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The Pattern Electroretinogram as an Indirect Measure of Dopaminergic Status in Iron Deficiency
Get PDFAnimal studies have suggested that iron deficiency negatively affects dopamine (DA) synthesis and reuptake, which in turn negatively affects memory and cognition. However, the literature on the possible relationships among iron deficiency, DA dysregulation, and deficits in memory and cognition in humans is sparse. This study was intended to assess whether the pattern electroretinogram (pattern ERG) could be used as an indirect measure of DA in college-age women and to assess the extent to which the features of the pattern ERG were related to measures of iron levels and measures of cognition. For the pattern ERG to be useful as an indirect measure of dopamine in the context of iron deficiency, at least two things need to be true. First, the features of the pattern ERG should be sensitive to variations in blood measures of iron. Second, the features of the pattern ERG need to be related to other measures that have been suggested as indirect measures of DA, such as blink rate. It is known that DA is present in the retina, and because the pattern ERG measures retinal activity, it has been used in a variety of contexts to assess dopaminergic functioning. The pattern ERG was measured in a total of 21 iron deficient non-anemic (IDNA) and 21 iron sufficient (IS) women, who also performed a contrast detection and probabilistic selection task, both with concurrent electroencephalography (EEG). In addition, both their spontaneous and task-related blink rates were measured. The implicit times of the two features of the pattern ERG—the A- and B- waves –were significantly longer for the IDNA than for the IS women. Both the amplitudes and implicit times of the A- and B-waves were significantly correlated with levels of serum ferritin (sFt). However, only the amplitude of the A-wave was correlated with spontaneous blink rate. IDNA women had higher contrast detection thresholds and lower levels of accuracy in the probabilistic selection task than did the IS women. Finally, there was evidence that the implicit times of the ERG features, as proxy measures of DA, mediated the relationship between iron levels and accuracy levels. The results suggest the utility of the pattern ERG in testing the hypothesis that iron deficiency affects DA levels in humans and that this may be on the mechanisms by which iron deficiency negatively affects cognition
Understanding the impacts of environmental, economic, and policy factors on developing economies
Get PDFThe first chapter of this dissertation studies the long-term effects of climate conditions during an individual's birth year on their life cycle. Drawing on data from the India Human Development Survey and monthly rainfall data from the Global Historical Climatology Network, the study focuses on adults born between 1965 and 1978. The analysis reveals that higher rainfall levels during the birth year are associated with improved socioeconomic outcomes in an individual's health, schooling, and income over time. However, the presence of birth-year rainfall volatility has a contrasting negative impact, with men experiencing a stronger effect compared to women due to pre-existing gender inequality in India. Notably, regions relying on rice farming show heightened susceptibility to the influence of rainfall on health and schooling during adulthood. These findings underscore the significance of early-life climate conditions, particularly the importance of adequate nutrition during infancy, in shaping an individual's long-term well-being. In the second chapter, we delve into the evaluation of the IMF's Structural Adjustment Programs (SAP) and their impact on the IMF's yearly growth predictions for member countries. The analysis centers on a dataset consisting of 158 countries during the period from 1990 to 2004. The Structural Adjustment Programs were implemented by the IMF in the early 1980s and required member countries to fulfill specific conditions to receive loan tranches. We find that the IMF tends to overestimate future growth in countries subjected to a higher number of SAP conditions. This research sheds light on the IMF's perception of SAP allocation and its implications for a country's future growth. The effectiveness of SAP remains a contentious topic, and these findings contribute valuable insights into how these programs may impact a country's economic prospects. In the third chapter, the impact of China's Cleaner Production Law on firm behavior and long-term investment decisions is studied using a Synthetic Difference-in-Differences (SDID) framework. We focus on the role of county governments' environmental budgets in shaping firms' investment decisions, highlighting the importance of effective monitoring mechanisms. Although the implementation of environmental laws resulted in changes in firm behavior, we did not find statistically significant reductions in pollution levels after the implementation of the law. This is owing to the fact that pollution levels are affected by multiple variables apart from manufacturing activities. We also run a battery of sensitivity tests to check the validity of our results and find that the main results are consistent across various frameworks
Improving Quantification of Nanoscale Interactions by Engineering Monodisperse Gold Nanoparticles
