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Criminal Organizations and Nuclear Threats in Southeast Asia
No full textIncreasing global interest in nuclear energy and peaceful uses of nuclear technology has led to facilities in emerging countries with nuclear materials and radioactive sources that could be stolen, sabotaged, or otherwise accessed by criminals. In this paper, we created a framework to assess the motivations and capabilities of criminal networks and measure the threats they may pose to different stages of the nuclear fuel cycle in emerging nuclear states. We applied the framework to a unique dataset, capturing characteristics of criminal organizations active in Southeast Asia, which allowed us to assess which criminal organizations are most likely to pose a threat to nuclear security in the region. We found that local Southeast Asian criminal groups are relatively immature in the threats they may pose to nuclear security, but criminal groups with bases outside the region may be more likely to possess the motivations and capabilities associated with nuclear security risk. This finding has implications for nuclear security policy
The Caitlin Clark Effect: Evidence of Athlete-Driven Market Disruption in Women’s Collegiate Basketball
No full textCaitlin Clark’s emergence as a generational collegiate basketball talent triggered a profound shift in consumer behavior, known as the “Caitlin Clark Effect” (CCE) (Lucas, 2025). This study examined attendance and venue utilization data from the University of Iowa’s women’s basketball program, spanning pre-, during-, and post-Clark periods. Results from one-way ANOVA analyses showed a statistically significant increase in average game attendance (home, away, and neutral), rising from 5,387 pre-Clark to 13,877 in her senior year (p \u3c .001), with a sustained post-Clark average of 9,890. Arena capacity utilization followed a similar trajectory, increasing from 37.3% to 92.4%. Notably, post-Clark utilization remained at 74.3%, indicating durable fan interest. These findings provide time-sequenced evidence of a singular athlete catalyzing lasting institutional and market change in women’s collegiate sports. The study advances sport business theory by illuminating the strategic implications of athlete-driven branding and challenges assumptions underpinning facility planning and resource allocation
Increased Cholinergic Activity in the Prefrontal Cortex Attenuates Opioid-induced Respiratory Depression Through Gain Modulation in C57BL/6J Mice
No full textSafety and Safeguards for Molten Salt Reactors in Integrated Energy Systems
Get PDFThe research conducted in this work investigates the dynamic behavior of a fast spectrum molten salt reactor (MSR) when used in an integrated energy system (IES) with both a regenerative Rankine heat cycle balance of plant for electricity production and a hydrogen production plant using the hybrid sulfur thermochemical cycle. The research was accomplished by constructing dynamic models of the systems in OpenModelica, debugging, and making a combined IES model. From there, a suite of simulations were performed on the models meant to determine the systems’ response to three types of accidents: reactivity initiated accidents (RIA), loss of flow accidents (LOFA), and loss of heat sink accidents (LOHSA). Also included in this research is analysis of multiple types of safeguards techniques for MSRs with a specific focus on a novel technique whereby passive monitoring of the MSR’s offgas provides unique plutonium signatures in a timely manner. The other MSR safeguards techniques discussed are frequency analysis, archival monitoring, and accountancy transition. The overarching goal of the research is to make a comprehensive safety and safeguards investigation of the use of an MSR in an IES as a means of promoting awareness of the benefits of the technology and improving its potential deployability
Mapping Global Environmental Change Under Current Conditions and Projected Future Climate Scenarios with Machine Learning
Get PDFAnthropogenic climate change is the greatest threat our world faces. Because the impacts of climate change are linked to location, mapping is a meaningful way to convey results. I map 3 different phenomena and investigate methodological improvements and the associated uncertainty of acid deposition, heat waves, and soil organic carbon. My research on acid deposition updates the 2010 global budget for reactive nitrogen and sulfur components, improving the results of models from the second phase of the United Nation’s Task Force on Hemispheric Transport of Air Pollution (HTAP-II). My analysis is a step towards the World Meteorological Organization’s goal of global products for mapping harmful air pollution. Acid deposition is also relevant to the future climate; one potential response to climate change is stratospheric aerosol injection (SAI), where sulfur dioxide is injected into the stratosphere to block incoming solar radiation. I use outputs from the Geoengineering Model Intercomparison Project (GeoMIP) to track sulfur deposition from SAI through comparison with historical climate and two future Shared Socioeconomic Pathways (SSPs). My research emphasizes the lack of agreement between models and the importance of resolving these conflicts. The most common and recognizable climate change indicators are those related to