OSU Theses

Browse

Recent Submissions

  • Item
    Effects of exercise on heartbeat detection and self-focus in social anxiety
    (2024-07) Hahn, Burkhart J.
    Social anxiety (SA) is one of the most common psychological disorders, with a lifetime prevalence rate of 13%. Further, SA is accompanied by various distressing (e.g., negative emotions, perception of poor social skills) and impairing (e.g., attentional bias, social avoidance) symptoms. Of these symptoms, ruminative self-focus serves as a maintenance factor for SA. For example, a person may have difficulty shifting focus away from threatening internal sensations (e.g., sweating, increased heartrate) to focus on the task at hand (e.g., conversation topic). However, aerobic exercise may serve as a health behavior which limits the impact of this attentional bias and reduces SA overall. Psychophysiological measures of attention (e.g., EEG) can provide objective markers of the salubrious effect of exercise on ruminative self-focus in those with SA. Thus, this study sought to examine the effect of acute aerobic exercise on cognitive performance, internal attentional bias, and behavioral responses in those with high SA and those with low SA. This study recruited 51 participants using an online recruitment system to examine this research question. Results indicated a main effect of ruminative self-focus when comparing high and low SA. Additionally, this study found an exposure or habituation effect of exercise in a social anxiety sample. This indicates exercise may serve as a normalizing effect of interoceptive attention and supports previous literature indicating exercise provides a safe place to experience threatening internal sensations. Research and clinical implications are explored.
  • Item
    Investigation of rock-fluid interactions using geomaterial microfluidics
    (2023-05) Joshi, Ayush
    Illite and Illite-Smectite clays are reportedly the Caney Shale's most prevalent clay minerals. The swelling and fines migration of clays may occur when water-based fluids contact the clay minerals. This may result in the reduction of pore space and permeability, and wettability alteration. Therefore, we quantified the swelling potentials, fines migration and wettability alteration of Illite and Illite-Smectite clays upon exposure to model brines and a produced water, and a model oil and a crude oil. We measured density, viscosity, pH, TDS, and interfacial tension as they are important in multiphase flow and displacement characteristics. Geomaterial microfluidics is recently being used to study physicochemical interactions of solid-fluid systems. It facilitates visualizing the surface behavior upon exposure to various fluids. This study includes preparation and characterization of Illite-Smectite clay-coated glass capillary tubes. Illite and Illite-Smectite clay-coated geomaterial microfluidic surfaces were prepared to investigate the effects of first contact fluid, brine salinity, and aging on wettability. In this work, advancing and receding contact angles of model brine-air, model oil-air, produced water-air, crude oil-air, model brine-model oil systems, and produced water-crude oil systems have been measured in the untreated, and clay-coated microfluidic channels of 1000 µm width and 50 µm depth. The aging effect was studied by retaining the non-aqueous and aqueous solutions in the corresponding microfluidic channels for approximately 24 h in the case of channels first contacted by aqueous and non-aqueous solutions, respectively. The advancing and receding contact angles of Caney shale-crude oil-produced water systems were also measured. The experimental findings indicate the swelling potential, fines migration, and wettability alteration of Illite and Illite-Smectite clays. The results signify the influence of first contact fluid, brine salinity, and aging on wettability of the untreated and clay-coated microfluidic surfaces. The experiments also demonstrate the wetting nature of the Caney shale samples from reservoir and non-reservoir zones.
  • Item
    Weight loss strategies and experiences in people maintaining or attempting weight loss
    (2024-07) Geist, Caroline
    Although nearly half of US adults attempted weight loss at least once from 2013-2016, not much is known about the experience of weight loss, especially the difference in experiences between those who achieve and maintain weight loss (WLM) and those who attempt and do not lose weight (WLA). Using a quantitative survey and semi-structured interviews, this study aimed to examine these differences. The responses from nineteen individuals were collected, mostly female (n=13). Quantitative results were measured using a Likert scale (1=Not at all,, 5=Completely) and found that there was no statistical difference in several aspects of the weight loss experience, including perceived change to diet (WLM: 3.6 ± 0.8 au; WLA: 3.5 ± 0.7 au; p=0.66) or perceived change in exercise habits (WLM: 3.8 ± 1.0 au; WLA: 3.2 ± 1.1 au; p=0.13). However, there was a significant difference in perceived difficulty of weight loss (WLM: 3.4 ± 0.7 au; WLA: 1.7 ± 1.0 au; p=0.008). The qualitative results found that themes unique to WLA included dichotomous thinking and restrictive strategies. Both negative (ex. Discouragement and frustration) and positive attitudes (Ex. Feeling hopeful) were present in this group. WLM demonstrated themes of flexible thinking, the ability to form habits, and making small, incremental changes. Themes present in both groups included health motivations and the intention to make long-term changes to promote weight loss. This finding is in contrast with current assumptions based on previous studies that study only WLM, the findings of which imply that these themes are associated with only that group. However, this study not only found that these associations may be misleading but emphasizes the importance of examining the experiences of each group alongside the other.
