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A Low-power Mixed-signal Potentiostat System-on-Chip with Integrated Dual-slope ADC
No full textThis thesis presents the design and characterization of a low-power mixed-signal potentiostat that was integrated with a 65 nm core in a SoC for low-power electrochemical sensing applications. The system integrates a low-noise transimpedance-based potentiostat front end with a 12-bit dual-slope analog-to-digital converter (ADC) for accurate current-to-digital conversion. The potentiostat core—comprising the control amplifier, current-mirror network, and transimpedance amplifier—consumes 38.2 µA from a 2.5 V supply (95.5 µW) and achieves an input-referred noise floor of 113 µVRMS over a 330 Hz bandwidth, while having an input current range from 1 nA to 20 µA and a noise-limited sensitivity of 56.4 pA. The dual-slope ADC analog section draws 26.4 µA from a 2.5 V supply (66 µW) and achieves a sampling rate of 732 Hz, and a sample accuracy with all measured conversion points deviating by no more than 1 LSB from the ideal transfer characteristic. Together, the active measurement path operates at 324 µW, including the overhead due to bias circuits, maintaining sub-milliwatt power while achieving high measurement fidelity. The combined architecture demonstrates stable operation across process variations, validating its suitability for portable electrochemical sensing systems requiring high precision and low-power.
Advisor: Sina Balkı
Nebraska Transcript (University of Nebraska College of Law), Fall 2025
No full textDean’s message
Nebraska Law students achieve outstanding results in competitions
Nebraska Law recognized for excellence in mental health and well-being
Clifton, ’08, honored as 2025 Alumni Master
Uecker, ’25, selected as a 2025 Next Generation Leader
Unexpected path to Nebraska Law leads Haratsis, ’25, to home, calling
Client Counseling program celebrates 50 years
Big Ten law schools present series of panel discussions on rule of law
A reflection of the past six years, College’s strategic plan now complete
A culture of strengths: CliftonStrengths and the College of Law
Celebrating 50 years of Ross McCollum Hall
Johnson studies how election law changes are impacting votes
A celebration of the 50 year history of clinical legal education at Nebraska Law
Professor Elana Zeide: protecting digital privacy
Faculty notes
Hoetger explores how technology challenges Fourth Amendment protections
Schuyler Project clarifies immigration process, builds community
Nebraska Children’s Justice and Legal Advocacy Center will address rural attorney shortage and support Nebraska children
Nebraska Law builds bridges through international partnership with Palacký University
Medill named Outstanding Legal Educator by Nebraska State Bar Association
Ehmke Sergeant, Pearlman, Rivera honored with campus awards
Leading with purpose: Cunningham’s, ’05, journey from Nebraska Law to Cincinnati Athletics
Gould, ’01, Boyer, ’69, Duncan and Lund, ’25, recognized by Dean\u27s Advisory Board
Meet Claire Bass: bridging health law and policy at Nebraska Law
Magilton named 2025 Emerging Leader by AALS Externship Committee
Placzek retires after 26 years dedicated to students and the Nebraska Law community
Professor Jack Beard: a legacy of impact for Nebraska Law students and in the fields of space, cyber and national security law
Class of 2025 celebrates Spring Commencement
AlumNotes
In memoriam
Report on givin
Changepoint Detection as Model Selection: A General Framework
No full textThis dissertation presents a general framework for changepoint detection based on model selection. The core method, Iteratively Reweighted Fused Lasso (IRFL), improves upon the generalized lasso by adaptively reweighting penalties to enhance support recovery and minimize criteria such as the Bayesian Information Criterion (BIC). The approach allows for flexible modeling of seasonal patterns, linear and quadratic trends, and autoregressive dependence in the presence of changepoints.
Simulation studies demonstrate that IRFL achieves accurate changepoint detection across a wide range of challenging scenarios, including those involving nuisance factors such as trends, seasonal patterns, and serially correlated errors. The framework is further extended to image data, where it enables edge-preserving denoising and segmentation, with applications spanning medical imaging and high-throughput plant phenotyping.
Applications to real-world data demonstrate IRFL’s utility. In particular, analysis of the Mauna Loa CO\textsubscript{2} time series reveals changepoints that align with volcanic eruptions and ENSO events, yielding a more accurate trend decomposition than ordinary least squares. Overall, IRFL provides a robust, extensible tool for detecting structural change in complex data.
