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Title: Searching for kinetic control of excited-state evolution in Fe(II) polypyridyl chromophores
Creator: Adelman, Sara Linnae
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Iron(II) polypyridyl chromophores represent an earth-abundant alternative to ruthenium-based complexes in photo-induced electron transfer applications, yet the sub-150 fs metal-to-ligand charge transfer (MLCT) excited-state lifetime endemic to low-spin Fe(II) polypyridyls has hampered their widespread use. One promising avenue towards achieving a longer-lived MLCT excited-state lifetime is through the exertion of kinetic control, made possible through the identification and subsequent...
Show moreIron(II) polypyridyl chromophores represent an earth-abundant alternative to ruthenium-based complexes in photo-induced electron transfer applications, yet the sub-150 fs metal-to-ligand charge transfer (MLCT) excited-state lifetime endemic to low-spin Fe(II) polypyridyls has hampered their widespread use. One promising avenue towards achieving a longer-lived MLCT excited-state lifetime is through the exertion of kinetic control, made possible through the identification and subsequent disruption of the nuclear coordinate of excited-state deactivation. With this aim, a series of structurally similar iron(II) polypyridyl complexes spanning from low-spin to high-spin, including a spin crossover complex, were synthesized, which allowed for the determination of reorganization energy from the lowest-energy excited state (5T2) to the ground state (1A1) through a combination of variable temperature transient absorption and magnetic susceptibility measurements. In addition to experimentally determining the reorganization energy and electronic coupling constant associated with this conversion, we will deduce the kinetically competent degree of freedom associated with this transition through a convergence of analyses from semi-classical to fully quantum mechanical non-radiative decay theories. A ruthenium(II)-based analog of the spin crossover complex provided insight into the geometric distortions coupled to the deactivation of the MLCT excited states. Coupled together, these results offered new guidelines for ligand design, inspiring the synthesis of new iron(II) complexes with unique photophysical dynamics and establishing new roadmaps towards controlling excited-state dynamics in this class of compounds.
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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: Transmission timing modulation for information coding in energy-constrained wireless networks
Creator: Feng, Dezhi
Date: 2020
Collection: Electronic Theses & Dissertations
Description: The objective of this thesis is to develop a framework of transmission timing-based modulation framework for improving energy efficiency, security, and information transfer capacity in embedded wireless networks with very thin energy budgets. The key idea is to modulate both intra-PDU (Protocol Data Unit) and inter-PDU timing for addressing energy, security, and information transfer capacity in wireless embedded networks. As for energy efficiency, we developed a novel pulse position-coded PDU...
Show moreThe objective of this thesis is to develop a framework of transmission timing-based modulation framework for improving energy efficiency, security, and information transfer capacity in embedded wireless networks with very thin energy budgets. The key idea is to modulate both intra-PDU (Protocol Data Unit) and inter-PDU timing for addressing energy, security, and information transfer capacity in wireless embedded networks. As for energy efficiency, we developed a novel pulse position-coded PDU (PPCP) paradigm. The core idea is to encode a protocol data unit (PDU) in terms of the silence duration between two sets of delimiter pulses, whose positions are modulated based on the value of the PDU. This PPCP architecture achieves significant energy savings by using a lesser amount of bit/pulse transmissions, and by eliminating long multi-bit preambles and headers, which are normally used in traditional packets. The proposed multi-access pulse-based PDU scheme enables medium sharing among many sensor nodes without requiring per-PDU frame synchronization. As for security, we developed the concept of a novel chaotic pulse position coded protocol data unit (CPPCP) for secure embedded networking. The core idea of CPPCP is to encode a protocol data unit (PDU) with a wideband pulse train with chaotically-varied inter-pulse intervals. The architecture ensures communication security by introducing randomness between data symbols, noise-like frequency spectrum, and significant energy savings by using a smaller number of pulse transmissions compared to existing secure coding schemes such as Bluetooth Low Energy (BLE). Compared with the traditional key-based cryptographic techniques, CPPCP suppresses decipherable information by eliminating symbol periodicity. The mechanism can also be piggy-backed on traditional cryptography solutions to achieve higher levels of security. Finally, for enhancing the information transfer capacity, we developed a data packet position modulation (DPPM) paradigm. Packet transmissions in low duty cycle networks are often scheduled as TDMA slots, whose periodicity is determined based on application sampling requirements and the energy in-flow, often in the form of energy harvesting. The key idea of DPPM is to modulate the inter-packet spacing for coding additional information without incurring additional transmission energy expenditures. We first developed a have a DPPM based networking solution for single-hop transmit-only networks in which a number of low-energy nodes transmit data to an aggregator. The architecture is developed for a two-node point-to-point link, followed by a multipoint-to-point multi-access network. Detailed analytical and simulation models are developed to demonstrate the performance of a symmetric and an asymmetric version of DPPM.
