2020-

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https://hdl.handle.net/10217/182111

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Open Access
A local characterization of domino evacuation-shuffling
(Colorado State University. Libraries, 2024) McCann, Jacob, author; Gillespie, Maria, advisor; Peterson, Christopher, committee member; Huang, Dongzhou, committee member
We consider linear intersection problems in the Grassmanian (the space of k-dimensional subspaces of Cn), where the dimension of the intersection is 2. These spaces are called Schubert surfaces. We build of the previous work of Speyer [1] and Gillespie and Levinson [2]. Speyer showed there is a combinatorial interpretation for what happens to fibers of Schubert intersections above a "wall crossing", where marked points corresponding to the coordinates of partitions coincide. Building off Speyer's work, Levinson showed there is a combinatorial operation associated with the monodromy operator on Schubert curves, involving rectification, promotion, and shuffling of Littlewood-Richardson Young Tableaux, which overall is christened evacuation-shuffling. Gillespie and Levinson [2] further developed a localization of the evacuation-shuffling algorithm for Schubert curves. We fully develop a local description of the monodromy operator on certain classes of curves embedded inside Schubert surfaces [3].
Open Access
American Indian adolescent methamphetamine use: an examination of region/identity variations and the impact of protective factors
(Colorado State University. Libraries, 2024) Fredrickson, Gereon J., author; Prince, Mark, advisor; Emery, Noah, committee member; Swaim, Randall, committee member; Zimmerman, Toni, committee member
Objective: Studies suggest that American Indians (AI) have high rates of methamphetamine use and indicate that AI youth have a significantly higher prevalence of past year methamphetamine use relative to non-Hispanic Whites. Methamphetamine use has been associated with an increased risk of morbidity and many adverse long-term effects. Minimal research explores region and identity differences with methamphetamine use and primarily focuses on risk-factors that lead to higher levels of use. The proposed study sought to identify protective factors that increase abstinence and reduce patterns of use among adolescent AIs by exploring the impact of parental monitoring, positive social/peer support, positive self-esteem, ethnic pride, and ethnic experience on age of initiation and past-year methamphetamine use. Method: This study is a secondary data analysis of survey data collected form an epidemiological research study with AI youth. The current study uses data collected from the Fall of 2015 through the Fall of 2019. Participants included 14,769 adolescents, grades 7-12th, from 103 different schools, across seven distinct regions of the contiguous United States. Analysis Plan: Since lifetime methamphetamine use was reported in only 3.7% of the data, past-year use was dichotomized to account for varying modeling effects and model convergence. Means, frequencies, and standard deviations were calculated for all variables as well as bivariate correlations. To model the protective factors, Structural Equation Modeling (SEM) was used which included testing for model fit and psychometrics of the protective factor scales. An Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) were completed to determine fit of the items for each protective factor, with invariance testing at the configural, metric, and scalar levels. Firth's Penalized Likelihood logistic regression and censored regressions were used to examine direct effects between the five protective factors (parental monitoring, positive peer/social influence, self-esteem, ethnic pride, and ethnic experience) and two methamphetamine use outcome variables (i.e., age of initiation and past-year use). Results: Key findings in this study were that males in middle school that identified as AI-multi-ethnic living in the Northeast region and males in high school that identified as AI-multi-ethnic living in the Southern Great Plains region endorsed significantly more methamphetamine use in the past year with an earlier age of initiation. Additionally, parental knowledge, positive peer/social influence, and internal self-esteem increased the likelihood for AI adolescents to have not initiated methamphetamine use. Lastly, parental knowledge, positive peer/social influence, internal and external self-esteem, and ethnic experience factors were significant in increasing the likelihood that AI adolescents did not engage in methamphetamine use in the past year. Conclusions: This study provides powerful recommendations for programs that target AI adolescent methamphetamine use to further prevent initiation and build resilience. It demonstrates the need to foster parental knowledge, positive peer/social influence, self-esteem, and ethnic experience as protective factors. Understanding these factors within the AI community that contribute to positive outcomes for adolescents can help further programs, schools, and communities as prevention strategies implore techniques to maximize effectiveness in reducing overall AI adolescent substance use. Further, these results have implications for future research on prevention of AI adolescent methamphetamine use.
Open Access
The effects of personality and social determinants of health on sports-related concussion risk: an examination of symptom reporting, concussion incidence, and return to play
(Colorado State University. Libraries, 2024) Weishaar, Megan Gardner, author; Conner, Bradley T., advisor; Prince, Mark A., committee member; Davalos, Deana B., committee member; Stephens, Jaclyn A., committee member
Sports-related concussion (SRC), a form of mild traumatic brain injury (TBI) that occurs during sport participation or recreation, has emerged as a public health concern among adolescent athletes in the United States in recent decades due to increasing knowledge of high incidence rates. Important factors such as return to play (RTP) timeline and symptom reporting behaviors have been shown to contribute to SRC incidence. As a result, recent research has called for work that identifies a parsimonious group of variables that are salient in identifying athletes most at risk of outcomes such as early RTP, higher SRC incidence, and symptom nondisclosure. A small body of work has established that certain personality characteristics and social determinants of health are associated with these SRC outcomes. However, few specific personality and social determinants of health factors have been examined, few studies have investigated predictors of SRC incidence and RTP outcomes specifically, and a small number of these studies have investigated these research questions among adolescent athletes despite high rates of athletic participation and SRC incidence. The current study sought to expand previous work to further elucidate relations between a myriad of personality and social determinants of health predictors, and time to RTP, diagnosed SRC, and symptom reporting outcomes among adolescent athletes (N = 317, ages 14-19). The ultimate goal of the study was to identify personality and social determinants of health factors most salient in SRC outcomes to inform practical tailoring of prevention and intervention strategies. Participants were adolescents who were currently enrolled in high school or college or were enrolled in high school within the past calendar year, participated in a high school or club sport in the past year, and either denied sustaining a diagnosed SRC in the past year (N = 156) or endorsed sustaining a diagnosed SRC in the past year (N = 161). Data were collected through a one-time online survey that took participants 20-30 minutes to complete. Participants were compensated via an online gift card or course credit. Recruitment methods included outpatient medical clinics, high school athletic trainers, sports gyms and tournaments, Twitter, and university research pools. Analyses included a series of Cox proportional hazards and logistic regression models investigating associations between personality and social determinants of health predictors and time to RTP, diagnosed SRC incidence, and symptom reporting outcomes (i.e., honesty and comfort in symptom reporting). Overall, study results bolstered the conclusion that 1. Personality and social determinants of health factors are important in predicting SRC outcomes and 2. The relations between personality and SRC outcomes are highly nuanced, depending upon specific personality facets, outcome, and sample characteristics. Study results inform athletes, peers and family of athletes, coaches, athletic trainers, and other medical professionals about which personality and social determinants of health variables are most salient in SRC risk, thus informing prevention and intervention efforts for SRC such that they can be more personalized and tailored at the individual, environmental, and systems levels.
Open Access
Hearts and minds in the operating room: co-constructing a shared mental model with surgery teams for more predictable and more highly reliable collaborative voice and response
(Colorado State University. Libraries, 2024) Grieser, Skip, author; Gloeckner, Gene, advisor; Lynham, Susan, committee member; Gibbons, Alyssa, committee member; Martelli, Peter, committee member
Overview: This qualitative case study explored nontechnical human factors—values, beliefs, attitudes, and behaviors—that make it easier or more difficult for surgeons, as team leaders, to encourage team members to voice safety concerns, clinical opinions, and learning questions; for team members to actually speak up; and for surgeons to respond collaboratively. Research site and participants: The research site was a major academic hospital in the western United States. Five surgeons and five anesthesiologists volunteered to participate. Perioperative nurses and surgical technologists were recruited but did not participate. Purpose, methodology, and methods: The purpose of the study was to co-construct, with participants, a shared mental model for collaborative voice and response. The study followed the constructivist inquiry paradigm and methodology, which posits that individuals and groups construct, co-construct, and can reconstruct their social realities. Using adaptive work theory and methods, semi-structured interviews were used to gather data on what values, beliefs, attitudes, and behaviors participants perceived to be essential versus expendable for more collaborative, predictable, and highly reliable voice and response. Thematic content analysis identified six themes, from which a proposed shared mental model was constructed by the researcher. Member checking with participants confirmed that the themes were accurate and comprehensive; that the proposed shared mental model comprehensively reflected the themes; and that, used in practice, the shared mental model could help collaborative voice and response be more predictable and more highly reliable. Results: Themes were let's be best-in-class; respect and be kind to all; value patient safety and well-being of all team members; explicitly encourage and appreciate voice; do speak up; and am I really that approachable? The proposed shared mental model constructed from the themes was represented by the mnemonic REVAT, the first letters of each component: Respect and be kind to all, Encourage voice, Voice (do speak up), Appreciate voice, and Thrive (all of us). The study also identified two subthemes, hierarchical abuses of power and production pressures or time pressures that hinder collaborative voice and response; and should also be understood and well-managed, so that patient safety and clinician well-being are less at risk. Conclusion: Well-being is essential for clinicians' own sakes, for patient safety, and for clinical performance and outcomes. REVAT, the proposed shared mental model for collaborative voice and response, is simply stated as "respect, encourage, voice, appreciate, and thrive." As such, it is a "simple rule" much like "first do no harm," that could help caregivers better succeed in their goals and thrive.
