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Multistage Stochastic Optimization for Agricultural Operations in Arid and Semi-Arid Regions
No full textExtreme weather events, particularly droughts, pose significant risks to agriculturalproductivity and economic stability in arid and semi-arid regions. Addressing these challenges requires a comprehensive approach that integrates advanced optimization techniques and machine learning to enhance decision-making under uncertainty. This dissertation develops multistage stochastic optimization models to improve agricultural operations, like water irrigation, crop rotation, harvesting, machinery scheduling, resource allocation, and yield prediction, contributing to more resilient and sustainable farming systems.
With developed multistage stochastic optimization models for planting planningand harvest scheduling, decision-making tools are designed to minimize costs, maximize profit, and minimize the risk of water scarcity and extreme weather events like drought in arid and semi-arid regions. These models incorporate multi-method irrigation strategies, machinery allocation, and harvesting logistics, ensuring efficient resource utilization and economic viability under drought scenarios. To complement these optimization strategies, machine learning is utilized to enhancepredictive capabilities for crop yields. By integrating weather and soil data, machine learning techniques, including hybrid deep learning architectures, are employed to capture complex relationships between environmental variables and agricultural output. Comparative analyses across different climatic regions provide insights into yield variability, improving forecasting accuracy, and informing adaptive management practices. Additionally, precision agriculture techniques, such as precision irrigation, offer targeted solutions for managing limited water resources in arid and semi-arid regions. By integrating data from soil moisture sensors and weather forecasts, machine learning models with multistage stochastic optimization can generate adaptive andcost-effective irrigation schedules under uncertain weather conditions, ensuring efficient resource allocation while maintaining crop productivity. This research advances decision-making for agricultural operations by integratingmultistage stochastic optimization and machine learning. The findings offer actionable strategies for farmers, policymakers, and stakeholders to enhance sustainability, mitigate economic losses, and improve resilience against climate uncertainties.Release after 08/22/202
Bridging the Gap: The Role of Internships in Shaping Professional Identity Among Equine Science Students
No full textThis study explored how undergraduate students in the Equine Science and Race Track Industry programs at the University of Arizona perceive their professional skill development and the role internships play in that process. The research aimed to assess self-reported abilities in communication, horse handling, and professionalism, and to compare skill perceptions between students who had completed an internship and those who had not. A total of 27 students participated in the Equine Science Student Professional Development Survey.Findings revealed moderate to high self-assessment scores across all skill areas, with the highest averages reported in professionalism and foundational horse handling tasks. Independent samples t-tests indicated statistically significant differences in haltering, leading, approaching, and hoof handling, with students who had completed internships reporting higher confidence in these areas. Students who had not participated in internships also shared their future intentions, barriers to participation, and anticipated learning outcomes. Common barriers included lack of time, financial limitations, and unawareness of available opportunities. Despite these challenges, students recognized internships as valuable for gaining hands-on experience and industry insight. These results underscore the importance of integrating experiential learning into equine science education and suggest that improved access, communication, and curriculum design may enhance student readiness and engagement in the field
Persistent Places, Storied Spaces: An Ethnogeography of Indigenous Land Use in Western Colorado
