Masters Theses

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Duke migrated to an electronic-only system for theses between 2006 and 2010. As such, theses completed between 2006 and 2010 may not be part of this system, and those completed before 2006 are not hosted here except for a small number that have been digitized.

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  • ItemEmbargo
    Digital Hydraulics Simulation in Mathematica on Sudden Expansion Flows
    (2023) Frechette, August

    In this work, we offer readers the ability to numerically simulate flow through a sudden expansion themselves. We choose to study the sudden expansion due to its prevalence in engineered and natural water distribution networks (i.e., pipes and rivers, respectively). The simulation is written in the Wolfram Language, also known as Mathematica. The symbolic nature of this programming language enables readers to implement physical theory directly, resulting in a highly readable numerical flow solver; a stark contrast with commonplace commercial flow solvers, which operate like “black box” technologies, and low-level programming languages, which require an advanced level of syntax knowledge and programming proficiency. Upon completion of this laboratory exercise, users should be able to: (i) describe the main principles underpinning the numerical simulation of non-linear models, (ii) apply numerical models to investigate the accuracy of simplified analytical models, (iii) demonstrate a beginner-level understanding of Mathematica and, more broadly, symbolic coding environments, (ii) and most generally, (iv) understand the proper context for physical and numerical experimentation. The novelty of this work is attributed to the fact that no such simulation tool is detailed and provided in the literature for readers to utilize and alter at their discretion.

    This work was developed and undertaken in collaboration with my co-authors, Dr. Anil Ganti (A.G.), and Dr. Zbigniew Kabala (Z.J.K), my master’s advisor. Author contributions are as follows: conceptualization, Z.J.K.; methodology, A.H.F, A.G. and Z.J.K.; software, A.H.F and A.G.; validation, A.H.F, A.G. and Z.J.K.; formal analysis, A.H.F; investigation, A.H.F, A.G. and Z.J.K.; resources, Z.J.K; data curation, A.H.F, A.G. and Z.J.K.; writing—original draft preparation, A.H.F and Z.J.K.; writing—review and editing, A.H.F, A.G. and Z.J.K.; visualization, A.H.F.; supervision, Z.J.K.; project administration, A.H.F and Z.J.K.

    Partial funding for this project has been received from Duke University Undergraduate Program Enhancement Fund (UPEF) grant 399-000226.

  • ItemOpen Access
    Towards Alternative Queerness: on the Photographic Work of Chinese Artists Chen Ronghui and Ren Hang
    (2023) Peng, Liangyu

    This thesis examines the works of Chinese photographic artists Chen Ronghui and Ren Hang and reflects upon and expands the ways in which queerness is commonly approached and understood in photography. Rather than be simply equated to the nonheteronormative sexualities of either artists or the represented subjects, queerness in the artists’ works are exceeding the framework of identity politics and the queer figures within the frame. The first chapter focuses on the photograph Sworn Brothers from Chen Ronghui’s series Freezing Land (2016-2019), a project that documents the underprivileged life of the younger generation in shrinking cities in Northeastern China. In this image that captures two young men intimately smoking together, I read their queerness as feeling--- loving attention, tenderness, mutual reliance--- that becomes palpable against the larger background of the regional dismal conditions. Since the two subjects and relationship are anonymous to the viewers, the image indeed forces a consideration of queerness as knowable as only feeling. The second chapter examines late artist Ren Hang’s explicit portraitures of young, naked Chinese bodies. Despite a minimal proportion of gay sex photos in Ren’s oeuvre, I understand his work’s queerness as an emergent property that allows us to see a once-existed queer lifeworld in which Ren and his models who are mostly his friends within 2010’s Beijing subcultural community, collectively and playfully created naked images while cultivating friendship and intimacy exceeding the accustomed categorical boundaries for relationality.