Open Access
Integrating geometric deep learning with a set-based design approach for the exploration of graph-based engineering systems
(Colorado State University. Libraries, 2024) Sirico, Anthony, Jr., author; Herber, Daniel R., advisor; Chen, Haonan, committee member; Simske, Steven, committee member; Conrad, Steven, committee member
Many complex engineering systems can be represented in a topological form, such as graphs. This dissertation introduces a framework of Graph-Set-Based Design (GSBD) that integrates graph-based techniques with Geometric Deep Learning (GDL) within a Set-Based Design (SBD) approach to address graph-centric design problems. We also introduce Iterative Classification (IC), a method for narrowing down large datasets to a subset of more promising and feasible solutions. When we combine the two, we have IC-GSBD, a methodological framework where the primary goal is to effectively and efficiently seek the best-performing solutions with lower computational costs. IC-GSBD is a method that employs an iterative approach to efficiently narrow down a graph-based dataset containing diverse design solutions to identify the most useful options. This approach is particularly valuable as the dataset would be computationally expensive to process using other conventional methods. The implementation involves analyzing a small subset of the dataset to train a machine-learning model. This model is then utilized to predict the remaining dataset iteratively, progressively refining the top solutions with each iteration. In this work, we present two case studies demonstrating this method. In the first case study utilizing IC-GSBD, the goal is the analysis of analog electrical circuits, aiming to match a specific frequency response within a particular range. Previous studies generated 43,249 unique undirected graphs representing valid potential circuits through enumeration techniques. However, determining the sizing and performance of these circuits proved computationally expensive. By using a fraction of the circuit graphs and their performance as input data for a classification-focused GDL model, we can predict the performance of the remaining graphs with favorable accuracy. The results show that incorporating additional graph-based features enhances model performance, achieving a classification accuracy of 80% using only 10% of the graphs and further subdividing the graphs into targeted groups with medians significantly closer to the best and containing 88.2 of the top 100 best-performing graphs on average using 25% of the graphs.
Open Access
Muon neutrino reconstruction with machine-learning techniques at the ICARUS detector
(Colorado State University. Libraries, 2024) Mueller, Justin J., author; Mooney, Michael, advisor; Harton, John, committee member; Brandl, Alexander, committee member; Brewer, Samuel, committee member; Terao, Kazuhiro, committee member
The ICARUS T600 LArTPC detector successfully ran for three years at the underground LNGS laboratories, providing a first sensitive search for LSND-like anomalous electron neutrino appearance in the CNGS beam. After a significant overhauling at CERN, the T600 detector has been placed in its experimental hall at Fermilab, fully commissioned, and the first events observed with full detector readout. Regular data-taking began in May 2021 with neutrinos from the Booster Neutrino Beam (BNB) and neutrinos six degrees off-axis from the Neutrinos at the Main Injector (NuMI). Modern developments in machine learning have allowed for the development of an end-to-end machine-learning-based event reconstruction for ICARUS data. This reconstruction folds in 3D voxel-level feature extraction using sparse convolutional neural networks and particle clustering using graph neural networks to produce outputs suitable for physics analyses. The analysis presented in this thesis demonstrates a high-purity and high-efficiency selection of muon neutrino interactions in the BNB suitable for the physics goals of the ICARUS experiment and the Short-Baseline Neutrino Program.
Open Access
The foreign policy ambitions of the European Union: a relational theoretical approach
(Colorado State University. Libraries, 2024) Marinova, Iren, author; Harris, Peter, advisor; Stevis, Dimitris, committee member; Weitzel, Daniel, committee member; Johnson, Merrill, committee member
What drives the European Union (EU) to develop leadership ambitions in some issue domains, such as climate change governance, but not in others? In this dissertation, I approach this question by focusing on the relational dynamics that constitute the EU. By situating my dissertation in the ontological premises of relationalism in International Relations as part of the "relational turn" in the discipline, I develop a theoretical approach and framework to capture and study the historical relational dynamics of power that make up the EU and exert driving effects for the foreign policy ambitions it sets for itself on the global stage. To demonstrate the value and applicability of my theoretical framework, I employ the case of the EU's leadership ambitions in the domain of global climate change governance. I identify two categories of relations that, separately and jointly, exert determining influence for its ambitions in this domain: 1) relations in the transatlantic space between the United States and the European project that developed during and since the inception of the latter; and 2) relations between the EU member states on the East-West axis that have long historical roots on the continent. The temporal range of the study encompasses the period from 1990 to 2015. I analyze the theorized relational dynamics and my argument in two empirical chapters that focus on each one of the relational categories separately and on subsequent parts of the temporal range. In the analysis of the first category, I employ qualitative counterfactual analysis to trace the transatlantic leadership transition between the United States and the EU that began in the 1990s and culminated with the American announcement of withdrawal from the Kyoto Protocol in 2001. Complemented by three shadow cases that represent different temporal and issue-domain foci, the counterfactual analysis reveals that the EU would not have been likely to develop and pursue its leadership ambitions in the same manner that it did had the United States not withdrawn from the Kyoto Protocol. The analysis of the second category shifts the focus to the internal EU policy environment and the EU's foreign policy-making process by exploring the existence and extent of the theorized historical relational power dynamics among Eastern and Western EU member states in the expression of their national positions during the public deliberations in the Environment Council configuration of the Council of the EU through qualitative content analysis. The period at focus here is 2014-2015 for the purposes of capturing the dynamics prior to the Paris Agreement in 2015 and following the accession of all Central and Eastern European member states. Their positions are compared to the level of EU ambition expressed in the proposals under discussion at the given Council deliberation. The findings in this empirical chapter suggest that there is a clear alignment of Western interests with the ambitions of the EU, while the interests of Eastern member states are more rarely matched in the proposals, especially in the initial drafts, indicating that existing relational asymmetries along the East-West axis are present in and exert an effect on the EU's ambition-setting and climate foreign policy-making processes. This dissertation makes an important contribution to the study of the EU and its ambitions as an actor on the global stage and to the growing literature of relational approaches in the discipline of International Relations.
Embargo
Changes in shortwave solar radiation under local and transported wildfire smoke plumes: implications for agriculture, solar energy, and air quality applications
(Colorado State University. Libraries, 2024) Corwin, Kimberley A., author; Fischer, Emily, advisor; Pierce, Jeffrey, committee member; Chiu, Christine, committee member; Corr-Limoges, Chelsea, committee member; Burkhardt, Jesse, committee member
The emission and transport of pollutants from wildfires is well-documented, particularly at the surface. However, smoke throughout the atmospheric column affects incoming shortwave solar radiation with potentially wide-ranging consequences. By absorbing and scattering light, smoke changes the amount and characteristics of shortwave radiation–a resource that controls plant photosynthesis, solar energy generation, and atmospheric photochemical reactions. In turn, these influence ecological systems as well as air quality and human health. This dissertation examines how wildfire smoke alters boundary layer and surface-level shortwave radiation in ways that are relevant for agricultural, energy, and air quality applications. First, I present an analysis of smoke frequency and smoke-driven changes in the total and diffuse fraction (DF) of photosynthetically active radiation (PAR; 400-700 nm) at the surface. I compare PAR and PAR DF on smoke-impacted and smoke-free days during the agricultural growing season from 2006 to 2020 using data from 10 ground-based radiation monitors and satellite-derived smoke plume locations. I show that, on average, 20% of growing season days are smoke-impacted and that smoke prevalence has increased over time (r = 0.60, p < 0.05). Smoke frequency peaks in the mid to late growing season (i.e., July, August), particularly over the northern Rocky Mountains, Great Plains, and Midwest. I find an increase in the distribution of PAR DF on smoke-impacted days, with larger increases at lower cloud fractions. On clear-sky days, daily average PAR DF increases by 10 percentage points when smoke is present. Spectral analysis of clear-sky days shows smoke increases DF (average: +45%) and decreases total irradiance (average: −6%) across six wavelengths measured from 368 to 870 nm. Optical depth measurements from ground and satellite observations both indicate that spectral DF increases and total spectral irradiance decreases with increasing smoke plume optical depth. My analysis provides a foundation for understanding smoke's impact on PAR, which carries implications for agricultural crop productivity under a changing climate. Second, I examine smoke's impact on two key measures used to assess a location's baseline solar resource availability for solar energy production: direct normal (DNI) and global horizontal (GHI) irradiance. I quantify smoke-driven changes in DNI and GHI at different spatial and temporal scales across the contiguous U.S. (CONUS) using radiative transfer model output and satellite-based smoke, aerosol, and cloud observations. Importantly, I expand the scale of previous studies on smoke and solar energy by including areas primarily affected by dilute, aged, transported smoke plumes in addition to areas with dense, fresh, local smoke plumes. I show that DNI and GHI decrease as smoke frequency increases at the state, regional, and national scale. DNI is more sensitive to smoke with sizable losses persisting downwind of fires. Although large reductions in GHI are possible close to fires, mean GHI declines minimally (< 5%) due to transported smoke. Overall, GHI–the main resource used for photovoltaic energy production–remains a relatively stable resource across most of CONUS even in extreme fire seasons, which is promising given U.S. solar energy goals. Third, I investigate smoke-driven changes in surface-level and boundary layer downwelling actinic flux (F↓)–a crucial component of determining the rate of photooxidation in the atmosphere. I present a case study of changes in F↓ at 550 nm (process validation) and 380 nm (NO2 photolysis) along a research flight through the California Central Valley during the 2018 Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN) aircraft campaign. F↓ was measured onboard via the HIAPER Airborne Radiation Package (HARP), and I use the National Center for Atmospheric Research (NCAR) Tropospheric Ultraviolet and Visible (TUV) Radiation Model to compute F↓ under smoke-free and smoke-impacted conditions. Modeling F↓ with TUV facilitates calculating the change in F↓ and provides a means of assessing F↓ at altitudes not sampled by the aircraft, such as the ground. I find that the smoke-impacted F↓ from TUV aligns closely with HARP observations: all modeled fluxes are within 20% of measurements at 550 nm and 85% are within 20% of measurements at 380 nm. The average modeled-to-measured ratios (F ↓550=0.96; F ↓380=0.89) indicate that TUV minorly underestimates the observed F↓. On average, observed F↓380 decreased 26%, 17%, and 9% at 0-0.5 km, 0.5-1 km, and 1-1.5 km, respectively, while TUV estimates larger reductions of 41%, 26%, and 19% at the same altitudes. At the ground-level, I calculate a 47% decrease in F↓380 using TUV, which is likely an upper bound given the model slightly underestimates observations. As wildfire smoke increases with climate change, understanding how smoke aloft changes photochemistry is increasingly important for constraining future air quality.