  • Item
    Grafted vegetable propagation and production in soilless systems
    (2023-05) Deer, Ché Luis
    Tomato (Solanum lycopersicum L.), pepper (Capsicum annuum L.), and watermelon (Citrullus lanatus L.) are some of the most common crops selected for vegetable grafting in the United States. Grafted plants express resistance to soil-borne diseases. Thus, improving the disease tolerance to vegetables grown in Oklahoma is essential as soil-borne pathogens are ever present in outdoor cultivated areas. Grafted tomato (‘Cherokee Purple’ x ‘RST-106-04-T’), pepper (‘King Arthur’ x ‘Dorado’) and watermelon (‘Delta’ x ‘Cobalt’) combinations were made to evaluate compactness and survival in homemade healing chambers with a volume of 0.38 m3 in three different treatments (greenhouse, indoor, outdoor) in spring and fall 2021 and 2022. The results indicated spring is the best time to graft watermelon, pepper and tomato. Compactness values during the spring were not different among locations for watermelon; however, when grafting in the fall, greenhouse and outdoor environments performed similarly. For watermelon survival, greenhouse environments performed the poorest in the spring; for pepper, the greenhouse environment resulted in the greatest survival rates. Recommendations concerning survival and compactness are limited as the study needed more power relating to replicated experimental units. ‘Cherokee Purple’ tomato (Solanum lycopersicum L.) plants are a highly sought-after heirloom cultivar in the United States but are low yielding and highly susceptible to soil-borne pathogens. Moreover, soilless systems like aquaponics and hydroponics help increase yield, mitigate disease, and optimize space and resources like fertilizer and water. A grafting combination of ‘Cherokee Purple’ x ‘Maxifort’ and non-grafted controls were grown in six 1.85 m2 media grow beds with three hydroponic and aquaponic systems in a greenhouse. Hydroponics systems were fed 0.63 g of water-soluble fertilizer (Masterblend 4N-7.9P-31.5K Tomato Formula, Morris, IL), 0.63 g of calcium nitrate (15.5N-0P-0K PowerGrow, Vineyard, UT), and 0.32 g of magnesium sulfate (PowerGrow, Vineyard, UT) per liter of water with EC levels of 0.8 mS/cm for seedlings, 1.0-1.5 mS/cm for early growth, and 2.0-2.3 mS/cm for flowering and fruiting stages. Aquaponics systems utilized copper nose bluegill (Lepomis macrochirus) to create a nutrient-dense solution of 0.25 ppm NH3, 0 ppm NO2-, and 50 ppm NO3- with an EC of 0.77-0.83 mS/cm. Treatments were either aquaponic or hydroponic systems and grafted or nongrafted plants. Grafting increased stem diameter, leaf count, stem height, flower count, bud count compared to nongrafted plants. In aquaponics, grafting increases P over nongrafted aquaponic plants. Lastly, grafting resulted in greater fresh (49.2%) and dry (40%) shoot biomass. Grafting resulted in fresh (33.3%) and dry (42.8%) root biomass. Grafting also increased the uptake of copper and sulphur in aquaponics Hydroponic systems resulted in greater leaf count, SPAD, stem height, shoot biomass, and greater boron, phosphorus, potassium, iron, and manganese than aquaponics systems. Total fruit number and weight were greater in hydroponics systems than aquaponics systems by 35.4% and 30.4%, respectively. Aquaponics resulted in more significant root fresh weight. Nutrients zinc and copper increased with the usage of aquaponic systems over hydroponics systems.
