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Title: NUMERICAL ANALYSIS ON MAXIMUM LIKELIHOOD ESTIMATORS FOR LINEAR PARABOLIC STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS
Creator: Zhang, Jun
Date: 2019
Description: The thesis contributes to the numerical analysis on statistical inference for stochastic partial differential equations (SPDEs). We study the...
Show moreThe thesis contributes to the numerical analysis on statistical inference for stochastic partial differential equations (SPDEs). We study the maximum likelihood estimation problem of the drift parameter for a large class of linear parabolic SPDEs. As in the existing literature on statistical inference for SPDEs, we take a spectral approach, and assume that one path of the first N Fourier modes is observed continuously in a fixed finite time interval [0, T]. We first provide a review of the asymptotic properties of the maximum likelihood estimator (MLE) of the drift parameter in the large number of Fourier modes regime, N  ∞, while the time horizon T > 0 is fixed. The main part of this thesis is dedicated to the numerical study of the asymptotic properties of the MLEs for two examples of linear parabolic SPDEs: the one-dimensional stochastic heat equation and a d-dimensional linear, diagonalizable, parabolic SPDE, where d  ℕ. For the one-dimensional stochastic heat equation, we perform the sensitivity analysis to assess the effect of changes in model parameters on the speed of convergence of the MLE. For the second linear parabolic SPDE, our simulations verify the theoretical results in the literature that both the consistency and asymptotic normality of the MLE hold for such equation only when d ≥ 2.
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Title: Mathematics of Civil Infrastructure Network Optimization
Creator: Rumpf, Adam Andrew
Date: 2020
Description: We consider a selection of problems from civil infrastructure network design that are of great importance in modern urban planning but have,...
Show moreWe consider a selection of problems from civil infrastructure network design that are of great importance in modern urban planning but have, until relatively recently, gone largely ignored in mathematical literature. Each of these problems is approached from the perspective of network optimization-based modeling, with a major focus placed on the development of efficient solution algorithms.We begin with a study of the phenomenon of interdependent civil infrastructure networks, wherein the functionality of one network (such as a telecommunications system) requires the input of resources from another network (such as the electrical power grid). We first consider a linear relaxation of an established binary interdependence minimum-cost network flows model, including its unique modeling applications and its use as part of a randomized rounding approximation algorithm for the mixed integer model. We also develop a generalized network simplex algorithm for the efficient solution of this generalized minimum-cost network flows problem. We then move on to consider a trilevel network interdiction game for use in planning the fortification of interdependent networks subject to targeted attacks. A variety of solution algorithms are developed for both the binary and the linear interdependence models, and the linear interdependence model is used to develop an approximation algorithm for the more computationally expensive binary model.We then develop a public transit network design model which incorporates a social access objective in addition to traditional operator cost and user cost objectives. The model is meant for use in planning minor modifications to a public transit network capable of improving equity of access to important services while guaranteeing that service levels remain within a specified tolerance of their initial values. A hybrid tabu search/simulated annealing algorithm is developed to solve this model, which is then applied to a test case based on the Chicago public transit network with the objective of improving equity of primary health care access across the city.
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Title: An experimental study on the effects of partial sleep deprivation on disordered-eating urges and behaviors
Creator: Johnson, Nicole Kathryn
Date: 2020
Description: Previous research has linked sleep disturbances with disordered eating. Studies have also shown that one night of partial sleep deprivation...
Show morePrevious research has linked sleep disturbances with disordered eating. Studies have also shown that one night of partial sleep deprivation causes increases in food intake and appetite disturbances. However, the effects of sleep deprivation on disordered eating are unclear as research has yet to examine the effects of one night of partial sleep deprivation (≤ 4 hours of sleep) on disordered eating in a representative adult female sample. Adult, female participants (N=40) completed eligibility and baseline measures reporting medical conditions, eating disorder symptoms, sleep disturbances, depressed mood, and anxiety symptoms. Participants were randomized to either the sleep-deprived condition (~50% of their average sleep duration) or the habitual-sleep condition (~100% of their average sleep duration). The morning after the sleep condition, participants completed self-report appetite and disordered eating measures before and after consuming a test meal and later that evening. The following statistical analyses, adjusted for multiple comparisons (p<0.002), found no significant group differences: independent samples t-tests (outcome: pre-meal appetite, disordered eating, and test-meal consumption), multivariate analyses of variance (MANOVAs; outcome: pre- and post-meal area under the curve disordered eating and appetite), repeated measures ANOVAs (time X group; outcome: pre- and post-meal appetite and disordered eating), analyses of covariance (ANCOVAs; controlling for pre-meal ratings; outcome: disordered eating at follow-up), and chi-square tests (outcome: follow-up appetite and disordered eating). Despite finding no support for the effect of sleep deprivation on disordered eating, this study extends previous research as a novel study using the experimental manipulation of sleep deprivation to examine its effects on disordered eating.