Open Access
Essays on local economic development and social capital
(Colorado State University. Libraries, 2024) Poerbonegoro, Anna Farina, author; Weiler, Stephan, advisor; Alves Pena, Anita, advisor; Zahran, Sammy, committee member; Suter, Jordan, committee member
Creative Sector activities and social capital are interconnected in the same spectrum of local economic development, even though is not always immediately apparent. The two are related in that social capital is a product of, and simultaneously a determinant for, the Creative Sector. The three essays in this dissertation address each component separately. The first two essays examine the Creative Sector, and the third focuses on social capital. Motivated by the increasing role of the role of Creative Sector as growth driver and the economic base approach, in Chapter 1 titled Role of Creative Initiatives in Economic Performance: Case Study on Colorado's Creative Districts and Main Street Communities I examine the influence of Colorado's place-based initiative / policy on economic performance. Two dependent variables are chosen to represent performance, namely Business Establishments and Net Job Creation. In addition, sectoral employment (the Creative Sector and NAICS sector 71 (Arts, Entertainment and Recreation) and employment in sectors outside of the two) are examined as a supplement; for the placed-based policy, Creative District Certification program and the Main Street Communities program are selected, along with a set of control variables and a set of interaction terms that signify co-existence of the two policies in any particular county. The data used in estimation is a panel dataset for Colorado's 64 counties in a ten-year period (2010 – 2019). Results indicate that both place-based initiatives affect business establishments but not their birth rates, but each influence is opposite direction; co-location of the two is also playing a role, which is positive in Urban areas but negative in Rural areas. Job creation is positively influenced by the MS Communities program in the Rural region but not by Creative District certification program. Creative Sector employment is slightly negatively influenced by the initiatives; in contrast, they do not influence employment in either Sector 71 or Other Sectors. The results suggest that the two initiatives are beneficial, but each for different types of counties. Chapter 2, titled Sectoral Employment Spillover in Colorado, focuses on spatial spillover effects of employment in two leading industrial sectors – namely the Arts, Recreation and Entertainment (NAICS 71 or Sector 71) and the Creative Sectors – on employment in Other Sectors in Colorado, based on the Economic Base Theory. The analysis is performed using county-level Quarterly Census of Employment and Wages (QCEW) data. The study aims at answering the question of whether sectoral employment in one county affects that in a neighboring county (in other words, whether spatial correlation exists). Moreover, the analysis also examines how sectoral employment (Creative Sector and Sector 71) in one county influences employment in sectors outside the two, in different counties; this is the employment spillover question. Two variations of model specifications are tested, examined spatially and non-spatially, using lagged variables in one model and lagged log variables in another. The result suggests that overall, the two sectoral employments do influence Other Employment, but the spatial spillover is not detected. More specifically, the Creative Sector is negatively associated with the next period's employment in Other Sectors in both models. However, the significance of Sector 71 employment's relationship with employment in Other Sectors depends on how it is modeled. Social Capital is discussed in Chapter 3, County Level Social Capital in Colorado. While social capital is acknowledged as being a fuzzy concept, it embeds both demand and supply side within itself. While the demand side typically addresses how social capital affects other dimensions in economics, Chapter 3 here focuses on the supply side, by inquiring how social capital at county level in Colorado is affected by various socio-economic aspects. The discussion covers various standpoints of social capital contexts and definitions that are indicative of the fuzziness of the concept itself. Empirically, I employ a quantitative measure of social capital in the form of an index portraying civic participation (developed by Rupasingha et al. (2006)). A short panel regression was performed using a series of explanatory variables (physical infrastructure, poverty, unemployment, personal and regional incomes, education, and an economic recession). The results indicate that poverty and economic shock have the tendency to reduce social capital in Colorado in the form of civic engagement particularly in Urban regions, while larger pool of the unemployed in the society indicates a positive relationship with civic participation. Physical infrastructure, proxied by new housing permits, is negatively associated with civic participation in all three regions.
Open Access
Model-based systems engineering application to data management for integrated sustainable human settlement modeling
(Colorado State University. Libraries, 2024) Adjahossou, Anicet, author; Grigg, Neil, advisor; Bradley, Thomas, committee member; Conrad, Steven, committee member; Willson, Bryan, committee member; Fremstad, Anders, committee member
The challenges associated with the transition from current approaches to temporary humanitarian settlement to integrated, sustainable human settlements is largely due to a significant increase in the number of forcibly displaced people over the last few decades, the difficulties of sustainably providing the needed services to the required standards, and the prolongation of emergencies. According to the United Nations High Commissioner for Refugees (UNHCR)'s Global Appeal 2023, more than 117.2 million people were forcibly displaced or stateless in 2023, representing a little over 1% of the world's population. The average lifespan of a humanitarian settlement is between 17 and 26 years (UNHCR), and factors such as urban growth and adverse environmental changes have exacerbated the scale of the difficulties. Despite these problematical contexts, short-term considerations continue to guide the planning and management of humanitarian settlements, to the detriment of more integrated, longer-term perspectives. These factors call for a paradigm shift in approach to ensure greater sustainability right from the planning phases. Recent studies often attribute the unsustainability of humanitarian settlements to poor design and inadequate provision of basic resources and services, including water, energy, housing, employment and economic opportunities, among others. They also highlight apparent bottlenecks that hinder access to meaningful and timely data and information that stakeholders need for planning and remediation. More often than not, humanitarian operations rely on ad hoc methods, employing parallel, fragmented and disconnected data processing frameworks, resulting in the collection of a wide range of data without subsequent analysis or prioritization to optimize potential interconnections that can improve sustainability and performance. Furthermore, little effort has been made to investigate the trade-offs involved. As a result, major shortcomings emerged along the way, leading to disruption, budget overruns, disorder and more, against a backdrop of steadily declining funding for humanitarian aid. However, some attempts have been made to move towards more sustainable design approaches, but these have mainly focused on vague, sector-specific themes, ignoring systemic and integrative principles. This research is a contribution to filling these gaps by developing more practical and effective solutions, based on an integrated systemic vision of a human settlement, defined and conceptualized as a complex system. As part of this process, this research proposes a model-driven methodology, supported by Model-Based Systems Engineering (MBSE) and a Systems Modeling Language (SysML), to develop an integrated human settlement system model, which has been functionally and operationally executed using Systems Engineering (SE) approach. This novel system model enables all essential sub-systems to operate within the single system, and focuses on efficient data processing. The ultimate aim is to provide a global solution to the interconnection and integration challenges encountered in the processing of operational data and information, to ensure an effective transition to sustainable human settlements. With regard to the interconnectedness between the different sectors of the sub-systems, this research proposes a Triple Nexus Framework (TNF) in an attempt to integrate water, energy and housing sector data derived from one sub-system within the single system by applying systems engineering methods. Systems engineering, based on an understanding of the synergies between water, energy and housing, characterizes the triple nexus framework and identifies opportunities to improve decision-making steps and processes that integrate and enhance quality of data processing. To test and validate the performance of the system model, two scenarios are executed to illustrate how an integrated data platform enables easy access to meaningful data as a starting point for modeling an integrated system of sustainable human settlement in humanitarian contexts. With regard to framework performance, the model is simulated using a megadata nexus, as specified by the system requirement. The optimization simulation yields 67% satisfactory results which is further confirmed from a set of surveyed practitioners. These results show that an integrated system can improve the sustainability of human settlements beyond a sufficiently acceptable threshold, and that capacity building in service delivery is beneficial and necessary. The focus on comprehensive data processing through systems integration can be a powerful tool for overcoming gaps and challenges in humanitarian operations. Structured interviews with question analysis are conducted to validate the proposed model and framework. The results prove a consensus that the novel system model advances the state of the art in the current approach to the design and management of human settlements. An operational roadmap with substantial programmatic and technical activities required to implement the triple nexus framework is recommended for adoption and scaling-up. Finally, to assess the sustainability, adaptability and applicability of the system, the proposed system model is further validated using a context-based case study, through a capacity assessment of an existing humanitarian settlement. The sustainability analysis uses cross-impact matrix multiplication applied to classification (MICMAC) methodologies, and results show that the development of the settlement are unstable and therefore unsustainable, since there is no apparent difference between influential and dependent data. This research tackles an important global challenge, providing valuable insights towards sustainable solutions for displaced populations, aligning with the United Nations 2030 Agenda for Sustainable Development.