No full textArchaeological research on Great Basin landscapes primarily emphasizes resource acquisition and survival strategies, as interpreted from material artifacts. This approach has established the critical role of seasonal mobility for the region’s Indigenous populations but has disregarded social and ontological aspects of their land use practices, including the significant roles that local philosophies, as expressed in material and non-material manners, play in landscape relationships. To better address the nature of Indigenous knowledge and landscape-based experiences, my dissertation draws from Indigenous Studies and Indigenous Archaeology to construct a new framework for exploring how Indigenous peoples have engaged with the landscape at rock art sites over time. This decolonizing and Indigenizing theoretical approach reframes land use as a relational process. Using concepts like Native Science, Storywork, and local epistemologies, I employ this approach to investigate how a broad range of Indigenous groups constructed and used particular “persistent places” in western Colorado between 8,000 BCE–1800 CE. My dissertation integrates three unique datasets: geospatial analyses of regional site patterns from almost 400 rock art sites in western Colorado, specific iconographic data from field survey at 25 of those sites, and traditional knowledge and history communicated in more than 100 Ute oral traditions. I use these lines of evidence to identify trends in placemaking practices within western Colorado and to document how people created layered landscapes. With an emphasis on multicomponent rock sites, this study provides a rich analysis of how multiple identity groups left their mark on the same landscape over time. My dissertation presents a unique contribution to the theoretical literature on Indigenous land use, which has largely ignored the concept of placemaking in the “pre-contact” era and rarely focuses on iconography. This research rigorously employs Indigenous knowledge and local oral traditions to develop a new “storied landscape” approach for studying land through archaeology, which lays the groundwork for future collaborative inquiry
Social Norms and Heat Resilience: Testing and Extending the Theory of Normative Social Behavior to Heat Adaptation Behavioral Intentions
No full textGuided by the Theory of Normative Social Behavior (TNSB), this study investigated how perceived static and dynamic norms, outcome expectations, and risk perceptions influence heat adaptation intentions. By conducting an online survey with 317 participants based in the U.S., the study examines the theoretical propositions within the TNSB framework, extends these propositions to include dynamic norms, and investigates how risk perceptions moderate normative influence. Results revealed that perceived static descriptive norms, dynamic injunctive norms, outcome expectations, and risk perceptions had significant main effects on intentions to engage in heat adaptation behaviors. Dynamic injunctive norms moderated the association between dynamic descriptive norms and heat adaptation intentions, such that when dynamic injunctive norms increased, the association between dynamic norms and heat adaptation behaviors was strengthened. Notably, outcome expectations moderated the relationship between both perceived static and dynamic descriptive norms and behavioral intentions; however, these moderation patterns were opposite to the theoretical predictions. Consistent with theoretical expectations, risk perceptions moderated the association between dynamic descriptive norms and intentions, such that risk perceptions attenuated the association between dynamic descriptive norms and intentions. Implications for the advancement of theory and the development of effective health campaigns were discussed
Behavior of Hybrid Thick- and Thin-Skinned Orogenic Wedges in the Western Interior USA and South-Central Andes
No full textThe western interiors of North and South America host two of the largest fold and thrust belts on Earth, recording upper-plate processes active during ocean-continent convergence and the construction of Cordilleran orogenic systems. These systems are at dramatically different stages in their tectonic evolution, enabling a comparison of the actively forming Andes with their ancient counterpart in North America. Despite this advantageous geologic situation, fundamental questions remain concerning the long-term structural, thermal, and kinematic behavior of thrust belts. Cordilleran systems are inherently linked; therefore, answering questions related to the mechanics of thrust belts is critical to illuminating their feedback with other components such as the orogenic plateau, magmatic arc, and foreland basin system. This dissertation addresses the tectono-thermal history of relatively neglected segments of the thrust belt in the northern US Cordillera and south-central Andes using field mapping, cross section construction, structural analysis, low-temperature thermochronology, thermal history modeling, and regional space-time tectono-magmatic syntheses. Appendix A provides the first low-temperature thermochronologic data from the Little Belt Mountains of west-central Montana, showing that exhumation of the northernmost intraforeland uplifts occurred in the Late Cretaceous. These data, considered in the context of a regional synthesis from an adjacent salient in the Sevier thrust belt, are used to highlight abundant field evidence for Cretaceous out-of-sequence deformation and propose a new model linking thin- and thick-skinned structures in the region. In Appendix B, the highest thermochronology transect from the South American continent constrains uplift and exhumation of the