Advisors: Xueheng Shi and Bertrand Clark
Soil Characterization with Proximal Geophysics
No full textHigh quality soil data is crucial for addressing numerous threats to human well-being such as water scarcity, food insecurity, and intensified natural disasters. True soil property values are determined by analyzing soil samples in a laboratory, but soil sampling is often expensive and time-consuming. Some in-field point sensors and remote sensing products are available to measure soil properties, but they have inherent limitations in measurement extent and resolution. Geophysical methods can fill the measurement scale gap between point measurements and remote sensing products, but various research questions remain open. This dissertation aims to advance understanding of geophysics-derived soil property measurements by providing contextual knowledge of the discipline’s evolution and analyzing experimental data to answer questions about the behavior and accuracy of specific geophysical signals. Chapter 1 provides an introductory overview of this dissertation. Chapter 2 is a review analyzing the trends in agricultural applications of geophysics (agrogeophysics) since the field’s emergence in 1986. Chapter 3 investigates the relationship between soil moisture and passive gamma-ray spectroscopy. Chapter 4 assesses network-wide calibration of cosmic-ray neutron soil moisture sensors in a mountainous watershed and presents a relationship between bare neutron counts and vegetation dynamics. Chapter 5 summarizes the research contributions of Chapters 2–4 and discusses directions for future research. Together, these dissertation chapters support progress in measuring soil properties with approaches that are accurate, spatially and temporally relevant, cost-effective, and scalable. Continued research will facilitate mitigation of threats to human well-being through accessible, high quality soil data.
Advisor: Trenton Fran
An Integrated Modeling Framework to Evaluate Circularity of the Corn–Water–Ethanol–Beef Nexus
No full textThis dissertation examines the transition from conventional linear agricultural and food bioenergy systems toward more circular, resilient, and resource-efficient configurations. Prior research indicates that spatial and temporal variability in soil, weather, animal biological responses, and management decisions strongly influences productivity, nutrient-use efficiency, and profitability. Studies have also shown that a diversified circular system can buffer these sources of variability, improving stability and adaptive capacity. Building on these insights, the central focus of this work is to develop an integrated modeling framework to evaluate circularity within the Corn-Water-Ethanol-Beef (CWEB) nexus and explore how climate variability and management choices shape system-wide performance.
Chapter 1 reviews the sources of variability and uncertainty across Food-Energy-Water (FEW) systems, emphasizing how environmental heterogeneity, climate fluctuations, biological processes, and management interactions shape outcomes in interconnected agricultural and bioenergy contexts. The chapter evaluates existing modeling approaches to study FEW systems and identifies the limitations of relying exclusively on agent-based or system dynamics methods. These insights underscore the need for a hybrid simulation approach that can model cross-sector flows, nonlinear responses, and feedback mechanisms within the CWEB network.
Chapter 2 presents a hybrid Agent-Based and System Dynamics model built in AnyLogic® that links crop production, ethanol processing, cattle feeding, coproduct utilization, and manure nutrient recycling. The model incorporates seasonal dynamics, lifecycle processes, and key sustainability indicators, including circularity indices, water footprint, and greenhouse gas emissions. Scenario experiments demonstrate how herd size, diet composition, and manure application rates influence circularity metrics, resource efficiency, and system stability, illustrating the value of hybrid modeling for evaluating bioeconomy pathways.
Chapter 3 integrates climate-driven yield variability by estimating an Autoregressive Distributed Lag (ARDL) model using historical climate records for Nebraska. The resulting coefficients are embedded in AnyLogic® to update annual crop yields under nine climate shock scenarios representing warming trends, drought and moisture extremes, and precipitation changes. The combined ABM-SD-ARDL framework captures how climate induced yield shifts propagate through feedstock availability, ethanol output, DDGS supply, manure nutrient recovery, and system idle periods over a three-year horizon, offering insights into short-term resilience within food-bioenergy systems. The appendix includes technical supplementary material detailing feed calculations, manure assumptions, and model parameters.