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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: Effect of suspect's gender on police use of physical force
Creator: Ishola, Oluwatobi Taiwo
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Police use of force has received much research attention as researchers attempt to explain various predictors of this phenomenon. This topic is of great interest to police practitioners, policy makers, researchers, scholars, and criminal justice students. Several studies have examined various predictors of this behavior, including officer education, race, experience, age, and sex. However, most of these studies focused on either the officers' or suspect's sex, while research on the interplay...
Show more"Police use of force has received much research attention as researchers attempt to explain various predictors of this phenomenon. This topic is of great interest to police practitioners, policy makers, researchers, scholars, and criminal justice students. Several studies have examined various predictors of this behavior, including officer education, race, experience, age, and sex. However, most of these studies focused on either the officers' or suspect's sex, while research on the interplay between suspect's sex and officer sex as a predictor of police use of force is lacking. Drawing on criminal threat theory and research on chivalry, this study will examine how the interplay between officer and suspect sex influences the likelihood and severity of police use of physical force. Further, given the influence of social norms on chivalry, the study will further investigate whether the presence of bystanders moderates the influence of officer and suspect sex on use of physical force. The study is based on data from the 1996-1997 (ICPSR 3172) study titled 'Understanding the use of force by and against the police in six jurisdictions in the United States'."--Page ii.
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Title: Bridging gaps in information : strategies for improving natural resource management in a changing climate
Creator: Tracy, Erin
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "The Great Lakes region has an abundance of natural resources that are ecologically and socioeconomically valuable yet threatened by changing climate. To effectively address impacts of climate change within the Great Lakes region will require managers to mitigate the causes of climate change as well as adapt to current threats and to future changes in both social and ecological systems. This thesis addresses those needs by providing natural resource managers with strategies to increase...
Show more"The Great Lakes region has an abundance of natural resources that are ecologically and socioeconomically valuable yet threatened by changing climate. To effectively address impacts of climate change within the Great Lakes region will require managers to mitigate the causes of climate change as well as adapt to current threats and to future changes in both social and ecological systems. This thesis addresses those needs by providing natural resource managers with strategies to increase support for climate change mitigation policies and by providing them with information on how social and ecological systems may change with changing climate so that they can develop and apply novel management strategies. Results from Chapter 1 show that while Michigan conservation organizations vary in their current engagement with climate change issues and in their willingness to increase engagement with their membership depending on perceived barriers, every organization expressed interest in receiving more information on how climate change will affect the state's fish and wildlife populations. In Chapter 2, we characterized how resilient Michigan river fish habitat may be to anticipated changes in climate. Our results indicate that while cumulative resilience is generally higher in the Upper Peninsula and in the Northern Lower Peninsula, resilient streams are also found in the Southern Lower Peninsula, suggesting that managers have opportunities in every part of the state for protecting and/or improving stream resiliency to changing climate. Collectively, outcomes of this research offer managers new information and strategies for mitigating and adapting to climate change, ultimately facilitating the sustainable management of natural resources in a changing climate."--Page ii.
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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: Development of a fast and cost-effective asphalt mixture fatigue test system
Creator: Seitllari, Aksel
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Fatigue cracking is one of the critical distress modes in asphalt pavements. Accurate prediction and evaluation of fatigue performance are crucial to extending the service life of asphalt mixtures. Naturally, laboratory testing methods for fatigue characterization are time-consuming and require sophisticated procedures. Any effort to improve the speed and quality of the information gained from laboratory fatigue tests is valuable. This research work presents the results of a study...
