UC Merced

Despite their ecological importance, many aspects of chondrichthyan (cartilaginous fishes; sharks, skates, rays, and chimeras) biology remain poorly understood, even as their populations face widespread decline due to anthropogenic pressures. Native to California’s estuarine and coastal systems, the Leopard Shark (Triakis semifasciata) is a generalist mesopredator whose foraging ecology, movement, and response to environmental change are still not fully understood—particularly in heavily impacted estuaries like the San Francisco Bay Estuary (SFBE). This dissertation uses bulk stable isotope analysis (SIA) and compound-specific isotope analysis of amino acids (CSIA-AA) to investigate the trophic ecology, site fidelity, and habitat connectivity of Leopard Shark subpopulations across four Northern California sites: the SFBE, Drakes Estero, Tomales Bay, and Bodega Bay. These estuarine systems differ in hydrodynamics, nutrient regimes, and conservation protections, making them ideal for exploring how environmental context shapes resource use. Here, I develop high-resolution δ13C and δ15N isoscapes across the SFBE to track spatial variation in baseline isotope values, which are influenced by nutrient inputs, especially from wastewater. I then use bulk tissue SIA and chronological tooth samples to assess seasonal movement and localized habitat use, revealing long-term site fidelity and distinct isotopic niches among regions. CSIA-AA δ13C fingerprinting further shows that estuarine and bay habitats support different productivity pathways. Finally, I pioneer the use of eye lenses as a novel chronological tissue to reconstruct long-term trophic life histories in Chondrichthyans, offering insight into lifetime dietary patterns and habitat use. Together, these studies demonstrate that Leopard Sharks exhibit high habitat fidelity and flexibility in resource use, shaped by the isotopic and ecological characteristics of their environment. This work provides critical insight into how anthropogenic change impacts mesopredator ecology and highlights the utility of isotope-based tools for studying long-term movement and foraging strategies in estuarine systems.

Historically, suicide rates among African Americans were comparatively low to other racial/ethnic groups despite the significant generational trauma, racial discrimination, inequity, and poverty experienced by African Americans. However, African Americans have experienced the greatest recent increases in suicide rates compared with all other racial/ethnic groups, giving renewed urgency to understanding risk factors for suicidal behavior in this population. This dissertation makes a contribution to the literature on suicidal behavior among African Americans by investigating socioeconomic risk factors for suicidal behavior and clinical risk factors for suicide mortality among African Americans. The first study examines the association between educational attainment, annual family income, and suicidal behavior among a representative sample of African American adults. The second study investigates the association between clinical factors (e.g., chronic illness, injuries, mental/substance use disorders) and suicide morality among African American emergency department patients. This dissertation also examines the risk of cause-specific mortality (e.g., heart disease, cerebrovascular disease, suicide) in the context of mental illness among African Americans. The results indicate that socioeconomic risk factors may not be strong predictors of suicidal behavior among African Americans. Lower income African American males in particular, may be a high-risk population for suicidal behavior. Mental disorders are strongly associated with suicidal behavior among African Americans. African Americans with mental disorders may also have an elevated risk of cause-specific mortality. Reducing the burden of suicidal behavior among African Americans may require community-based suicide prevention programing and reducing stigma associated with mental health. Improving chronic disease management and health behaviors among African Americans with mental disorder may help reduce mortality associated with mental illness in this population. Future studies should further investigate the causal mechanisms underlying the relationship between mental illness, suicidal behavior, and cause-specific mortality among African Americans.