Advisor: Deepak Keshwan
Assessing Reproductive Health in Zoo-managed African Elephant Bulls (\u3cem\u3eLoxodonta africana\u3c/em\u3e)
No full textPopulations of zoo-managed African elephant (Loxodonta Africana) exhibit substantial individual- and population-level variation in reproductive success, yet research has largely focused on females, leaving male fertility poorly understood. Subfertility in bulls, characterized by low libido and inconsistent semen quality, poses significant challenges to genetic management and long-term population sustainability. This study a) systematically evaluates semen quality, b) identifies physiological, behavioral, social, and environmental determinants of fertility, and c) advances ex situ conservation through the expansion of the African elephant sperm bank. Between January 2023 and July 2025, 209 semen collection events were conducted from 13 sexually mature bulls across ten North American zoos. Semen samples were evaluated using macroscopic and microscopic metrics, including volume, concentration, total count, motility, forward progression, morphology, viability, acrosome integrity, agglutination, appearance, and pH. Samples were classified into low (0–29%), moderate (30–59%), and high (60–100%) motility groups, revealing substantial variability both within and among individuals. High motility was consistently associated with greater viability, acrosome integrity, normal morphology, and reduced agglutination, while volume and concentration were less predictive of motility. Physiological analyses revealed that testosterone, the glucose-to-insulin ratio, and triglycerides, were positively associated with high motility, whereas high insulin was negatively associated. Management and environmental factors further influenced semen quality: high motility was positively associated with female elephant luteinizing hormone surges, as well as increased exercise, forage-based enrichment, time outdoors, and higher ambient temperatures, whereas a greater percentage of time spent indoors was negatively correlated with semen motility. Mean semen motility also differed according to reproductive history: bulls that had never sired offspring exhibited the lowest motility, whereas bulls that had sired via artificial insemination or natural breeding had progressively higher motility. Finally, the African elephant sperm bank was expanded to store 13,070 straws from eight bulls, including 10,125 straws from previously unrepresented individuals, increasing genetic diversity and supporting artificial insemination and long-term population management. Collectively, this work establishes the most detailed multi-institutional dataset on African elephant bull semen quality, elucidates key physiological, behavioral, and environmental determinants of fertility, and demonstrates the critical role of cryobanking in ex situ conservation. These findings provide evidence-based guidance for reproductive management, health monitoring, and genetic sustainability in zoo-managed African elephants, ultimately supporting the long-term conservation of this iconic species.
Advisor: John Carrol
Residential HVAC Installation Faults: Field Prevalence, Drivers, and Energy Impacts
No full textFaults in residential comfort systems can have detrimental effects on the performance of the system, reducing the energy efficiency, affecting indoor comfort, and shortening equipment lifespan. Many of the faults occur at installation. However, there has not previously been a systematic and nationally representative study to indicate the prevalence of the faults, meaning the distribution of faults by fault type and fault intensity. Understanding true fault prevalence is essential to be able to identify derivers, and to assess the incremental electricity consumption of the new installation systems.
This study presents on-site data from 341 new central cooling systems—air conditioners and heat pumps—in eight U.S. cities across various climate zones. Using non-invasive diagnostics, I classified three installation faults—refrigerant charge deviation, indoor-coil airflow, and liquid-line restriction—by type and intensity, producing fault distributions at state and regional levels. I then analyzed potential drivers using house/system metadata (such as floor area, vintage, efficiency, thermostat behavior, contractor participation), along with climate and regional practice indicators, employing multivariate models to find fault correlates. To estimate energy impacts for 2023, I allocated national AHRI shipments to states through three streams: new construction, replacements, and first-time installs. A baseline of annual electricity use without faults was created using state-level operating intensity, shipment tonnage, and SEER standards. Finally, fault distributions were mapped to COP-based energy multipliers to estimate excess electricity use in 2023 for new installations.
Some key findings on fault intensities, prevalence, and energy impacts include: Evaporator airflow fault intensity: On average 16% below the 400 cfm/ton nominal; –20% (~360 cfm/ton) is the most common level; heat pumps lower than ACs. Refrigerant charge fault intensity: Average –6.5% (undercharge); 23% of systems have a serious deviation (≥ 20% under/over). Liquid-line restriction fault intensity: ~25% minor restriction; ~1% serious (rare). Socioeconomic status showed no meaningful association with any fault type. Energy: 2.49 TWh excess electricity use for 2023 new installs above the no-fault baseline (8.94% of 27.86 TWh), driven chiefly by South Atlantic (~856 GWh), West South Central (~504 GWh), and Pacific (~249 GWh).