  • Item
    Impact of Incident Command System training on non-governmental organizations' emergency response operations in the United States
    (2024-05) Edler, David
    This qualitative study delves into Incident Command System (ICS) training dynamics and its efficacy in enhancing collaborative efforts between non-governmental organizations (NGOs) and government agencies during emergency response operations. Anchored in a post-positivist paradigm, the research uncovers the complexities and variabilities of human and organizational behavior in crises through an in-depth thematic analysis of interviews with seasoned emergency response professionals. The analysis illuminates the pivotal role of communication, training, and collaborative strategies in enabling the effective integration of NGOs into emergency responses. It sheds light on the challenges of emergency management collaboration, particularly the issues of miscommunication, the need for a shared operational language, and the transformative potential of ICS training to address these issues. Research findings underscore the necessity for ICS training programs that are customized and adaptable to the diverse needs and operational contexts of NGOs. Structured collaboration and communication strategies are highlight for emergency professionals who navigate the complexities of varied operational languages and protocols. The study advocates a holistic approach to integrating NGOs into ICS-driven emergency responses, promoting cross-cultural communication, leadership across organizational boundaries, and responsive management strategies. It emphasizes the importance of specialized training and sophisticated communication strategies within a comprehensive collaborative framework to enhance NGO contributions to emergency responses. Recommendations include establishing an iterative learning and development cycle to refine collaboration mechanisms and continually, fostering ongoing dialogue and engagement between NGOs and government agencies. The study also identifies the need for adaptable emergency response frameworks, signaling the continuous need for research, improvement, and adaptation. By paving the way for practical applications, the research suggests longitudinal analyses to assess the long-term impact of ICS training, cross-jurisdictional comparisons to understand implementation benefits widely, and the development of training modules tailored specifically to the needs of NGOs. Additionally, the study points to the exploration of technology and digital communication tools as means to modernize emergency response infrastructures, contributing to a more resilient and collaborative national emergency response system.
  • Item
    Migration narratives: Visualizing the Iranian migration experiences
    (2024-05) Faridfar, Mahshad
    This thesis explores the rich and multifaceted experiences of Iranian migration through the lens of generative design, aiming to visualize and interpret these narratives in a nuanced manner. Generative design, characterized by its use of algorithms to create dynamic visual representations, serves as the primary methodological tool in this study. It enables the transformation of migration stories into engaging and deeply informative visual formats and facilitates a broader understanding of these experiences. The narrative of Iranian migration is complex, influenced by a confluence of socio-political, cultural, and personal factors. By harnessing the capabilities of generative design, this research translates these intricate stories into graphic visualizations that capture the essence of emotions and memories associated with migration. Projects such as "Synesthesia," "The Migrant Garden," "Typographic Narratives," and "CommUnity" illustrate the application of these methodologies. Each project employs specific generative design techniques to address different aspects of the migration experience—from the emotional and psychological impacts to the communal and social dynamics involved. "Synesthesia" translates audio narratives into visual data, emphasizing the sensory overlap and the emotional depth of migration stories. "The Migrant Garden" uses 3D printing to create tangible representations of individual narratives, allowing for a physical interaction with the stories. "Typographic Narratives" focuses on the power of text and design to vividly convey personal stories, enhancing emotional engagement through typography. Lastly, "CommUnity" utilizes interactive installations to demonstrate the supportive role of communities in the migration process. These projects not only demonstrate the power of generative design in storytelling but also underscore its potential to foster empathy and understanding among audiences. By breaking down complex narratives into accessible and engaging visual formats, this research contributes to a deeper public understanding of the challenges and triumphs of Iranian immigrants. Importantly, this work highlights the role of innovative design approaches, such as generative design, in shaping the discourse on migration and cultural identity, offering new perspectives and insights.
  • Item
    From Witchcraft to Tarot: Religious individualism among evangelical/Christian women
    (2024-07) da Silva, Taline Alonso
    This study examines the process of religious individualization among evangelical/conservative Christian women through Witchcraft and Tarot practices. This thesis draws on 31 semi-structured, in-depth interviews with Christian Witches who self-identify or self-identified previously as evangelical or conservative. The findings indicate that Witchcraft and Tarot are used as spiritual bridges by women to find God and consequently themselves, share learnings and further intellectualism on Christian Witchcraft online, and reach spiritual autonomy by differentiating religion and spirituality into their belief systems. This thesis furthers discussion on femininity expectations within conservative religious realms, and the interplay of women’s agency, spirituality, and religion.