This thesis includes two parts discussing two fascinating areas of fundamental physics. \textbf{Part (I)} explores the enigma of quark confinement within the intricate domain of quantum field theory, addressing a foundational puzzle in particle physics. Quark confinement dictates that quarks are bound within hadrons, so we cannot observe quarks as free, isolated particles. Despite extensive efforts over the past fifty years, the theoretical foundation of quark confinement in quantum chromodynamics (QCD) is still unclear. Studying the Schwinger effect (particle-antiparticle pair creation in vacuum in the presence of a strong external electromagnetic field) can pave the way to explore the behavior of quarks within hadrons. We utilize an indirect method, in particular the so-called AdS/QCD correspondence, to investigate the response of a QCD-like gauge theory to a static electromagnetic field. AdS/QCD correspondence is a form of gauge/gravity duality. This duality connects a gauge theory (representing particle physics) to a gravitational theory (specifically, string theory with an Anti-de Sitter background metric). Leveraging this method enables us to study the Schwinger effect for quark-antiquark pairs through potential analysis and calculation of the pair-production rate $\Gamma$. Our findings show that both the potential analysis and the calculation of the pair-production rate yield consistent results. We identify two critical electric fields $E_{s}$ and $E_{c}$ as lower and upper bounds of a range in which pair production can occur only by tunneling through a potential barrier. Below $E_{s}$, the potential barrier is insurmountable, and pair production cannot happen. Above $E_{c}$, there is no potential barrier to restrict the pair production. While previous studies have explored various aspects of the Schwinger effect using AdS/QCD duality, further investigation is required for scenarios involving QCD-like gauge theories with simultaneous electric and magnetic fields. Addressing this research gap, our findings reveal that a magnetic field perpendicular to the electric field suppresses $\Gamma$ and increases $E_{s}$. Conversely, a purely parallel magnetic field does not influence the system's response to an external electric field but enhances $\Gamma$ in the presence of a perpendicular magnetic field. \textbf{Part (II)} ventures into the cosmos, examining the formation of young stellar groups (both bound star clusters and unbound stellar associations) within a full cosmological context. A young stellar group is a collection of newly born stars moving together as a relatively coherent unit through a galaxy. Recent observational advancements, driven by improved precision of Gaia DR3, along with complementary near-field studies like PHANGS-HST and PHANGS-JWST, have significantly enhanced our understanding of stellar groups in the Milky Way and local universe galaxies, enabling us to study the conditions and environment that set clustered star formation across a statistically significant sample. Yet despite the exciting progress in observations, there is still a notable absence of robust theoretical cosmological models to interpret the data. Recent advancements in generating galaxy zoom-in simulations enable the comprehensive study of the formation and evolution of giant molecular clouds and stellar groups within a cosmological galactic framework and, in turn, facilitate filling the gap between observations and theoretical models. We present the fundamental properties of young massive stellar groups, both bound and unbound, formed within or near the galactic disk at the present time (at redshifts $z < 0.008$) in the \Latte suite of FIRE-2 Milky Way-like galaxy simulations. Our analysis encompasses the measurement of various characteristics for each stellar group, including its boundedness, mass, size (stellar group’s radius), 1D velocity dispersion, dispersion in age, and dispersion in metallicity [Fe/H]. We find the properties of simulated stellar groups with ages between 0 and 3 million years are within the range of values reported in observational studies. Our results depict the capability of \Latte simulations to generate reasonably realistic star clusters and associations and set the stage for the forthcoming project that will focus on generating synthetic images of the simulated stellar groups and measuring their properties by utilizing the conventional pipelines used in observational studies. This approach will allow a more consistent comparison between simulations and observations, aiding in the establishment of benchmarks for interpreting observations and advancing our understanding of various aspects of galaxy formation, such as stellar evolution, the impact of feedback on galactic dynamics, and the processes involved in star and planetary system formation.

Active matter systems are those whose individual constituents convert energy to move or perform mechanical work. Physicists have long been fascinated by active matter systems as they are inherently out of thermal equilibrium, making them much more difficult to classify and quantify using the traditional techniques of statistical mechanics. Biology, being comprised of many such systems, has become one of the most sought-after fields for the physics community. In this work, we are predominantly interested in biological machines that consume chemical energy, like ATP, and use this fuel to exert forces on their surroundings. We utilize theoretical and computational techniques to investigate these systems as in silico is a cost effective way to span the parameter space and learn design principles that can both decipher the current generation of in vivo and in vitro experiments and propel the next. Here, we develop minimal mechanical models, conduct computer simulations, and apply quantitative analytics at the cellular level (chapters 2, 3, and 4) and subcellular scale (chapter 5) to both gain insight into relevant design principles and make testable predictions regarding the system constituents and emergent behavior thereof. Specifically, in chapter 2, we ask if cells modeled solely as coarse grained anisotropic contractile force dipoles are sufficient to produce branched multicellular network structures and how the mechanical properties of the substrate and cell response to the substrate affect this tendency. In chapter 3, we ask if cells modeled as contractile dipoles in a discretized elastic medium can give rise to a strong nonlinearity in force production as a function of density suggested by recent experiments of fibroblasts embedded in collagen gels. In chapter 4, motivated by a wide variety of systems like synthetic Janus colloids in an alternating electric field and magnetotactic bacteria, we explore the collective behavior of highly motile contractile anisotropic dipoles. Lastly, in chapter 5, we ask if the geometric helicity of microtubules coupled to motor propulsion is sufficient to produce emergent chiral motion of isolated microtubules, rather than a fundamental chirality given by intrinsic curvature.

