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Numerical Calibration of the Cambrian Earth-System and Paleoproterozoic Assembly of Western Laurentia via High-Precision U-Pb Geochronology
No full textThe rock record is the archive of events and processes that control the evolution of our ever-changing planet; from granites born deep in the heart of an orogenic belt under tremendous heat and pressure to sandstones deposited on a quiescent passive margin. A long-held question in geology is how do we transpose this rock record into time? It is not a simple question as the Earth operates on many different timescales, from the timescale of burial during orogenesis, to the timescale of deposition during sea level rise, to the timescale of biotic evolution. There are indicators all around us that provide a relative timescale when viewed through the laws of superposition, cross-cutting relationships, and inclusion. However, these do not provide a numerical timescale; for that we must harness the spontaneous decay of unstable radionuclides. The steady radioactive decay of uranium to lead within the zircon lattice as long been known as a chronometer able to record numerical time on the scale of millions to billions of years. The gold standard method for making these measurements is chemical abrasion isotope dilution thermal ionization mass spectrometry, which can be complemented with microbeam methods like laser ablation inductively coupled plasma mass spectrometry place to numerical constraints on the timing and duration of Earth processes in deep time. The chapters below describe my use of U-Pb geochronology using both techniques to explore the timescales of diverse earth processes.
In chapter one of my dissertation, I outline the methods, results, and implications of high-precision U-Pb geochronology and Bayesian age modeling applied to different temporal-scales and geologic processes preserved in rocks of the American west. In chapter two, I develop a novel application of high-precision U-Pb zircon geochronology, high resolution trilobite biostratigraphic compilations, and Bayesian age modeling to refine the global Furongian (late Cambrian) timescale, and the timing, duration, and causes of the Steptoean Positive Isotopic Carbon Excursion (SPICE) from a stratigraphic section in northeastern Utah. In chapter three I take the methods explored in chapter two and apply them to the unique stratigraphic record of the Cambrian Tonto Group of Grand Canyon. In doing so, I created the first lateral Bayesian age model, which has implications for the tempo of the Sauk transgressions, the Cambrian Explosion, associated global carbon cycle perturbations, and the Miaolingian timescale. In chapter four I present high-precision U-Pb zircon and titanite geochronology from Proterozoic rocks of the Lower Granite Gorge of the Grand Canyon, which archive the assembly of the North American continent. The new radioisotopic ages presented herein offer a unique snapshot into the timescales of middle crustal tectonometamorphic processes during orogenesis
Induction of Hypohalous Acid Formation by Photoinducible Carbon Nitride Complexes
No full textDue to the continuous rise in antibiotic resistance, there is an urgent need to develop novel antimicrobial compounds and therapeutic approaches to combat biofilm-associated infections. The rise in antibiotic resistance has contributed significantly to increased global healthcare costs. Graphitic carbon nitrides are photoinducible, metal-free semiconductors that release free electrons when irradiated with 405 nm light. These free electrons interact with atmospheric oxygen to produce reactive oxygen species (ROS) that can further interact with halide ions (Cl-, Br-, I-) to form hypohalous acids, such as hypochlorous acid (bleach) that have antimicrobial activity. In this thesis research, a specific carbon nitride formulation that incorporated a nonasodium nonatungstobismuthate hexadecahydrate (Na9[α-β-BiW9O33] · 16H2O) catalyst, was evaluated for enhanced ROS generation and subsequent hypohalous acid production. Compared to the carbon nitride complex alone, incorporation of the (Na9[α-β-BiW9O33] · 16H2O) catalyst led to increased antimicrobial activity against Gram-negative Pseudomonas aeruginosa (PAO1) biofilms. The mechanisms of antimicrobial action were evaluated by analyzing the production of ROS and reactive halogen species (RHS) and the halogenation of quorum-sensing molecules using high-performance liquid chromatography coupled mass spectrometry (HPLC-MS). The ultimate goal of examining these carbon nitride complexes is to develop novel treatments for chronic wounds, biofilm infections, and other topical applications in the healthcare industry