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Title: Combining Simulation and Emulation for Planning and Evaluation of Smart Grid Security, Resilience, and Operations
Creator: Hannon, Christopher
Date: 2020
Description: The modern power grid is a complex, large scale cyber-physical system comprising of generation, transmission and distribution elements....
Show moreThe modern power grid is a complex, large scale cyber-physical system comprising of generation, transmission and distribution elements. However, advancements in information technology have not yet caught up to the legacy operational technology used in the electric power system. Coupled with the proliferation of renewable energy sources, the electric power grid is in a transition to a smarter grid; operators are now being equipped with the tools to make real-time operational changes and the ability to monitor and provide situational awareness of the system. This shift in electric power grid priorities requires an expansive and reliable communication network to enhance efficiency and resilience of the Smart Grid. This trend calls for a simulation-based platform that provides sufficient flexibility and controllability for evaluating network application designs, and facilitating the transition from in-house research ideas into production systems. In this Thesis, I present techniques to efficiently combine simulation systems, emulation systems, and real hardware into testbed systems to evaluate security, resilience, and operations of the electric power grid. While simulating the dynamics of the physical components of the electric power grid, the cyber components including devices, applications, and networking functions are able to be emulated or even implemented using real hardware. In addition to novel synchronization algorithms between simulation and emulation systems, multiple test cases in applying software-defined networking, an emerging networking paradigm, to the power grid for security and resilience and phasor measurement unit analytics for grid operations are presented which motivate the need for a simulation-based testbed. The contributions of this work lay in the design of a virtual time system with tight controllability on the execution of the emulation systems, i.e., pausing and resuming any specified container processes in the perception of their own virtual clocks, and also lay in the distributed virtual time based synchronization across embedded Linux devices.
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Title: Exploring Growth After Vision Loss
Creator: BANGLE, MELISSA
Date: 2020
Description: Despite recent advances in our knowledge of positive growth following the onset of chronic illness or disability, little to no effort has been...
Show moreDespite recent advances in our knowledge of positive growth following the onset of chronic illness or disability, little to no effort has been made to understand how the phenomenon of growth might be experienced by individuals who are blind or visually impaired. This not only limits our understanding of how growth is experienced, but also our understanding of the experiences associated with vision loss. This qualitative study explores the perspectives and experiences of growth held by 35 adults with acquired disability due to severe vision impairment and blindness. Additionally, participants discussed their views on how growth can be experienced within the context of adjusting to vision loss. Results indicate that some individuals do experience positive psychological growth after vision loss which can lead to positive changes in one’s life. They also demonstrate that the structure of growth after vision loss shares some similarities with existing growth models like the model for Post Traumatic Growth. Results also suggest that growth may be an outcome of becoming well-adjusted to vision loss; although, the nature of the transition from adjustment to growth remains less clear. Specific factors that may facilitate growth are explored and implications for facilitation of successful adjustment and growth in the context of vision rehabilitation are discussed.
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Title: Is emotion regulation a mediator between parenting skills and treatment outcome in Parent-Child Interaction Therapy?
Creator: Butler, Kristina
Date: 2020
Description: Disruptive behavior disorders are prevalent in preschool children and are associated with a range of negative developmental sequelae. There is...