Get PDFMechanisms of nanoparticle-cell interactions are dependent upon the size of the administered nanoparticles. At pre-clinical and clinical levels, precise control over the size and monodispersity of nanoparticles is required to produce consistent, effective, well-understood results. Gold nanoparticles (AuNPs) are a commonly used model nanoparticle for understanding nano-bio interactions based on AuNPs relative ease of synthesis and characterization. While ensemble characterization methods of AuNPs made using citrate-based synthesis approaches indicate relative size monodispersity, single nanoparticle analytical techniques reveal a wide size distribution. This wide size distribution decreases confidence in exact size-interaction correlations within nano-bio interactions and confounds sensitivity of single nanoparticle analysis. There is a need for AuNPs possessing a lower size distribution for improving single cell and single nanoparticle analyses of nano-bio interactions. In the current dissertation, single particle inductively coupled mass spectrometry (SP-ICP-MS) is used to characterize AuNPs synthesized using two different synthesis methods – citrate-based and CTAC-based – to identify differences in size monodispersity. Our analysis confirmed that CTAC-based AuNPs possess a tighter size distribution compared to citrate-based AuNPs. SP-ICP-MS was used to assess size prediction and synthesis scale-up models for each of the two synthesis methods. Further, AuNP growth kinetics of CTAC-based synthesis were characterized. AuNPs synthesized using CTAC-based methods are innately cytotoxic, making them unfit for biomedical use immediately after synthesis. To overcome this challenge, different methods of surface modification were developed that improved biocompatibility and biofunctionalization of CTAC-based AuNPs. SP-ICP-MS measurements confirmed that surface modification strategies did not result in a change in monodispersity, maintaining a tight size distribution for CTAC-based AuNPs. Biocompatible, biofunctional CTAC-based AuNPs were compared to citrate-based AuNPs in cell viability, cell uptake, and surface ligand interaction experiments. The overall findings of these results provide tools and methods by which highly monodisperse AuNPs may be synthesized, modified, and applied to better understand nano-bio interactions. Further, these results illuminate the possibilities and advantages of applying biocompatible monodisperse AuNPs in nanomedicine
Study of advanced resonant photonic gratings in the mid-infrared spectrum for the chemical sensing applications
Get PDFThis dissertation focuses on developing advanced Mid-IR optical devices for chip-scale chemical sensing. Various Mid-IR techniques based on Beer-Lambert’s law offer valuable insights into molecular interactions but suffer from bulkiness and
high cost. Towards the compact and cost-effective sensing purpose, many efforts have been made in light sources (e.g., QCLs), photodetectors (e.g., PbSe, MCT detectors), and gas sampling chambers via on-chip photonic waveguides. Despite
the progress achieved through these new technologies, there is still plenty of room for enhancing the performance and cost-effectiveness of miniaturized Mid-IR gas sensing systems.
Thus, this dissertation explores new photonic engineering pathways to address existing challenges through on-chip integration and downsizing in three core mid-IR gas sensing components, including the light source, detector, and interaction path. In this dissertation, a simple yet versatile and powerful resonant grating platform has been utilized as the foundation to develop innovative engineering methods. Herein, due to the nontrivial properties of High Contrast Gratings
(HCGs), such as broadband reflectivity, and high Q factor resonance, I focus mostly on these types of grating resonators.
Through a new design, HCGs are used to enhance absorption in uncooled PbSe-based photodetectors. Moreover, for shrinking the interaction path, a high
Q factor HCG resonator was designed, showing 600 times light absorption
enhancement in a micro-size path length. Furthermore, integrating active HCGs
with Parity-Time (PT) symmetry concept offers near-zero bandwidth photonic
resonant emission with application in Mid-IR light sources. Besides the
exploration of new photonic design methods, another important aspect of this
work has been focused on the development of a suitable mid-IR material platform to allow the implementation of the aforementioned photonic design methods.
Specifically, a modified chemical deposition method is used to synthesize
Oriented-Attached (OA) PbSe nanocrystals (NCs) on amorphous substrates
with strong quantum confinement and broad size-tunability. This optimized and
cost-effective growth technique demonstrates promising illumination in the
Mid-IR range, contributing to the potential of OA PbSe NCs synthesized by this
novel method as a material for fabricating Mid-IR photonic components. At the
end of this dissertation, an experimental exploration of a low-cost and large-area
patterning nanofabrication method is also presented as an extended effort from
the core photonic design and novel material synthesis works towards the
overarching goal to develop smaller, cost-effective, and efficient on-chip mid-IR
optical devices for chemical sensing applications
Does economic redistribution affect voting for populist radical right parties in Europe?