  • Item
    Changes in bone parameters in rat model of chronic early life stress
    (2024-07) Chandrashekar, Ranjitha Hubbanahalli
    Objective: Early life factors have been shown to play a role in child health and development and stress is one of the factors that could have major impact on host health. Thus, our objective was to investigate chronic early life stress (CES) impact on bone development, mineralization, and microarchitecture at various postnatal stages using rat model. Methods: Pregnant Sprague-Dawley rats were subjected to a limited bedding and nesting model to induce CES. The offspring were assessed at PND 10, 21, and 35. Tibial length as well as tibial and lumbar (L4) BMD, BMC, and bone mineral area (BMA) were measured using dual-energy X-ray absorptiometry (DXA). Bone microarchitecture was examined using microcomputed tomography (μCT). Changes in gene expression from the L4 vertebra were analyzed by RNA sequencing. Statistical analysis was performed using two-way ANOVA with CES and sex as factors. P < 0.05 was considered statistically significant. Results: At PND 10, there were no significant differences in BMD and BMC between the treatment groups, but tibial length was significantly decreased by CES. By PND 21, BMC and tibial area were significantly reduced in the CES group, indicating impaired bone mineral accumulation. At PND35, tibial length remained significantly reduced by CES, while BMD and BMC differences were less affected. L4 vertebral BMA and BMC were all reduced by CES. μCT analysis of tibial cortical bone showed significant changes in cortical thickness and bone volume at PND10 and 21, respectively. For the L4 vertebra, μCT data indicated significant increases in the degree of anisotropy and structural model index at PND21 and 35, respectively. Transcriptome analyses revealed significant differential expression of genes involved in immune response, cellular repair, and stress adaptation at PND 21 but not at PD10 and PD35. Conclusion: CES significantly disrupts BMC, BMD, length and microarchitecture differently at various stages of postnatal development. Transcriptome analyses suggests that these changes are mediated by alterations in gene expression related to immune function and cellular repair. Future research should focus on tracking the longitudinal impacts of CES on bone health from infancy into adulthood, and exploring nutritional interventions, stress reduction programs, and molecular studies that can mitigate the negative effects of CES on bone.
  • Item
    Does economic inequality really hurt democracy?
    (2024-07) Sourav, Hasan Habibur Rahman
    Scholars have shown great interest in the relationship between democracy and economic inequality for a long time. Based on the literature currently available, political scientists, economists, and academics from several disciplines concur that excessive economic inequality is detrimental to democracy. Scholars have generally depended on survey data or specific democratic metrics, which consistently demonstrate that as economic inequality increases, the quality of democratic institutions and public satisfaction with democracy decreases. To learn more about whether inequality hurts democracy as the current consensus suggests is my main objective for this paper. To do this, I am using survey data from the World Value Survey (WVS) and the core measurements of democracy from the V-Dem indices in conjunction with the disposable Gini inequality index from SWIID (Standardized World Income Inequality Data) to determine the potentially negative relationship between economic inequality and democracy. According to my research, while not all democratic procedures or institutions are harmed, an increase in economic inequality appears to negatively impact institutional democracy partially. Meanwhile, a growth in economic inequality has little effect on citizens' satisfaction with democracy. However, my findings mostly go counter to the body of existing research, and therefore, more research is necessary to comprehend the potentially detrimental consequences of inequality on democracy fully. Meanwhile, my research is the first of its kind given that I try to show economic inequality’s impacts on democracy through both democratic institutions and individual citizens’ assessment. Also, I take a broader account of democracy by using all five V-Dem core democracy indices which will help us to understand inequality’s impacts on democracy much more comprehensively.