Show moreDisruptive behavior disorders are prevalent in preschool children and are associated with a range of negative developmental sequelae. There is extensive evidence that Parent-Child Interaction Therapy (PCIT) is an effective behavioral parent training program for decreasing disruptive behaviors in young children. However, the mechanism that accounts for the reduction in externalizing behaviors in PCIT is not well understood. Children’s emotion regulation (ER) is one possible mechanism that accounts for treatment effectiveness. Parenting skills focused on in PCIT serve to increase warmth in caregiver-child interactions, which, in turn, lead to increases in children’s ER skills. ER also has been shown to moderate externalizing behaviors in PCIT. However, to date, there are no longitudinal studies that have examined ER as a mediator in PCIT. The aim of this study was to determine if child ER serves as a mediator between changes in parenting skills and decreases in externalizing behavior problems after PCIT treatment. A diverse sample of 67 children and their mothers participated in PCIT treatment in a community mental health center. All variables were assessed twice, at baseline and after treatment. Positive parenting skills (“Do Skills”) and negative ones (“Don’t Skills”) were assessed during a video recorded 5-minute task using the Dyadic Parent-Child Interaction Coding System. Child ER was assessed during a video recorded 5-minute clean-up task with a behavioral coding scheme adapted from previous research. Child behavior problems were measured using the Child Behavior Checklist Externalizing Scale. Difference scores used in the final analyses were calculated by subtracting the baseline score from the final assessment score for each measure.Results of linear regression analyses revealed a significant, negative relation between changes in ER and externalizing behavior problems. Findings did not support ER as a partial mediator between parenting skills and child externalizing problems. However, moderation analyses indicated that change in ER moderated the relation between change in positive parenting skills (Do Skills) and change in behavior problems, such that the interaction was significant for greater changes in ER. Specifically, increases in Do Skills led to less improvement in disruptive behaviors in children whose ER skills decreased. Also, increases in Do Skills led to greater reductions in behavior problems in children whose ER skills showed greater improvement. This study provides evidence that change in ER moderates changes in Do Skills and change in externalizing problems in PCIT. Findings also suggest that adding strategies to PCIT that focus on increasing child ER may enhance effectiveness of this treatment.
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Title: CULTURALLY SENSITIVE HELP-SEEKING AMONG ASIAN INTERNATIONAL AND ASIAN AMERICAN COLLEGE STUDENTS
Creator: Tsen, Jonathan Yee-jon
Date: 2020
Description: Asian populations are rapidly rising, representing the fastest growing racial group of immigrants in the U.S. with many seeking higher...
Show moreAsian populations are rapidly rising, representing the fastest growing racial group of immigrants in the U.S. with many seeking higher education. While many face risk for poor mental health outcomes and high suicidal ideation, Asian college students report lower rates seeking mental health services than White Americans. The purpose of this study was to test a culturally sensitive help-seeking model for Asian international and Asian American college students, and to capture relevant psychological and cultural factors that influence help-seeking. This study used an observational design to build on the current research and evaluated the effects of acculturation, enculturation, public stigma of help-seeking, self-stigma of help-seeking, and attitudes on willingness to seek psychological services. Four hundred and fifty-eight students (Age M = 23.93, SD = 4.36) represented by 265 Asian International Students and 193 Asian American Students. Using a path analysis, results demonstrated a poorly fitted model, suggesting that acculturation, enculturation, public stigma, self-stigma, attitudes, and willingness do not relate significantly to each other when viewed altogether in a model. This remained true even when modifications to the model were made, and when observing the model within only Asian American student sample or Asian international student sample. However, significant direct effects were observed between enculturation and public stigma in the total sample, as well as separately in Asian American or Asian international samples. These findings highlight the importance of exploring with different methodological approaches to gain insight on other important psychological and cultural factors that impact help-seeking among Asian international and Asian American college students.
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Title: A Complete Machine Learning Approach for Predicting Lithium-Ion Cell Combustion
Creator: Almagro Yravedra, Fernando
Date: 2020
Description: The object of the herein thesis work document is to develop a functional predictive model, able to predict the combustion of a US18650 Sony...
Show moreThe object of the herein thesis work document is to develop a functional predictive model, able to predict the combustion of a US18650 Sony Lithium-Ion cell given its current and previous states. In order to build the model, a realistic electro-thermal model of the cell under study is developed in Matlab Simulink, being used to recreate the cell's behavior under a set of real operating conditions. The data generated by the electro-thermal model is used to train a recurrent neural network, which returns the chance of future combustion of the US18650 Sony Lithium-Ion cell. Independently obtained data is used to test and validate the developed recurrent neural network using advanced metrics.
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Title: Gaussian Process Assisted Active Learning of Physical Laws
Creator: Chen, Jiuhai
Date: 2020
Description: In many areas of science and engineering, discovering the governing differential equations from the noisy experimental data is an essential...
