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Bridging Perception and Performance: Generating, Calibrating, and Evaluating Multimodal Sensory Stimuli
No full textHuman sensorimotor control is inherently multimodal: our actions are shaped not by one sense alone, but by the integration of various sensory channels. Yet most motor rehabilitation tools and experiments still rely on single-modality feedback, overlooking the richness of our perceptual systems. This thesis investigates how multimodal sensory cues can be perceptually calibrated and effectively integrated to augment motor performance and inform the design of more intuitive human-machine interfaces.
We begin by establishing a principled method for calibrating different sensory modalities. Through a cross-modal matching paradigm, we demonstrate how visual and haptic stimuli can be perceptually equalized within individuals in motor control tasks. We further introduce a reduced-order protocol that significantly shortens experimental time – reducing duration by over 80% – while preserving perceptual mapping accuracy, offering a step toward practical clinical implementation.
Building on this perceptual framework, we evaluate how visual, haptic, and combined (visual + haptic) feedback affect motor performance in a virtual precision grip task. We assess objective metrics like success rate and force regulation, alongside subjective measures of workload. Our results reveal that multimodal feedback is not universally beneficial: while some participants leveraged combined cues to enhance performance, others relied on a single dominant modality, particularly vision. Even when perceptually balanced, multimodal cues may offer limited advantages if not aligned with task demands or the individual's inherent integration methods.
Lastly, to enable multimodal tactile feedback in wearables, we introduce “pneumatactors” – soft pneumatic actuators that deliver both transient and continuous haptic stimuli. Unlike traditional devices, pneumatactors independently target both fast- and slow-adapting mechanoreceptors at the same skin location, enabling more naturalistic tactile feedback. We characterize their mechanical behavior and actuation dynamics, laying the groundwork for applications in human-robot interaction.
Together, these studies offer a cohesive framework spanning perception, performance, and hardware. In addition to practical tools for multimodal rehabilitation, this thesis offers conceptual insight: more sensory stimuli are not inherently better for motor learning; rather, the true benefits depend on how humans perceive and integrate these cues. We suggest that bridging perception and performance – through frameworks centered on perceptual alignment – is essential for transforming multimodal feedback into meaningful, functional improvement
IMAGING BRAIN FUNCTION AND CEREBRAL BLOOD AND LYMPHATIC VESSELS USING ADVANCED MRI TECHNIQUES
Full text linkBlood oxygenation level-dependent (BOLD) functional MRI (fMRI) has played a crucial role in brain research, enabling the investigation of neural activity by detecting changes in blood oxygenation. This dissertation is aimed to develop novel MRI approaches to study brain function and the physiological parameters underlying the BOLD fMRI signal. First, we assessed the recently developed T2-prepared (T2prep) BOLD fMRI approach in event-related functional tasks. The T2prep BOLD fMRI method can provide fMRI images with minimal susceptibility artifacts, improving signal detection in regions prone to signal dropouts and distortion. The hemodynamic response functions (HRFs) measured using T2prep BOLD fMRI are compared with the widely used gradient-echo (GRE) and spin-echo (SE) echo-planar imaging (EPI) BOLD fMRI methods in human subjects.
Next, since blood vessels—especially pial arteries and veins—are the primary sources of fMRI signals, we developed novel MRI methods to enhancing their visualization in the human brain. Iron-based MRI contrast agents have shown promise in this regard. Our work showed that Iron Dextran can be used as an MRI contrast agent to enhance the visualization of small blood vessels using multi-echo susceptibility-weighted imaging (SWI) at 7T, enabling a more detailed examination of the cerebrovascular network.