  • Item
    Assessing dietary quality of collegiate track and field and cross-country athletes and relationship to performance
    (2024-07) White, Grace
    The purpose of this study was to determine the dietary quality (DQ) and nutrient adequacy of athletes in track and field only (TF) and athletes in both track and field and cross country (TF & CC) and determine the relationship between the nutrient adequacy and DQ of diets and physical performance of TF and TF & CC athletes. METHODS: A cross-sectional study was completed using 55 athletes. Tools included ASA24 24-hour food recall, the Healthy Eating Index (HEI) 2015, and Dietary Reference Intakes (DRIs), as well as looking at soft and hard tissue injuries, handgrip strength, and Pittsburgh Sleep Quality Index (PSQI) score. RESULTS: The average (standard deviation, SD) HEI score of participants was 66.9 (SD 14.79). There was a significant difference between male and female average HEI scores (p=0.003). Fifty-five percent of athletes were within the Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates, 100% for protein, and 47.3% for fat. A significant difference was seen in the number of soft and hard tissue injuries between participants within and not within AMDR range for carbohydrates (p=0.026). Multiple significant correlations were seen between mean hand grip and % kcal for macronutrients, % DRIs met, and HEI total and sub scores, including vitamin C % (r=-0.365, p=0.035), iron % (r=0.349, p=0.005), HEI total score (r=-0.311, p=0.021), total fruit score (r=-0.308, p=0.022), whole fruit score (r=-0.312, p=0.021), and refined grains score (r=-0.286, p=0.035). Significant correlations between PSQI scores and % kcal for macronutrients, % DRIs met, and HEI total and sub scores included folate (r=0.389, p=0.035), copper (r=0.289, p<0.001), magnesium (r=0.232, p=0.035), and potassium (r=0.385, p=0.023) % DRI met. CONCLUSION: Diets of TF & CC athletes need improvement in terms of overall DQ and macronutrient adequacy. Assessing and intervening to improve DQ may be beneficial for improving athletic performance. However, the HEI alone may not be the best tool to use for athletes in its current form. Overall, some results of this study did indicate a potential relationship between DQ and performance factors, but further research is needed to determine the extent of that relationship with a more appropriate DQ scoring system.
  • Item
    Conspiracy theories as a value game
    (2024-05) Winegarten, Jonathan David
    Many conspiracy theorists use conspiracy theories in order to justify harmful and false beliefs. Others use conspiracy theories as reasons to not trust others, especially experts. Yet, conspiracy theories are a unique form of false belief. Conspiracy theories seem to be self-insulated and are completely immune to counter-evidence, unlike other more mainstream scientific theories. Conspiracy theorists also seem to trust a completely separate set of experts than mainstream science. Building off of C. Thi Nguyen’s analysis of the gamification of Twitter, I aim to show that conspiracy theories gamify values in a similar way that Twitter does. Conspiracy theories switch values that experts care about (i.e., falsifiability, evidential support, etc.) with values that resonate with the experience of the conspiracy theorist (i.e., subjective clarity, safety, etc.) and notes this as “truth”. This connection of an explanation to some non-epistemic value helps self-insulate conspiracy theories by disguising claims about certain non-truth-related values as claims about truth. These gamified values also manipulate trust within the conspiracy theory by allowing for “experts” who share the same values of “truth” that the conspiracy theorist cares about. This is due to the fact that we naturally seem to trust those who share deeper values with us.
  • Item
    Dung beetle response to fire, grazing and experimental trap design
    (2023-05) Middleton, Gregory, Jr.
    Dung beetles (Coleoptera: Scarabaeidae) are important members of many ecosystems that contribute to dung decomposition and nutrient cycling. Dung beetle populations, however, have been in decline recently due to factors including habitat loss, increasing CO2 levels and anthelmintics like ivermectin, used to treat cattle parasites. Baited in ground pitfall traps are the most common method for capturing and observing dung beetles but are prohibited or unsuitable in some areas. Three alternative trap methods were deployed, and none were found to have a higher capture rate when compared to in-ground pitfall traps. Only 137 beetles were captured in the comparative study and additional trap development is warranted. Dung beetles are attracted to dung of large grazers including cattle and bison. Oklahoma has remnant prairies that support grazing along with improved pasture lands for beef animals. These areas need to be preserved for their biodiversity, and one management technique is prescribed burns. The effects of fire and types of grazers on dung beetles in the southern Great Plains has not been well-researched. Dung beetles were sampled in recently burned patches and recorded for one, four and nine weeks after the burn. Directly following a burn, dung beetle numbers were lower but recovered within 4 weeks. At the tallgrass prairie, 4,811 dung beetles were associated with bison grazing compared with 560 associated with cattle and goat grazing. These studies demonstrate that burning and mixed animal grazing maintain dung beetle communities.