  • ItemEmbargo
    A Radiomics Machine Learning Model for Post-Radiotherapy Overall Survival Prediction of Non-Small Cell Lung Cancer (NSCLC)
    (2023) Zhang, Rihui

    Purpose: To predict post-radiotherapy overall survival group of NSCLC patients based on clinical information and radiomics analysis of simulation CT. Materials/Methods: A total of 258 non-adenocarcinoma patients who received radical radiotherapy or chemo-radiation were studied: 45/50/163 patients were identified as short(0-6mos)/mid(6-12mos)/long(12+mos) survival groups, respectively. For each patient, we first extracted 76 radiomics features within the gross tumor volume(GTV) identified in the simulation CT; these features were combined with patient clinical information (age, overall stage, and GTV volume) as a patient-specific feature vector, which was utilized by a 2-step machine learning model for survival group prediction. This model first identifies patients with long survival prediction via a supervised binary classifier; for those with otherwise prediction, a 2nd classifier further generates short/mid survival prediction. Two machine learning classifiers, explainable boosting machine(EBM) and balanced random forest(BRF), were interrogated as a comparison study. During the model training, all patients were divided into training/test sets by an 8:2 ratio, and 100-fold random sampling were applied to the training set with a 7:1 validation ratio. Model performances were evaluated by the sensitivity, accuracy, and ROC results. Results: The model with EBM demonstrated an overall ROC AUC (0.58±0.04) with limited sensitivities in short (0.02±0.04) and mid group (0.11±0.08) predictions due to imbalanced data sample distribution. In contrast, the model with BRF improved short/mid group sensitivities to 0.32±0.11/0.29±0.16, respectively, but the improvement of ROC AUC (0.60±0.04) is limited. Nevertheless, both EBM (0.46±0.04) and BRF (0.57±0.04) approaches achieved limited overall accuracy; a noticeable overlap was found in their feature lists with top 10 feature weight rankings. Conclusion: The proposed two-step machine learning model with BRF classifier possesses a better performance than the one with EBM classifier in the post-radiotherapy survival group prediction of NSCLC. Future works, preferably in the joint use of deep learning, are in demand to further improve the prediction results.

  • ItemEmbargo
    Impact of Resource-Extractive Land Concessions on Malaria Incidence in the Peruvian Amazon: A 2015 to 2020 Retrospective Study
    (2023) Balch, Kaila

    Malaria is a life-threatening vector-borne disease (VBD) that remains a major health concern for the northernmost region of Loreto, Peru. Increased malaria incidence has been connected to extractive industries such as mining and logging through factors such as increased deforestation, human mobility, and limited healthcare access. Due to limited knowledge on the impact of concessionary activity on malaria incidence, this study aims to: (1) investigate district-level malaria outbreak patterns across concessionary mining sites in Loreto, Peru and (2) determine the districts and population at most risk of malaria exposure in concessionary areas. Data was obtained from the Peruvian Ministry of Mines, Agriculture, and Health, as well as the Global Forest Watch (GFW). A Bayesian spatiotemporal Poisson regression model was fit for P. vivax and P. falciparum for the epidemiological weeks of 2015 to 2020 to see test the relationship between active mining concessions (in hectares and site number) and malaria incidence for the 53 districts of Loreto, Peru. We found that as mining hectares increased, malaria increased. Conversely, as mining sites increased, malaria incidence fell, possibly due to distribution of health services in condensed concessionary areas. Overall, this research will contribute to a better understanding of malaria reemergence and incidence in the Peruvian Amazon, and the relationship between concessionary land activity and VBDs. Results from this project could improve malaria forecasting models and land-use management practices.

  • ItemEmbargo
    Nishi Amane’s Reception and Translation of Political Thought in the Early Meiji Era
    (2023) Pyo, Seung Hyeon

    This project will explore Meiji Japan’s reception of right training its sights on Nishi Amane 西周 (1829-1897)’s discussion of the concept in Meiroku Zasshi. The importation of numerous western political concepts, which had not existed in the Japanese language, naturally entailed intellectual efforts to come up with new words, or neologisms, and political ways of thinking. In this project, from the understanding that right as in Nishi’s analysis resulted from the Dutch political economic thinking in the nineteenth century, I intend to examine both the historicity of the concept and semantic clash involved in Meiji Japan’s translation of right as ken權. From the exploration of Nishi’s ken, illuminating epistemological shifts that occurred both in the target and source languages, I hope to observe the originality with which he attempted to articulate the new political economic make-up of the new Japanese state.