Show moreIn many areas of science and engineering, discovering the governing differential equations from the noisy experimental data is an essential challenge. It is also a critical step in understanding the physical phenomena and prediction of the future behaviors of the systems. However, in many cases, it is expensive or time-consuming to collect experimental data. This article provides an active learning approach to estimate the unknown differential equations accurately with reduced experimental data size. We propose an adaptive design criterion combining the D-optimality and the maximin space-filling criterion. The D-optimality involves the unknown solution of the differential equations and derivatives of the solution. Gaussian process models are estimated using the available experimental data and used as surrogates of these unknown solution functions. The derivatives of the estimated Gaussian process models are derived and used to substitute the derivatives of the solution. Variable-selection-based regression methods are used to learn the differential equations from the experimental data. The proposed active learning approach is entirely data-driven and requires no tuning parameters. Through three case studies, we demonstrate the proposed approach outperforms the standard randomized design in terms of model accuracy and data economy.
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Title: The Relation Between Community Violence Exposure and Young Children's Psychopathology Symptoms
Creator: Gibson, Lynda L
Date: 2020
Description: Chronic community violence exposure (CVE) has become an everyday issue for many children living in inner-city neighborhoods. However, few...
Show moreChronic community violence exposure (CVE) has become an everyday issue for many children living in inner-city neighborhoods. However, few studies have examined the effects of CVE on symptoms of psychopathology in young children. The primary aim of this study was to examine the relation between CVE and internalizing and externalizing symptoms in preschool children. Another goal was to determine if the relations between CVE and both types of symptoms were affected by the type of exposure, the location of the event, and the relationship between the child and the individual involved in the event. A signal-contingent ecological momentary assessment (EMA) design was used in which 32 caregivers reported on their age 3-5 year-old children’s exposure to community violence, and their internalizing and externalizing symptoms for one week. A total of 152 events of community violence were reported during this period, revealing that the children were exposed to an alarmingly high frequency of these events. Results of multilevel model (MLM) analyses showed that increased frequency of momentary CVE was associated with more severe caregiver-reported internalizing and externalizing symptoms throughout one-week. Additionally, witnessed CVE, situations occurring near home, and situations involving someone known by the child strengthened the association between CVE and symptom severity. The present findings reveal that some of the long-term negative effects associated with trauma exposure occur in a shorter time-span when children are exposed to community violence on a daily basis. They also provide guidelines that can be used to inform future assessment of CVE and strategies that may be effective for intervention.
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Title: A Biodegradable Microsphere-Hydrogel Ocular Drug Delivery System for Treatment of Choroidal Neovascularization
Creator: Liu, Wenqiang
Date: 2020
Description: Current standard of care for neovascular age-related macular degeneration (AMD) requires repeated intravitreal bolus injections of anti...
Show moreCurrent standard of care for neovascular age-related macular degeneration (AMD) requires repeated intravitreal bolus injections of anti-vascular endothelial growth factors (anti-VEGFs). This frequent repeated injection regimen present increased risks of potential complications including endophthalmitis, retinal detachment, intravitreal hemorrhage, and cataract. In addition, pharmacokinetic profiles of drugs are non-optimal, since the peak level of drug after bolus injections may cause potential toxic effect while the quick clearance later may render subtherapeutic concentration. Finally, the significant socioeconomic burden upon patients, family, and healthcare systems cannot be ignored. Therefore, a controlled delivery system for anti-VEGF drugs is in high demand to reduce injection frequencies, minimize potential risks, and improve efficacy.The overall goal of this study was to develop a biodegradable and injectable drug delivery system (DDS) capable of releasing therapeutic anti-VEGF (aflibercept) for six months. Based on our previous non-degradable DDS for anti-VEGFs, this work sought to introduce biodegradable polymeric crosslinker into the hydrogel matrix to make the DDS biodegradable. To accomplish this goal, three specific aims were pursued: (1) Development of a biodegradable and injectable microsphere-hydrogel DDS for controlled release of aflibercept for six months, important biomaterial parameters including thermoresponsive behavior, injectability, in vitro degradation and biocompatibility, release kinetics, and drug bioactivity were characterized to obtain the optimal DDS formulation; (2) Evaluation of long-term in vivo efficacy of aflibercept-loaded DDS in laser-induced CNV model; (3) Investigation of in vivo safety and biocompatibility of DDS injection and its degradation products.
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Title: Essays in Corporate Risk Management for Oil Industry
Creator: Lu, You
Date: 2020
Description: This dissertation includes three chapters with a series of empirical investigations in areas of corporate risk management in the oil industry...