Lowering Barriers to Voting for Individuals with Disabilities: Mail in Ballots and No Excuse Absentee Ballots
No full textThe right to vote is an important part of the democratic process in America, but for individuals with disabilities it may not be as simple as simply showing up on election day and voting. Individuals with disabilities may face multiple barriers when it comes to voting. This paper looks at some of the common barriers to voting for individuals with disabilities, and focuses on ways that could improve turnout for individuals with disabilities. I look specifically at the data on mail in ballots and absentee ballots as a way to improve turnout for voters with disabilities. We do know from the data that reducing barriers to voting in the 2020 election increased voter turnout for all voters. The minor changes made could help give us a path forward to help increase turnout for voters with disabilities
Infrasound from Snoqualmie Falls, WA, USA
No full textThis is one of the datasets referred to in a paper on waterfall infrasound by Anderson, Ortiz, and Barber, that relates a waterfall\u27s infrasound to its physical characteristics (height, discharge, and power), maps infrasound power over the waterfall\u27s surroundings, and models audibility distance for pigeons as an example of a well-studied infrasound-sensitive animal
What Women Intercollegiate Coaches Say: Decision-Making Factors When Navigating Career Choices
Get PDFTo address misconceptions about the lack of women in sport coaching, factors influencing intercollegiate women coaches\u27 career decisions, including their choices to leave positions, apply for new ones, and accept or deny job offers were explored. Utilizing a multi-level analysis underpinned by critical feminist theory, a comprehensive understanding of the systemic and structural barriers women coaches faced, as well as the strategies they employed to navigate their careers were illuminated. Key findings revealed that unequal pay, lack of administrative support, insufficient resources, and pervasive gender biases significantly impacted women\u27s career choices. The importance of supportive workplace environments, flexible working conditions, professional development opportunities, and organizational commitments to diversity and inclusion emerged as crucial for attracting and retaining women coaches. By gathering women coach’s perspectives (n = 118, NCAA Division I, II, and III), data refuted common ‘blame the women’ narratives and emphasized the need for systemic change within intercollegiate sports. This research contributed to the ongoing dialogue on gender equity and practical strategies for athletic departments to create more inclusive and supportive environments, thereby enhancing the recruitment and retention of women coaches are offered
Representing Structural Isomer Effects in a Coarse-Grain Model of Poly(Ether Ketone Ketone)
Get PDFCarbon-fiber composites with thermoplastic matrices offer many processing and performance benefits in aerospace applications, but the long relaxation times of polymers make it difficult to predict how the structure of the matrix depends on its chemistry and how it was processed. Coarse-grained models of polymers can enable access to these long-time dynamics, but can have limited applicability outside the systems and state points that they are validated against. Here we develop and validate a minimal coarse-grained model of the aerospace thermoplastic poly(etherketoneketone) (PEKK). We use multistate iterative Boltzmann inversion to learn potentials with transferability across thermodynamic states relevant to PEKK processing. We introduce tabulated EKK angle potentials to represent the ratio of terephthalic (T) and isophthalic (I) acid precursor amounts, and validate against rheological experiments: The glass transition temperature is independent to T/I, but chain relaxation and melting temperature is. In sum we demonstrate a simple, validated model of PEKK that offers 15× performance speedups over united atom representations that enables studying thermoplastic processing-structure-property-performance relationships
Dataset for Mechanical Properties of Eye Lens Cortical and Nuclear Membranes and the Whole Lens
No full textPurpose: To elucidate the mechanical properties of the bovine lens cortical membrane (CM), the nuclear membrane (NM) containing cholesterol bilayer domains (CBDs), and whole bovine lenses.
