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“Self-Compassion Has to Be the Heartbeat of How I Move Through Life”: A Mixed Methods Study of Family Caregiver Emotional Well-being
No full textOften referred to as “hidden patients,” family caregivers endure numerous physical, emotional, psychological, and social hardships due to the demands of caregiving, which often results in their own needs going unmet. With the projected 61.3 million of the baby boomer generation entering the long-term care phase by 2029 along with a mass shortage of professional caregivers post-pandemic, more and more family members are expected to fill in for the role of care without sufficient access to support services (Pollard & Scommegna, 2014; Smith & Chang, 2016). An exploratory, mixed-methods study using a three-group intervention design was utilized to investigate the perceived value of self-compassion practices for family caregivers between the ages of 30–50 years old, a subgroup that has yet to be researched in depth. Quantitatively, pre- and post-intervention survey data assessed caregiver burden, emotional well-being, caregiver identity, and self-compassion across three groups: a self-compassion group, a peer support group, and a control group. Results indicated: (a) significant improvements in self-compassion and emotional regulation in the self-compassion group, (b) reductions in caregiver burden and burnout post-intervention, and (c) increased awareness of how caregiving had come to define one’s identity and overshadow aspects of emotional well-being. Qualitatively, participants described feeling less isolated, more emotionally equipped, and reported feeling more supported and content as caregivers. Findings contribute to the limited research on self-compassion as a supportive intervention for family caregivers, particularly within a younger caregiving cohort navigating high-intensity care with limited systemic support. Additionally, this study adds to the evolving research on family caregiving by deepening understanding of caregivers’ lived experiences and highlighting the multifaceted emotional, relational, and systemic factors that shape caregiving over time.
Advisors: Cody Hollist and Holly Hatto
\u3cem\u3eOpNet\u3c/em\u3e: Pixel Synthesis Neural Network for Interactive Volume Visualization
No full textVolume visualization systems responsive to the user’s data-dependent operations, like changing the color and opacity transfer functions, can significantly enhance the efficiency of uncovering critical intrinsic patterns within the volumetric data. However, existing volume visualization systems often require re-execution of the entire visualization pipeline whenever the transfer functions are altered, resulting in substantial computational overhead and hindering real-time interactivity. In this work, we proposed a pixel synthesis neural network, OpNet, to directly predict the pixel results in constant time by jointly considering the data, viewing parameters, and transfer functions. Our approach decouples the data and color/opacity mapping from the compositing process of ray casting by learning features from data and transfer functions separately. This design enables efficient rendering for modified transfer functions by inferring only a subset of the network, thereby significantly reducing input latency. Furthermore, OpNet extracts a latent representation from rays to accurately model pixel-level similarities, and leverages superpixel rendering through ray grouping to further optimize the rendering performance. Experimental results demonstrate that OpNet achieves superior rendering latency with high rendering quality compared to traditional GPU-accelerated ray casting and state-of-the-art generative image synthesis methods, offering a promising solution for real-time, interactive volume visualization.
Advisor: Hongfeng Y
MEMS Stiction Quantification and ALD Coating Evaluation Through a Combined Experimental and Modeling Framework
No full textStiction—unintended adhesion between microsurfaces—remains a critical reliability challenge for microelectromechanical systems (MEMS), particularly in high-g inertial sensors where movable elements repeatedly contact travel stops. Existing surface treatments, like self-assembled monolayers, suffer from limited thermal stability and integration complexities, while wafer-level quantitative adhesion characterization methods remain scarce. This work presents a production-oriented framework to quantitatively measure and understand MEMS stiction under varying contact conditions and surface states.