Show moreFatigue cracking is one of the critical distress modes in asphalt pavements. Accurate prediction and evaluation of fatigue performance are crucial to extending the service life of asphalt mixtures. Naturally, laboratory testing methods for fatigue characterization are time-consuming and require sophisticated procedures. Any effort to improve the speed and quality of the information gained from laboratory fatigue tests is valuable. This research work presents the results of a study investigating the possibility of implementing a new approach to characterize asphalt mixture fatigue behavior. This new approach includes cyclic tests run on cylindrical asphalt specimens in three-point beam mode (herein referred to as three-point bending cylinder (3PBC) geometry). Timoshenko beam theory along with the viscoelastic continuum damage (VECD) theory was implemented to model the mechanical response of the specimens. An excellent correlation between the results of 3PBC tests and uniaxial push-pull fatigue tests were observed. The 3PBC setup possesses the most advantages of uniaxial push-pull tests and includes more advantages such as not requiring a saw to cut the ends of the sample, not requiring gluing operation (and the gluing jig) and the possibility of estimating Poisson's ratio from the data. The proposed 3PBC approach was evaluated through laboratory tests conducted on various asphalt mixtures with varying binder types, mix components, and volumetric properties. The approach proposed herein was validated through finite element analysis. In addition, ruggedness evaluation of the 3PBC testing approach through varying factors and their levels were investigated and presented.
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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: Fast edit distance calculation methods for NGS sequence similarity
Creator: Islam, A. K. M. Tauhidul
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Sequence fragments generated from targeted regions of phylogenetic marker genes provide valuable insight in identifying and classifying organisms and inferring taxonomic hierarchies. In recent years, significant development in targeted gene fragment sequencing through Next Generation Sequencing (NGS) technologies has increased the necessity of efficient sequence similarity computation methods for very large numbers of pairs of NGS sequences.The edit distance has been widely used to determine...
Show moreSequence fragments generated from targeted regions of phylogenetic marker genes provide valuable insight in identifying and classifying organisms and inferring taxonomic hierarchies. In recent years, significant development in targeted gene fragment sequencing through Next Generation Sequencing (NGS) technologies has increased the necessity of efficient sequence similarity computation methods for very large numbers of pairs of NGS sequences.The edit distance has been widely used to determine the dissimilarity between pairs of strings. All the known methods for the edit distance calculation run in near quadratic time with respect to string lengths, and it may take days or weeks to compute distances between such large numbers of pairs of NGS sequences. To solve the performance bottleneck problem, faster edit distance approximation and bounded edit distance calculation methods have been proposed. Despite these efforts, the existing edit distance calculation methods are not fast enough when computing larger numbers of pairs of NGS sequences. In order to further reduce the computation time, many NGS sequence similarity methods have been proposed using matching k-mers. These methods extract all possible k-mers from NGS sequences and compare similarity between pairs of sequences based on the shared k-mers. However, these methods reduce the computation time at the cost accuracy.In this dissertation, our goal is to compute NGS sequence similarity using edit distance based methods while reducing the computation time. We propose a few edit distance prediction methods using dataset independent reference sequences that are distant from each other. These reference sequences convert sequences in datasets into feature vectors by computing edit distances between the sequence and each of the reference sequences. Given sequences A, B and a reference sequence r, the edit distance, ed(A.B) 2265 (ed(A, r) 0303ed(B, r)). Since each reference sequence is significantly different from each other, with sufficiently large number of reference sequences and high similarity threshold, the differences of edit distances of A and B with respect to the reference sequences are close to the ed(A,B). Using this property, we predict edit distances in the vector space based on the Euclidean distances and the Chebyshev distances. Further, we develop a small set of deterministically generated reference sequences with maximum distance between each of them to predict higher edit distances more efficiently. This method predicts edit distances between corresponding sub-sequences separately and then merges the partial distances to predict the edit distances between the entire sequences. The computation complexity of this method is linear with respect to sequence length. The proposed edit distance prediction methods are significantly fast while achieving very good accuracy for high similarity thresholds. We have also shown the effectiveness of these methods on agglomerative hierarchical clustering.We also propose an efficient bounded exact edit distance calculation method using the trace [1]. For a given edit distance threshold d, only letters up to d positions apart can be part of an edit operation. Hence, we generate pairs of sub-sequences up to length difference d so that no edit operation is spilled over to the adjacent pairs of sub-sequences. Then we compute the trace cost in such a way that the number of matching letters between the sub-sequences are maximized. This technique does not guarantee locally optimal edit distance, however, it guarantees globally optimal edit distance between the entire sequences for distance up to d. The bounded exact edit distance calculation method is an order of magnitude faster than that of the dynamic programming edit distance calculation method.
