and in fact points toward cosmopolitan aspirations. Cosmopolitan liberals, and conservative nationalists, therefore, claim with reason that liberalism is not capable of conferring status and legitimacy on the nation's "arbitrary" restrictions of individual autonomy (Nussbaum and Cohen 1996, MacIntyre 2003). But, in doing so, cosmopolitan liberalism creates a grave problem, for liberalism depends upon citizens to uphold freedom and upon limits to freedom to make freedoms meaningful. One would think to turn toward so-called liberal nationalist theories of liberalism, like David Miller's On Nationality (Miller 1995). But these, in turn, defend the nation only by depleting it of any content and rendering the very concept of the nation hollow. Neither of these two possible corrections of liberalism solves its problems with particularity and social unity; each only exacerbates them. My work as a whole therefore shows that contemporary liberalism tends to undermine the nation, on which it nevertheless relies. I demonstrate each part of the argument in separate chapters: two on Rawls's liberalism, one on Nussbaum's cosmopolitanism, and two on David Miller's liberal nationalism. These three perspectives represent a fairly complete spectrum of contemporary liberal thinking about the status of the nation.
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Title: Advancing frontiers in reactive and selective iridium c-h borylation catalysis and targeted silsesquioxane synthesis
Creator: Dannatt, Jonathan E.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: The studies in this dissertation are aimed at uncovering reactive and selective Ir-catalyzed C-H borylation (CHB) catalysts. Due to the high versatility of organoboron species, green methodology to produce the C-B bond is poised to support a myriad of subsequent transformations. These transformations include Suzuki couplings, aminations, oxidations, halogenations, cyanations, and trifluoromethylations.Typical iridium catalyzed CHBs proceed through an iridium trisboryl with a bidentate ligand...
Show moreThe studies in this dissertation are aimed at uncovering reactive and selective Ir-catalyzed C-H borylation (CHB) catalysts. Due to the high versatility of organoboron species, green methodology to produce the C-B bond is poised to support a myriad of subsequent transformations. These transformations include Suzuki couplings, aminations, oxidations, halogenations, cyanations, and trifluoromethylations.Typical iridium catalyzed CHBs proceed through an iridium trisboryl with a bidentate ligand such as bipyridine or 1,10-phenanthroline. The selectivity of these standard catalysts is generally driven by sterics; however, many methods of overcoming the steric bias have been developed in the two decades since the first thermal catalytic C-H activation borylation. These methods include both inner- and outer-sphere directed mechanisms. Outer-sphere directed borylations have been accomplished by leveraging hydrogen bonding, Lewis acid-base, and ion-pairing as directing elements. In general this reactivity is activated by precise design of the bidentate ligand framework.Herein is reported a subtle electrostatic interaction to direct ortho-borylation of phenols by simply switching boron source from the common B2pin2 (pin = pinacolate) to B2eg2 (eg = ethyleneglycolate). This electrostatic interaction was revealed by a careful computational analysis of key C-H activation transition states. Understanding gained by the computational studies led to the redesign of the boron source which enabled by selectivities of > 99% ortho borylation. This methodology was extended to the highly selective ortho-borylation of anilines, and the underlying mechanism has been interrogated.Currently, iridium based catalysts have been generated to borylate ortho, meta, and even para to a variety of classes of substrates; however, control of selectivity can breakdown in many fluorinated arenes without a directing group. These substrates are challenging because the fluoro moiety being similar in size to a hydrogen offers little in the way of steric bias. While working to overcome these challenges, a serendipitously discovered hydrazone based ligand was discovered. Exploration of the catalysts generated by this ligand revealed not only impressive activity rivaling dtbpy but also incredible selectivity for meta to a fluoro group.In general iridium CHB catalysts selectively activate sp2 C-H bonds leaving all sp3 C-H bonds intact; however, a method to turn on sp3 C-H activation would be desirable. It was reasoned that a directing group able to increase the effective concentration of the iridium catalyst near a C(sp3)-H bond may enable this transformation. Indeed, it was discovered that catalysts able to accept amide directing groups were able to selectively borylate compounds with amide N-methyl substituents.
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Title: Weighting in multilevel models
Creator: Tong, Bing
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Large-scale survey programs usually use complex sampling designs such as unequal probabilities of selection, stratifications, and/or clustering to collect data to save time and money. This leads to the necessity to incorporate sampling weights into multilevel models in order to obtain accurate estimates and valid inferences. However, the weighted multilevel estimators have been lately developed and minimal guidance is left on how to use sampling weights in multilevel models and which...
Show moreLarge-scale survey programs usually use complex sampling designs such as unequal probabilities of selection, stratifications, and/or clustering to collect data to save time and money. This leads to the necessity to incorporate sampling weights into multilevel models in order to obtain accurate estimates and valid inferences. However, the weighted multilevel estimators have been lately developed and minimal guidance is left on how to use sampling weights in multilevel models and which estimator is most appropriate.The goal of this study is to examine the performance of multilevel pseudo maximum likelihood (MPML) estimation methods using different scaling techniques under the informative and non-informative condition in the context of a two-stage sampling design with unequal probabilities of selection. Monte Carlo simulation methods are used to evaluate the impact of three factors, including informativeness of the sampling design, intraclass correlation coefficient (ICC), and estimation methods. Simulation results indicate that including sampling weights in the model still produce biased estimates for the school-level variance. In general, the weighted methods outperform the unweighted method in estimating intercept and student-level variance while the unweighted method outperforms the weighted methods for school-level variance estimation in the informative condition. In general, the cluster scaling estimation method is recommended in the informative sampling design. Under the non-informative condition, the unweighted method can be considered a better choice than the weighted methods for all the parameter estimates. Besides, the ICC has obvious effects on school-level variance estimates in the informative condition, but in the noninformative condition, it also affects intercept estimates. An empirical study is included to illustrate the model.
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Title: I. amhb : (anti)aromaticity-modulated hydrogen bonding. ii. evaluation of implicit solvation models for predicting hydrogen bond free energies
Creator: Kakeshpour, Tayeb
Date: 2019
Collection: Electronic Theses & Dissertations
Description: My doctoral research under Professor James E. Jackson focused on hydrogen bonding (H-bonding) using physical organic chemistry tools. In the first chapter, I present how I used quantum chemical simulations, synthetic organic chemistry, NMR spectroscopy, and X-ray crystallography to provide robust theoretical and experimental evidence for an interplay between (anti)aromaticity and H-bond strength of heterocycles, a concept that we dubbed (Anti)aromaticity-Modulated Hydrogen Bonding (AMHB). In...
Show moreMy doctoral research under Professor James E. Jackson focused on hydrogen bonding (H-bonding) using physical organic chemistry tools. In the first chapter, I present how I used quantum chemical simulations, synthetic organic chemistry, NMR spectroscopy, and X-ray crystallography to provide robust theoretical and experimental evidence for an interplay between (anti)aromaticity and H-bond strength of heterocycles, a concept that we dubbed (Anti)aromaticity-Modulated Hydrogen Bonding (AMHB). In the second chapter, I used accurately measured hydrogen bond energies for a range of substrates and solvents to evaluate the performance of implicit solvation models in combination with density functional methods for predicting solution phase hydrogen bond energies. This benchmark study provides useful guidelines for a priori modeling of hydrogen bonding-based designs.Coordinates of the optimized geometries and crystal structures are provided as supplementary materials.
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