Frontal Cordillera to the Early-Middle Miocene (ca. 20 Ma), contemporaneous with surface uplift and crustal thickening in this segment of the Andes. Detailed and regional mapping, an orogen scale cross section, and low-temperature thermochronology results in Appendix C provide insights into the regional stratigraphy, structural geology, and thermal behavior of the south-central Andean thrust belt at 34°S. Special focus is placed on preexisting stratigraphy and inherited structures, highlighting their essential role on the development of cordilleran thrust belts and identifies them as a contributing factor to the decrease in crustal shortening magnitude along strike of the Andes. Appendix D contains double-dated apatite fission track and (U-Th)/He thermochronology data from the San Rafael Block, a low-relief basement-cored structure that interrupts the modern Andean foreland basin system at 35°S. New data and associated thermal history modeling constrain important aspects of the SRB’s low-temperature thermal history, including Late Jurassic intraplate deformation, uplift and exhumation within the nascent Late Cretaceous (ca. 100-90 Ma) foreland basin system, limited Cenozoic burial, and ca. 10 Ma rapid uplift and exhumation of the SRB during the most recent phase of Andean mountain building.Release after 08/27/202
Expansion of Methods for the Anionic-Amino Cope Cascade to Enable the Synthesis of Nitrogen Containing Heterocycles
No full textThe work described is the development of an efficient strategy for the synthesis of a diverse array ofcomplex pyridines from acyclic starting materials via the use of annulation cascades to rapidly form complex cores along with a platform for the synthesis of the key starting materials for this platform to be initiated. Together these platforms enable the synthesis of a chiral complex pyridines with up to four of the five positions substituted, in three steps from an aldehyde. This dissertation is divided into four chapters.
Chapter 1 contains works related to new developments and the expansion of the scope of the anionic amino-Cope cascade for the development of complex cyclohexenones and post-modification of these described cyclohexenones. Chapter 2 contains a platform for the aromatization of the scope of the anionic amino-Cope cascade in addition to post-modifications thereof by various additions and cross-coupling reactions to obtain a wide range of complex phenols and arenes. Chapter 3 describes a new methodology revolving around a modification to a Horner-Wadsworth-Emmons reagent and details the effective use thereof, which streamlined the synthesis of conjugated sulfinylimines to enable rapid access to complex cyclohexenones through the anionic amino-Cope cascade which enabled deeper investigation as to alkylation of the resulting cyclohexenones cores and additional post-modifications. Chapter 4 describes a new pyridine and isoquinoline forming methodology which leveraged the cyclohexenone motifs obtained from the anionic amino-Cope cascade to form vinyl triflates which were then coupled with vinyl boronic esters to enable an irreversible 6π electrocyclization to form complex pyridine rings, or when coupled with allenylstannanes enabled a 6π electrocyclization followed by an irreversible aza-Mislow-Evans to furnish piconol motifs.Release after 08/22/202
Essays on Information Economics
No full textThis dissertation studies problems in information economics. The first chapter investigates monopolistic information selling when the Seller and the Buyer hold different prior beliefs about the state of the world. The main result shows that the Seller’s revenue is maximized by gradually selling information over multiple periods. The second chapter examines optimal communication when multiple Senders share the same information but have access only to a limited language. The main result shows that Senders use their language heterogeneously, and assign non-convex meanings to individual messages while ensuring that the meaning of message profiles remains convex. The final chapter studies strategic communication when a decision-making Receiver must acquire a limited skill set in advance. The main result shows a negative relationship between the informativeness of the Sender’s advice and the Receiver’s skill capacity
Empirical Analysis and HEC-HMS Modeling of Green Stormwater Infrastructure: Capture, Ponding, and Infiltration in Urban Tucson