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Title: Bifurcation phenomenon in bi-layered system with thin films and its application in the development of stretchable bendable devices
Creator: Sinha, Mayank
Date: 2020
Collection: Electronic Theses & Dissertations
Description: "Bifurcation of equilibrium" is a term that is used to describe the condition in which a system admits multiple solutions to the equilibrium problem, in other words has multiple possible deformed configurations that can be considered equilibrated under the same load, usually referred to as the critical load. The loss of uniqueness of the equilibrium problem, also results in a loss of stability of the system, which is because the equilibrated configuration that is unstable becomes...
Show more"Bifurcation of equilibrium" is a term that is used to describe the condition in which a system admits multiple solutions to the equilibrium problem, in other words has multiple possible deformed configurations that can be considered equilibrated under the same load, usually referred to as the critical load. The loss of uniqueness of the equilibrium problem, also results in a loss of stability of the system, which is because the equilibrated configuration that is unstable becomes energetically more favorable over the stable one. An unstable equilibrated configuration can be described as a configuration in which a small change in parameter values, for example a small perturbation in the load or a small defect in the geometry of the system, will lead to a large change in the behavior of the system that can often be catastrophic for the system itself, one example of this is the buckling of a beam. Conventionally due its disruptive nature, instability is considered undesirable. For this reason, in the past few decades a lot of studies have focused on modeling and predicting the onset of instability in many systems and under many loading conditions. Since bifurcation events are specific for each system, namely are unique after the system is defined, some studies have had the intention to employ this information to learn more about specific systems. For example, several studies have focused on understanding how changing the material properties of a system can affect the onset of instability. The knowledge gained from that can also be employed to solve the inverse problem - in other words, if we identify the instability onset, we can use this information as a means to evaluate the mechanical properties of a specific system. This has proved especially useful for systems in which it is difficult to employ conventional methods to evaluate the mechanical properties. One example of that, is to use this principle to estimate mechanical behavior of a bilayered system of silicon nanocrystals (SiNC) deposited on a layer of polydimethylsiloxane (PDMS). Due to this unique combination of materials, conventional tests to evaluate mechanical properties, like uniaxial tensile or nano-indentation tests, cannot be performed. In this thesis, I employed the instability analysis for a bilayered system subjected to finite bending, to estimate the material behavior of the SiNC layer.In addition to studying instability in finite bending, I have developed a mathematical framework to study deformation and instability in a multilayered system undergoing unbending and eversion. First, I develop the solution of nonlinear elasticity to evaluate the change in geometrical parameters of the system due to deformation. Then, I solve the instability analysis to evaluate when a bifurcation occurs for a multi-layered system undergoing unbending or eversion. The solution for the instability problem is then obtained numerically by employing the compound matrix method.I have revealed that the stress states in a bilayered structure subject to unbending or eversion can result in the presence of multiple neutral axes, as previously observed in finite bending as well, or no neutral axes. Also, I found that the presence of a second layer significantly affects bifurcation behavior during unbending and eversion. Finally, I show that the presence of the stiff layer can significantly affect the bifurcation behavior just by moving the stiff layer from outside to inside in the reference configuration.
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Title: Examining organizational supports within domestic violence programs that support or hinder responses to reproductive coercion
Creator: McGirr, Sara
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Reproductive coercion (RC) is a newly identified but commonly experienced form of domestic violence (DV) with serious potential consequences for women's health and well-being. Despite the high prevalence of RC against DV survivors, initial reports suggest that few DV advocates regularly engage in RC-related practices with their clients. In order to better understand the factors that may be impeding advocates' RC-responsiveness, the study examined data collected via a brief online survey of...
Show moreReproductive coercion (RC) is a newly identified but commonly experienced form of domestic violence (DV) with serious potential consequences for women's health and well-being. Despite the high prevalence of RC against DV survivors, initial reports suggest that few DV advocates regularly engage in RC-related practices with their clients. In order to better understand the factors that may be impeding advocates' RC-responsiveness, the study examined data collected via a brief online survey of more than 300 domestic violence advocates across the U.S. and its territories. Results identified critical barriers and facilitators to RC-responsive practice in DV organizations on the intrapersonal and organizational ecological levels. While intrapersonal factors (levels of comfort discussing sexuality and comfort discussing reproductive health) influenced advocates' frequency of universal and targeted RC practice, the level of RC-responsive supports provided by advocates' organizations was much more impactful. In addition to supporting the assertion that intervention on multiple ecological levels has the greatest potential for successful change in professionals' behavior, the study's results also provide initial insight into a minimum level of organizational supports that may be necessary to promote more frequent RC-responsive practice in DV organizations. This guidance may prove useful for agencies aiming to improve their RC-responsiveness; by focusing on those factors, DV programs and their staff will ultimately be better prepared and better able to support survivors of RC in regaining their reproductive control.