  • ItemOpen Access
    Oral Health among Children and Adolescents with Disabilities in one Welfare School in Chengdu from 2018 to 2019
    (2023) Yang, Moxuan

    Background: To identify the oral health status of children and adolescent with disabilities in one welfare school in Chengdu. With several disabilities, physical and intellectual deficiency will affect disabled children’s daily life. They pay little attention to their own health status especially oral health. Therefore, this vulnerable group require some concerns. Examining their oral health status is necessary to change their situations of low access to oral health resources and failure of describing their feelings for various reasons, which could help them reduce the rate of having oral diseases. We aim to explore the severity of caries and periodontal status among child with disabilities.

    Methods: We included 173 disabled children, 92 participants in 2018 and 81 participants in 2019, who were at least three years old and less than 24. They obtained the treatment from West China Stomatological Hospital and participated in an examination of their oral health status. There were four outcomes: caries, gingivitis, dental calculus, and oral health. Although there were three indexes [decayed (dt/DT), missed (mt/MT), and filled (ft/FT) teeth] indicating decayed tooth, we combined three indexes into one (“caries”) to check whether one tooth is healthy or unhealthy. For gingivitis and dental calculus, “yes or no” is the statistical method. Oral health is a new index that represents whether one’s oral health status is healthy. If one person obtains caries or gingivitis or both, it means unhealthy. We used the logistic regression to examine how demographic characteristics (age, sex, household registration, and nationality) were jointly associated with each of the four outcomes (caries, gingivitis, dental calculus, and oral health) separately. 

    Results: Four indexes (caries, gingivitis, dental calculus, and oral health) were created to determine disabled children’s oral health status. Disabled children's mean of caries was 2.77, and they shared a caries prevalence rate of 63%. 31 (17.9%) had one caries and 78 (45.1%) had two or more caries. More than 75% of had obtained fewer than five caries. For caries prevalence, we found a significantly higher prevalence of dental caries among participants aged less than 12 years (87.7%) than those aged at least 12 years (50.9%). After mutually adjustment of socio-demographic characteristics, participants aged at least 12 years had a 86% (95% CI: 65%, 94%) lower odds of having dental caries than those aged less than 12 years. For gingivitis, we found a significantly higher gingivitis detection rate among Han (87.7%) than Qiang (18.8%) and Zang (7.9%). After mutually adjustment of socio-demographic characteristics, Zang had a 81% (95% CI: 17%, 96%) lower odds of having gingivitis than Han. For dental calculus, we found a significantly higher detection rate of dental calculus among males (14.6%) than females (3.9%). After mutually adjustment of socio-demographic characteristics, females had a 376% (95% CI: 22%, 1754%) higher odds of having dental calculus than males. For oral health rate, we found a significantly higher oral health rate among participants aged at least 12 years (38.8%) than those aged less than 12 years (10.5%). After mutually adjustment of socio-demographic characteristics, participants aged at least 12 years had a 82% (95% CI: 65%, 94%) lower odds of having good oral health than those under 12 years.

    Conclusions: We presented disabled children’s oral health status in three oral health criteria: caries status, periodontal health status (gingivitis and dental calculus), and general oral health status. The comprehensive oral health status of disabled children shared a high mean of caries and a high prevalence rate. Their periodontal health status was better than the Fourth National oral Health Epidemiological Survey criteria. The comprehensive oral health rate was poor. Therefore, additional studies are necessary to make improvements to it.

  • ItemEmbargo
    Inference for Dynamic Treatment Regimes using Overlap Sampling Splitting
    (2023) Wang, Shuo

    Dynamic treatment regime is a sequence of decision rules mapping patient informa- tion at a specific time to a recommended treatment, with the goal of maximizing long-term clinical outcome. However, the inference for the estimator of optimal regime is challenging due to the nonregularity resulting from the maximize operator. In this paper, we review methods for estimating optimal regimes and discuss the problem of nonregularity. We propose a novel approach based on sample splitting to construct valid confidence sets for both the optimal regime and the maximized value function. Additionally, we conduct a hypothesis test to compare the optimal regime to the treatment regime used in usual clinical practice. We evaluate the proposed approach using simulated data from the Sequential Multiple Assignment Randomized Trials (SMART) design and assess the coverage of the confidence sets and the power of the hypothesis test.