Intrinsically disordered proteins and protein regions (IDRs) are ubiquitous across all kingdoms of life and are essential to cellular function. Unlike folded proteins, IDRs exist in a collection of rapidly interchanging conformations known as an ensemble. An IDR’s amino acid sequence determines its ensemble, which in turn can play an important role in dictating function. Yet a clear link connecting IDR sequence, its ensemble properties, and its role as sensors of the cellular environment has not been directly established. This dissertation describes a series of projects aimed at understanding how IDRs act as sensors of the cellular environment. Chapter 2 compares in vitro and in-cell experiments of naturally occurring IDRs and establishes that IDR ensembles and sensitivities are recapitulated in live cells. Chapter 3 is unpublished data that builds on the finding that in vitro observations recapitulate in live cells and aims to test IDR sensitivity to different cancer cellular environments, focusing on a larger set of naturally occurring IDRs. This chapter aims to highlight key sequence features that play a role in sensing the cellular environment, specifically different types of cancers. Chapter 4 tests if the same sequence and structural features that enable sensitivity for naturally occurring IDRs holds true for synthetic sequences. This chapter describes a software and validation method to design and test synthetic disordered sequences based on user given parameters. Not only does this allow for an informed high-throughput design of sequences but it also allows scientists to design sequence mutants in a more informed manner. Chapter 5 concludes the dissertation, describes the contributions of the work to the field and suggests directions for further research.