  • Item
    Association between food insecurity and diet quality among pregnant adolescents and adolescent mothers in Ghana
    (2024-05) Posey, Isabelle Hunter
    Objectives: While adequate nutrition is essential for adolescents to achieve their growth and developmental potential, this need is even more critical among pregnant adolescents because of the negative impacts of inadequate nutrition on the growing young girl and the developing fetus. Food insecurity (FI) is a major global health problem and is likely a determinant of diet quality. However, data on diet quality and FI in this population remains limited. This study aimed to define diet quality and FI prevalence among pregnant adolescents and adolescent mothers in Ghana and examine the association between FI and diet quality. Methods: The Healthy Adolescent Nutrition in Ghana (HANIG) study was conducted in communities around Cape Coast, Ghana. As part of this community-based cross-sectional study, 422 adolescents aged 12-19 years old, pregnant (n=215) or with a child aged 5 years or less (n=207) were recruited from communities and health centers. FI information from the past month was collected using the Childhood Food Insecurity Experience Scale (CFIES). The Diet Quality Questionnaire (DQQ) described the diet quality indicators: Minimum Dietary Diversity for Women (MDD-W), all five recommended food groups (ALL-5), noncommunicable disease risk and protect (NCD-Risk and NCD-Protect), and Global Dietary Recommendations (GDR). Multiple logistic regression and multiple linear regression analysis was used to examine the association between FI and the diet indicators Results: Most participants reported FI, including 90.3% of mothers and 84.1% of pregnant adolescents. Overall, more than half participants met MDD-W (56.2%) and about a quarter met ALL-5 (23.2%). FI was associated with 60.7% greater odds of not meeting MDD-W (AOR= 0.393; 95% CI (0.20, 0.76); p=0.0057), a 0.64 decrease in NCD-Protect scores (β = -0.64, p =0.0042), and a 0.77 decrease in NCD-Risk scores (β = -0.77, p = 0.0032). Conclusions: FI is highly prevalent among pregnant adolescents and adolescent mothers in Ghana, and many are not reaching adequate diet diversity. Food insecurity was negatively associated with MDD-W, NCD-Protect, and NCD-Risk scores. Interventions to increase food security among this population are needed to address the high rates identified along with low dietary diversity.
  • Item
    Precision irrigation to improve greenhouse production by reducing water and fertilizer inputs of geranium, petunia, chrysanthemum, and poinsettia
    (2024-05) Morrison, Kayla
    Three different studies investigated optimal irrigation and fertilizer strategies to enhance water and nutrient use efficiency in ornamental crop production. For experiment 1, geranium and petunia plants were subjected to various irrigation methods (manual, tensiometer, and timer-based controller) and fertilizer rates (7 and 10 g controlled-release fertilizer) in a greenhouse. Petunia plants showed no significant interaction or main effects, while the -15 cb tensiometer setting for SPAD values and timer-based controller for root dry weight for geranium was significant. Water use efficiency (WUE) was not significant for either crop. In experiment 2, irrigation and fertilizer effects were again evaluated on poinsettia and chrysanthemum plants. For poinsettia, SPAD reading were greatest with -20 cb tensiometer irrigation and 10 g fertilizer, while all other parameters were greatest for the manual but not different than the timer-based controller. Chrysanthemum height, number of flowers, shoot and root dry weight were greatest with timer-based controller irrigation and 10 g fertilizer. There was an irrigation effect but the -15 and -20 tensiometers demonstrated the greatest WUE for poinsettia. In experiment 3, geranium growth and flowering was evaluated under different timer-based irrigation and fertilizer (3, 6, and 9 g) schedules. Watering 1 minute in the mornings with 6 g of fertilizer led to increased plant height, shoot dry weight, flower production, and WUE. Timer-based controlled irrigation methods showed promise in optimizing water and nutrient utilization, suggesting their role in reducing labor costs while maintaining crop quality. Optimum fertilizer rates varied from 6 or 10 g depending on the species.
  • Item
    Understanding the dynamics of violent recruitment of child soldiers in African conflicts
    (2024-05) Lako, Thomas Mark Joseph
    This study investigates the complex dynamics behind the violent recruitment of child soldiers in African conflicts, focusing on the impact of demographic pressures. Through the lens of Resource Mobilization Theory, I conduct quantitative analysis to understand how youth population density impacts the coerciveness of recruitment tactics used by rebel groups. I employ a negative binomial regression analysis on a country-year data spanning 9 African countries from 1984 to 2021. My findings indicate that while the proportion of youth is significant, socio-economic factors, including economic development, along with socio-political elements like liberal democracy, significantly shape recruitment tactics. These findings demonstrate the intricate interaction of demographic conditions and other factors in shaping recruitment tactics, underscoring the necessity for targeted interventions that tackle these underlying elements.