  • ItemEmbargo
    Making Enemies: Land Reform and State Violence in China
    (2023) Pan, Xinru

    Scholars of comparative politics have long recognized that coercive capacity is critical to the resilience and survival of authoritarian regimes. What explains the subnational variation in coercive capacity and repression intensity in authoritarian regimes? This paper traces the origin of state coercive capacity by linking land reform with state violence. I argue that the radicalism of land reforms is reflected in the elite configuration of coercive institutions, which subsequently shape repression outcomes. Using a novel dataset on land reform (1950-1955) and state violence in seven provinces of Southern China, I find that, counties that expropriated more land during the land reform recruited more poor and uneducated peasants into the local Party branches as well as more peasants into the Peasant Associations. Moreover, Peasant Associations that recruited more members would generate more ”fourtypes” by 1957. The findings contribute to the understanding of state violence in authoritarian regimes by probing the formation of its institutional foundation.

  • ItemOpen Access
    Validation of Attaining a Higher Threshold Using Double-Pass MWPM Decoding of CSS Codes Using X/Z Correlations
    (2023) Pendse, Ruchi Anant

    In this report we validate that Minimum Weight Perfect Matching (MWPM) decoding ofa surface code helps attain a higher code threshold than standard decoding by taking into account the correlations of errors that occur on the lattice. Correlated decoding cannot be directly performed using MWPM due to the presence of hyperedges in the graph. Decomposing correlated errors into simultaneous X and Z excitations, along with considering an asymmetric code for optimal performance of this scheme, yields a codecapacity threshold of 15% for standard depolarizing error by updating the weights of one decoding graph based on the corrections of another.

  • ItemEmbargo
    Arbitrary Acoustics Hologram Based on Structured OAM Beams
    (2023) Yu, Wenjun

    In this study, we present a novel on-chip 2D hologram device of an on-chip hologram device capable of generating both arbitrary 3D nodes and 2D microscale nodes. As the first true 3D hologram folded on chip, our approach combines a refined fabrication process with a novel theoretical framework, which employs Fresnel transformation to describe the patterns, enabling the shaping of patterns in 3D, thus broadening the potential applications of lab-on-chip devices and establishing a new generation of acoustic tweezers. We also reduced the complexity of setup and manufacturing thus achieving high resolution and low tolerance with lithographic techniques. Our work holds promise for a wide range of applications, including biomedical, material handling, and sensing technologies, marking a noteworthy advancement in the pursuit of efficient and precise acoustic manipulation.

  • ItemOpen Access
    THE IMPACT OF RAINFALL ON LANDSLIDE DYNAMICS: QUANTITATIVE ANALYSIS ON MOUNTAINOUS AREA IN NORTHERN ITALY USING MACHINE LEARNING ASSISTED APPROACHES
    (2023) Wang, Zhukun

    Landslides are a very common type of disaster. It happens in every state of the U.S and is defined as the movement of the mass of rock, debris, or earth down a slope. Debris flows, sometimes referred to as mudslides, mudflows, lahars, or debris avalanches, are common types of fast-moving landslides(Lynn et al. 1997). When a landslide takes place, it could bring down a large volume of mass which is enough to bury houses and buildings. Therefore, preventing or reducing the life and economic losses comes from landslides is an indispensable task for engineers. There are multiple factors that can cause landslides, including water level, stream erosion, changes in ground water. This paper will focus on examining the associations between rainfall and landslide displacement. The goal will be performing spatial and temporal estimation of landslide displacement in “Valle Febrraro” by using data during the slow-motion stage. We will analyze how we can possibly predict landslide dynamics in Valle Febrraro using precipitation data. We will adopt the concept of correlation coefficient to pinpoint at places where landslide dynamics might be sensitive to precipitation. In fact, we have identified dots with correlation coefficients close to negative 1 through calculation. Those dots are clustered in the lower left half of the selected region. After examining correlation coefficient for every single dot in the chosen space, we adopted kriging as a spatial estimation technique to predict the value of correlation coefficient at every place in the entire chosen space. Results indicate that for the regions where dots with correlation coefficient close to -1 are clustering have values close to -1 whereas those far away have values higher than -1. Besides kriging for the values of correlation coefficient for the entire chosen space, we also performed kriging for the displacement values everywhere inside the same space. We have seen that the results vary from one instant to another. The approach of kriging provides us with what are areas with high displacement values at each of the timestamp and therefore will provide useful insights for future landslide prediction. For temporal estimation, we use regression model to estimate landslide displacement values at one year. Besides, we will also modify the regression model in different ways to see how much better or worse the model will perform. In addition, we will also apply time series prediction technique auto-regression/auto-regressive models, make modifications to it and compare the results. The goal after creating and comparing these models is to perform some related error analysis. Although the results turn to be well in general, we have not noticed any obvious increase in the displacement when we increase the precipitation to several times of its original values when we are trying to optimize the model. Other ways for optimization do exist as we have found out that adjusting the model parameters or performing model for multiple times with each time predicting fewer values do help increase the accuracy.