Open Access
Characterizing and improving the adoption rate of model-based systems engineering through an application of the Diffusion of Innovations theory
(Colorado State University. Libraries, 2024) Call, Daniel R., author; Herber, Daniel R., advisor; Aloise-Young, Patricia, committee member; Conrad, Steven, committee member; Shahroudi, Kamran Eftekhari, committee member
As the environment and operational context of new systems continue to evolve and become increasingly complex, the practice of systems engineering (SE) must adapt accordingly. A great deal of research and development has gone and continues to go into formulating and maturing a model-based approach to SE that addresses many of the shortcomings of a conventional, document-based SE approach. In spite of the work that has been done to advance the practice of model-based systems engineering (MBSE), it has not yet been adopted to a level that would be expected based on its demonstrated benefits. While research continues into even more effective MBSE approaches, there is a need to ascertain why extant MBSE innovations are not being adopted more widely, and if possible, determine a way to accelerate its adoption. This outcome is particularly important as MBSE is a key enabler to an agile systems engineering (ASE) approach that satisfies the desire of many stakeholders to apply agile principles to SE processes. The diffusion of innovations (DoI) theory provides a useful framework for understanding the factors that affect the adoption rate of innovations in many fields. This theory has not only been effective at explaining why innovations are adopted but has also been able to explain why objectively superior innovations are not adopted. The DoI theory is likely to provide insight into the factors that are depressing the adoption rate of MBSE. Despite prior efforts in the SE community to promote MBSE, the DoI theory has not been directly and deliberately applied to understand what is preventing widespread MBSE adoption. Some elements of the theory appear in the literature addressing MBSE adoption challenges without any recognition of awareness of the theory and its implications. The expectation is that harnessing the insights offered by this theory will lead to MBSE presentation and implementation strategies that will increase its use. This would allow its benefits to be more widely realized in the SE community and improve the practice of SE generally to address modern, complex environments. The DoI theory has shown that the most significant driver of adoption rate variability is the perceived attributes of the innovation in question. A survey is a useful tool to discover the perceptions of potential adopters of an innovation. The primary contribution of this research is the development of a survey to capture and assess a participant's perceptions of specified attributes of MBSE, their current use of MBSE, and some limited demographic information. This survey was widely distributed to gather data on current perceptions of MBSE in the SE community. Survey results highlighted that respondents recognize the relative advantage of MBSE in improving data quality and traceability, but perceived complexity and compatibility with existing practices still present barriers to adoption. Subpopulation analysis reveals that those who are not already involved in MBSE efforts face the additional adoption obstacles of limited trial opportunities and tool access (chi-squared test of independence between these populations resulted in p = 0.00). The survey underscores the potential for closer alignment between MBSE and existing SE methodologies to improve the perceived compatibility of MBSE. Targeted actions are proposed to address these barriers to adoption. These targeted actions include improving the availability and use of reusable model elements to expedite system model development, improved tailoring of MBSE approaches to better suit organizational needs, an increased emphasis on ASE, refining MBSE approaches to reduce the perceived mental effort required, a lowering of the barrier to entry for MBSE by improving access to the resources (tool, time, and training) required to experiment with MBSE, and increased efforts to identify and execute relevant MBSE pilot projects. The lessons and principles from the DoI theory should be applied to take advantage of the opportunity afforded by the release of SysML v2 to reframe perceptions of MBSE. Future studies would benefit from examining additional variables identified by the DoI theory, incorporating control questions to differentiate between perceptions of SE generally and MBSE specifically, identifying better methods to assess current MBSE use by participants, and measures to broaden the participant scope.
Open Access
Management and benchmarking strategies to improve financial health status of U.S. beef operators
(Colorado State University. Libraries, 2024) Krehbiel, Bethany Cornwell, author; Rhoades, Ryan D., advisor; Ahola, Jason K., advisor; Blackburn, Harvey D., committee member; Mooney, Daniel, committee member
The objective of this dissertation was to obtain, analyze, and summarize historical Standardized Performance Analysis (SPA) benchmark information and subsequently determine significant Key Performance Indicators (KPI) influencing beef producer's Unit Cost of Production (UCOP). Using the KPI's, a Ranch Health Index (RHI) was developed to assist producers in simply analyzing their financial health while analyzing beef production and financial relationships. Lastly, producer information using the significant KPI's incorporated into the RHI was analyzed for sensitivity to explore potential leverage points to enhance overall financial health. The SPA Beef cattle production performance and financial data was obtained from the SPA program conducted by Texas A&M AgriLife Extension which has records from three states: Oklahoma, Texas, and New Mexico. The dataset contained 25 years of beef financial and production metrics from 1992 – 2016. Three models (linear regression, random forest, and step-wise) were used to assess the SPA data for KPI. Upon further analyses, six variables were considered most impactful to predict Unit Cost of Production: Financial Grazing per CWT, Financial Raised/Purchased Feed per CWT, Livestock Cost Basis per CWT, Weaning Pay Weight per CWT, Pounds Weaned, and Number of Adjusted Exposed Females. The RHI was developed from the six variables using a Random Forest machine learning model and their corresponding importance factors as weights in the model. The model selected was tested and showed concordance with all the SPA variables predicting UCOP. Therefore, the RHI results showed utility in usefulness to assess financial health. Subsequently, three producers with 5 consecutive years of data were tested for sensitivity at ± 5% and ± 10% from the original value to determine sensitivity of each KPI variable. Finally, the models were investigated for maximum and minimum RHI values. Results showed changes in RHI up to $13,000 when accounting for all KPI improvements at 10% sensitivity. In conclusion, knowledge of the SPA data and ultimately the RHI provides information to cattle producers on what may be the most indicative variables for enhanced profits. In addition, this research has provided a simple and effective way for producers to analyze their beef operation.
Open Access
Three essays on gender inequality in Latin America: understanding labor market segregation, job quality, and environmental issues from a feminist perspective
(Colorado State University. Libraries, 2024) Machado Nunes, Débora, author; Braunstein, Elissa, advisor; Tavani, Daniele, advisor; Chatterjee, Sushmita, committee member; Barber, Edward B., committee member
For the past three decades, Latin America experienced remarkable progress in educational attainment and health care access for women, combined with decreasing household income inequality and higher wages across the board since 2002, especially at the bottom of the wage distribution for most countries. Yet, gender job segregation in the labor market has increased since the early 1990s. Urban women persistently occupy jobs in the informal sector, where jobs are generally characterized by low wages, lack of benefits, poor working conditions, and no promotion possibilities. Concerning both urban and rural women is Latin America's unique vulnerability to the impacts of climate change and the lack of progress in preventing deforestation, which disproportionally impacts impoverished communities, especially women and children. Despite some progress on reproductive rights in several countries, persistent economic challenges and constraints present serious barriers to the advancement of gender equality and reproductive justice—understood as the right to prevent and terminate undesired pregnancies, carry desired pregnancies, and raise a healthy and happy child to the best of one's ability. Based on the premise that such a complex scenario can only be understood through feminist research methodologies, this dissertation proposes three independent yet connected essays. Each essay focuses on a different research question that helps us better understand the gendered impacts of economic policies in Latin America, how women with different intersectional identities are impacted by them, and how to build useful scholarship for policy makers and activists to advance gender equality and reproductive justice in the region. The first essay focuses on the connections between gender job segregation, income distribution, and real exchange rates in Latin America. For the second essay, we propose a theoretical discussion, focusing on building reproductive justice as a research program within economics. Finally, the third essay focuses on rural women, exploring the relationship between deforestation and hours unpaid care work in the Amazonia rainforest.
