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Ocean-Ice Sheet Interactions During Super-Interglacial Mis 31: Comparison Of Rock Magnetic Records From The Scotia Sea (59.1°S) And Fram Strait (76.5°N), Olga Libman-Roshal Aug 2025

Ocean-Ice Sheet Interactions During Super-Interglacial Mis 31: Comparison Of Rock Magnetic Records From The Scotia Sea (59.1°S) And Fram Strait (76.5°N), Olga Libman-Roshal

Theses, Dissertations and Culminating Projects

The mid-Pleistocene transition (MPT) was a period spanning ~1.2-0.7 Ma when glacial-interglacial cyclicity changed from 41 kyr obliquity paced to 100 kyr eccentricity paced cycles with increased glacial-interglacial contrast post-MPT. Marine Isotope Stage (MIS) 31 was a “super-interglacial” within the MPT and occurred in the recent geological past (1.08-1.06 Ma). During MIS 31, the tectonic configuration resembled the present day, but Earth’s orbital parameters were marked by maximum values of eccentricity and obliquity while atmospheric CO2 remained at pre-industrial levels (below 280 ppm). MIS 31 therefore offers a valuable baseline for testing the impacts of modern anthropogenic CO2 levels combined …

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Improved Autofluorescence Lifetime Decay Analysis For Identification Of Cellular Autofluorescence Biomarkers For Label-Free, Single-Cell Assessment Of Mitochondrial Membrane Potential, Olivia Isabel Kolenc Aug 2025

Improved Autofluorescence Lifetime Decay Analysis For Identification Of Cellular Autofluorescence Biomarkers For Label-Free, Single-Cell Assessment Of Mitochondrial Membrane Potential, Olivia Isabel Kolenc

Graduate Theses and Dissertations

Optical imaging of metabolism using the autofluorescence of the metabolic cofactors NADH, NADPH, and FAD has a wide range of sensitivities and the capability to collect a great deal of metabolic information. Multiphoton microscopy (MPM) is a non-invasive, label-free optical imaging technique capable of performing fluorescence lifetime imaging (FLIM) using time correlated single photon counting (TCSPC). However, autofluorescence FLIM presents a challenge in collecting sufficient photons to provide adequate signal to noise ratios (SNR) for analysis. Additionally, the specificity of autofluorescence biomarkers of metabolism has not been well-defined. Contextualizing these autofluorescence measures using established functional biomarkers can improve interpretability of …

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How To Do Things With Little Talking Tubes: Nonideal Speech Acts In The Digital Age, Anthony Holdier Aug 2025

How To Do Things With Little Talking Tubes: Nonideal Speech Acts In The Digital Age, Anthony Holdier

Graduate Theses and Dissertations

In this work, I develop a view about what it means to share a social or conversational context with others, as well as what is normatively entailed by doing so. Working from a broadly Austinian perspective about the moral foundations of language use and how we use words to position ourselves within social space, as well as from a generally Stalnakerian social ontology (demarcating groups by dint of aligned or overlapping sets of commitments), I present three papers demonstrating how nonidealized, ordinary language philosophy can make sense of complex, real-world phenomena. Through analyses of heretical utterances, context collapse, and chatbot …

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Growth And Characterization Of Thin Film Gase On Si(111) And Sio2/Si(001) Substrates By Molecular Beam Epitaxy, Christopher John Hocevar Aug 2025

Growth And Characterization Of Thin Film Gase On Si(111) And Sio2/Si(001) Substrates By Molecular Beam Epitaxy, Christopher John Hocevar

Graduate Theses and Dissertations

Gallium selenide (GaSe) is a thin-film semiconducting material with promising optoelectronic properties, including a tunable bandgap, high photosensitivity, and atomic-layer scalability. These characteristics make it suitable for devices such as photodiodes, FETs, MOSFETs, Hall effect sensors, and p–n diodes. In this study, GaSe thin films were grown on SiO2 and Si(111)-7×7 substrates using molecular beam epitaxy (MBE) to compare growth behavior across different substrates. The films were characterized using Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) spectroscopy, and reflection high-energy electron diffraction (RHEED). RHEED confirmed the 7×7 reconstruction of the Si(111) surface and the amorphous nature …