Get PDFThis thesis adds to our understanding of what contributes to populist radical right voting by looking at the role of redistribution in relation to populist radical right voting. Additionally, the empirical testing in this thesis utilized European regional level data to examination a closer connection between redistribution and voting data. To investigate this relationship, first the threat posed to liberal democracy by the populist radical right is examined and suggested as a reason to lower populist radical right voting. Classifications of the populist radical right are then considered, particularly clarifying how this party family differs from fascism. Arguments regarding the growth of the populist radical right are presented. These are categorized into cultural and economic arguments. The former considering identity and racism, as well as a clash of values between generations; while the latter considers economic insecurity, precarity of work, inequality, and social mobility as reasons for populist racial right growth. Ultimately though the section concludes that these reasons often do not need to be mutually exclusive.
The methodology to examine the relationship between populist radical right voting and redistribution is provided. OLS regressions were used with voting as the dependent variable and redistribution as the prime independent variable. Redistribution is measured by subtracting the post-tax and transfers Gini coefficient of a region from the pre-taxes and transfers coefficient from that region. The main finding of this testing is that redistribution appears to have no effect on populist radical right voting, but poverty has a positive, statistically significant relationship with it. Accordingly, a discussion of the connection between poverty and populist radical right voting is offered, as well as a consideration of whether inequality should be considered unimpactful on populist radical right voting since redistribution is. This latter discussion is left as an open question with a call for more research into the psychological impacts of redistribution
Finding the Key: Unlocking Engagement & Alleviating Anxiety Through Escape Rooms
No full textTo celebrate National Library Week, RSU Libraries created a custom escape room entirely from scratch with little-to-no previous escape room experience. This session will cover the design, development, and implementation process of our unique escape room experience. We will share the challenges we faced and the innovative solutions we devised to create a successful and engaging escape room. Attendees will leave with practical tips and insights on how to create their own escape rooms from scratch, as well as the benefits of incorporating this type of activity into library programming. Whether you have experience with escape rooms or not, this session will inspire you to think creatively and take risks in your programming efforts.N
Towards a More Inclusive Flute Pedagogy: Analysis and Pedagogical Strategies for the Teacher to Facilitate Student Learning of Odd-Year Oklahoma Honor Band Flute Audition Etudes
Get PDFThe purpose of this study is to provide a pedagogical guide for students preparing the odd-year honor band flute audition etudes in Oklahoma. This document expands access to specialized flute instruction and is a resource for students in all regions of Oklahoma. The etudes in this document were analyzed, leveled based on the National Flute Association (NFA) leveling criteria, and matched with pedagogical advice appropriate to the level determination. This analysis was then used to determine learning outcomes expected of beginning, intermediate, and advanced level flute students in Oklahoma. To determine the performance skills and associated technical problems expected at each level, several band and flute method books were evaluated.
The summary that follows the etude analyses details the various problems associated with learning the flute and addresses each in turn. The pedagogical summary includes instruction to overcome the following list of issues associated with playing the flute: poor instrument balance, poor hand position, poor tone quality, technique issues, inconsistent articulation, poorly managed breath control, weak low register tone and projection, and poor upper register response, intonation, and dexterity
Evolution of the Tornado and Near-Tornado Wind Field of the Selden, Kansas Tornadic Supercell on 24 May 2021 Using a Rapid-Scan, X-Band, Mobile, Doppler Radar
Get PDFOn 24 May 2021, a supercell in Selden, KS produced tornadoes which were probed by RaXPol, the University of Oklahoma’s rapid-scan, mobile, X-band, polarimetric Doppler radar. According to the National Weather Service, the primary tornado was on the ground for 30 minutes and attained a maximum width of 850 yards as a multiple vortex tornado. Throughout this time, the tornado produced EF-1 damage in and around Selden. RaXPol was deployed twice on this tornado; RaXPol moved once as the tornado was approaching. During the first deployment, data from shortly after tornadogenesis to right after a transition to multiple vortex phase were collected. After rapidly redeploying to a safer location, data were then recorded from the end of the tornado’s multiple vortex phase through its dissipation. While the cyclonic tornado was ongoing during the second deployment, a strong anticyclonic vortex or marginal tornado at the southern end of the Rear Flank Gust Front (RFGF) passed directly over RaXPol. Along with a high-definition video taken of the cyclonic tornado from the first deployment location, the high-resolution data collected by RaXPol throughout the lifespan of both vortices provide a rare opportunity to correlate structural features of the cyclonic tornado, anticyclonic vortex, and cyclonically rotating parent supercell to changes in tornado movement and behavior. Using the data captured by RaXPol, a thorough analysis of the tornado pair and the parent supercell was completed and cross sections through both vortices were constructed through their respective Doppler velocity couplets roughly perpendicular to the radar beam. Ultimately, the RaXPol data help to construct a detailed narrative of the Selden tornado pair.