Custom paddle test structures were fabricated across a 4-inch wafer, providing uniform displacement and well-defined contact areas. By varying beam thickness and stop counts (1–5 discrete stops and continuous-contact designs), devices spanned stiffnesses of ~1–4 N/m without altering geometry. Electrostatic pull-in and release voltages were recorded automatically using a Keysight LCR meter and automatic probe station, with triple-sweep trials demonstrating repeatability within ~0.2 V. A lumped-mass electromechanical model, incorporating bending rigidity, parallel-plate electrostatics, and tensile residual stress (~10–15 N/m), was calibrated to experimental pull-in data. Deviations from ideal (no-adhesion) release behavior yielded a closed-form expression for stiction forces, enabling purely electrical wafer-level extraction of adhesion forces.
To investigate surface modification effects, a conformal 50 nm HfO2 film was deposited by Atomic Layer Deposition (ALD) at 350 °C. Analytical modeling showed only a negligible stiffness increase (~0.3 N/m), confirmed by post-ALD testing. Devices were then systematically evaluated using the developed methodology across surface conditions and contact geometries. A subsequent 500 °C anneal showed no significant changes in stiction behavior relative to the as-deposited state. Importantly, while a measurable stiction increase was observed for the ALD-coated devices relative to uncoated silicon, this reflects the specific experimental conditions and should not be interpreted as a general conclusion regarding HfO2 coatings.
Overall, the methodology integrates automated design, predictive modeling, and high-throughput electrical testing, providing a quantitative framework to distinguish stiction contributions from mechanical and surface effects. The findings highlight that while the ALD coating introduced negligible mechanical changes, the developed methodology successfully captured and quantified stiction behavior variations, emphasizing the importance of comprehensive characterization for MEMS design and surface treatment evaluation.
Advisor: Fadi Alsalee
Application of Cementitious Materials and Fiber Reinforcement to Enhance Lime Stabilization for Nebraska Shale Soils
No full textLime stabilization is a widely used technique to improve weak subgrades; however, its effectiveness under freeze-thaw cycles remains a critical challenge. This study investigates the incorporation of cementitious materials and fiber to enhance the mechanical properties and environmental resistance of lime-stabilized soils under such conditions. Two types of soil, gray shale (plasticity index of 37.8) and clay soil (plasticity index of 19.0) from Nebraska, were used. Stabilization mixtures included lime dosages of 0%, 3%, and 6% by weight, combined with either 10% fly ash or 3% and 6% cement by weight, and 0% and 1% fiber. The experimental program comprised a multi-tiered approach: characterization of physical properties through geotechnical tests (e.g., particle size distribution, Atterberg limits, and standard Proctor tests), preparation of composite specimens for unconfined compressive strength (UCS) and direct shear testing, and evaluation of environmental resistance through freeze-thaw cycles (7 cycles after 14 days of curing and 12 cycles after 28 days of curing). Additionally, large-scale testing was conducted using the Large-Scale Track Wheel test to simulate field conditions. Results showed that lime and fly ash significantly reduced the plasticity index of gray shale, with less pronounced effects on clay soil. The UCS values for gray shale ranged from 61.2 to 300.7 psi for lime stabilization, 137 to 272 psi for lime and fly ash stabilization, and 129 to 490.8 psi for lime-cement stabilization. For clay soil, UCS values ranged from 68 to 149 psi for lime stabilization, 119 to 146 psi for lime and fly ash stabilization, and 204 to 379.2 psi for lime-cement stabilization. The inclusion of fiber further enhanced the shear strength parameters of the soils, particularly increasing cohesion. Cement-lime stabilization demonstrated superior UCS retention and resistance to freeze-thaw cycles for both soil types, outperforming lime alone and lime-fly ash treatments. These findings highlight the importance of incorporating cementitious materials to enhance the durability and performance of lime-stabilized soils under harsh environmental conditions
Statistical Computing Using R and Python
No full textThis book is designed to explain and demonstrate statistical programming concepts and techniques. I started this project in Summer 2020 as a less-tedious way to learn programming compared to hours and hours of video lectures. I’ve always found that watching someone code and talk about code is not usually the best way to learn how to code. It’s far better to learn how to code by … coding, but it’s hard to start from nothing, too.
