Open Research Oklahoma (Oklahoma State Univ.)
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Assessment of environmental impacts from septic tank irrigation systems in Oklahoma
No full textSeptic tank irrigation systems are widely used for decentralized wastewater management. While effective in treatment, their environmental impacts, particularly on soil microbial processes and resulting greenhouse gas (GHG) emissions are not well understood. This study examined soil microbial contributions to GHG fluxes from irrigated and non-irrigated plots using soil flux measurements in the field and microbial enzyme assays in the lab. Results showed negative fluxes of methane (CH₄) and nitrous oxide (N₂O) in control plots, indicating net uptake, while carbon dioxide (CO₂) exhibited positive fluxes. Statistically significant differences in CH₄ and N₂O fluxes were observed between irrigated and non-irrigated zones, with cumulative mean fluxes higher for all three GHG in irrigated soils. Soil and water quality assessments revealed elevated pH, hardness, and nutrient loads, particularly ammonium and orthophosphate, exceeding EPA-recommended thresholds. In-vitro targeted enzymatic assays for mcrA and nosZ indicated elevated potential for CH₄ and N₂O production in the treated zone. Amplicon sequencing of microbial communities showed distinct differences in taxonomic composition and functional gene diversity, including a heterogeneous distribution of mcrA in irrigated soils. Quantitative PCR revealed significantly higher abundance of nosZ operational taxonomic unit 1, which encodes nitrous oxide reductase, in the irrigated plot. Overall, the study highlights that septic tank irrigation systems can alter microbial activity and increase trace gas emissions, suggesting potential adverse effects on ecosystem function and the need for revised management strategies
Mixed methods exploration of the influence of NAS and PCAST reports in judicial decision-making
No full textThe National Academies for Science (NAS), its National Research Council (NRC), and the President’s Council of Advisors on Science and Technology (PCAST) have published comprehensive reports that assess various forensic science disciplines. These reports have played a pivotal role in shaping the discourse and altering perceptions surrounding forensic science. Although numerous publications discuss these reports and their anticipated impact, very few studies have evaluated the role and impact of these reports in judicial decision-making. This study aims to decrease that gap by investigating the influence that six reports—DNA Technology in Forensic Science (1992), the Evaluation of Forensic DNA Evidence (1996), Forensic Analysis: Weighing Bullet Lead Evidence (2004), Ballistic Imaging (2008), Strengthening Forensic Science in the United States: A Path Forward (2009) (NAS 2009), and Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods (2016)—have on judicial decision-making. 621 criminal judicial decisions were evaluated using an embedded mixed methods design. that the use of these reports in litigation did not substantially change the claims and arguments made by legal actors; rather, they served to substantiate or refute those existing claims that were previously dismissed as speculation. Overall, courts engage with these reports in three ways: 1) to explain, 2) to challenge or support, and 3) as the basis of the argument. Some reports proved to be more influential than others (χ2 = 48.411, p=<.001). Specifically, the Evaluation of Forensic DNA Evidence was the most influential report and was primarily referenced to bolster the prosecution’s argument and validate the forensic evidence presented. The data reflects an unwavering confidence in the credibility of forensic evidence and the judiciary created by established precedents that may or may not be based on scientifically accurate posits
Border dynamics in the art of the Mexican diaspora in the United States from 2010 to 2020
No full textContemporary artists of the Mexican diaspora in the United States have engaged with the complexities of the U.S.-Mexico border. The migration crisis between 2010 and 2020 prompted particularly powerful artistic expressions about this area known as the deadliest migration route globally. Inspired by José David Saldívar’s theory of the U.S.-Mexico border as a “machine of control, identity and resistance”, this project proposes a framework to analyze these artistic responses through three predominant dynamics: control, identity, and resilience. The term "resistance" was replaced by "resilience" to emphasize that resistance as an inherent concept in every action that opposes and gives visibility to this crisis, positioning art, its documentation, and the research about it as acts of resistance. This thesis analyzes three main artworks created by artists that have experienced the impact of the border themselves. Emilio Rojas’s "Heridas abiertas (A Gloria) / Open Wounds (To Gloria)" conveys the repercussions of power execution and trauma around the border by translating psychological pain into physical pain, questioning the segmentary character of the political boundary and advocating for greater visibility of the human consequences under the control dynamic. Isabella Cruz-Chong’s work explores identity through raw matter to reflect on notions of origin, belonging, displacement, and identification and transnationalism using interactive pieces like "Border Crossing Fortune Tellers" to evoke experiences of border crossing and demonstrate the pedagogical power of art. Rafael Lozano-Hemmer’s "Border Tuner / Sintonizador Fronterizo" illustrates resilience through a digital participatory installation that promotes connection and community building at the border, shifting dominant narratives of trauma and division towards shared histories and unity through connective micropolitical acts of resistance. Across these artworks, the human body is a central component, serving as a subject, a medium and an activator of meaning, denoting existence and movement intrinsic to border experiencing, displacement and identification. Despite its history as a site of intense control, violence and division, the U.S.