  • Item
    Impacts of aggregate gradation and glass fibers on concrete mixture
    (2024-05) Bani Maria, Mohd Hashem
    This study investigates the influence of aggregate gradation, glass fibers, and larger nominal maximum coarse aggregate size on the performance and properties of concrete mixtures. A novel bridge deck concrete mixture design was developed for the Minnesota Department of Transportation utilizing a mobile mixer, known as a "volumetric mixer truck," aimed at reducing carbon footprint. The design incorporated an improved aggregate gradation based on the optimized Tarantula Curve method. Testing was conducted to ensure the newly formulated mixture met the desired properties. Various tests, including assessments of fresh properties, Drying Shrinkage, Hardened Air Voids Analysis, Freeze-Thaw Durability, Split Beam Test, Ion Penetration Test, electrical resistivity, and Compressive Strength, were conducted. Further investigation focused on enhancing the concrete mixture by adding glass fibers using a fiber chopper attached to the volumetric mixer truck. This enhanced mixture underwent testing for fresh properties, split beam test, electrical resistivity, and compressive strength. Additionally, concrete mixtures with a 1.5-inch nominal maximum coarse aggregate size were prepared and tested. The Tarantula Curve design method was employed to adjust the coarse aggregate amount while maintaining the fine aggregate constant. The study examined the influence of the percent retained on the 1-inch sieve size on various aspects including workability performance, compressive strength, electrical resistivity, mass change, and shrinkage strain. Findings from these tests provide valuable insights into the performance characteristics of concrete mixtures with different aggregate gradations, inclusion of glass fibers, and variations in nominal maximum coarse aggregate size. This research contributes to the optimization of concrete mixture designs for improved structural performance and durability, particularly relevant for infrastructure projects.
  • Item
    Evaluation of the role of the current network of protected areas in conserving cold adapted predators of north america under climate change scenarios for 2050 and 2070
    (2017) Pandey, Ranjit
    Climate change has determined shifts in distributions of species and changing climates in the near future are likely to affect many species. In this study, we used ecological niche modeling to estimate the potential future distributions of apex predator and mesopredator species above 45° N in North America. We projected the niche models of apex predators and mesopredators on future climate datasets based on three Global Circulation Models and four greenhouse gas emission scenarios. We report average change in potential distributions of species for 2050 and 2070 at the extent of North America, as well as at subcontinental extents above 45° N and below 45 °N, to compare climate change effects on species’ distributions in colder and warmer regions of the continent, respectively. Under future climate scenarios, the potential distributions of all studied predators decreased at lower latitudes (below 45° N) and increased at higher latitudes (above 45° N) in North America. Furthermore, the potential distribution of the majority of apex predators decreased compared to that of mesopredator species. Estimate of change in potential distributions within current protected area system showed that all predator species, except for P. lotor in 2050, will have a higher percentage of potential distribution within protected areas both in 2050 and 2070. Species richness was predicted to increase at higher latitudes.
  • Item
    Impact of life experiences on risk-induced behavioral responses and a comparison of multiple types of risk responses
    (2024-07) Aguiar, Olivia K.
    Animals are exposed to different types of stressors throughout their lives. Stressors can range from temperature, competition, and predation risk. These stressors can occur with varying frequency and an individual may be exposed to multiple types of stress at the same time. This thesis endeavored to investigate how risk responses change with experience and if there is any relationship between different types of risk responses. In Chapter 1 I investigated how Physa acuta predation risk responses change with age and number of previous exposures. I studied risk responses through behavior by measuring time to exit water after being exposed to predator cue. I found that previous experience did not impact predation risk responses, but age did. Predation risk responses grew stronger as individuals became older, becoming strongest just before onset of reproduction. This result provides support for the asset protection principle. I also found that there were consistent individual differences in how individuals responded to predation risk, suggesting that individual identity is an important component of predation risk responses. Because of these results, I suggest that future investigations of predation risk responses control for age and consider individual identity. In Chapter 2 I compared the previous trends of predation risk responses to a toxicant risk response to determine if fear generalization was present, and investigated if exposure to multiple stressors at once affected risk responses. I found that P. acuta responded in similar ways to predation risk and atrazine risk. Responses to both types of risk became stronger as individuals became older and consistent individual differences were present. Individuals exposed to both types of risk during the experiment had a weaker negative relationship between age and time to exit water. However, responses to predation risk and atrazine risk were not correlated within individuals, suggesting that fear generalization was not present. I suggest that future investigations of fear generalization include multiple measures of behavior and consider weaker concentrations of atrazine than those used in this thesis. Overall, this thesis provided evidence that the asset protection principle may be driving risk responses, and although fear generalization was not supported it did demonstrate that there are similarities in trends between different types of risk responses.