Show moreThis dissertation includes three chapters with a series of empirical investigations in areas of corporate risk management in the oil industry.In the first chapter, I overview the oil industry. I introduce different crude oil-related business segments and how market risks affect them. The types of available financial hedging strategies and hedging instruments are also discussed.The second chapter studies the rationales for corporate risk management and the effects of the financial hedging activities on firm value. I revisit the hedging positions of U.S. oil producers and find evidence that for firms that purely involving in upstream activities, the hedging activities add to their market value. The sensitivity of Tobin’s Q to oil price variance is stabilized by hedging activities. Besides, there is an optimal hedging level, and over hedging will hurt firm value. Though firms claim that their hedging decisions are subject to the oil price movement in their annual report, my evidence does not support that firm’s hedging decisions are impacted by oil price movement.The third chapter investigates the effects of operational hedging on firm value and commodity price risks. It explores a novel type of operational hedging - the natural operational hedging positions between the upstream crude oil producers and the downstream oil consumers. Using hand-collected data of 272 unique oil-producing firms, I find that operational hedging is a substitute for financial hedging. Operational hedging is sufficiently effective in reducing firms’ exposure to oil price risk. Consistent with hedging theory, I also find that operational hedging adds to the firm value measured by Tobin’s Q.
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Title: Control Surface Synthesis of Propane Dehydrogenation Catalysts
Creator: Zhao, Yiqing
Date: 2019
Description: Alkane dehydrogenation is one of the primary chemical reactions to convert light alkanes into light olefins. The conversion of small alkanes...
Show moreAlkane dehydrogenation is one of the primary chemical reactions to convert light alkanes into light olefins. The conversion of small alkanes to alkenes by dehydrogenation reactions is important for polymer and chemical industrial process because it makes direct producing the possible alkenes. Controlled synthesis of single-site catalysts are still challenges. This makes tuning of the catalysts structure and active sites difficult. We developed method of Zirconium modified SiO2 to support single-site catalysts. My research is focusing on the synthesis new single-site heterogeneous catalysts for high selectivity alkane dehydrogenation reaction and the general principles to design better preformed catalysts (e.g., more active, more selective, more stable) for dehydrogenation reaction, especially on propane dehydrogenation. The study described in this thesis was conducted to understand how zirconium ions can modify the electronic properties and catalytic performance.In this study, with the Zr promoted cobalt catalysts show high propane conversion and propene selectivity compared to the previous reported Co/SiO2 catalyst by our group previous work. The Co/Zr/SiO2 material exhibited good catalytic activity, stability and high propylene selectivity which can reach up to 97% for catalytic propane dehydrogenation at 550 ℃. The catalyst was characterized by TEM, STEM, EPR, DRIFTS, UV-vis, XANES and EXAFS for synthesized material, under reaction conditions and post reaction samples. We hypothesized the reason behind is due to the π donation of Zr will lead to ease of heterolytic cleavage of the propane by have a lower metal-oxygen bond dissociation energy in the rate-determining step which is consistent with the previous calculations found that weaker catalyst-oxygen bonds led to facile heterolytic cleavage. A varieties of single-site Ga catalysts supported on Zr modified SiO2 were synthesized by different methods. The Ga/Zr/SiO2 catalysts prepared by the difference method also exhibit higher or similar activity and selectivity. Those catalysts have more isolated active sites show that rational catalyst design method, such as surface organometallic chemistry synthesize, can be applied in heterogeneous systems using homogeneous catalyst design method. But the origin of those effects is unclear, some discussion of possible origins of observation of catalysts behavior are discussed in Chapter 4. And we will do more characterization to find the origins behind.
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Title: Integrated Design Framework For Electric Motor Drive Systems
Creator: Salameh, Mohamad
Date: 2020
Description: This thesis aims to develop a flexible and time-efficient framework for machine design optimization that considers driving cycles,...
Show moreThis thesis aims to develop a flexible and time-efficient framework for machine design optimization that considers driving cycles, multiphysics domains and current design. The proposed development of the framework is based on the enhancement of three key aspects in the machine design process. A data mining algorithm – the X-means – is employed in the driving cycle analysis, to establish a trade-off between the optimization objectives and the computational intensity. A novel vibration surrogate model is proposed to evaluate the vibroacoustic behavior of the machine in an accurate and time-efficient way. In the identification process, the time effectiveness of the model is attained with a minimized number of finite element simulations. Furthermore, the principle of simultaneous coupled optimization is considered in the framework, where current design variables are included in the optimization environment to allow identifying design candidates with improved performance.