Modern-day entrepreneurial ventures and workplaces are dynamic ecosystems wheretraditional boundaries between business setups, employees, teams, and organizational goals are constantly redefined and reshaped. During my PhD journey, I have explored three interconnected dimensions of organizational life: understanding the developing nature of entrepreneurship beyond the limits of high-tech startups, the collaborative dynamics in organizations through technology, and the transformative potential of corporate team-based sports on organizational outcomes. These three studies convey an interrelated narrative about fostering inclusivity and promoting interconnectedness inside and in the organizational ecosystem. The first study, "Entrepreneurship Without Borders," contests the narrow outlook on entrepreneurship as a high-tech startup. This is a reason for a broader and more encompassing definition that includes diverse activities in the entrepreneurship realm. It puts forward a framework for mentoring and education that empowers a wide range of entrepreneurial endeavors. This paper emphasizes that entrepreneurship goes beyond its definition to encompass development and creativity as inclusive endeavors that individuals across various sectors and environments can adopt. The second research paper, called "Share or Not to Share: A Framework for Understanding Coworker Collaborative Consumption," is concerned with sharing behavior in the workplace. It explores the factors influencing coworkers' collaborative consumption of personal and work-related goods and services via organizationally sponsored sharing platforms. Factors affecting employees' eagerness to share include technological factors, attitudes, motivations, and culture. The study advocates a framework for understanding how to connect employee attitudes with actions in collaborative 2 sharing practices by combining the theory of Psychological Ownership and the Technology acceptance model theory. The study illustrates how psychological ownership attitudes, sustainable consumption norms, and technology usability perceptions influence employees' sharing motivations and intentions in organizations. The ongoing third paper, "The Impact of Corporate Team-Building Sports Programs on Organizational Outcomes," explores the distinctive role of corporate team-based sports programs in shaping organizational outcomes. Grounded in three theories: Social Identity Theory, Self-Determination Theory, and Psychological Ownership Theory, this study argues that organizations that participate in regular corporate sports events can take advantage of fostering a sense of belonging, strengthen team dynamics, and enhance employee motivation. Corporate team-based sports programs go beyond helping employees with their mental and physical health, as in traditional employee wellness programs. They promote interdepartmental engagement, break down hierarchical barriers, and create a more profound sense of identity within the organization. The study gives businesses a broad theoretical framework that could help them innovate and thrive. In summary, the studies meet on three unifying themes. First, value creation in various uncertain contexts could be transformed by redefining the entrepreneurial concept and its activities and broadening its theoretical framework to be more inclusive. Second, the research on collaborative consumption in organizations shows how technology and shared platforms may foster community and employee involvement while increasing organizational efficiency. Finally, research on corporate wellness initiatives, especially corporate team-based sports programs, highlights employee participation's profound impact on organizational outcomes. When taken as a whole, these studies provide useful information for businesses trying to handle the difficulties and complexities of a workplace that is changing quickly. They emphasize how important innovation, inclusivity, and a common goal are to fostering longterm success and worker satisfaction. The findings indicate how employee and team dynamics and engagement influence organizational outcomes. The papers suggest theoretical and practical implications for organizations to promote teamwork via team-based sports, collaboration through technology, or rethinking entrepreneurship. It encourages a significant change in how businesses are set up, how workers interact with each other, and how resources are shared. Using these tactics can make places stronger, more flexible, and better prepared for success in a world that is becoming more and more connected.Modern-day entrepreneurial ventures and workplaces are dynamic ecosystems where traditional boundaries between business setups, employees, teams, and organizational goals are constantly redefined and reshaped. During my PhD journey, I have explored three interconnected dimensions of organizational life: understanding the developing nature of entrepreneurship beyond the limits of high-tech startups, the collaborative dynamics in organizations through technology, and the transformative potential of corporate team-based sports on organizational outcomes. These three studies convey an interrelated narrative about fostering inclusivity and promoting interconnectedness inside and in the organizational ecosystem. The first study, "Entrepreneurship Without Borders," contests the narrow outlook on entrepreneurship as a high-tech startup. This is a reason for a broader and more encompassing definition that includes diverse activities in the entrepreneurship realm. It puts forward a framework for mentoring and education that empowers a wide range of entrepreneurial endeavors. This paper emphasizes that entrepreneurship goes beyond its definition to encompass development and creativity as inclusive endeavors that individuals across various sectors and environments can adopt. The second research paper, called "Share or Not to Share: A Framework for Understanding Coworker Collaborative Consumption," is concerned with sharing behavior in the workplace. It explores the factors influencing coworkers' collaborative consumption of personal and work-related goods and services via organizationally sponsored sharing platforms. Factors affecting employees' eagerness to share include technological factors, attitudes, motivations, and culture. The study advocates a framework for understanding how to connect employee attitudes with actions in collaborative 2 sharing practices by combining the theory of Psychological Ownership and the Technology acceptance model theory. The study illustrates how psychological ownership attitudes, sustainable consumption norms, and technology usability perceptions influence employees' sharing motivations and intentions in organizations. The ongoing third paper, "The Impact of Corporate Team-Building Sports Programs on Organizational Outcomes," explores the distinctive role of corporate team-based sports programs in shaping organizational outcomes. Grounded in three theories: Social Identity Theory, Self-Determination Theory, and Psychological Ownership Theory, this study argues that organizations that participate in regular corporate sports events can take advantage of fostering a sense of belonging, strengthen team dynamics, and enhance employee motivation. Corporate team-based sports programs go beyond helping employees with their mental and physical health, as in traditional employee wellness programs. They promote interdepartmental engagement, break down hierarchical barriers, and create a more profound sense of identity within the organization. The study gives businesses a broad theoretical framework that could help them innovate and thrive. In summary, the studies meet on three unifying themes. First, value creation in various uncertain contexts could be transformed by redefining the entrepreneurial concept and its activities and broadening its theoretical framework to be more inclusive. Second, the research on collaborative consumption in organizations shows how technology and shared platforms may foster community and employee involvement while increasing organizational efficiency. Finally, research on corporate wellness initiatives, especially corporate team-based sports programs, highlights employee participation's profound impact on organizational outcomes. When taken as a whole, these studies provide useful information for businesses trying to handle the difficulties and complexities of a workplace that is changing quickly. They emphasize how important innovation, inclusivity, and a common goal are to fostering longterm success and worker satisfaction. The findings indicate how employee and team dynamics and engagement influence organizational outcomes. The papers suggest theoretical and practical implications for organizations to promote teamwork via team-based sports, collaboration through technology, or rethinking entrepreneurship. It encourages a significant change in how businesses are set up, how workers interact with each other, and how resources are shared. Using these tactics can make places stronger, more flexible, and better prepared for success in a world that is becoming more and more connected.