  • Item
    Surficial geology of Cimarron River Valley from one mile east of Perkins eastward to Oklahoma Highway 18, North-central Oklahoma
    (1979-07) Nayyeri, Cyrus
    The main purposes of this thesis are to differentiate and map the diverse and widespread unconsolidated surficial deposits of Quaternary age and to reconstruct the geologic history of the study area. The study area encompasses approximately 150 square miles of North-Central Oklahoma: including the Cimarron River Valley from one mile east of Perkins eastward to Oklahoma Highway 18. This project includes a bedrock geologic map, a surficial geologic map, a geomorphic map, longitudinal profiles of alluvial surfaces, and cross-sections. Field work supplemented by the analysis of longitudinal profiles, aerial photographs, and topographic maps was used in mapping the surficial geology. Structurally, the study area is a part of the Central Oklahoma Platform, west of the Ozark Province and east of Nemaha Ridge. The Cushing Anticline, The Ingall Anticline, The Mehan nose, and The Ripley nose are local structures readily recognized in the subsurface. Geomorphically, the area lies in the Northern Limestone Cuesta Plains Geomorphic Province. The bedrock in the study area is characterized by alternating limestone, shale, and lenticular sandstone and is Lower Permian and Upper Pennsylvanian in age. Regionally, the bedrock within the study is a part of west-dipping homocline which varies from 30 to 50 feet per mile. Four major terraces and related deposits found within the study area are, from the oldest to the youngest, the Paradise Terrace, the Summit View Terrace, the Perkins Terrace, and the Lawrie Terrace. Flood plains border the Cimarron River and its tributaries, Stillwater Creek and Council Creek. Abrupt but subtle changes in flood-plain gradient along the Cimarron River apparently relate to changes in bedrock lithology beneath the bedrock valley. Projection of the Summit View Terrace and the Perkins Terrace on longitudinal profiles possibly indicates a distinct off-set between the north and south sides of the Cimarron River Valley. This off-set appears to be a possible fault system parallel to the axis of the valley. Only one unit of the Paradise Terrace has been mapped in the extreme western part of the study and the remnants of this unit in the rest of the area have possibly eroded away. Sand dunes of two ages (old and young) and eolian sand sheets were differentiated by their topographic feature and thicknesses of the soil developed from the aforementioned units in the study area. Clay mineral analysis of 25 samples collected from unconsolidated materials suggests that clay mineralogy may be useful in correlating terrace deposits that cannot be directly related to terrace surfaces. Clay mineral interpretation shows that most predominate clay constituents are mixed-layer clay, montmorillonite, kaolinite, vermiculite, illite, and chlorite. Grain-size analysis strongly suggests that distinct variations in texture of alluvial deposits are related to the amount of weathering that has occurred.
  • Publication
    Comparison of speech rate in individuals with Parkinson's disease and healthy controls
    (2024-05) Young, Ezekiel
    Speech rate deficits are commonly observed in individuals with Parkinson’s disease (PD). Previous literature has presented a variety of outcomes regarding the speech rate of individuals with PD compared to healthy controls, ranging from an increased speech rate to a decreased speech rate. The current study aims to determine the differences in speech rate profile between individuals with PD and healthy controls. Additionally, it attempts to determine the effect of stimulus on speech rate for those with PD compared to healthy controls as well as the correlation between demographic conditions and speech rate. This was achieved through collecting audio recordings of 62 individuals via Zoom and in-person meetings. These meetings included a monologue task, reading task, and picture description task. A repeated measures ANOVA was completed to determine the effect of stimulus on speech rate, and a Pearson bivariate correlation to determine correlation between demographic information and speech rate. The findings of this study found that the participants with PD presented with a significantly faster speech rate compared to the neurologically healthy participants, especially when focusing on the picture description task. The author suggests that the cognitive burden coupled with cognitive-linguistic differences in those with PD may have contributed to the differences in speech rate profile between those with PD and the healthy controls. Additionally, only a significant positive correlation between speech rate and MoCA score was determined in this study, suggesting a faster rate of speech in those with higher cognitive functioning. Further research is required to determine the true nature of speech rate deficits in the overall population of those with Parkinson’s disease.