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Title: Assessment of Sleep Characteristics and Their Effects in People with Type 1 Diabetes for the Development of a Sleep Module for the Multivariable Artificial Pancreas System
Creator: Brandt, Rachel
Date: 2021
Description: his work is focused on the relationship between sleep and blood glucose control in people with Type 1 Diabetes and on the development of a...
Show morehis work is focused on the relationship between sleep and blood glucose control in people with Type 1 Diabetes and on the development of a sleep module incorporating new variables and rules for use in automated insulin delivery and advisory systems. Through this research, sleep effects were identified, quantified and incorporated into a multivariable artificial pancreas system (mvAP) that is currently being developed. The mvAP uses different physiological signals acquired through non-invasive wearable sensors along with a continuous glucose monitor (CGM) to detect the state of the user to predict future blood glucose values to aid in insulin dosing decisions. The overall objective of the research was to develop and add a module to further improve the successful mvAP by incorporating sleep related information while retaining the functionality and safety of the system and improving the effectiveness in maintaining good glycemic control. Two types of sleep effects were studied: effects of sleep characteristics and stages in real-time (during sleep) and effects of sleep on glucose metabolism the next day. It was found that poor sleep quality was related to higher glycemic variability overnight in adults with Type 1 Diabetes. However, in adults without diabetes, there were no consistent relationships found between sleep stages and changes in blood glucose levels overnight. For adults with Type 1 Diabetes, it was determined that Sleep Quality, Total Sleep Time, Wake After Sleep Onset (WASO), Number of Awakenings >5 minutes, and amount of Deep sleep could be used in conjunction with insulin on board and the amount of time that has passed since the user has woken up to predict how much more insulin may be needed at the first meal of the day. This Insulin Multiplier Algorithm was tested and validated in replay simulations. Finally, in order to incorporate these relationships into the mvAP, a sleep stage detection algorithm was developed using the Empatica E4 wristband.
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Title: Modeling the Glycemic Response to Physical Activity and Athletic Competition Anxiety in People with Type 1 Diabetes
Creator: Hobbs, Nicole B.
Date: 2021
Description: The first observational study of recreational athletes with T1D during a meaningful athletic competition and a non-competitive exercise...
Show moreThe first observational study of recreational athletes with T1D during a meaningful athletic competition and a non-competitive exercise session was conducted. Non-invasive wearable devices and surveys are used to identify the presence or absence of competition stress during physical activity and to estimate physical activity intensity. An elevated glycemic trend on the day of an athletic competition is a frequent complaint among people with T1D and this increase was consistently observed in our study population. The elevation in glycemia is impacted by the individual behavior related to diabetes management and this behavioral change is impacted by the individual’s duration of diabetes and other demographic traits. A physical activity-intensity dependent model of glucose-insulin dynamics was developed for a type 1 diabetes simulator as a basis for the development of multivariable artificial pancreas systems. Several potential model structures were compared to assess the influence of model terms related to endogenous glucose production, glucose utilization, and glucose transfer. The model including all three terms accurately describes the relation of plasma insulin and physical activity intensity upon glucose production and glucose utilization to generate the appropriate glucose response for each physical activity condition ranging from low to maximal intensity efforts. All artificial pancreas performance metrics have been determined based upon physician-defined metrics for success. An online survey was conducted to assess individual goals for diabetes management, and for many individuals, the ability to achieve personalized metrics is unnecessary as their goals match the general metrics. As individual targets may be set by the individual or their doctor, the ability to achieve those are still of interest. A framework to target the individual management goals with the multivariable artificial pancreas system is developed which increased the percentage of time spent in each individual target range in simulations.
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Title: Sense of Community and Virtual Community Among People with Autism Spectrum Conditions
Creator: Rafajko, Sean I
Date: 2020
Description: Individuals with autism spectrum conditions (ASC) face poorer quality of life (QOL) and psychological well-being. Sense of community (SOC) has...