  • ItemOpen Access
    Multiple Possibilities for the Realization of Immersive Worlds
    (2023) Gao, Xinyue

    In recent years, discussions about immersive experiences have become ubiquitous, but there have been vague definitions of immersion. This thesis aims to explore multiple possibilities to realize immersive worlds and conduct user experience research to think about the diverse dimensions of immersion. As a result, I created two projects—a digital project named “A VR Trip to a Chinese Courtyard in Mid-Autumn Festival” and an art installation called “Land of Idyllic Beauty”—and I gathered audience feedback on how audiences perceived immersive experiences. The findings indicate that users’ perceptions of immersion are highly overlapping, but there is still opportunity for both digital and physical initiatives to improve users’ immersive experiences, therefore further research is worthwhile.

  • ItemOpen Access
    The Logic of Government’s Response to Protests in China New Evidence from Protests Recorded in Social Media
    (2023) Chen, Luyan

    Scholarship on protests in China, though prolific in recent years, faces serious data issues. Since there is no comprehensive dataset for a systematic analysis of protests in China, previous scholars can only quantitatively study the pattern of repression of protests. Most studies related to the protest outcomes or government responses in China can only use qualitative methods. Drawing on an original dataset of 508 protests I collected from the Wickdonna website, this article first offers a systematic analysis of the response pattern to protests in China. My paper shows that domestic media coverage and the government's perception of political threats and economic costs are the most significant determinants of the government's response to a protest. While the size of the protest, the disruptiveness of the protest, and the geographical location of the protest have no direct impact on the government's results, they significantly increase the odds of media coverage of a protest. Overall, my paper contributes to a more comprehensive understanding of daily contentions in authoritarian China.

  • ItemOpen Access
    The Moon is Rounder on the Other Side: Foreign Vloggers and Chinese Nationalism
    (2023) Xu, Yinjie

    This paper seeks to explain the phenomena of popular foreign vloggers in domestic Chinese media by using existing theories in propaganda, nationalism, and social identity theory. Selecting six videos from domestic Chinese social media Bilibili, I generate original data of 1,125 comments from these six videos. I find that holding everything else equal, videos with foreign vloggers who speak fluent Chinese will elicit more positive comments from the audience than foreign vloggers who do not. Moreover, the word “China”, “U.S.” and “foreign” appeared more frequently in videos by Chinese-speaking vloggers, and comments praising foreign vloggers’ Chinese skills constitute half of all the positive comments in one video. This study contributes to people’s understanding of nationalism and propaganda. It is also the first time, to the author’s knowledge, that social identity theory has been applied to the Chinese context in the discipline of political science. This study has implications for future studies and studies outside of China as well.

  • ItemOpen Access
    Stable Variable Selection for Sparse Linear Regression in a Non-uniqueness Regime
    (2023) Zhang, Xiaozhu

    This thesis presents a comprehensive investigation of the LASSO method in a non-uniqueness regime and its ability of stable variable selection. We characterize when LASSO may have non-unique solutions through a sufficient and necessary condition, and how these non-unique solutions behave geometrically: all solutions must lie in the same simplex within the same orthant, and they form a polytope structure in which each corner represents the most parsimonious collection of features that does not contain other corners. Leveraging this geometric structure, this work then explores what to do to practically obtain these estimators, by proposing an efficient sampling algorithm that returns uniformly distributed points on the polytope.