Finally, we developed new MRI methods to study CSF circulation in the brain, another important aspect related to brain function and physiology. Recent discoveries have identified dural lymphatic vessels that are hypothesized to facilitate CSF drainage to peripheral lymph nodes. Using Gadolinium-based contrast agent (GBCA) based MRI methods, dynamic distribution of GBCAs from dural blood vessels to nearby fluid spaces were analyzed. The high spatial resolution in our methods allows us to measure the time courses of blood and CSF signal changes in two separate layers of the dura mater in the meninges
Navigating Uncertainty: Understanding Housing Insecurity Among Low-Income Families
Full text linkThis dissertation examines the persistent U.S. affordable housing crisis and its implications for low-income families through three related studies. Using qualitative narrative data from in-depth interviews with Housing Choice Voucher recipients in the Seattle metropolitan area, it explores how housing insecurity is experienced, navigated, and responded to. Together, these chapters provide a comprehensive analysis of the dynamics of housing insecurity, emphasizing the interplay between structural limitations, social relationships, and individual decision-making. Chapter 2 examines the common drivers of housing insecurity, revealing both a high frequency of forced and reactive moves and a high prevalence of such moves across the sample. Based on these findings, this study provides recommendations to improve common survey measures, advocating for broader frameworks to capture housing insecurity fully. Chapter 3 focuses on doubling up arrangements, this sample's most common response to housing crises. I present three categorizations of doubling up arrangements—stable and supportive, stable yet strained, and fragile—demonstrating that while under the best conditions, doubling up can offer stable housing, childcare, and emotional support, even hosts that are secure or willing to provide consistent support encounter challenges that strain these arrangements. Less stable shared housing arrangements, such as when hosts depend on housing assistance, tend to be short-lived and precarious. Chapter 4 more broadly examines the decision-making process of families seeking shelter following a housing crisis. Families facing tight timelines and scarce resources must make challenging compromises on their well-being. In addition, selecting from a suboptimal set of housing strategies creates additional consequences for families and their children. Together, these chapters reveal that housing insecurity is often an ongoing process in which one episode of insecurity contributes to the next and the solutions families turn to can leave them vulnerable to additional precarity. The insights from this dissertation contribute to our understanding of how poverty and inequality are reproduced among low-income families
Controllability and Configuration Space Enhancement of Powered Multi-DOF Upper Limb Prostheses
Full text linkThe control paradigm for commercial electrically powered prosthesis has remained relatively unchanged since the advent of this technology in the late 1960s. Electromyographic (EMG) signals are measured from a user's residual limb as a means to estimate motor intention. Today machine learning-based `pattern-recognition' algorithms that classify EMG signals into a predefined set of motion classes are considered the state of the art in research and have seen increasing use in clinical settings. Unfortunately, these methods are not well suited to multi-DOF systems, and there is a great body of research demonstrating the deficits of modern upper limb prostheses. Even when presented with multiple controllable DOF, patients using interfaces that require sequential joint modulation tend to utilize just one of the available DOF, leading to inefficient, unnatural motion, and eventually long-term overuse injuries. It is important to note that the issue with prosthesis functionality is not due to dexterity issues with the mechatronics. The field of robotics shows us that purely mechanical systems are capable of autonomous dexterous object manipulation. This indicates that issues with prosthesis dexterity stem from the user interface and the ability to reliably interpret and execute user intent. This dissertation specifically explores the translation of user will to prosthesis action. First we maximize the efficacy of existing techniques for decoding motion intent from EMG by developing a tool for rapid and effective electrode placement during prosthesis fitting. Next we develop and test a hybrid gaze+ EMG semi-autonomous prosthesis interface that is capable of interpreting task-level intent, allowing for functional control of higher DOF systems. We demonstrate that through use of such an interface, users can effectively utilize full 3DOF prosthetic wrists, demonstrating a significant (p < 0.01) decrease in compensatory motion over PR systems. Thirdly, we develop a bio-mimetic method for implementing these interpreted actions by developing a human-in-the-loop trajectory planner for cooperative hand placement with a prosthetic elbow. This work spans methods to estimate motion intent, interfaces to enable exertion of that will onto high DOF systems, and algorithms to generate machine motion that are effective and efficient for the user
Inside Newsrooms & Beyond: A Qualitative Study of the Experiences of Palestinian Journalists in the United States During the Ongoing Gaza Genocide
No full textThis exploratory study examines the personal and professional experiences of Palestinian journalists and media workers in the United States. Using Muted Group Theory as a foundation, the study employed a qualitative survey and interviews to investigate the experiences of this population to understand their connections and reactions to the ongoing genocide in Gaza, resulting changes to their relationships in their professional environment, and reflections on the current political climate in the United States and how that relates to their reporting experiences.
The results show that Palestinians in the United States are deeply impacted by the ongoing genocide and staggering death toll of journalists in Gaza. Palestinian journalists described maintaining neutral relationships to their employers but hold somewhat unfavorable attitudes towards the larger industry, a politicization of their Palestinian identity, and an increase in activity by watchdog groups to suppress the Palestinian perspectives in reporting. Participants shared their verbal and nonverbal communication tactics as they navigate their identity and professional expectations within newsrooms. Overall, participants said they feel media coverage has shifted slightly to sympathize more with the Palestinian cause since October 2023.