Show moreIndividuals with autism spectrum conditions (ASC) face poorer quality of life (QOL) and psychological well-being. Sense of community (SOC) has been studied in the general population as well as in other disability populations and found to be associated with increased QOL outcomes. However, SOC has never been examined quantitatively in the ASC population. Additionally, a number of communities exist online, and there has been recent research showing that people may feel sense of virtual community (SOVC), which may be particularly important to the ASC population, as internet use is higher in the population, and people with ASC report positive experiences with online communication and relationships. The purpose of this study was to examine SOC and SOVC in the ASC population. A sample of 60 participants with ASC completed an online survey about their communities, SOC, SOVC, QOL, and psychological distress, and their results were compared with a sample of 60 general population participants (N = 120). Results indicated that people with ASC reported participating in a greater number of smaller relational communities compared to the general population sample. There were no significant differences between the ASC and general population samples on levels of SOC or SOVC, suggesting that the differential relationship of the ASC group with their communities does not reduce the experience of SOC. SOC significantly contributed to QOL but not psychological distress. Results indicated that the magnitude of the relationship between SOC and SOVC on QOL was not different between those with ASC and those in the comparisons sample. Findings from this study help frame the different ways in which people with ASC interact with their communities and inform individual and community-level interventions.
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Title: Novel Chelating Agents for Positron Emission Tomography Imaging and Theranostic Applications
Creator: Zhang, Shuyuan
Date: 2022
Description: Positron emission tomography (PET) is a molecular imaging technology that can be used to detect various diseases including cancer. Zirconium...
Show morePositron emission tomography (PET) is a molecular imaging technology that can be used to detect various diseases including cancer. Zirconium-89 (t1/2 = 78.4 h) is one of the positron-emitting radionuclides that has been widely explored for PET imaging because its half-life matches the long biological half-life of antibody. Research efforts have been devoted to the development of chelation chemistry for 89Zr, a bone-seeking radionuclide. Deferoxamine (DFO) is the most frequently used chelator for 89Zr in both clinical and preclinical trials. DFO can rapidly sequester 89Zr to form 89Zr-DFO complex. However, DFO is not an ideal ligand for 89Zr because 89Zr-labeled DFO-antibody conjugate showed high bone uptake in mice. We wanted to develop novel small molecule donors and novel chelators for 89Zr. We discovered N-methyl-N-(pyridin-2-yl)hydroxylamine (Py-HA) and 2,6-bis(N-methylhydroxylamino)pyridine (Py-BHA) as small molecule donors for 89Zr. Based on the new small molecule donors (Py-HA and Py-BHA), we have designed and synthesized a series of novel macrocyclic chelators containing TACN (1,4,7-triazacyclononane), CYCLEN (1,4,7,10-tetraazacyclododecane), and a diaza-crown ether backbone for 89Zr-based PET imaging applications. Moreover, bifunctional chelators (BFCs) structured on TACN and diaza-18-crown-6 were synthesized for conjugation to antibody. Theranostics contains a diagnostic agent and a therapeutic drug that can be used for simultaneous therapy and imaging of diseases. Radiotheranostics includes radiometal complexes for both therapy and imaging. 177Lu is a promising radiotheranostic metal because it can emit gamma radiation for single photon emission computed tomography (SPECT) imaging and emit β radiation for radiotherapy. A radioisotope pair with complementary emission such as 64Cu/67Cu and 86Y/90Y, can be used for PET imaging and radiotherapy. In this study, we synthesized nonfunctional TACN and diaza crown ether-backboned chelators containing different donor groups for 177Lu, 64Cu/67Cu, and 86Y/90Y. Finally, two bifunctional chelators were synthesized for coupling with hydroxamic acid-based small molecule as a potential histone deacetylase (HDAC) inhibitor to generate a small molecule ligand-chelator conjugate (SMLC) for theranostic applications.
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Title: Improvement and Validation of Multiyear Auroral Analysis to Categorize Scintillation Event Layer
Creator: English, Breanna R.
Date: 2022
Description: Ionospheric irregularities scintillate electromagnetic waves, such as Global Positioning System (GPS) signals, as they pass through the...