    We present a non-asymptotic analysis of the l_2 coefficient error and feature selection consistency for the non-unique LASSO, by restricting necessary conditions (the eigenvalue condition and mutual incoherence condition) to a certain direction or a subset of features. Our theoretical results show that, under strong assumptions, the non-unique LASSO is as theoretically efficient as the original LASSO. Moreover, when dealing with linearly combined features in a dataset, numerical experiments demonstrate the superior stable variable selection performance of our proposed non-unique LASSO over other existing algorithms, particularly if the proper tuning parameters can be selected.

  • ItemOpen Access
    Anything For Views Parenting: Framing Privacy, Ethics, and Norms for Children of Influencers on YouTube
    (2023) Hamilton, Bridie E.

    Children who appear as the main characters or primary consumers of YouTube content have been the focus of emerging academic literature and public debate (Feller & Burroughs, 2022; Ferguson, 2018; Kumar, 2021). Sharenting, or posting information, photos, or videos about one's children on social media, has also been a discussion and concern among researchers, legal scholars, and parents (Kumar, 2021). Sharenting has online and offline consequences. It exposes personal information, such as a child’s name and whereabouts, which may lead to unwanted attention or safety risks (Brosch, 2016; Blum-Ross, 2015). However, there is a significant subsection of YouTube media where children appear as integral supporting characters of an adult’s content that has yet to be meaningfully researched.The normalization of sharenting has coincided with an upsurge of influencers and influencer marketing (Abidin, 2018). The influencer marketing industry was estimated to be worth 16 billion dollars in 2022, projected to increase to 21 billion dollars in 2023 (Geyser, 2023). Influencers who involve their children in content position them, at times, as unintentional microcelebrities or brand assets (Abidin, 2015). When this happens, their appearance in user-generated content contributes to the premise and profitability of their parent’s brand. However, children who consistently contribute to their parent’s brand have no rights to the money their names, images, and likenesses generate. They have no working hours to abide by and no access to representation by a third party acting without a personal stake in their profitability (Geider, 2021). Children are unaware of the long-term consequences of exposure to a digital audience, including potential privacy violations, online harassment, or reputational harm. They may also not fully understand the implications of having a digital identity established for them before they can make decisions for themselves. While existing literature demonstrates that social media platforms, laws, and policies do not adequately regulate or protect the children of influencers, there has been no effort first to define the child of an influencer and, second, to identify at what point that regulation becomes necessary. In other words, when do influencer parents go beyond mere sharenting? This research project examines the complex interplay between the potential long-term impacts of children's involvement in influencer content and the gaps in regulations related to children’s work on social media. I aim to analyze the regulatory gray area children of influencers inhabit on YouTube and to identify salient features of influencer content which place children at disproportionate risk of undesirable exposure online. The present study scopes the value children provide to user-generated monetized content. It constructs a typology to describe the unique privacy and psychological risks they are exposed to when their parents' income involves their presence. It outlines common arguments influencer parents use to justify their children's use in content production and discusses the impossibility of informed consent for children in this context.

  • ItemOpen Access
    “Sky Eye”: Infrastructure, Politics and Livelihood in Southern Guizhou
    (2023) Wang, Zhushengyuan

    This thesis sheds light on rural life in Kedu Town, southern Guizhou. Drawing from the idea of “doubling of infrastructure” (Muehlmann 2019), I see the FAST (Five-hundred-meter Aperture Spherical Telescope) project as a channel for the state to highlight the political importance of scientific research, serving a “visible” purpose. This infrastructural project has what I call an “invisible” intention: it produces social activism at the local level, as villagers critique the politics of displacement, call for better compensation, and worry about future livelihoods in the pandemic and now post-Zero Covid policy era. Based on fieldwork and interviews, the thesis is that the FAST project unveils its “invisible” intention due to conflicts between the displaced residents and the local government. I also drawn attention to how the emergence of COVID-19 created new challenges to local livelihoods in the FAST era, revealing how the FAST project now has an increasingly complicated presence in Kedu Town.