The tactics described by Muted Group Theory that appeared in the experiences of participants include self-censorship, avoidance, increased visibility, utilization of liaisons, and confrontational tactics. The findings of this study demonstrate the impact of the political environment and U.S. foreign policy on newsrooms, the impact of the genocide on Palestinian identity in the U.S., and heightened feelings of responsibility amongst Palestinian journalists in the U.S. The findings underscore the dangers of attacks on Palestinian voices in journalism and media, and the heightened importance of amplifying Palestinian stories and sources in media coverage. This study was limited by the timing and political environment, as security was a consistent concern for participants. Future research is required to analyze a deeper understanding of the Palestinian experience during the Gaza genocide globally, investigate the role of news organizations in the U.S. in manufacturing consent for the genocide, and the experiences of Palestinians belonging to various critical industries
The Social-Medical Network: The Integration of Personal and Professional Healthcare Networks for Older Adults
Full text linkOlder adults represent a substantial and growing proportion of the population. Because of this, we have also seen an increase in the demand on the healthcare system and on family and friend caregivers. These two groups of individuals providing care to older adults create healthcare networks. The social-medical network is the larger network comprised of the personal and professional healthcare subnetworks.
To investigate the social-medical network, we conducted a cross-sectional observational pilot study that included a quantitative survey and social network inventory. The social network inventory included three sections: 1) Personal healthcare network; 2) Professional healthcare network; and 3) Integration of the social-medical network. Our population of interest was community-dwelling older adults (65 years or older) living with Type 2 diabetes in Maryland. Over a period of two years, we enrolled 128 individuals and completed data collection with 122 participants. We assessed the relationship between emergency department visits and network-level constructs, adjusting for demographic and social covariates of interest.
We found that for each additional professional alter providing care for five years or more, older adults had an inverse relationship with the incidence rate of emergency department visit. Though not marginally associated, this indicates a potential protective effect of longer care relationships. We also quantified the relationship between emergency department visit and integration of the social-medical network. For each 1-unit increase in social-medical network integration, older adults with two or more personal alters had an inverse relationship with the incidence rate of emergency department visit. The direction of this relationship was reversed for older adults with only one personal alter. Although both results were not marginally associated, these findings indicate that social-medical network integration may be important in terms of utilization outcomes and could have different impacts among subgroups.
Given that this was a pilot study, these relationships require further confirmatory inquiry. For older adults living with Type 2 diabetes, care relationships and integration of family and friends with healthcare providers may prove to be advantageous in protecting and promoting health and well-being
Understanding and Addressing the Decay of Nucleic Acid-Based Electrochemical Sensors in Biofluids
No full textNucleic acid-based electrochemical sensors (NBEs) have emerged as a promising approach to continuous molecular monitoring in vivo. NBEs consist of electrically conducting gold surfaces coated with self-assembled monolayers of a mixture of electrode-passivating alkylthiols and functional alkylthiol-modified oligonucleotides (oligos). The oligos are further modified with redox reporters able to transfer electrons to the underlying electrode. Although sufficiently robust for continuous, multihour sensing of small molecules and proteins in biological fluids both in vitro and in vivo, NBEs decay over periods longer than 12 hours of continuous operation if unprotected, thereby limiting the translation of NBEs to the clinic. To address this issue, here I first report two investigations into why NBEs degrade. Firstly, I show that in cases of patients with afflictions, overexpressed protein biomarkers may act as nucleases and degrade alkylthiol-modified oligos, demonstrated via human cyclophilin B, a marker for pancreatic cancer. Secondly, I performed a fundamental investigation into possible pathways of degradation. I highlighted that voltage-induced desorption of monolayer elements and competitive displacement of alkylthiol-modified oligos by naturally occurring cysteine and glutathione are the two greatest driving forces of NBE decay under continuous sensor operation in biofluids. Leveraging this knowledge and experimental framework, I report strategies to mitigate sensor degradation pathways and improve operational sensor stability, progressing the future development of NBEs towards extended operational lifetimes
DEVELOPING A CELLULAR MODEL FOR HEAT SHOCK PROTEIN RESEARCH