This dissertation explores how the preferences of individual small donors are shaped by various factors they are exposed to during an election cycle. Who are these small donors and what influences their decision to donate? This question is the overarching question that this dissertation investigates. Despite their growing importance, small donors remain understudied compared to other forms of political behavior. This dissertation addresses this gap by exploring the factors influencing small donor behavior and their implications for modern campaigns. Specifically, the research makes three significant contributions. Chapter 1 investigates how candidate attributes, including demographics, work experience, and policy positions, affect donation decisions using a conjoint design experiment. Chapter 2 examines how the competitiveness of electoral races influences small donor behavior, focusing on markers such as incumbency, party endorsements, and polling status. Chapter 3 analyzes the emotional content of fundraising messages—anger, anxiety, and enthusiasm—and their impact on donation behavior through a factorial vignette experiment. Together, these studies provide new insights into the motivations and preferences of small donors, advancing our understanding of their critical role in contemporary political campaigns.

Islands have long captivated evolutionary and ecological biologists, especially since Darwin’s pivotal insights on natural selection during his visit to the Galapagos Islands. While islands account for only 6% of the Earth’s land area, they harbor 20% of global species diversity, hosting many endemic species and unique morphological diversity, providing textbook examples of adaptive radiation. However, island biodiversity has been severely affected during the Anthropocene, with three out of four island species becoming extinct, with the disappearance of the dodo (Raphus cucullatus) in the 17th century being one of the first recognized human caused extinctions on islands. The extinction of a species can profoundly affect an entire ecosystem, leading to changes in both ecological and evolutionary dynamics. Focusing on the evolution of morphological traits, I combined theoretical and empirical approaches to explore the ecological and evolutionary consequences of extinctions on island communities. In Chapter 1, I explored the interplay between colonization, extinction, and coevolution, and how these intersecting dynamics shape species’ traits and the structure of mutualistic networks on islands. For that, I used a stochastic mathematical model, integrating Island Biogeography Theory with coevolutionary dynamics. My results show that as extinction rates increase, the number of interactions needed for a species to achieve maximum persistence on the islands also rises, but only up to a threshold. Moreover, islands with higher extinction rates have species with greater trait similarity. In Chapter 2, I used data from historical Hawaiian honeycreepers, a group of Hawaii-endemic birds that have lost several species in the last century. I test whether greater morphological variation and larger niche breadth increases resilience to extinction in each species. Using geometric morphometrics and stable isotope ratios, I show that within guilds, species that have gone extinct exhibited lower morphological variation. Lastly, in Chapter 3, I used phylogenetic comparative methods to investigate the evolution of beak shape in the Hawaiian honeycreepers and the loss of unique adaptive peaks with species extinctions. I show that the extinction of Hawaiian honeycreepers is leading to a drastic reduction in the occupied morphospace, resulting in a homogenization in their trait space, which can directly impact ecosystem functioning and the provision of ecosystem services, such as seed dispersal. Taken together, my dissertation broadens the understanding of how extinction can affect both ecological and evolutionary dynamics of island communities.

Neotropical leaf-nosed bats are an incredible example of adaptive radiation within mammals. This family of bats exhibits a wider range of dietary habits than any other mammalian family and they possess a high level of morphological variation to accommodate their dietary habits. With carnivorous, nectarivorous, frugivorous, and even sanguivorous species, they make an exceptional study system to understand patterns in the evolution of diet and morphology. In particular, the morphological spectrum between incredibly long-faced nectar specialists and very short-faced fruit specialists allows for an investigation of the limits and consequences of specialization. In Chapter 2, I outline the relationship between different measures of specialization within this family using stable isotope analysis of the hair of wild caught individuals. These stable isotope ratios are compared with morphological data from museum specimens and dietary data from previous studies. In Chapter 3, I examine biogeographic patterns in specialization within two different dietary groups to understand the limitations of specialization. Palate aspect ratio, a morphological proxy for diet, is compared between Caribbean endemic and continentally distributed frugivorous and nectarivorous bats to identify different patterns of specialization in different evolutionary contexts. Lastly, in Chapter 4 I use geometric morphometrics to examine the relationship between the shape of the cochlea, the shape of the skull, and diet within these bats. These analyses reveal a complicated network of impacts on the shape of the cochlea in this family of bats. Overall, I describe different metrics of specialization, identify different ecological consequences of specialization on different resources, and possible structural trade-offs driven by high levels of specialization under ecological and structural constraint.

As the affordability and availability of virtual reality hardware increases, its adoption is also rapidly growing. Yet, input and interaction in virtual reality remains a significant challenge. Existing interaction techniques often lack intuitiveness, precision, and the spatial feedback users are accustomed to in the real world. They can also be cumbersome and lack mobility, further limiting usability and immersion. Furthermore, virtual reality lacks effective and efficient methods for text input. These limitations restrict the widespread adoption of virtual reality, primarily confining it to entertainment and training simulations. Furthermore, since virtual reality is still in its infancy, there is a lack of design guidelines to help designers and developers, leading to decisions driven primarily by intuition. This dissertation investigates the use of wearable and haptic technologies to overcome these limitations and create more intuitive and efficient virtual reality experiences.