Open Access
Investigating the salinity impacts on current and future water use and crop production in a semi-arid agricultural watershed
(Colorado State University. Libraries, 2024) Hosseini Ghasemabadian, Pardis, author; Bailey, Ryan T., advisor; Arabi, Mazdak, committee member; Smith, Ryan, committee member; Andales, Allan, committee member
Soil salinity can have a significant impact on agricultural productivity and crop yield, particularly in arid and semi-arid irrigated watersheds wherein irrigation and inadequate drainage often combine to increase salt ion concentrations in soil water. In conjunction with intense irrigation in semi-arid agricultural regions, increasing population resulting in boosted water demand, adverse impacts of climate change on water availability, in other words, water scarcity, future land use and land cover changes, changes in applied irrigation practices, and introducing new point-sources and non-point sources of salinity in the region all can govern the salinity and crop yield consequently. Taking into account the aforementioned impactful components on crop reduction via salinity increase, the overall objective of this dissertation is to provide insights for policymakers to better address the current and future salinity issues to sustain crop production in semi-arid regions under progressive salinity. This will be accomplished by i) investigating the controlling factors on salinity in the soil, groundwater, and river water using the SWAT-Salt model which simulates the reactive transport of 8 major salt ions in major hydrological pathways applied to a 1118 km2 irrigated stream-aquifer system located within the Lower Arkansas River Valley (LARV) in southeastern Colorado, USA ii) Assessing the salinity impacts on crops production blue and green water footprint as a measurable indicator for water being used per unit of a given crop production using the SWAT-MODFLOW-Salt model applied to a 732 km2 irrigated stream-aquifer system located in the LARV, iii) quantify the impact of environmental factors alteration including changes in climatic and irrigation practices in the LARV on future salinity content and its impact on crop production in the region using the SWAT-MODFLOW-Salt model. To control salinity, more importantly in semi-arid irrigated areas, the principal step is to identify the key environmental and hydrologic factors that govern the fate and transport of salts in these irrigated regions. To accomplish this objective, global sensitivity analysis was applied to the newly developed SWAT-Salt model (Bailey et al., 2019), which simulates the reactive transport of 8 major salt ions (SO4, Ca, Mg, Na, K, Cl, CO3, and HCO3) in major hydrologic pathways in a watershed system. The model was applied to a saline 1118 km2 irrigated stream-aquifer system located within the Lower Arkansas River Valley in southeastern Colorado, USA. Multiple parameters including plant growth factors, stream channel factors, evaporation factors, surface runoff factors, and the initial mass concentrations of salt minerals MgSO4, MgCO3, CaSO4, CaCO3, and NaCl in the soils and in the aquifer were investigated for control on salinity in groundwater, soils, and streams. The Morris screening method was used to identify the most sensitive factors, followed by the Sobol' variance-based method to provide a final ranking and to identify interactions between factors. Results showed that salt ion concentration in soils and groundwater was controlled principally by hydrologic factors (evaporation, groundwater discharge and up flux, and surface runoff factors) as well as the initial amounts of salt minerals in soils. Salt concentration in the Arkansas River was governed by similar factors, likely due to salt ion mass in the streams controlled by surface runoff and groundwater discharge from the aquifer. Sustainable agriculture in intensively irrigated watersheds, especially those in arid and semi-arid regions, requires improved management practices to sustain crop production. This depends on factors such as climate, water resources, soil conditions, irrigation methods, and crop types. Of these factors, soil salinity and climate change are significant challenges to agricultural productivity. To investigate the long-term impact of salinity and climate change on crop production from 1999 to 2100 in irrigated semi-arid regions, we applied the water footprint (WF) concept using the hydro-chemical watershed model SWAT-MODFLOW-Salt, driven by five General Circulation Models (GCMs) and two climate scenarios (RCP4.5 and RCP8.5), to a 732 km2 irrigated stream-aquifer system within the Lower Arkansas River Valley (LARV), Colorado, USA. In this study we estimated the green (WFgreen), blue (WFblue), and total (WFtotal) crop production WFs for 29 crops in the region, both with and without considering the impact of salinity on crop yield. The results indicate that during the baseline period (1999-2009), the total annual average WFgreen, WFblue, and WFtotal increased by 7.6%, 4.4%, and 6.5%, respectively, under salinity stress, with crop yields decreasing by up to 4.6%, 1.6%, and 2.3% for green, blue, and total crop yield. The combined impact of salinity and the worst-case climate model (IPSL_CM5A_MR) under the higher emission scenario (RCP8.5) resulted in increases of 3.3%, 1.9%, and 3% in green, blue, and total crop production WFs. Additionally, the study found that the proportion of green, blue, and total crop production WFs in the LARV exceeded the world average. This discrepancy was attributed to various factors, including different spatial and temporal crop distribution, irrigation practices, soil types, and climate conditions. Notably, salinity stress had a more significant impact on green crop yield and green WF compared to blue crop yield and blue WF across all GCM models. This finding highlights the need to prioritize management practices that address salinity-associated challenges in the region. The adverse effects of salinity on soil health, crop yield, and environmental ecosystem require comprehensive strategies for managing salinity in agricultural watersheds by adopting improved irrigation practices and effective salinity management strategies for mitigating these impacts and sustaining agricultural productivity in salinity-affected regions. The complex dynamics between various irrigation practices and soil salinity play a pivotal role in shaping agricultural productions and managing soil salinity. In semi-arid regions like the LARV, salinity poses a significant threat to agriculture, exacerbated by climate change and historic irrigation practices. To evaluate the interplay between salinity, climate change, and irrigation management in affecting crop yields within the Lower Arkansas River Valley (LARV), focusing on corn and alfalfa, we utilized the SWAT-MODFLOW-Salt model to examine how changes in irrigation management influence crop production under various scenarios projected through the year 2100. This study addresses the differential responses of corn and alfalfa to the impact of incremental increases and reductions in irrigation efficiency and irrigation water loss (5%, 10%, 15%, and 20%) on corn and alfalfa yields dynamics under salinity stress, utilizing projections from five global climate models under two distinct Representative Concentration Pathway (RCP) scenarios, RCP4.5 and RCP8.5 and two irrigation scenarios. The findings from irrigation practice scenario (1), maintaining a constant amount of irrigation water, revealed that corn yields improved by up to 13.8% under salinity stress and 16.5% under non-salinity conditions with a 20% increase in irrigation efficiency and a 20% reduction in water loss under RCP4.5. Alfalfa, demonstrating greater salinity tolerance, showed similar benefits, with yield increases of 9.1% under salinity stress and even higher improvements under non-salinity conditions. These results highlight the effectiveness of tailored irrigation practices in mitigating environmental stresses. In contrast, scenario (2), which involved reducing irrigation water by half, resulted in more pronounced negative outcomes. Corn yields exhibited greater sensitivity to salinity stress, with yield reductions ranging from -9.8% under salinity stress to -9.3% under non-salinity conditions, particularly under the RCP8.5 scenario. Alfalfa yields also declined, though less severely than corn, with reductions ranging from -8.9% under salinity stress to -8.3% under non-salinity conditions. Despite improvements in irrigation efficiency and reduced water loss, the adverse effects of salinity stress were not fully mitigated in scenario (2), emphasizing the need for adequate water availability to sustain crop yields under salinity and climate change pressures. The research highlights the importance of adopting advanced irrigation technologies and practices that not only counteract the adverse effects of salinity but also adapt to evolving climatic conditions. This study offers valuable insights for policymakers and agricultural managers on strategic water resource management to sustain crop yields in salinity-affected and water-limited agricultural systems. The results of this study can be used in decision-making regarding the most impactful land and water management strategies for controlling salinity transport and build-up in soils, both for this watershed and other similar semi-arid salinity-impacted watersheds for present and future purposes.
Embargo
Assessment and intervention strategies for agricultural inhalation exposures in occupational and community environments
(Colorado State University. Libraries, 2024) Erlandson, Grant, author; Schaeffer, Joshua, advisor; Magzamen, Sheryl, committee member; Abdo, Zaid, committee member; Martenies, Sheena, committee member
Agriculture represents an industry vital to the U.S. economy, supplying the public with nutritious food and providing millions of workers with employment. Also characterized as one of the most hazardous industries for workers, agricultural environments contain a variety of inhalation hazards capable of impacting the health of workers and adjacent community residents. Agricultural inhalation hazards include airborne organic and inorganic dusts; livestock associated gases, pesticides, bacteria, viruses, and antibiotics. This study will focus on (1) bioaerosol exposures in dairy operations and (2) inorganic dust pesticide exposures from agricultural applications. In dairy environments, workers are regularly exposed to high levels of organic dust (bioaerosols) and their inflammatory constituents (e.g., endotoxin, muramic acid, and β-glucans). Dairy bioaerosol exposure is associated with increased prevalence of respiratory disease (e.g., asthma, rhinitis, and chronic obstructive pulmonary disease) in dairy workers. While bioaerosol exposure in dairy environments has been well characterized in previous research, efforts to identify hygienic interventions that control exposure remain unsuccessful. In crop production agriculture, it is well documented that workers are exposed to high levels of pesticides associated with adverse health outcomes (e.g., respiratory and neurologic diseases). Further, in agricultural adjacent community environments, where lower chronic pesticide exposures are found, there is mounting evidence linking adverse health effects (e.g., adult and iii childhood cancers, neurologic and respiratory diseases, and birth outcomes) in residents to exposure from agricultural pesticide applications. However, weak and sometimes inconsistent associations previously reported highlight the limitations of current community exposure assessment techniques used for pesticides. For specific Aim 1, we pilot tested a novel low-cost nasal rinse intervention to modulate airway inflammation in ten bioaerosol exposed dairy workers. Dairy workers were randomly split into treatment (n = 5) and control (n = 5) groups and administered saline nasal rinses before and after their shift for five consecutive days. Treatment group participants received pre-shift hypertonic saline rinses while the control group received normotonic saline rinses. Both received normotonic rinses post-shift. Pro and anti-inflammatory cytokines were measured from recovered saline rinses. Linear mixed model results indicated treatment group participants experienced significantly higher concentrations of anti- (IL-10) and pro-inflammatory cytokines (IL-6 and IL-8) than the control group (p < 0.02, p <0.04, and p < 0.01 respectively). This study demonstrates the capacity of hypertonic saline nasal rinses to successfully upregulate anti-inflammatory cytokine production. However, conflicting upregulation of pro-inflammatory markers cloud interpretations of efficacy. For Aim 2, we further evaluated the immunomodulatory effects of hypertonic saline rinses vs. normotonic saline rinses longitudinally (2-5 shifts) in 45 bioaerosol exposed dairy workers. However, in this aim, treatment group participants received hypertonic rinses pre- and post-shift and 16S sequencing was added to analyses to capture potential washout effects on microbial diversity. No significant differences were observed between group or day for any of the measured markers or microbiome diversity metrics. Yet, non-significant increases in anti-inflammatory IL-10 concentrations across the study period were observed independent of iv treatment group suggesting the rinse itself may be more impactful than tonicity. This study provided mixed but encouraging results that justify further research on nasal rinses as an intervention in bioaerosol exposed dairy workers. For Aim 3, we evaluated the agreement between three exposure assessment techniques used to estimate residential organophosphate (OP) exposure in agricultural adjacent communities located in the Central Valley of California. OP exposure was estimated from household dust samples, California Pesticide Use Report (CPUR) pesticide use modeling, and urinary DAP metabolites across two sampling campaigns. Simple correlation tests revealed moderate correlations (ρs = 0.46) between household dust and use model exposure estimates. Estimates from urinary DAP metabolites exhibited low to no correlation with the other two estimates. Linear mixed model results also indicated no association between urinary DAP metabolites and household dust or use model estimates. This study illustrates a lack of agreement between community pesticide exposure assessment techniques regularly used in research and motivates the development of more robust assessment techniques.