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Title: Investigation of students' causal mechanistic reasoning in undergraduate organic chemistry
Creator: Crandell, Olivia Marie
Date: 2020
Collection: Electronic Theses & Dissertations
Description: The undergraduate organic chemistry course is a prerequisite course for many students who plan to pursue careers in chemistry and chemical engineering. It also serves those students who wish to pursue professional careers in medicine, dentistry, and veterinary sciences. Previous research on student learning in organic chemistry shows that students struggle to understand ideas such as acid-base reactions and structure-property relationships which are foundational concepts on which more complex...
Show moreThe undergraduate organic chemistry course is a prerequisite course for many students who plan to pursue careers in chemistry and chemical engineering. It also serves those students who wish to pursue professional careers in medicine, dentistry, and veterinary sciences. Previous research on student learning in organic chemistry shows that students struggle to understand ideas such as acid-base reactions and structure-property relationships which are foundational concepts on which more complex concepts are built. Furthermore, the typical organic chemistry course emphasizes students use of the electron-pushing formalism to represent how bonds are formed and broken in chemical reactions. Expert organic chemists use this formalism to represent predicted reaction mechanisms that explain the formation of products. Numerous studies have characterized student difficulties using electron-pushing mechanisms in an expert-like way as well as associating underlying chemical principle with the representations. We suggest that deep understanding of chemical reactions and their underlying chemical principles can be developed by engaging students in causal mechanistic explanation as part of a transformed organic chemistry course that emphasizes students using their knowledge of electrostatics, structure-property relationships, and energy to engage in explanation of chemical phenomena. Our goal is to engage students in as specific type of explanation called in casual mechanistic explanation which includes reasoning about the underlying causal factors in conjunction with the underlying entities and their activities that bring the phenomenon about. The studies reported here use a qualitative approach to elicit student' written explanations and drawn reaction mechanisms for various chemical reactions. Students were sampled at multiple time points over the course of their two-semester organic course to investigate how student reasoning changes overtime. Students participants were enrolled in either the beforementioned transformed organic chemistry course or were enrolled in an untransformed course that we refer to as the traditional context. This traditional context served as a control group for which to compare possible changes in reasoning for students enrolled in the transformed course sequence. Findings suggest that student engagement in causal mechanistic reasoning varies depending on students' general chemistry and organic chemistry course experience as well as the nature of the prompt eliciting the reasoning. Findings also suggest that students are generally capable of drawing mechanistic arrows that would generally be considered correct, however triangulating student reasoning with a detailed analysis of students' drawings, we found that typical organic chemistry assessment items that lack a reasoning component may overestimate student understanding. Our investigations also revealed student difficulties invoking the correct nucleophilic substitution process for a given reaction. Students often invoked an SN1 mechanistic process incorrectly, despite their engagement in casual mechanistic reasoning. Implications of these findings for organic chemistry instruction and assessment are discussed along with implications for future research.
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Title: Church and tower : graduate student negotiations of faith and learning communities
Creator: Espinoza, Hannah Brady
Date: 2020
Collection: Electronic Theses & Dissertations
Description: This project is a practice in telling a small part of a less common story: one about negotiating commitments to academic and church communities when the stories told across those communities don't always line up or are incomplete. Through the stories of my three participants as well as my own experiences, I will describe this in-between space and the individual negotiations we perform to explain those spaces to ourselves and to rest in them. In telling these stories from the in-between places...