No full textHeat shock proteins (HSPs) are essential for maintaining proteostasis, particularly under conditions of cellular stress. As a type I HSP40 co-chaperone, DNAJA2 interacts with HSP70 to regulate client protein folding, trafficking, and degradation. However, the specific role of DNAJA2 in coordinating stress responses remains incompletely understood. To build a foundational model for future functional studies, I generated a DNAJA2 knockout (KO) in human retinal pigment epithelial (RPE-1) cells using CRISPR-Cas9. Three single-guide RNAs (sgRNAs) targeting exon regions of DNAJA2 were designed and cloned into a PX330-based plasmid. After transfection and antibiotic selection, bulk and single-cell clones were screened via Sanger sequencing. Two independent clones, sg3-1 and sg3-2, were confirmed to harbor a clean 1 bp insertion, introducing a frameshift and premature stop codon. While I did not conduct downstream phenotypic assays in this study, this KO model holds strong potential for dissecting co-chaperone-specific functions under proteotoxic stress, including roles in stress granule assembly, client protein regulation, and neurodegeneration-related aggregation. Given RPE-1 cells’ near-diploid genome and high amenability to gene editing and synchronization, this model provides a robust and physiologically relevant platform for studying HSP networks. In summary, this work establishes a validated DNAJA2 KO cell line as a clean, versatile tool to probe the dynamics of protein quality control. This system will be critical for advancing our understanding of HSP40 functions in proteostasis
Deep Learning-based Content Creation: Relighting, Synthesis and 3D Editing
Full text linkIn an era where billions of people capture and share digital content, transforming casual captures into aesthetically compelling works often requires extensive manual editing. This dissertation explores deep learning-based approaches to facilitate and automate content creation, enabling high-quality visual content generation within seconds.
The first part of this dissertation focuses on portrait photography, particularly on synthesizing lighting effects—an essential aspect of portrait aesthetics. We develop deep learning techniques for (1) user-friendly interactive lighting editing, (2) creating realistic 3D effects such as shadows and novel views from a single image, and (3) designing a temporally consistent portrait performance relighting system leveraging video diffusion models.
Beyond portrait photography, the second part of this dissertation extends to general 3D scene editing. We explore a novel method for artistically stylizing 3D Gaussian Splatting models, enabling creative modifications to 3D representations.
The final part of this dissertation addresses privacy concerns in deep learning-based content creation. We introduce federated learning-based frameworks that enable high-quality visual synthesis while preserving data privacy. This is crucial for applications involving privacy-sensitive data, such as human faces, where data sharing for model training is prohibited.
Through these contributions, this dissertation aims to bridge the gap between high-quality
content creation and everyday digital capture, making advanced visual editing more accessible, efficient, and privacy-conscious
Health and Quality-of-Life Impacts of Industrial Food Animal Production Among Workers and Community Residents
Full text linkIndustrial food animal production (IFAP) is characterized by large-scale operations that are densely-stocked for the maximization of production and profit. Billions of animals are raised, slaughtered and sold in the United States annually. With these large numbers of animals comes millions of gallons or tons of waste. Emissions from these facilities can contaminate the air, water and soil near these operations, causing a multitude of health and quality-of-life effects. The goal of this dissertation was to quantify and explore the spatio-temporal distribution of the air, surface and health impacts of proximity to IFAP. Each aim utilized either a swine production intensity (SPI) metric, a poultry production intensity (PPI) metric, or both, calculated using the geolocation of each operation with respect to each data point, and the either the steady state live weight or animal count of each operation. We measured gas emissions, methane (CH4), hydrogen sulfide (H2S), and ammonia (NH3), from IFAP waste structure using cars equipped with gas concentration analyzers in North Carolina, the Delmarva Peninsula and in the Baltimore-Washington region. We quantified swine fecal filth inside and outside community members’ homes using Pig-2-Bac, a swine-specific Bacteroidales genomic DNA marker in North Carolina. Lastly, we developed a novel bead-bead salivary immunoassay to measure immune response to 48 antigens (38 pathogens) and applied it to a study of workers in IFAP, neighbors of IFAP and Metro residents in North Carolina. Increasing SPI and PPI increased the odds of gas plume detection and proximity to IFAP biofuels waste infrastructure resulted in large plumes of H2S and CH4. In addition to air pollution, swine fecal filth was detected both inside and outside of community residents’ homes and was associated with increasing SPI. Lastly, immune responses to biological emissions from facilities, like bacteria, viruses and parasites, were higher in workers in these facilities and IFAP neighbors compared to Metro residents. These findings provide more evidence of the impact of emissions from IFAP facilities, as well as necessitate the need for a cumulative impacts approach to understanding the burden of exposure of communities who live near IFAP