Embargo
Investigating the association between public health system structure and system effectiveness
(Colorado State University. Libraries, 2024) Orr, Jason, author; Golicic, Susan, advisor; Bradley, Thomas, committee member; Miller, Erika, committee member; Gutilla, Molly, committee member; Magzamen, Sheryl, committee member
Public health systems in the United States face significant challenges due to their complexity and variability. This dissertation follows a three-paper format and examines these systems through a comprehensive analysis, using systems approaches, latent transition analysis (LTA), and ordinal regression to uncover patterns and inform improvements in public health governance and service delivery. The first essay (Chapter 2) explores the application of systems approaches to the design and improvement of public health systems. A scoping review was conducted, revealing a paucity of literature on the use of "hard" systems methodologies like systems analysis and engineering in public health. The findings highlight the potential for systems approaches to enhance the efficiency, effectiveness, and equity of public health services. However, the limited engagement by public health practitioners and the lack of depth in existing literature indicate significant gaps that need to be addressed to fully leverage systems science in public health governance and service delivery. Building on the literature review, the second essay (Chapter 3) introduces a novel typology of local health departments (LHDs) using LTA based on the National Association of County and City Health Officials (NACCHO) Profile study data. The LTA identified six distinct latent statuses of LHDs, characterized by variables such as governance centrality, colocation, and integration. This typology provides a robust framework for understanding the structural and operational diversity of LHDs, offering insights into how these factors influence public health outcomes. The final essay (Chapter 4) applies ordinal regression analyses to explore the relationship between the latent statuses of LHDs and various community health outcomes. Initial analyses using a cumulative logit model indicated a violation of the proportional odds assumption, necessitating a shift to a generalized logit model. This approach revealed significant predictors of latent statuses, such as poor physical health days, preventable hospital stays, and life expectancy. The findings underscore the complexity of public health systems and the need for careful selection of statistical models to accurately capture these dynamics. The study provides actionable insights for public health policy and strategic planning, highlighting areas for future research and potential interventions to optimize public health system design and operations. This dissertation underscores the importance of systems approaches in understanding and improving public health systems. By leveraging advanced statistical models and exploring the structural characteristics of LHDs, it contributes to a deeper understanding of the factors influencing public health governance and service delivery. The findings offer a foundation for future research and policy development aimed at enhancing the efficiency and effectiveness of public health systems to better serve communities.
Open Access
On the integration of materials characterization into the product development lifecycle
(Colorado State University. Libraries, 2024) Dare, Matthew S., author; Simske, Steve, advisor; Yourdkhani, Mostafa, committee member; Herber, Daniel, committee member; Radford, Donald W., committee member
The document is broken down into four sections whereby a more complete integration of materials characterization into the product development lifecycle, when compared to traditional approaches, is researched and considered. The driving purpose behind this research is to demonstrate that an application of systems engineering principles to the characterization sciences mechanism within materials engineering and development will produce a more efficient and comprehensive understanding of complex material systems. This will allow for the mitigation of risk, enhancement of relevant data, and planning of characterization procedures proactively. The first section proposes a methodology for Characterization Systems Engineering (CSE) as an aid in the development life cycle of complex, material systems by combining activities traditionally associated with materials characterization, quality engineering, and systems engineering into an effective hybrid approach. The proposed benefits of CSE include shortened product development phases, faster and more complete problem solving throughout the full system life cycle, and a more adequate mechanism for integrating and accommodating novel materials into already complex systems. CSE also provides a platform for the organization and prioritization of comprehensive testing and targeted test planning strategies. Opportunities to further develop and apply the methodology are discussed. The second section focuses on the need for and design of a characterizability system attribute to assist in the development of systems that involve material components. While materials characterization efforts are typically treated as an afterthought during project planning, the argument is made here that leveraging the data generated via complete characterization efforts can enhance manufacturability, seed research efforts and intellectual property for next-generation projects, and generate more realistic and representative models. A characterizability metric is evaluated against a test scenario, within the domain of electromagnetic interference shielding, to demonstrate the utility and distinction of this system attribute. Follow-on research steps to improve the depth of the attribute application are proposed. In the third section, a test and evaluation planning protocol is developed with the specific intention of increasing the effectiveness of materials characterization within the system development lifecycle. Materials characterization is frequently not accounted for in the test planning phases of system developments, and a more proactive approach to streamlined verification and validation activities can be applied. By applying test engineering methods to materials characterization, systems engineers can produce more complete datasets and more adequately execute testing cycles. A process workflow is introduced to manage the complexity inherent to material systems development and their associated characterization sciences objectives. An example using queuing theory is used to demonstrate the potential efficacy of the technique. Topics for further test and evaluation planning for materials engineering applications are discussed. In the fourth section, a workflow is proposed to more appropriately address the risk generated by materials characterization activities within the development of complex material systems when compared to conventional engineering approaches. Quality engineering, risk mitigation efforts, and emergency response protocols are discussed with the intention of reshaping post-development phase activities to address in-service material failures. While root cause investigations are a critical component to stewardship of the full system lifecycle during a product's development, deployment and operation, a more tailored and proactive response to system defects and failures is required to meet the increasingly stringent technical performance requirements associated with modern, material-intensive systems. The analysis includes a Bayesian approach to risk assessment of materials characterization efforts through which uncertainty regarding scheduling and cost can be quantified.
Embargo
Probing the metabolic secrets of Anopheles stephensi mosquitoes to enhance cryopreservation techniques
(Colorado State University. Libraries, 2024) Ramirez, Gabriela, author; Dobos, Karen, advisor; Ebel, Greg, committee member; Barfield, Jennifer, committee member; Broeckling, Corey, committee member
The lipid profile and cryopreservation methods of Anopheles stephensi mosquitoes have significant implications for mosquito management and research. The intricate life cycle of mosquitoes is governed by lipid metabolism, involving lipogenesis, lipolysis, and fatty acid metabolism, which are critical for transitioning between life stages. Despite the importance of these processes, mosquito cryopreservation has faced challenges, mainly due to the impenetrable nature of mosquito eggs to traditional cryoprotective agents. While other insects like honeybees and fruit flies have seen some success in cryopreservation, mosquitoes have posed unique difficulties. Initial attempts to cryopreserve mosquito eggs were unsuccessful, and there remains a need for effective cryopreservation protocols that maintain the viability and normal development of mosquitoes post-thaw. This study investigates lipid metabolism across mosquito life stages and advances cryopreservation techniques. The lipid profile analysis focused on major lipids such as phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelins (SM), and triacylglycerides (TGs), as well as non-bilayer lipids like diacylglycerol (DG) and lysophospholipids (LysoPC, LysoPE). For cryopreservation, a new protocol using methylformamide (MF) with trehalose was developed for first-instar larvae (L1s) older than 1.5 hours post-hatching. The hypotheses were that 1) Lipid metabolism plays a crucial role in the successful development and reproduction of mosquitoes, and 2) Inducing diapause and using suitable cryoprotectants can improve the recovery rates of cryopreserved mosquitoes. The lipid profile analysis revealed that PE is vital for protein anchoring required for embryogenesis and immune responses and that steroids like 20-hydroxyecdysone (20E) are crucial for molting and development. The cryopreservation study showed that supercooling larvae for up to 60 minutes resulted in normal development to adulthood, although longer durations inhibited adult emergence. Supercooled larvae and their offspring exhibited typical sex ratios and developmental patterns, indicating genetic and phenotypic stability. This research underscores the well-orchestrated metabolic strategies in mosquitoes. It suggests that understanding these biochemical processes is essential for effective cryopreservation, potentially paralleling natural cold survival strategies seen in other insects.