Because this book was begun as an alternative to recorded lectures with slides, I have included all of the comics, snark, and gifs that I would normally have put in lecture slides. I’ve also supplemented this with other things that you can’t usually put in slide presentations: YouTube videos, extra resources, links to other textbooks that are more specific than this one. My goal is to make this a collection of the best information I can find on data science and statistical programming.
There is a downside to this approach: in most cases, this book includes way more information than you need. Everyone starts with a different level of computing experience, so I’ve attempted to make this book comprehensive. Unfortunately, that means some sections will seem like they are stating the obvious, and some sections will have more detail than you ever wanted to know. Use this book in the way that works best for you - skip over the stuff you know already, ignore the stuff that seems too complex until you understand the basics. Come back to the scary stuff later and see if it makes more sense to you
How Developers Use Type-system Related Programming Language Features
No full textOptional type annotations are a popular feature of programming languages that allow developers to omit explicit type information in code while, in some cases, retaining many of the benefits of static typing, such as in-code documentation, improved detection of type errors, or enforcement of code properties. However, how developers use and understand optional type annotations is not clear. The focus of this dissertation is to understand the use and comprehension of optional type annotations.
Optional type annotations are examined through four lenses: first, by examining the evolution of usage in a statically typed programming language (Kotlin, the default language for Android), we find that locations tend to retain their annotation (or lack thereof) over time, and some locations such as initialized class fields and single-expression method return types receive type annotations more frequently than others.
Second, by examining the output of large language models (LLMs) for the presence of type annotations when generating code, we find differing behavior between languages, with Python being minimally annotated unless explicitly requested. But explicitly requesting types also leads to more syntax errors.
Third, by using eye tracking to better understand developer reference behavior (such as looking back at a line containing a declaration) with respect to type annotations, we find that developers did not engage in reference behavior more frequently in code with type annotations.
Finally, through direct intervention, asking developers why they made a particular change to a type annotation, we find the three most common reasons type annotations are modified (or added/removed) are due to an incorrect type causing an error, to improve their function as documentation, or to adhere to a formal convention.
Together, this confirms that developers view type annotations as documentation, especially in certain locations, even if they are rarely modified. However, how this information gets utilized by other developers or LLMs is unclear: we do not see evidence that developers refer to it during bug localization, and we see that requesting type annotations can cause downstream problems for popular tools such as LLMs.
Advisor: Robert Dye
2024–2025 Christmas Bird Counts
No full textFor the second year in a row, all twenty CBCs [Christmas Bird Counts] were run during the 2024–2025 season. The weather was generally cooperative, although five circles reported fog and two others had rain. Branched Oak-Seward was postponed a week due to icy conditions on the originally scheduled day. The average high temperature for all circles on count day was 41 and the average low temperature was 22. Because December had remained relatively mild, there was a good deal of open water, which encouraged many species of water birds to remain. Consequently, most of the circles reported species totals higher than average, led by Lake McConaughy with 106 species. Five other circles found more than 80 species. The total number of species for all circles (153) is four more than the previous high of 149 from 2010. However, the total number of individuals (310,304) was fairly typical. There were 937 total party hours, with Lincoln accounting for 228 of them.