Advisor: David Yuil
Evaluation of Waste Plastic Addition via Dry Method on Asphalt Mixture Performance
No full textIncorporating waste plastic (WP) into hot mix asphalt (HMA) offers a promising approach to enhance recycling rates and improve asphalt concrete (AC) performance, particularly in moisture damage resistance. However, results vary widely due to differences in WP types, sizes, and mixing methods. The lack of standardized procedures, especially for the dry process, has led to inconsistent integration and unclear roles of WP in AC mixtures. Studies suggest that introducing WP to pre-heated aggregates at temperatures exceeding its melting point can enhance mixture resistance to rutting, cracking, and moisture damage. In this context, this study was conducted in two phases to evaluate the feasibility and implementation of WP-modified asphalt. Phase 1 focused on WP selection and characterization, development of a laboratory mixing protocol, performance testing, and evaluation of bonding characteristics at the binder-aggregate interface. Three mixtures were examined: a control mix, and two polypropylene-modified mixes (AC-PP-MM1 and AC-PP-MM2) with 1% WP and different pre-heating temperatures. The Hamburg Wheel Tracking Test (HWTT) and Indirect Tensile Asphalt Cracking Test (IDEAL-CT) were used to evaluate mechanical performance. Results showed that higher mixing temperatures improved polypropylene melting and aggregate coating, enhancing rutting and moisture damage resistance. The study also compared the effects of two WP types (LDPE and PP). Both improved moisture damage resistance, with LDPE showing superior performance. WP incorporation enhanced binder-aggregate bond strength, reduced water wettability, and increased compatibility. However, PP-modified mixes exhibited poor cracking resistance based on IDEAL-CT results. Phase 2 assessed the practical implementation of a Nebraska Superpave Recycled Mixture (SPR NDOT) with WP in South Sioux City, NE. Laboratory results indicated that combining Reclaimed Asphalt Pavement (RAP) and 1% LDPE improved moisture and rutting resistance. Lower RAP contents resulted in softer mixes with better cracking performance. A mix of 25% RAP and 1% LDPE was plant-produced and field-implemented for performance monitoring. Future works will compare laboratory and plant-produced mixes to validate whether the lab-developed procedure is scalable for full-scale asphalt production.
Advisor: Jamilla Emi Sudo Lutif Teixeir
Morgan Stanley’s Competitive Strategy and Industry Environment: An External and Internal Analysis
No full textMorgan Stanley is a global financial services firm that trades, manages, and distributes capital for a wide range of clients. Its competitive position is dependent on a number of factors including reputation, quality, and innovation, and the firm is subject to many internal and external factors that affect its competitive position. This work seeks to examine the factors that affect Morgan Stanley’s strategy and competitive position, looking at both historical factors and potential future outcomes. A PESTEL analysis as well as an analysis of Porter’s Five Forces in the financial industry are used to demonstrate the external factors that influence Morgan Stanley. This analysis is followed by an analysis of Morgan Stanley’s current strategy and competitive advantages, considering what qualities will be long-term competitive advantages. These qualities include strong capital and liquidity, high levels of technological investment and innovation, and company acquisitions. Brand reputation and diversified business offerings provide Morgan Stanley a long-term competitive advantage. Looking to the future, the firm should closely watch macroeconomic shifts both locally and globally. It should also continue to invest in artificial intelligence and cybersecurity
Proposed Civil Design Package for Lincoln Youth Sports Complex
No full textThe following report is a proposal of civil work and an engineering design package for the City of Lincoln to construct a Youth Sports Complex on the vacant lot at 2100 North 1st Street, Lincoln, Lancaster County, Nebraska. The city has requested five U10 to U14 combination baseball and softball fields, one championship softball field, and one championship baseball field. Additionally, a playground area, concessions building, and designated parking areas have been requested. This design package includes introductory company and project information, a summary of the design request and constraints, three overall design alternatives, discipline-specific engineering designs and recommendations, and a cost estimate and schedule for civil engineering and construction work. The public health, welfare, and safety analysis outlines the recommended considerations to use during planning and construction in order to maintain the health and safety of the population living and working in close proximity to the site. The cultural, societal, and economic analysis shows that this project does not infringe on the rights of any group of people and provides services with limited burden to the community. The included topographic survey, environmental review, and floodplain analysis further address issues that may arise so that proper planning to mitigate and/or remediate said issues may commence forthwith. Design details are provided for each sub-discipline of civil engineering work, including structural, water resources, transportation, and environmental considerations. This proposal and design are intended to serve as the basis for future construction of the Lincoln Youth Sports Complex