Embargo
Cu-P-Se nanoparticles: understanding the reaction pathways for the colloidal synthesis of energy conversion and storage materials
(Colorado State University. Libraries, 2024) Neisius, Nathan A., author; Prieto, Amy L., advisor; Finke, Richard, committee member; Herrera-Alonso, Margarita, committee member; Paton, Robert, committee member
Nanotechnology has garnered considerable interest over the last 40 years, owing to the unique, desirable properties that can be targeted through established synthetic methods for tuning the size of materials at the nanoscale. As no one single material has properties suitable for a wide range of applications, property driven synthesis has been at the forefront of the nanoparticle (NP) field. Particularly, colloidal NP syntheses provide a large synthetic landscape to explore as a result of the vast synthetic tunability to target specific parameters such as, particle size, morphology, composition, and defects. Although significant efforts have been made toward deciphering the transformation processes of unary and binary NPs, traditionally the colloidal NP field has been driven by a top-down approach, driven by trial-and-error methods, limiting the design of desired, complex materials. Thus, to further progress nanoparticle technology, understanding the underlying transformation processes occurring throughout the formation of colloidal nanoparticles is essential to develop novel materials as well as control the structure/property relationships. The copious amounts of both organic and inorganic interactions, as well as the complexity of capturing the transformation from molecular to the solid-state regime, complicates the reaction landscape for more complex, ternary phases. The purpose of the work included and explained in this dissertation is to develop stoichiometric syntheses for both Cu-P-Se ternary phases, Cu3PSe4 and Cu7PSe6, and to then understand the reaction pathways for an improved retrosynthetic analysis and enable translation of the synthetic knowledge to other systems. Cu-P-Se ternary chalcogenide NPs are of particular interest, owing to the synthetic complexity of navigating a rich phase space with thermodynamically stable binary phases close in energy to the desired ternary phases, as well as applicable structural properties for thermoelectrics, photovoltaics, and battery applications. Therefore, to contribute to the progression of the nanoparticle field the general objectives of this study are, (1) analyzing the transformation of commonly employed precursors and solvents (2) capture the influence of precursor reactivity on ternary phase formation, and (3) perform careful characterization of speciation and final nanoparticles, all of which to establish a full scope of Cu-P-Se nanoparticle formation and the impact of individual synthetic parameters on chalcogenide-based precursors. In Chapter 1, the relevant literature for the following chapters is reported and reviewed to provide the essential background information. This chapter is divided into 6 subsections; (1) Need for renewable energy and how nanoparticles provide solutions, (2) State of nanoparticle synthesis field, current limitations, and progress towards developing a better understanding of nanoparticle reaction pathways, (3) Motivation for exploring the Cu-P-Se phase space, (4) Se reactivity in NP syntheses, (5) Cu3P – the required precursor for Cu-P-Se formation, (6) Dissertation overview, publications, and presentations. The first colloidal NP synthesis report on Cu3PSe4 was developed by a previous group member, Dr. Jennifer Lee, which demonstrated that the phase purity of Cu3PSe4 requires the use of Cu3P NPs and selenium powder (Se) in ODE as precursors. Alternate reaction precursors, and therefore pathways, were disproven throughout this study, leading to the working hypothesis that the interactions of Se and ODE were a necessary step to form active species that then react with Cu3P NPs. Although frequently employed in NP research, and heavily characterized, the implications of the Se/ODE solution on Cu3PSe4 phase formation are still misunderstood. Therefore, the studies presented in Chapter 2 are aimed at probing the Cu3PSe4 reaction landscape and the findings are separated into (1) ex situ reactions that are characterized with molecular and solid-state characterization techniques to determine the implications of the solution dynamics on Cu-P-Se NP phase formation, and (2) how different Se/ODE speciation can be isolated and subsequently favor the alternate, metastable Cu-P-Se phase, Cu7PSe6. A persistent limitation to the previous study is that ODE contaminates the final products, making the findings and analysis of Se/ODE rather difficult to interpret, thus requiring a simplified, cleaner reaction to produce phase pure Cu3PSe4. For that reason, Chapter 3 shifts the direction of the Cu3PSe4 synthesis towards a more stoichiometric, atom-economical reaction by eliminating ODE as the solvent. Rather, a long-chain, aliphatic solvent, octadecane (ODA) is employed that proves to be an operationally inert solvent under the standard synthetic conditions and produces cleaner, phase pure Cu3PSe4 NPs as determined by powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). If ODA was reacting with Se0 powder, the most favorable pathway, commonly cited in literature, is the formation of H2Se and oxidized ODA (alkene). Hence, molecular characterization techniques, nuclear magnetic resonance (NMR, 1H and 13C) and fast-Fourier infrared spectroscopy (FT-IR), were utilized to demonstrate the absence of oxidized ODA species, which is consistent with Se0 preferentially reacting with Cu3P, promoting a more direct reaction pathway. Eliminating the presence of alternate, competing reaction pathways in the ODE synthesis and establishing a near-stoichiometric reaction, allows us to capture the underlying transformation process of Cu3P to Cu3PSe4. From these systematic improvements, we hypothesize that Se0 powder is dispersed in ODA, which promotes a formal eight-electron transfer between Cu3P and 4 Se0. Extracting the synthetic information from the previous chapters to target the metastable Cu-P-Se phase, Cu7PSe6, provides the framework for Chapter 4. Previous methods to isolate Cu7PSe6 are based on traditional, solid-state techniques, where the elemental precursors are ground and subsequently heated to high temperatures (>1000K). Although a colloidal or solution-based synthesis has yet to produce phase-pure Cu7PSe6 particles, attempts explained in Chapter 2 provide a basis on the phase space complexity, where the products consisted of Cu7PSe6 but with thermodynamic byproducts, Cu-Se phases and Cu3PSe4 present. Therefore, an alternate Se precursor, diphenyl diselenide (Ph2Se2), is employed to form the metastable phase, which effectively avoids Cu3PSe4 formation. Importantly, an alternate route to form Cu3PSe4 is with analogous dialkyl diselenide precursor, dibenzyl diselenide, where a key finding is the presence of amorphous phosphorus (P) on Cu1-xSe binaries at low temperatures, which then efficiently reincorporates once the desired 300 ˚C reaction temperature is reached. Thus, in Chapter 4 we investigate why Cu7PSe6 is favored with Ph2Se2 as a precursor, which is predicated on the formation of byproduct species that effectively "trap" P. A proof of concept is explored to further demonstrate the dynamics of P in solution, where the Cu-P-Se phase space can be controllably toggled across by injecting P(5+) species. A drawback for the Cu-P-Se syntheses is the lack of compositional understanding of the pre-synthesized Cu3P NPs, thus further complicating the reaction stoichiometries. Chapter 5 first investigates the previously published synthesis by Liu et al., by thoroughly characterizing the final Cu3P nanoparticles under identical reaction conditions and exploring alternate reaction stoichiometries to reduce the presence of residue precursors. From such, it is determined that the particles substantially deviate from the stoichiometric Cu3P composition, with a Cu:P ratio around 1.5:1.0. Particular focus is also placed on monitoring the degradation of a green phosphorous source, triphenyl phosphite, P(OPh)3. Although triphenyl phosphite (TPOP) has been previously used for transition metal phosphide systems, a lack of systematic investigations leads to questions on the reduction of TPOP en route to forming Cu3P, a formal P(3+) to P(3-) event. Additionally, limited characterization of the final organic byproducts in the original synthesis, begs to question what, if any, byproducts could be contaminating the Cu3P NPs. Therefore, we develop and probe stoichiometric syntheses that isolate phase pure Cu3P NPs to avoid the original 30-fold excess of P. The transformation of hexadecylamine (reductant and ligand) and TPOP were characterized with 1H and 31P NMR to evaluate the role of each en route to forming Cu3P. As this is project is still developing, the necessary future directions are given to systematically approach this problem, with an emphasis on first-step experiments and essential characterization methods to completely grasp the decomposition mechanism of TPOP. Ultimately, this has implications when systematically applying TPOP to alternate transitional metal phosphide NP syntheses, as well as developing more precise Cu-P-Se syntheses. Finally, the work presented herein is summarized in Chapter 6 along with an outlook on the project as a whole. Specifically, future directions and preliminary insight into the underlying reaction pathways and mechanism of Cu3PSe4 formation are explored. Additionally, we explore preliminary data on an analogous material Ag-P-Se, which was plagued for years by the lack of a reproducible Ag-P precursor synthesis that limited our ability to extract the synthetic intuition from the Cu-P-Se system. However, recent literature findings on a potential Ag3P precursor provides promise on synthesizing Ag-P-Se phases in the future, which is critically analyzed to ensure that any bottlenecks in future syntheses are limited. Ultimately, the work provided in the following chapters is aimed at making strides to developing a more in depth understanding of precursor interactions between transition metals and main group elements, as well as properly monitoring such reactions to extract synthetic information to analogous systems. With the knowledge gained on the presented studies, we aspire to contribute to the NP field in order to continually improve NP synthesis and therefore nanomaterials. Finally, this work is supported by NSF Macromolecular, Supramolecular, and Nanochemistry (MSN #2109141).