No full textGreen Stormwater Infrastructure (GSI) has gained momentum in recent years for its dual ability to mitigate urban flooding through infiltration and enhance surface water quality by reducing runoff volumes and travel times. However, a gap remains in understanding the long-term performance and post-construction management of these systems. This study presents a detailed empirical analysis and hydrologic modeling effort for four GSI parks designed for stormwater harvesting in Tucson, Arizona. Results demonstrate that stormwater harvesting performance varies significantly across sites and is strongly influenced by local-scale heterogeneity. While some parks captured minimal runoff, others collected substantial volumes. Infiltration capacity did not appear to decline substantially over the less than two-year study period. HEC-HMS modeling and extreme event scenario analyses revealed that the flood mitigation potential of these systems is closely tied to rainfall intensity, with high-intensity storms overwhelming basin capacity and reducing effectiveness. These findings highlight the importance of continued monitoring and adaptive design improvements. Expanding research on GSI contributes to more resilient urban water management by supporting stormwater reuse strategies in the face of increasing climate and water resource variability
Forget Me Not: A Content Analysis of Memorable Messages Retained by Adults with ADHD
No full textThe goal of the present study was to examine what memorable messages are received in response to a person’s ADHD symptoms and how these messages are associated with receivers’ psychological outcomes. In an online survey, 147 adults with ADHD described the most memorable message they had received in response to their ADHD behaviors. Using an integrative content analysis approach, these messages were analyzed for mentions of inattention and hyperactivity ADHD symptoms, message valence, and stigmatizing content/effects. The associations between these messages and receivers’ self-esteem, sense of self-efficacy, and internalized stigma were then analyzed. Additionally, the sources of these messages and the developmental periods during which receivers first heard their memorable messages were examined. Results revealed predominantly negative memorable message experiences associated with ADHD symptoms and behaviors, and these negative messages were associated with worse psychological outcomes for receivers. The strongest associations with participants’ psychological outcomes were for the quantity of inattention symptoms they experienced and message valence. Most memorable messages originated during early or later childhood, and authority figures and parents, followed by peers/friends, were the most commonly identified message sources. Keywords: ADHD, memorable messages, stigma, psychosocial development, content analysi
Phenotypic Profiling of Colon Tumor Organoid Monolayers Characterizes a FOLFOX-Induced, AKT-Driven Subpopulation of Chemoresistant Cells
No full textColorectal cancer (CRC) is the third most commonly diagnosed cancer in the US as well as the third most common cause of cancer-related death. Standard treatment includes surgical resection and adjuvant chemotherapy with multidrug regimens such as FOLFOX (Folinic Acid, 5-Fluorouracil, Oxaliplatin). However, due to high heterogeneity in colon tumors, patient response is variable and tools to predict drug response are few. Additionally, resistance, which can lead to recurrence and metastasis, is not uncommon. As such, there is a need for improved treatment options, better methods for predicting drug response, and better understanding of resistance mechanisms in CRC. Here, we introduce a host of new methodologies to phenotypically characterize CRC with the long term goals of better understanding chemotherapy resistance and creating actionable clinical tools that can model and predict individual tumors’ drug response. We have curated a set of colon tumor organoids, titled the Heterogeneity Library, that represents a variety of CRC subtypes. We used our newly designed phenotypic profiling pipeline, which leverages DAPI, pAKT, CD44v9, and H2AX, to characterize a FOLFOX-induced, PI3K/AKT-driven survival signature originally identified in our transcriptomic data. Unbiased subpopulation analysis confirms a cohort of cells with high PI3K/AKT signaling, high DNA damage, and high levels of stem cell markers across organoids. We believe that cells increasingly upregulate survival signaling, including extracellular matrix components and growth factor receptors, which all activate AKT, which in turn leads to a protective, resistant phenotype. Ultimately, we posit the observed FOLFOX dose-dependent increases in the fraction of these resistant cells across tumor types is a combination of adaptation down this proposed Resistance Trajectory in combination with a selection process whereby susceptible cells are readily eliminated, leaving the increasingly mesenchymal progenitor- and stem-like cells to expand despite FOX exposure.
Finally, we endeavored to target this resistant population by treating organoid monolayers with a combination of FOLFOX and Dactolisib, the PI3K/mTOR dual inhibitor, which exhibited significant synergy across organoids. Even the most FOLFOX-resistant organoid – made up almost entirely of the previously described highly damaged, AKT-driven, stem-like resistant cells – demonstrated increased FOLFOX efficacy when also treated with Dactolisib. We hope that with further validation, the novel contributions of this dissertation can be developed into actionable tools for use from bench to bedside