temperature. However, most studies rely on a single dynamically downscaled model or an ensemble of statistically downscaled models. My work evaluates future heat wave risk in the US with an ensemble of dynamically downscaled models and an ensemble of statistically downscaled models. My results emphasize the importance of state-of-the-science modeling techniques for fine-resolution, domain-specific climate projections. In order to mitigate climate change, decarbonizing many industries will need to be a priority. A requirement of this work is an understanding of baseline soil organic carbon (SOC), before it is modified. My research focuses on SOC in the US from the 1980s to the present day. I incorporate satellite imagery, climatic and land use variables, and apply machine learning methods to produce high resolution, temporally and spatially continuous maps. Overall, my research aims to elucidate the human and environmental costs of climate change and bring clarity to complex, multidimensional data through mapping techniques and thorough analysis
Applications of Reduced Order Modeling Techniques in Computational Neuroscience
Get PDFHuman brains are highly nonlinear dynamical systems comprised of neurons that communicate through electrical and chemical synapses. These neurons produce brain rhythms which play a functional role in cognitive processes. The disruption of these cognitive processes through abnormal brain rhythms can result in a variety of neurological disorders, such as Parkinson’s disease, epilepsy, and treatment-resistant depression. This work is motivated by the importance of understanding neural brain rhythms in both experimental and computational settings. In this work, we implement model reduction strategies, specifically phase and phase-amplitude reduction, to explore and analyze neural behavior from a reduced order framework. Using these model reduction techniques, we develop a control strategy that drives a population of synchronized neural oscillators towards a desynchronized state, mirroring the effect of deep brain stimulation on pathologically synchronized neural oscillators. We then examine the impact of synaptic plasticity on critical coupling strength estimates for a population of inhibitory neurons with all-to-all coupling. Finally, we derive terms for a data-driven phase-amplitude model of a complicated network of neuronal subnetworks with a complex coupling structure and additive noise
Neuroendocrine mechanisms contributing to individual differences and experience-dependent plasticity in stress-related behavior
No full textStress is a contributing factor in the etiology of several mood and anxiety disorders, and animal models of social defeat have been used to investigate the biological basis of stress-related psychopathologies. Syrian hamsters are highly aggressive and territorial, but after social defeat they exhibit a conditioned defeat (CD) response which is characterized by increased submissive behavior and a failure to defend their home territory against a smaller, non-aggressive intruder. We have previously shown that obtaining a dominance status in male hamsters will contribute to a reduced conditioned defeat response compared to subordinate counterparts. We have also shown that dominant males obtain greater androgen receptor (AR) expression and display greater expression of c-Fos+ cells in the posterior medial amygdala (MeP) after social defeat exposure compared to subordinates. Together, this suggests that the development of a dominance status contributes to neuroplasticity in the MeP including neuroendocrine mechanisms such as AR that contribute to the resistance of social defeat stress. The overall goal of the research projects in this dissertation was to discover neuroendocrine mechanisms that contribute to experience-dependent changes in stress-related behavior. The overarching hypothesis that distinct neuroendocrine mechanisms in the MeP contributes to changes in stress vulnerability in dominant and subordinate hamsters. Chapter 1 provides an overview of the current literature with aims for the research conducted. Chapter 2 investigated whether male and female hamsters differ in their patterns of agonistic behavior during the formation and maintenance of dominance relationships. Chapter 3 investigated whether AR+ cells in the MeP are activated during social defeat stress or testing for anxiety-like behavior in dominant and subordinate male hamsters. Chapter 4 aimed to determine whether activation of MeP and medial prefrontal cortex (mPFC) neurons are associated with female status-dependent differences in resistance to social defeat stress and defeat-induced loss of social motivation. Chapter 5 tested whether AR expression in BNST-projecting MeP cells is essential for resistance to social defeat stress in dominant males. Collectively, these projects delineate neuroendocrine mechanisms by which dominance status influences stress-related behavior
An evaluation of vegetation response and forage availability for Odocoileus virginianus to fire seasonality in pine ecosystems in the southeastern United States