RaXPol observed several important phenomena concerning the Selden tornado pair. Numerous significant shifts in the track of the primary cyclonic tornado were identified, and the tornado as well as its parent low-level mesocyclone were observed to occlude with time leading up to the tornado’s dissipation. During analysis, various Rear Flank Downdraft momentum surges (RFD surges) were identified, and they were found to be of critical importance to the occlusion and track behavior of the Selden tornado. The transition of the Selden tornado into and out of a multiple vortex phase were also observed, and the initial transition of the tornado into its multiple vortex phase was found to be the result of a temporary inflow disruption associated with RFD surges. While the primary cyclonic tornado was ongoing, RaXPol observed two independent anticyclonic vortices with different behavior, including a ‘rogue’ anticyclonic vortex and the marginally tornadic anticyclonic member of the Selden tornado pair. The ‘rogue’ anticyclonic vortex appeared very near the Selden tornado for a brief time, and numerous ideas for its origin and nature are discussed. The marginally tornadic anticyclonic vortex was found to form when a potent RFD surge impinged on the southern end of the RFGF, and the vortex was observed to occlude in a similar manner as the primary Selden tornado leading up to its dissipation
Development and characterization of advanced nanocomposites with enhanced mechanical and thermal properties
Get PDFThe mechanical and thermal properties of composites made of polydimethylsiloxane (PDMS), glass micro-balloons (GmBs), and carbon nanotubes (CNTs) were investigated in this thesis. The objective of this study was to determine the effects of varying concentrations of GmBs and CNTs on the mechanical, resistive, and thermal behavior of the composites. The experimental approach involved preparing composite samples using a casting method, where the PDMS polymer was mixed with a fixed 1.25% of CNTs and varying concentrations of GmBs. The mixing and casting process was carefully crafted to ensure no GmBs were crushed during the process and to allow for quality samples to be produced for more accuracy during testing. Next, the samples were then subjected to mechanical and thermal tests to evaluate their properties. The mechanical properties were evaluated using two main types of tensile tests, testing until fracture and cyclic testing. During these tests the resistivity properties were measured to determine the max resistance change and the repeatability of the resistance measurements. The thermal properties were evaluated using LFA technology to determine the thermal diffusivity and to calculate thermal conductivity. Finally, the resistance was measured while the sample underwent heating to determine the effects of temperature on resistance. The results of the study showed that the incorporation of GmBs and CNTs in PDMS improved and can alter the mechanical, resistive, and thermal properties of the composite material. The addition of GmBs resulted in a significant decrease of the thermal conductivity while increasing the resistance change during tensile tests. Those samples with the highest loadings of GmBs had the best resistance stability at the widest temperature range. The combination of GmBs and CNTs resulted in a synergistic effect, where the material properties of the composite were enhanced to a greater extent than when either component was added alone. Overall, these experiments added valuable insight to the abilities of CNT and GmB composites, but farther testing can still be completed. Testing higher loadings of GmBs would be very beneficial but more complex mixing methods would be required. Since the CNT loadings remained constant, varying the CNT amount could possibly make the material properties more favorable for different applications
Improvement and Characterization of Direct-Ink-Write Manufactured Continuous Fiber Reinforced Photopolymer Matrix Composites
Get PDFFiber reinforced polymer (FRP) composites play a significant and continuously growing role in engineering applications that require high strength, weight optimized structural components. Additive manufacturing (AM) has proven to be an extremely powerful tool in expanding the limits of part complexity and optimization. The present work aims to combine the two by reliably and efficiently additively manufacturing continuous fiber reinforced thermoset polymer composites. Building off previous efforts, a novel 3D printer was refined that utilizes direct ink write (DIW) technology to simultaneously extrude both an in-situ cured UV resin and continuous reinforcing fiber. Improvements to the system ensured that the most common failures were significantly mitigated or eliminated. The capabilities of the printer, specifically the maximum print size, were also increased by a wide margin. The printer’s more predictable state allowed the creation of samples for material characterization. Tensile specimens showed strengths as high as 209 MPa and an average tensile modulus of 19.5 MPa. Volume fraction testing using carbonization in a nitrogen atmosphere gave an average fiber volume fraction of 8.3%. These are competitive with the results of other investigations of similar continuous fiber AM processes. The printed material was further characterized with scanning electron microscopy, showing that the bonding between matrix layers and resin impregnation within fibers were both ideal. Printed cones and honeycombs also showed that the process can produce complex geometry. Future efforts can serve to increase the fiber volume fraction and overall strength optimization of the printed material. The introduction of new materials into the process, like fiberglass or nanoparticles, could also change the properties of the products to have better curing behavior or higher strength