Thirteen species including Bald Eagle were counted in every circle, but 34 species were found in only one circle, and 17 of those were single birds. Three species new to Nebraska counts were White-faced Ibis, Eastern Kingbird and a very out-of-place Couch’s Kingbird
Distribution and Ecology of the Cedar Keys Mole Skink (\u3cem\u3ePlestiodon egregius insularis\u3c/em\u3e)
No full textWe conducted surveys for the Cedar Keys Mole Skink, Plestiodon egregius insularis (Mount), during 1989– 1999 and 2015–2024, examined museum vouchers, and compiled personal observations from others to determine the status and distribution of this subspecies, which has the smallest geographic distribution of the five subspecies and is being considered for federal listing. We observed Cedar Keys Mole Skinks on Airstrip Island, Atsena Otie, Cedar Point, Deer Island, North Key, Scale Key, Seahorse Key, Snake Key, and possibly Dog Island. We have anecdotal reports of Mole Skinks on Way Key, which contains the most potential habitat and is the main island occupied by the City of Cedar Key. We found Mole Skinks along shorelines in tidal wrack and under debris but seldom searched island interiors, which presumably shelter populations from storm surges that periodically scour beaches of refugia. This subspecies, which has been proposed for federal listing as endangered, is primarily threatened by habitat loss from rising sea levels and more frequent and intense storms resulting from climate change
FARMNAV-UAV: A Field-ready Autonomous UAV for Tracking Static and Dynamic Trajectories in Agricultural Applications
No full textThis study presents the design and development of a custom-built uncrewed aerial vehicle (UAV) tailored for precision agriculture. Unlike commercial UAVs, which are often constrained by proprietary systems and limited hardware customization, the proposed platform emphasizes modularity, upgradeability, and cost-effectiveness. The UAV is equipped with a Cube Blue flight controller for reliable low-level actuation and a Raspberry Pi 4 companion computer that executes a Model Predictive Control (MPC) algorithm for high-level trajectory optimization and stability enhancement.
Most conventional UAV autopilot systems rely on non-optimal control strategies, such as proportional–integral–derivative (PID) controllers, which can be inadequate for dynamic or resource-constrained environments. In contrast, this work implements an optimal control strategy using MPC, resulting in smoother trajectory tracking and optimized computational efficiency. Additionally, traditional mission planning approaches based on static waypoints lack the flexibility required for dynamic field conditions. To overcome this, the proposed architecture integrates MPC with Kalman filtering, enabling adaptive flight planning and allowing the UAV to continuously track and follow a moving uncrewed ground vehicle (UGV) in real time.
The system was first validated through simulations in the AirSim environment and later tested in real-world field trials. Experimental evaluations encompassed both static and dynamic waypoint tracking, as well as complex figure-eight trajectory navigation under windy conditions. The UAV demonstrated high precision and responsiveness across all test scenarios. During autonomous takeoff and landing operations, the root mean square error (RMSE) ranged between 8 cm and 20 cm. For complete mission cycles, including takeoff, navigation, and return-to-launch the RMSE remained within this same range. During figure-eight trajectory execution, RMSE values increased slightly, ranging from 20 cm to 35 cm. Notably, the UAV was able to track the UGV successfully, even along curved, row-crop style paths, demonstrating adaptability to non-linear trajectories. These results confirm the system’s effectiveness and reliability, highlighting its potential for deployment in precision agriculture and other dynamic, real-world robotic applications.
Advisor: Santosh Pitl
A Discrete-time Adaptive Sliding Mode Controller for a Multicopter with a Suspended Payload
No full textThis thesis presents a Discrete-time Adaptive Sliding Mode Controller (DASMC) for control of a multicopter with a suspended payload. DASMC is designed to stabilize the multicopter at a desired position while minimizing the load oscillations induced by a significant hanging payload. The proposed DASMC minimizes the need for system-specific parameters like tunable gains and improves robustness to both external disturbances and model uncertainties compared with existing controllers. The controller is designed for direct digital implementation on a variety of multicopter platforms with considerations like discrete-time design, adaptive gain shrinking, and saturation handling. When deployed on a real multicopter in an outdoor field environment, our DASMC demonstrates tracking accuracy of less than \qty{20}{\cm} despite high wind speeds of up to \qty[per-mode=symbol]{6}{\meter\per\second} and up to 50\% uncertainty in model parameters.
The DASMC is specifically applied to the problem of multicopter-based bridge inspection. An end effector with a robotic hammer mechanism suspended below a multicopter physically impacts connection members (bolts or rivets) on a steel truss bridge and determines if the connection members are loose based on vibrational response. Because the DASMC precisely stabilizes the end effector and prevents payload oscillations, the robotic hammer mechanism can accurately contact the target connection member. This novel bridge inspection method eliminates the need for manual inspection of steel bridges and increases the safety and efficiency of steel bridge monitoring.
Advisor: Justin Bradle