-Mexico border is at-heart a dynamic zone of meaningful cultural intertwining and resilience. This research provides insights into social, cultural, and political issues related to the complex region and offers a framework applicable to other controversial borderlands in the world, highlighting borders as sites of both division and connection
Towards efficient water management in agriculture: Insights from farmers and development of a global crop evapotranspiration forecasting tool
No full textImproving water management in agriculture involves many factors, including understanding social realities and the development of practical tools that targets existing constraints. As climate variability intensifies and water availability becomes more uncertain, it is critical to develop technological innovations that align with the needs of water managers. This research addresses that need by investigating the perspectives of farmers on water consumption and challenges and by presenting the development of a global crop evapotranspiration forecasting tool. The first study explores the perspective of farmers on water-related concerns, water management practices, and technology adoption in the rural, water-stressed region of Southwest Oklahoma, USA, with a focus on irrigation, livestock, and drinking water. Semi-structured qualitative interviews were conducted with 24 agricultural producers across the study region. The results show that water availability and quality are of primary concern to the participants regarding irrigation and livestock water sources in the region. The study also highlights the perspectives of farmers in technology adoption. Participants value affordable, reliable, and user-friendly technologies to support them in irrigation management. The second study complements this finding by focusing on the development of a globally-available crop evapotranspiration forecasting tool. It utilizes crop images and data from the Canopeo app to generate crop- and location-specific forecast estimates. The system has been implemented on Amazon Web Services (AWS) cloud platform, which automates data retrieval, processing and forecast delivery to the users via email. Within the AWS system, reference evapotranspiration is fetched from the Open-Meteo web service, crop coefficient for the respective growth stage is estimated for the forecast period, and crop evapotranspiration forecast estimate is generated. The tool addresses barriers to technology adoption by requiring minimal input from users, providing user-friendly output, and being economically accessible, making crop water use information accessible to a wide range of agricultural producers and water planners. Together, these studies provide an integrated approach towards efficient water management in agriculture
Impacts of shared language erosion on ethnic identity and ethnic socialization among first- and second-generation Hispanic immigrant youth
No full textThis study applied Bioecological Systems Theory to investigate the impacts of Shared Language Erosion (SLE) on ethnic identity development, family ethnic socialization and anxiety among Hispanic immigrant middle-school-aged youth in a new settlement area. SLE is the loss of fluency in a shared common language between the parent-child dyad that likely has consequences on these processes. The rise of anti-immigrant rhetoric poses a risk to immigrant youth’s mental health, necessitating the identification of factors that inhibit the positive effects of family ethnic socialization and ethnic identity development, such as SLE and discrimination. Challenges in ethnic identity development may partly explain why second-generation immigrant youth experience worse health outcomes than their first-generation and non-Hispanic U.S. born peers – a phenomenon known as the immigrant paradox. Multiple group analysis was used to test generational differences; a double mediation model (n=137) to test SLE’s the associations among ethnic identity development (i.e. resolution), family ethnic socialization, and youth anxiety; discrimination, gender, age, and years in the U.S. were modeled as covariates. The results of the multiple group analysis reveal that the two groups were not statistically different (p=.628). SLE was not significantly associated with declines in socialization, or increased symptoms of anxiety. However, family ethnic socialization was significantly associated with ethnic identity development (b=.428, p <.001). Notably, discrimination was significantly associated with resolution (b=.145, p <.05) and anxiety (b=. 409, p <.001). The findings suggest that parents’ ethnic socialization efforts are positively contributing to ethnic identity development, but discrimination is still having a substantive effect on youth anxiety