First, addressing the challenges of text input in virtual reality, this dissertation begins with an investigation into the impact of key shape and dimension on text entry performance and preference. The aim is to contribute to the standardization of design practices in virtual reality through empirical data. We compare three common key shapes: hexagonal, round, square, in both two-dimension (2D) and three-dimension (3D). The results indicate that the 3D square keys provide superior performance in terms of accuracy and user preference. This suggests that replicating familiar real-world elements can significantly enhance usability, especially when a technology is in its infancy.

Second, building on these findings, we investigate mid-air text input, which is a common scenario in virtual reality environments. To address the lack of spatial feedback resulting from the absence of a physical surface, we utilize an ultrasonic haptic feedback device. In addition to incorporating the design insights from the first study, we develop three different ultrasonic haptic feedback methods: feedback only on keypress, on both touch and keypress, and gradual feedback that increases in intensity as users push down a key. A pilot study revealed that the touch & press feedback performed significantly better, both quantitatively and qualitatively. We therefore compare a mid-air keyboard with and without touch & press feedback in a user study. Results revealed that haptic feedback improves entry speed by 16% and reduces the error rate by 26%. In addition, most participants feel that it enhances presence and spatial awareness in the virtual world by maintaining a higher consistency with the real world and significantly reduces mental demand, effort, and frustration.

Third, extending upon mid-air interaction, we investigate the effectiveness of different selection gestures augmented with ultrasonic haptic feedback. We compare four commonly used mid-air target selection methods: Push, Tap, Dwell, Pinch, with two types of ultrasonic haptic feedback: feedback upon selection only, and feedback on both hover and selection, in a Fitts' law experiment. Results reveal that Tap is the fastest, the most accurate, and one of the least physically and cognitively demanding selection methods. Pinch is relatively fast but error-prone and physically and cognitively demanding. Dwell is slowest by design, yet the most accurate and the least physically and cognitively demanding. Both haptic feedback methods improve selection performance by increasing users' spatial awareness. Participants perceive the selection methods as faster, more accurate, and more physically and cognitively comfortable with the haptic feedback methods. Based on these findings, we provide guidelines for choosing optimal mid-air selection gestures considering technological limitations and task requirements.

Fourth, we further extend selection gestures and input methods in virtual reality by developing a custom wearable device that does not occupy the hands, thereby leaving them free for other tasks. We introduce a novel finger-worn device for gesture typing in virtual reality, termed the "digital thimble", which users wear on their index finger. This thimble utilizes an optical sensor to track finger movement and a pressure sensor to detect touch and contact force. We also introduce Shapeshifter, a technique that enables text entry in virtual reality through gestures and varying contact force on any opaque, diffusely reflective surface, including the human body. A week-long in-the-wild pilot study shows that Shapeshifter yields, on average, 11 words per minute (wpm) on flat surfaces (e.g., a desk), 9 wpm on the lap when sitting, and 8 wpm on the palm and back of the hand while standing in text composition tasks. In a simulation study, Shapeshifter achieves 27 wpm for text transcription tasks, outperforming current gesture typing techniques in virtual reality.

Finally, we extend the functionality of the digital thimble further and explore its usability in the context of target selection, sorting, and teleportation. We start with a Fitts' law study that compares the digital thimble with a commercial wearable mouse (previously unexplored in virtual reality contexts) and a traditional controller, using two selection methods: press and touch-release. A second user study investigates the devices for sorting and teleportation tasks. While the finger mouse demonstrated superior throughput and task completion speed, the digital thimble showed greater accuracy and precision. Participants also favored the digital thimble for its enhanced comfort, convenience, and overall user-friendliness. These findings highlight the digital thimble's potential as a versatile and comfortable input device for virtual reality applications, offering valuable advantages over traditional alternatives.

This dissertation makes significant progress in addressing the core challenges associated with input and interaction in virtual reality, setting the foundation for more intuitive and natural interactions within virtual environments. The insights gained have the potential to enhance the accessibility and applicability of virtual reality across a broad spectrum of fields, such as education, training, collaboration, and healthcare, thereby broadening its impact and utility.