Open Access
Presale diagnostic imaging in Thoroughbred horses: the prevalence and progression of radiological and ultrasonographical findings and their associations with racing performance
(Colorado State University. Libraries, 2024) Peat, Frances J., author; Kawcak, Christopher E., advisor; McIlwraith, C. Wayne, advisor; King, Melissa R., committee member; Selberg, Kurt T., committee member; Barrett, Myra F., committee member
Background: The sale of young horses at bloodstock auctions plays an important role in the success of the Thoroughbred industry worldwide. The Keeneland September Yearling Sale in Lexington, Kentucky, is the largest sale of Thoroughbred yearlings in the world. Conducted over 12 days and presenting between 2500 and 3000 horses through the auction ring, the sale now records gross receipts exceeding 400 million United States Dollars (USD) per year. Veterinarians at the sale perform presale inspections on future racing prospects and consult with prospective purchasers regarding a horse's suitability for its intended use. Radiography and ultrasonography are used in presale examinations to identify orthopaedic issues that may affect soundness during athletic training and racing. Modern diagnostic imaging technology produces high quality images that have enabled the detection of a number of presale findings of unknown significance in young horses. Variable interpretation of these findings and conflicting assignments of potential clinical importance have become a source of contention in the Thoroughbred industry and this requires resolution. Specific imaging findings for which further scientific evidence is needed include radiological changes in the equine medial femoral condyles (MFCs) and proximal sesamoid bones (sesamoids) and ultrasonographic findings in the medial and lateral branches of the suspensory ligament (branches). Changes in the sesamoid and the insertional region of the adjacent suspensory branch are of particular importance in young Thoroughbreds, due to the potential for catastrophic injury to the suspensory apparatus in which they are an integral structure. Little is known about the prevalence of concurrent ultrasonographic branch change relative to the various grades of radiological sesamoid appearance seen in horses. Objective scientific data would enable prepurchase and training management decisions to be made that are in the best interests of the horse and its connections and the wider industry. Objectives: In the equine stifle (femorotibial joint) and fetlock (metacarpo/metatarsophalangeal joint), the objectives of this doctoral research were firstly to identify the prevalence of subchondral lucencies (SCLs) in the distal aspect of the MFC and the prevalence of various sesamoid changes on sales repository radiographs in yearling and 2-year-old Thoroughbreds, and to identify the prevalence of ultrasonographic suspensory branch changes in the same population of horses. Secondly, the studies aimed to monitor changes in MFC, sesamoid and suspensory branch grades between yearling and 2-year-old sales in horses that presented for sale at both ages. Thirdly, the research aimed to determine any associations between grade of MFC, sesamoid or suspensory branch findings and future racing performance. Lastly, the research was designed to examine the existence of concurrent radiological and ultrasonographic findings in individual sesamoid-branch units in sales horses; to determine whether there are any radiological findings that are consistently accompanied by a particular degree of insertional branch change and to provide practical recommendations as to when suspensory branch ultrasonography may be warranted in the sales environment. The overriding objective was to provide an evidence-based determination of which presale imaging findings should be regarded as an acceptable appearance at a given age in sales horses and which findings constitute a risk to future performance. Methods: The research was performed via prospective cohort studies using enrolled samples. Sales repository radiographs were obtained with consignor permission from the 2016 Keeneland September Yearling Sale and the five major North American 2-year-old sales in 2017 run by Fasig-Tipton Company and Ocala Breeders' Sales Company. Ultrasonography was performed immediately prior to the sales on the forelimb suspensory branches of horses with consignor permission. Stifle and fetlock radiographs were evaluated for MFC and sesamoid changes, respectively. MFC SCL were graded on a scale of 0-3 according to radiological size and axial MFC lucencies were recorded separately. Sesamoid findings relating to vascular channel appearance (0-3), abaxial contour changes and apical and abaxial fragments were graded according to a grading system established for the purposes of this study. Ultrasonographic findings relating to suspensory branch size, fibrillar pattern, the presence of hyperechoic foci, periligamentar tissue thickness and the adjacent proximal sesamoid bone surface were recorded during post-sale image evaluation. Racing performance was assessed for all study horses until the end of their 4-year-old racing season and performance data was obtained from Equibase Company LLC. Racing performance was measured via eight outcome variables: whether the horse started at least one race by the end of their 4-year-old year, age at first race start, total number of race starts, total prizemoney earned, earnings per start, class of career best start achieved, weighted Listed and Group race starts and Class Performance Index. Clinical follow-up was sought to ascertain why horses that did not race never started. Distributions of imaging findings were examined using descriptive statistics at the individual bone and branch level and at the horse level. Associations between imaging findings and racing performance from 2 to 4 years of age were examined using multivariate regression analyses, controlling for horse sex. Analysis was via logistic, negative binomial or linear regression as appropriate, with the threshold for significance set at a=0.05. Results: Sales radiographs from 2,508 yearlings and 436 2-year-olds were included. This sample represented 11% of the annual US Thoroughbred foal crop. It comprised 36% of all yearlings sold at auction in North America in 2016 and 20% of all 2-year-olds sold at auction in North America in 2017. Radiographs of 5,016 yearling stifles and 872 2-year-old stifles were evaluated. MFC SCLs of Grades 1-3 were observed in 242 yearlings (9.7%) and 49 2-year-olds (11.2%). Bilateral MFC SCLs of Grades 1-3 were observed in 54 yearlings (2.2%) and 12 2-year-olds (2.8%). Yearling Grade 1 MFC SCLs had either resolved (11/31), remained unchanged (14/31) or progressed to a Grade 2 (6/31) by 2-year-old sales. Yearling Grade 2 MFC SCLs had either improved to a Grade 1 (2/10), remained unchanged (6/10) or progressed to a Grade 3 (2/10) by 2-year-old sales. Yearlings with a Grade 3 MFC SCL had a 78% probability of starting a race (95% Confidence Interval (CI): 58.2-89.6%), compared to 84% for MFC Grade 0 yearlings (95% CI: 82.7-85.8%). Six of the seven yearlings with axial MFC lucencies raced. Radiographs of 20,064 yearling sesamoids and 3,488 2-year-old sesamoids were evaluated. Interobserver agreement using the new radiological grading system was substantial. Yearling findings associated with a significantly reduced probability of starting a race were: Grade 3 vascular channels in forelimb sesamoids (0.52, P<0.001, 95% CI: 0.37-0.67), abaxial new bone in forelimb sesamoids (0.62, P=0.01, 95% CI: 0.49-0.73), apical or abaxial fragments in forelimb sesamoids (0.55, P=0.005, 95% CI: 0.37-0.72). For affected horses that did race, Grade 3 vascular channels in forelimb sesamoids were associated with fewer race starts (9.9 starts, P=0.03, 95% CI: 8.0-12.2) and Grade 3 vascular channels in hindlimb sesamoids were associated with a delayed start to racing careers (54 days, P=0.01, 95% CI: 20-89). Abaxial new bone in forelimb sesamoids was associated with a 54% reduction in total earnings (P=0.003, 95% CI: 24-72) and a 46% reduction in earnings per start (P=0.002, 95% CI: 21-64). Abaxial concavity occurred predominantly in yearling medial forelimb sesamoids, had no impact on racing performance and mostly resolved by two-year-old sale. A total of 593 sales yearlings and 367 2-year-olds had ultrasonography performed on all four forelimb suspensory branches per horse. Grade ≥2 fibrillar branch change was present in 8.9% of yearlings and 14.4% of 2-year-olds. A 0.25cm increase in branch width was associated with a 49-day delayed start to racing careers (P<0.001, 95% CI: 21-77 days). The presence of Grade 2 hyperechoic foci was associated with significantly lower total earnings (P=0.01, 95% CI: $2,000-$16,022) and lower earnings per start (P=0.003, 95% CI: $349-$1,718) in USD. Grade 3 fibrillar branch change had clinically important reductions in the probability of racing, calibre of racing performance and earnings. Grade 1 fibrillar pattern was associated with significantly higher earnings per start (P=0.004, 95% CI: $2,641-$5,759). A total of 2,204 yearling forelimb sesamoid-branch units and 1,336 2-year-old forelimb sesamoid-branch units were available for evaluation of concurrent imaging findings. The proportion of yearling sesamoids with Grade ≤1 vascular channels that had adjacent Grade ≥2 fibrillar branch change was 1.2%. The same proportion for 2-year-olds was 3.8%, with medial forelimb sesamoids with Grade 1 vascular channels overrepresented in 2-year-olds. In yearlings, 31% of sesamoids with Grade 2 vascular channels had adjacent Grade ≥2 fibrillar branch change and 59% of sesamoids with Grade 3 vascular channels had adjacent Grade ≥2 fibrillar branch change. In 2-year-olds, 47% of sesamoids with Grade 2 vascular channels had adjacent Grade ≥2 fibrillar branch change and 67% of sesamoids with Grade 3 vascular channels had the same. Only 1 yearling and 1 2-year-old sesamoid with radiological abaxial concavity had Grade 2 fibrillar branch change. Limitations: The samples used in this research are representative of the population of interest at Thoroughbred sales but may underestimate the prevalence of severe lesions in non-sale horses. The study design could not address exclusions prior to sale. The findings are applicable to horses prepared for public auction and deemed fit to be entered for sale by consignors and their veterinarians. Clinical examinations were not performed for the purposes of this research. Conclusions: Regarding stifle lucencies, Grade 1 MFC SCLs were the most common type seen in yearling and 2-year-old sales horses. The majority of yearling Grade 1 MFC SCLs resolved or remained unchanged by 2-year-old sales. It was also possible for Grade 2 and 3 MFC SCLs to improve one grade between sales. Fewer sales yearlings with a Grade 3 MFC SCL raced, but in those that did race there was no evidence of worse performance compared to unaffected peers. Axial MFC lucencies did not affect racing performance. For sesamoids, Grade 3 vascular channels, forelimb sesamoid abaxial new bone and forelimb sesamoid fragments are important findings in sales repository radiology. The new grading scale assigns a numerical grade for vascular channel appearance that matches the number of enlarged vascular channels evident in a given sesamoid. Abaxial contour changes, when present in sesamoids that are Grade 0 for vascular channels, are noted separately as either abaxial new bone or abaxial concavity. Fragments are also noted and interpreted separately. Reference values specific to young Thoroughbreds have been established for suspensory branch ultrasonography. Grade 1 fibrillar suspensory branch change should be regarded as an acceptable appearance in sales yearlings and 2-year-olds. Approximately one third of Grade 2 yearling branches progressed to a Grade 3 lesion. Evidence of enlarged branch width and Grade 2 hyperechoic foci at 2-year-old sales constitute a risk to racing performance. The existence and prevalence of concurrent radiological and ultrasonographic findings in the proximal sesamoid bones and adjacent suspensory ligament branches has been established in yearling and 2-year-old Thoroughbred sales horses. General recommendations have been made for selective branch ultrasonography on the basis of sesamoid radiological appearance. The results support a separate aetiology for radiological sesamoid abaxial concavity that does not primarily involve the suspensory branch insertion. This research provides veterinarians and the wider Thoroughbred industry with evidence-based determinations of the importance or otherwise of the various presale imaging findings seen in the MFCs, sesamoids and suspensory branches of yearlings and 2-year-olds. Many findings can be regarded as an acceptable appearance in yearlings and 2-year-olds. For those findings that are associated with reduced performance, sale and management decisions can be made based on quantitative evaluations of risk that are in the best interests of the horse.