Assessing spatial accessibility of maternal healthcare in Cape Coast, Ghana
No full textGhana has seen encouraging improvements in reducing infant and maternal mortality rates over the past decades, but it remains a challenging issue. This is as a result of several factors, including transportation and socioeconomic factors, which affect maternal healthcare access, and eventually affect the healthcare outcomes. A clear understanding of the spatial accessibility patterns of healthcare services can help policymakers identify potential problems and make wise decisions to improve maternal healthcare in an area. In this study, we examined the spatial variability in access to maternal healthcare services across the Cape Coast Metropolitan area in Ghana. Incorporating transportation conditions and socioeconomic factors in our analysis, we implemented an augmented two-step floating catchment area (A2SFCA) method to investigate the spatial accessibility to maternal healthcare facilities in Cape Coast. The method uses different catchment area sizes to reflect the resource capacity of healthcare facilities and applies varying network-based distances to capture the reality that people may have different transportation modes available to them when visiting facilities due to their socioeconomic status. Accessibility analysis results reveal significant disparities in maternal healthcare access between population clusters of different socioeconomic status in the Cape Coast Metropolitan area. High socioeconomic areas enjoy better access to maternal healthcare, while low socioeconomic groups, especially those living at the peripheries, experience poor or no access. Consequently, these underserved areas have been identified as problematic areas for potential interventions. To enhance access to maternal healthcare, three potential solutions were proposed and evaluated: (1) adding one large hospital, (2) improving transport conditions, and (3) implementing small multiple healthcare facilities known as the Community-Based Health Planning and Services (CHPS) in Ghana. Evaluation results suggest the third potential solution as the most effective, ensuring that almost all communities in the region have access to maternal healthcare services. The study provides useful findings that will help assist healthcare policymakers, planners, and the government in improving maternal access across the region
Publications in agricultural economics, Oklahoma State University, July 1, 1972 - June 30, 1973
No full textExploring variance partition coefficient in generalized linear mixed models: Theoretical foundations and application
No full textWe present a unified framework for estimating the variance partitioning coefficient (VPC) in generalized linear mixed models (GLMMs), extending existing methods by incorporating a general structure for covariates and random effects. We conceptualize the VPC conditional on the values of the covariates and provide a general expression for the conditional VPC that allows researchers to derive specific formulations for their use cases by choosing the relevant components: (1) the underlying probability distribution of the data, (2) random effects structure such as random intercept model versus random slope model, and (3) the model's canonical link function.We have also developed asymptotic inferential methods related to the VPC in a GLMM framework.
We have derived the limiting distribution of the VPC using asymptotic distribution of the maximum likelihood estimator (MLE) under non-standard conditions such as when one or more parameters of interest or nuisance parameters are on the boundary of the parameter space. Several hypotheses tests and confidence intervals have been developed to answer potential research questions.
Finally, we apply our proposed framework for estimating and testing heritability for intermediate expression traits obtained using high-throughput sequencing technologies. Heritability, the proportion of variation in traits due to genetic factors within a population, serves as a fundamental metric in quantifying these influences. Traditional approaches for estimating heritability, such as family-based designs or intra-class correlations in ANOVA, have provided foundational insights. However, more sophisticated models are necessary for the count data obtained from high-throughput sequencing. An earlier study introduced model-based heritability scores using linear mixed models and generalized linear mixed models, focusing solely on genetic factors without considering covariates. This limitation presents a gap in understanding how different treatments, age, and other covariates influence heritability estimates. We propose a more comprehensive framework for estimating heritability that incorporates covariates, offering a nuanced view of heritability in high-throughput sequencing data. Both simulated and real data sets are used to assess our proposed methods
Technical & economic proposal: Blue hydrogen to improve the atmosphere (BIA)
No full textThe American Institute of Chemical Engineers (AIChE) has determined that the growing hydrogen demand has warranted the preliminary design of a new Blue Hydrogen Plant on the U.S Gulf Coast. This Blue Hydrogen plant is hoped to support the hydrogen demand within the vicinity and lay the groundwork of greener hydrogen future.