Methods: The total lipids (lipids plus cholesterol) from the cortex and nucleus of a single bovine lens were isolated using the monophasicmethanol extraction method. Supported CMs and NMs were prepared from total lipids extracted from the cortex and nucleus, respectively, using a rapid solvent exchange method and probe-tip sonication, followed by the fusion of unilamellar vesicles on a flat, freshly cleaved mica surface. Topographical images and force curves for the CMs and NMs were obtained via atomic force microscopy (AFM) in a fluid cell. Whole bovine lenses were affixed to custom-built glass Petri dishes, and an AFM was used to obtain force curves. Force curves were analyzed to estimate the breakthrough force, membrane stiffness (KA and Em), and lens stiffness (EL).
Results: The NMs containing CBDs exhibited significantly lower breakthrough force, KA, and Em than the CMs without CBDs. The Em values for CMs and NMs were significantly higher than the EL for the whole lens.
Conclusions: The significantly higher stiffness of the CM and NM compared to the stiffness of the whole lens suggests that slight modulation in CM and NM composition may play a crucial role in altering the overall lens stiffness. Furthermore, the NMs containing CBDs were less stiff than CMs without CBDs, suggesting that CBDs decrease lens membrane stiffness and possibly protect against lens hardening and presbyopia
Bridging the Gap: GFRP Bar Integration in Natural Fiber Reinforced Concrete Pavement Joints
No full textThe construction industry is increasingly adopting sustainable practices, with Natural Fiber Reinforced Concrete (NFRC) emerging as a promising eco-friendly alternative to conventional concrete. While NFRC exhibits enhanced mechanical and thermal properties, its application in pavement systems remains underexplored, largely due to limited research on its performance and load transfer behavior. Traditionally, steel dowels are used to transfer loads across pavement joints, but their susceptibility to corrosion undermines long-term durability. Glass Fiber Reinforced Polymer (GFRP) bars offer a corrosion-resistant, sustainable alternative while maintaining structural integrity. This study investigates the potential of GFRP dowels in improving joint performance in NFRC pavements incorporating flax fibers. In the initial phase, flax fibers were used to partially replace cement by weight and fine aggregates by volume at 0.5% and 1%. Cement replacement led to minor reductions in compressive strength but improved flexural strength, with increases in the modulus of rupture by 4.4% and 8.66%. Building on these results, the study will (a) optimize flax fiber content for enhanced mechanical properties, (b) evaluate load transfer efficiency of GFRP versus steel dowels, and (c) perform pullout tests to assess bond strength. These efforts aim to advance the structural viability of GFRP-reinforced NFRC in sustainable pavement applications
Measuring Flow Rates on the Perrine Coulee Using Photogrammetry and UAS
No full textWater flow measurement is crucial for managing water resources, irrigation, and environmental monitoring. In dry, semi-arid, steppe climates, such as those found in Southern Idaho, management of water flow is critical for providing reliable information to water managers. Traditional methods like weirs and current meters offer reliable, direct measurements but can be infrastructure-intensive, time-consuming, cause in-stream disturbance, and be limited in scope. This project compares these conventional techniques with photogrammetry and Unmanned Aircraft Systems (UAS), which provide a non-contact, high-resolution approach for estimating discharge. UAS-based photogrammetry can potentially offer rapid, wide-area data collection and minimize in-stream disturbance. The current study analyzes the accuracy and drawbacks of both approaches, aiming to demonstrate how these advanced technologies can complement or possibly replace traditional methods for more comprehensive water resource assessments
Virtual Fencing LoRa Frequency Comparison
No full textThe goal of this research is to evaluate the suitability of two different radio frequencies for usage in Virtual Fencing technology. The radios being compared operate in the 2400 and 915 MHz bands, both common for LoRa networks. They are being compared based on several factors relevant to their performance in Virtual Fencing applications. We are measuring straight line performance as well as obstructions from terrain, foliage, and other obstacles that are likely to be encountered in this application. We aim to measure and quantify the performance advantage of the 915mHz radio in these scenarios. Both radios perform exceptionally well in a line-of-sight scenario with minimal obstructions. However, the 915mHz radio demonstrates a significantly reduced rate of signal integrity decrease with distance