Get PDFI evaluated the response of vegetation composition and structure, forage availability, and nutritional carrying capacity (NCC) for white-tailed deer (Odocoileus virginianus) in four seasons of burning nine pine stands in Tennessee, Mississippi, Alabama, and South Carolina, 2020–2023. I used data that we collected during the growing seasons of those four years to examine changes in composition, structure, and selected white-tailed deer (Odocoileus virginianus) forage to dormant season (January–March), early growing-season (April–May), mid-growing-season (June–July), and late growing-season (September–October) prescribed fire after two treatment iterations. I observed significant changes in the plant community and structure. Fire treatments moved the composition of the understory to more herbaceous species, which increased species diversity indices and resulted in a more open structure compared to the unburned Control stands. Quality of selected deer forages increased after two iterations of fire treatments, where all burned units had a greater nutritional carrying capacity compared to unburned Control units. My results highlight the importance of burning during all seasons of the year to enable more burn opportunities and grater flexibility in managing for white-tailed deer as well as other wildlife species
Impact of Estrous Active Behavior and HEAT on Intrafollicular Hormone and Metabolite Levels in the Preovulatory Follicle in Beef Heifers
No full textEstrual females exhibit estrous active behaviors and varying levels of higher estrous associated temperatures (HEAT). This hormonally induced, sexually related form of exercise, alone or in combination with elevated body temperature affects circulating metabolites. To evaluate the extent to which intrafollicular components are impacted, preovulatory follicular fluid hormones and metabolites were compared in heifers that were comingled with others or restricted from engaging in estrus active behaviors. Estrus was induced in Angus heifers using a seven-day controlled internal drug release (CIDR)-PGF2α protocol. Vaginal temperature was recorded every 5 min using a Thermochron iButton. Estrus was defined as the first time a heifer stood to be mounted. Treatments were assigned alternately. Preovulatory follicle fluid was aspirated ~11.9 h after first mount and submitted for ultra-high-performance liquid chromatography-high resolution mass spectrometry metabolomic analysis (106 metabolites identified). Hierarchical linear regression models were performed using hormone and metabolite abundance (dependent variables) and total area under HEAT curve, treatment (estrous active or restricted) and respective interaction. Best fit models were determined using backwards manual selection. Intrafollicular and serum levels of estradiol ~11.9 ± 0.4 hours after 1st mount were negatively related to HEAT. Restricted heifers had higher intrafollicular estradiol levels compared to those allowed to comingle with others after 1st mount. Twelve follicular fluid metabolites were related to HEAT (P \u3c 0.05). Significantly enriched pathways (FDR \u3c 0.1) included ‘Pyrimidine metabolism’. Abundance of 25 other metabolites differed by treatment (P \u3c 0.05); all were higher in the preovulatory follicular fluid of heifers restricted from engaging in estrous active behaviors. Significantly enriched pathways (FDR \u3c 0.1) included ‘Arginine biosynthesis’ and ‘Phenylalanine, tyrosine and tryptophan biosynthesis’. Twelve other metabolites were interactively influenced by HEAT and estrous active behaviors. In summary, preovulatory follicle progression in estrual heifers is more advanced in females exhibiting estrous active behaviors and experiencing greater levels of HEAT. These initial, LH-induced changes are pivotal for granulosa cells to transition into lutein cells. Advanced follicle progression likely impacts the cumulus oocyte complex contained therein and other components that may be involved in events important for setting stage for ovulation later
Evaluation of a Novel 3D Proton Beam Tracking System Utilizing Radar Imaging
No full textProton therapy, a form of cancer treatment that involves the use of high-energy protons to destroy cancerous tissue, currently lacks a standardized method for physical quality assurance of the proton beam’s location, instead relying fully on computational simulations. The present thesis reports, to the author’s knowledge, the first evidence for the use of radar waves as a physical quality assurance method for proton therapy. This method works due to absorption and refraction interactions between the radar waves and the free electrons generated by interactions between the protons and the patient’s tissues during proton therapy treatment (similar to a plasma). Previous research has shown that radar waves can be used to image plasmas, but this has generally been used for the purposes of aircraft stealth or visualization of plasma movement within the ionosphere. However, this phenomenon has not currently been used for a medical application. The purpose of this thesis is to provide preliminary data that supports the use of radar waves to track the proton beam as well as address some of the challenges associated with the design of such a system (e.g., antenna placement, antenna shielding, electrical noise). The data in this thesis indicates that the 6 GHz radar system used for testing purposes is capable of detecting the presence of what is likely a relatively low-frequency plasma source (similar free electron generation to the proton beam), although significant modifications (e.g., carrier frequency) must be made to the system to image a patient