This preliminary design aimed to determine the economic viability of the Blue Hydrogen Project, as well as determine an effective process to capture the CO₂ produced to minimize environmental effects. The proposed design produces 250 MMSCFD of hydrogen through Autothermal Reforming of methane and utilizes pressure swing adsorption to recover the produced hydrogen, and a monoethanolamine (MEA) scrubber to capture the CO₂.
Safety concerns for this process are due to the possibility of a runaway reaction, loss of containment and potentially catastrophic results if the hazardous gases contained in this process are exposed to the atmosphere. To make this process inherently safer, a detailed control system has been designed for the Auto Thermal Reforming unit since it must operate well above the temperature and pressure envelope. To minimize risk further, hazard identification was conducted for each chemical present within the process and a hazard and operability study (HAZOP) was conducted on the largest unit and the largest distillation column.
Economic analysis was performed on the proposed design for an evaluation life of 20 years, including FEL-3 and construction time, at a tax rate of 35%. The net present value of the proposed design is 2.05B is required to purchase the necessary equipment. FEL-3 is estimated to cost 1.40 per kg. The payback period for the project is 8.7 years, so Company A will obtain positive cash flow by the BIA plant by August 2033. The overall probability of success for the proposed project is 98.6%. Therefore, the proposed BIA plant project should be pursued because it is an economically attractive opportunity for Company A
Mechanistic machine learning approach applied in evaluation and modification of rate of penetration models for hard rock drilling
No full textThis study evaluates, modifies, and develops multiple Rate of Penetration (ROP) models tailored for hard rock drilling applications, with particular emphasis on geothermal drilling. Polycrystalline Diamond Compact (PDC) bits of four-bladed and five-bladed variants were tested under a range of confining pressures (up to 2000 psi) and operational settings (weight on bit, RPM, and torque) in a laboratory. Additionally, one of the ROP models was explored with operating conditions in the field at UTAH Forge. The research introduces methodologies for phase detection of drilling efficiency, incorporating Random Forest regression, cubic spline interpolation, and the Pruned Exact Linear Time (PELT) algorithm. These techniques identify transition points that separate inefficient from efficient drilling phases. Thereby, it guides parameter adjustments to optimize ROP. Modified versions of classical ROP models- Bingham (1965), Bourgoyne et al. (1974), Hareland and Rampersad (1994), Motahhari et al. (2010), and Kerkar et al. (2014) - were derived to incorporate the effect of confining pressure on effective rock strength. Their performance was compared on laboratory datasets for a 4-bladed PDC bit. Each model was evaluated based on its retained post-outlier-removal dataset for subset optimization to preserve calibration integrity. Additionally, symbolic regression was employed to discover data-driven ROP equations that reconcile mechanistic accuracy with minimal structural complexity. Finally, their generalizability on field tests was determined. A separate, log-linear ROP model with variance-inflation-factor (VIF) pruning was proposed, and a time-series SARIMAX model was developed to forecast depth-indexed drilling data. Results suggest that modified Motahhari and Hareland–Rampersad models demonstrate superior accuracy (R² exceeding 0.96) in controlled laboratory tests. In contrast, classical Bingham and Bourgoyne formulations exhibit comparatively lower explanatory power. Symbolic regression further provided parsimonious equations with strong predictive accuracy. Field validation reveals that direct use of lab-calibrated parameters yields moderate accuracy. This highlights the importance of domain-specific calibration. Overall, the study underscores the need to include confining pressure effects, employ robust phase detection algorithms, and incorporate data-driven calibration for accurate ROP modeling in hard rock geothermal drilling applications