  • ItemOpen Access
    Arthritis and Physical Activity among Adults in the United States: Cross-sectional Analyses of the National Health and Nutrition Examination Survey
    (2023) Yu, Xin

    Arthritis is a chronic condition affecting millions of older adults worldwide and a leading cause of pain and disability. Physical activity is effective and recommended in managing arthritis and promoting overall health in older adults. However, many older adults with arthritis struggle with participation consistent in physical exercises and activity as a result of pain, stiffness, and fatigue. A cross-sectional study design is applied to derive the findings in this study using the National Health and Nutrition Examination Survey (NHANES). We found that 9467(27%) participants reported as Arthritis from 2007 to 2018. Compared with non- arthritis subjects, Arthritis participants tended to be older (62.2 ± 13.8 vs. 45.3 ± 17.0, p<.001), female (59.5% vs. 48.5%, p<.001), lower level of education (3.2 ± 1.3 vs. 3.5 ± 1.3, p<.001). The multivariable logistic regression showed that Osteoarthritis was only negatively correlated with vigorous work activity (OR: 0.75, 95%CI: 0.59-0.95, p=.018). Participants with Osteoarthritis or degenerative were more likely to perform moderate work activity (OR:1.17, 95%CI:1.07-1.28, p<.001) and instead perform less walking or bicycle (OR:0.79, 95%CI: 0.71-0.88, p<.001), and moderate recreational activities (OR:0.84, 95%CI:0.77-0.92, p<.001). Patients with other types of Arthritis were more willing to engage in recreational activities than work activity. Further, we also included the population ≥65 years of age or older with Arthritis causing physical movement difficulties, to find out about the health status of these people and whether they are physically active or how often they are physically active. Compared to arthritis patients (≥65 years older) with non-functional limitations, arthritis patients with functional limitations tended to be female (63% vs. 53%), divorced (48% vs. 39%). In addition, minutes of sedentary activity were associated with having a higher functional limitations risk among arthritis patients with 65 years or older (OR, 1.59 for >480 mins, OR, 1.32 for (360~480) mins compared with ≤240 mins, Fig.2-3). Compared with arthritis patients doing less than 30 minutes of moderate recreational activities on a regular day, those doing above 180 minutes had a higher risk of functional limitations. The findings of this study will provide important insight for developing interventions to foster physical activity among older adults with arthritis and consequently improve their health and well-being.

  • ItemEmbargo
    Wearable Sensor-driven and Multi-biomarker Guided Closed-Loop Deep Brain Stimulation System
    (2023) Feng, Guangyu

    This paper implements the first closed-loop adaptive deep brain stimulation (DBS) system for Parkinson’s patients that updates with multiple input streams from disparate data sources analyzed in real time. Input data streams include the brain's local field potential (LFP) from DBS leads, hand tremors, and heart rate. This approach is designed to be evaluated on 6 patients with Parkinson's disease implanted with the Medtronic Summit™ RC+S systems and has the potential to be more effective in simultaneously controlling multiple symptoms commonly presented in Parkinson’s patients. In the case of the DBS control of both the bradykinesia and tremor, the system demonstrated in this paper has the ability to overcome the challenge of the “breakout tremor” presented in previous studies. The system in-lab testing characterization results indicated that the system could be used to control closed-loop deep brain stimulation systems with a high degree of accuracy and robustness.

  • ItemEmbargo
    Assessing Credibility: A Qualitative Analysis of Public and Private Signals in the Cuban Missile Crisis
    (2023) Framel, Paul

    Credibility has long been a subject of interest in international relations. However, recent works minimize some of the earliest and most intriguing credibility questions. To what degree is accuracy related to credibility, do private signals exist solely in the shadow of their public counterparts or do they have credibility of their own? Moreover, how do leaders weigh concurrent public and private signals during a crisis? In this thesis, I examine the nature of public and private signals in the Cuban Missile Crisis in an inductive, qualitative manner. I find that in the context of the Cuban Missile Crisis, despite some rationalist assertions, private signals are at times meaningful. Moreover, the divergences between public and private signals are limited. As such, the two exist in an interactional, almost double-helical state. This finding has distinct importance for the future of credibility scholarship.