Show moreThis project is a practice in telling a small part of a less common story: one about negotiating commitments to academic and church communities when the stories told across those communities don't always line up or are incomplete. Through the stories of my three participants as well as my own experiences, I will describe this in-between space and the individual negotiations we perform to explain those spaces to ourselves and to rest in them. In telling these stories from the in-between places, I use cultural rhetorics to permeate boundaries some scholars continue to hold between academic and community learning. Through the stories of participants and myself, I demonstrate that holding, challenging, and shifting community rhetorics is a complex process of critical thought and individual experience that carries religious rhetorics into the realm of belief and practice and beyond.Using methodologies and mixed methods from cultural rhetorics, Indigenous rhetorics, feminist rhetorics, and grounded theory, I emphasize practices of relationality, listening, and storying to share stories from three participants who participated in an Evangelical church community, pseudonymized here as "Hope Church," while completing graduate studies. Through a thorough exploration of these stories as well as my own, this study finds that individual negotiations of academic and Evangelical communities come out of and create a rhetorical space of faith and learning that allows them to hold multiple knowledges in constellation while shifting narratives across spaces.
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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: Meeting them where they are : the use of Twitter in youth civic education
Creator: Chapman, Amy L.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Many measures of youth civic engagement indicate that youth participation in civic life has long been in decline; however, some of these measures fail to take into account ways that youth interact and engage with civic life. This qualitative study explored the experiences of five high school social studies teachers who have used the social media platform Twitter with students in their teaching of civics. Data collected during in-depth interviews was analyzed using a two-step coding process:...
Show moreMany measures of youth civic engagement indicate that youth participation in civic life has long been in decline; however, some of these measures fail to take into account ways that youth interact and engage with civic life. This qualitative study explored the experiences of five high school social studies teachers who have used the social media platform Twitter with students in their teaching of civics. Data collected during in-depth interviews was analyzed using a two-step coding process: first, an open-coding phase of data analysis allowed for data to emerge without preconceived ideas influencing the data; and second, a theory-based coding phase of data analysis allowed for examination of how the collective perceptions and experiences of participants connected to a proposed model of constructivist teaching of civic education with Twitter. Findings showed that the participants were introduced to Twitter for educational purposes by an influential peer who provided support as teachers considered the affordances of Twitter for their teaching. The study's findings also showed that participants viewed citizenship as moving fluidly between online and offline spaces. Further, participants were concerned about their students' self-worth, and used Twitter as a means of amplifying student voice and foster student agency. These findings contributed to theoretical understanding of the use of social media in K-12 education as well as the use of social media in the teaching of civics. Further implications included suggestions for research on introducing social media for classroom use in both teacher education and professional development programs. Additional implications for research on the other ways in which teachers could support both online and offline civic engagement, the impact of the use of Twitter on student worth, and the impact of student worth on youth civic engagement are discussed. Finally, implications for teachers' adoption and use of social media for education are presented.
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Title: Precision measurement of the Beta-energy spectrum in 2076He decay
Creator: Huyan, Xueying
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Precision measurements of the β-energy spectrum in nuclear and neutron decays have a great potential to find possible signatures of new physics beyond the standard electroweak model. Such signatures would produce a distortion to the β-energy spectrum relative to the Standard Model prediction. In Gamow-Teller transitions, these distortions would indicate the presence of the exotic tensor type interactions. An interesting candidate for this study is 6He because the simplicity of its decay and...
Show morePrecision measurements of the β-energy spectrum in nuclear and neutron decays have a great potential to find possible signatures of new physics beyond the standard electroweak model. Such signatures would produce a distortion to the β-energy spectrum relative to the Standard Model prediction. In Gamow-Teller transitions, these distortions would indicate the presence of the exotic tensor type interactions. An interesting candidate for this study is 6He because the simplicity of its decay and other nuclear properties allow an accurate theoretical description of the spectral shape.At the National Superconducting Cyclotron Laboratory we have used a calorimetric technique for measuring the shape of the β-energy spectrum in 6He decay. The radioactive ions were implanted into the active volume of a detector; this eliminates the critical instrumental effect related to the backscattering of β particles. The goals of the experiment are to provide the first measurement of the weak magnetism form factor (bWM) in 6He decay and the first direct measurement of the Fierz interference term (bGT) in Gamow-Teller decay.This work summarizes the efforts on this experiment, focusing on the data analysis of the main systematic effects as well as the projected sensitivities to the observables. The estimates of bWM and bGT are bWM = ? ± 4.9stat ± 11sys and bGT = (? ± 3.1stat ± 4.7sys) × 10−3, where the central values of bWM and bGT will be determined in the future analysis. The predicted uncertainty of bGT satisfies the precision goal of O(10−3), a level which allows new constraints on tensor couplings beyond the Standard Model.
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