Show moreIonospheric irregularities scintillate electromagnetic waves, such as Global Positioning System (GPS) signals, as they pass through the ionosphere, especially in auroral zones. A previous method was developed to determine which layer of the ionosphere these scintillation events occurred in by analyzing optical all sky images (ASI). The results of determining the ionospheric scattering layer using the ratio of 630 nm (red) intensity to 428 nm (blue) intensity were compared to a radar-based method of determining the scintillation layer, and it was found that the results disagreed. In this work, the ASI method is critically analyzed to identify possible errors or sensitivities in the original method that might resolve the discrepancy. This is done by improving and validating the nighttime auroral cloud detection method by comparing to National Oceanic and Atmospheric Administration (NOAA) satellite cloud data. Then a sensitivity analysis is performed on the ASI method to determine which parameters of the method the results are sensitive to. The keogram cloud detection method is improved by automating the selection of the keogram time points that are used to calculate a flat-field gain correction, and by calculating the flat field gain for each year rather than calculatingit once and using it for all years of the study. Keogram cloud detection using the coefficient of variation is verified by comparing the keogram results to true sky conditions based on NOAA cloud mask data, and using detection theory to determine the optimal coefficient of variation threshold. We find that the ideal keogram threshold was 0.37 producing a disagreement rate of 22.4%. The ASI image analysis criteria tested are: the ASI azimuth and elevation mapping files, the magnetic zenith limit, the number of pixels of the ASI that are being analyzed, the duration of the scintillation event that is analyzed, and the red-to-blue ratio threshold. It is found that only changing the red-to-blue ratio threshold has a significant effect on the ASI method, with the red-to-blue ratio that minimizes the number of misattributed layers found to be 1.43.
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Title: GLOBAL ESTIMATION AND ANALYSIS OF IONOSPHERIC DRIVERS WITH A DATA ASSIMILATION ALGORITHM
Creator: López Rubio, Aurora
Date: 2022
Description: This dissertation studies a data assimilation algorithm that estimates the drivers of the ionosphere-thermosphere (IT) region of the Earth....
Show moreThis dissertation studies a data assimilation algorithm that estimates the drivers of the ionosphere-thermosphere (IT) region of the Earth. The algorithm, EMPIRE (Estimating Model Parameters from Ionospheric Reverse Engineering) can estimate 2 main drivers of the ionospheric behavior: neutral winds and electric potential by ingesting mainly ionospheric densities obtained through Global Satellite System (GNSS) measurements. Additionally, the algorithm can ingest FPI (Fabry-Perot interferometer) neutral wind measurements. The contributions include 1) Vector spherical harmonic basis function for neutral wind estimation, 2) Quantification of the representation error of the estimations of the algorithm EMPIRE, 3) Analysis of Nighttime Ionospheric Localized density Enhancement (NILE) events and 4) Ingestion of global ICON (Ionospheric Connection Explorer) neutral winds measurements. The IT region in the atmosphere is characterized by having a large concentration of free ions and electrons, electromagnetic radiation and Earth's magnetic field. The behavior of the region is dominated by the solar activity, that ionizes the free electrons of the region, forming ionospheric plasma and determining its density. Unusual solar activity or any atmospheric disturbance affects the distribution of the ionospheric plasma and the behavior of the IT region. The redistribution of the ionospheric density impacts technology widely used such as telecommunication or satellite navigation, so it is increasingly important to study the IT system response. The IT behavior can be characterized by what drives its changes. Two drivers that play a key role, the ones we focus on this dissertation, are electric potential, that directly affects the charged ions in the system, and neutral winds, that refers to the velocity of the neutral particles that form the thermosphere. To quantify these drivers, measurements and climate models are available. Measurements are limited as the IT region is vast and covers the entire globe. Climate models can provide information in all the region, but they are usually not as reliable during the unusual solar activity conditions or disturbances. In this dissertation we use a data assimilation algorithm, EMPIRE, that combines both sources of data, measurements and models, to estimate the IT drivers, neutral winds and electric potential. EMPIRE ingests measurements of the plasma density rate and models the physics of the region with the ion continuity equation. The drivers are represented with basis functions and their coefficients are estimated by fitting the expansions with a Kalman filter. In previous work and use of the algorithm, the neutral winds were expanded using power series basis function for each of the components of the vector. The first contribution of the dissertation is to use a vector spherical harmonic expansion to describe the winds, allowing a continuous expansion around the globe and self-consistent components of the vector. Before, EMPIRE estimated the correction of the drivers with respect climate model values. In this work, EMPIRE is also modified to directly estimate the drivers. Then, a study of the representation error, which is the discrepancy between the true physics and the discrete model that represents the physics of EMPIRE and its quantification is done. Next, EMPIRE is used to analyze two NILE events, using the global estimation of both winds, from the first contribution, and the electric potential, derived in previous work. Finally, global estimation of winds allows us to implement the ingestion of ICON global winds in EMPIRE, in addition to the plasma density rate measurements.
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