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The Effects Of Background Child-Directed And Adult-Directed Singing On Reading Comprehension Performance, Agnes Yeboah Amfo-Adu Aug 2025

The Effects Of Background Child-Directed And Adult-Directed Singing On Reading Comprehension Performance, Agnes Yeboah Amfo-Adu

Graduate Theses and Dissertations

Although music features in speech, such as those found in child-directed speech and song, are known to enhance language processing, the underlying mechanism of this benefit remains unclear. Prior research has primarily compared verbal materials presented in a musical, child-directed style to those in a less musical, adult-directed style, leaving it uncertain whether the benefit stems from the music style of verbal presentation or mere exposure to musical features. This study examined whether the language benefits of child-directed input persist when it is presented as background auditory stimuli rather than the primary focus of cognitive tasks. Experiment 1 found that …

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This Is Fine: A Reflexive Case Study On Beliefs, Institutional Rhetoric, And The Quiet Despair Of Capstone Completion, Dana Turner Blair Aug 2025

This Is Fine: A Reflexive Case Study On Beliefs, Institutional Rhetoric, And The Quiet Despair Of Capstone Completion, Dana Turner Blair

Graduate Theses and Dissertations

For graduate students, capstone writing is often a stressful process that involves significant obstacles to progress. This dissertation presents an exploratory multi-case study of four graduate capstone writers to examine how institutional contexts and rhetoric shape students’ beliefs and related emotions and behaviors during the high-stakes, low-structure settings of capstone research projects. Data for this study was collected through interviews and reflexively compared with reflections from the principal researcher. To gather insights into the relationship between writers’ internal beliefs and institutional contexts, interview excerpts were analyzed according to both cognitive behavioral coaching and institutional critique frameworks. Findings indicated that students …

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Predicting Case Clearance For Victims Of Anti-Transgender Homicide In The United States, Brittaney Alyssa Mann Aug 2025

Predicting Case Clearance For Victims Of Anti-Transgender Homicide In The United States, Brittaney Alyssa Mann

Graduate Theses and Dissertations

There is a shortage of research exploring case clearance of anti-transgender bias homicides. This study will comparatively examine the similarities and differences in anti-transgender bias homicide cases with and without arrests at the victim, situational and incident levels occurring in the United States between 2013 and 2023. Data are extracted from the Bias Homicide Database (BHDB), the National Coalition of Anti-Violence Programs (NCAVP), and the Human Rights Campaign (HRC). This project will address the gap in understanding case clearance of anti-transgender bias homicides, provide policy implications, and ideas to further the discipline’s understanding of the topic. Keywords: LGBTQIA+ victims, bias …

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Backpack Funding: What Happens When Dollars Follow The Student?, Alison Heape Johnson Aug 2025

Backpack Funding: What Happens When Dollars Follow The Student?, Alison Heape Johnson

Graduate Theses and Dissertations

A growing movement in the United States in recent years, accelerated by the COVID-19 pandemic, has brought a wave of school choice policies, which allow students to opt into an educational arrangement outside of their zoned traditional public schools (TPS) using public funds. Critics frequently express concern that these policies place an undue financial burden on both taxpayers and school districts. States adopting such policies may take on the additional financial responsibility of educating students who would otherwise privately finance their education, posing an additional cost to the state. When students do leave TPS to participate in private school choice …

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Exploring The Relationship Between Adhd, Mood Disorders, And Motivation Among Women Studying For The Ged: A Preregistered Study, Amanda Dawn Kennedy Aug 2025

Exploring The Relationship Between Adhd, Mood Disorders, And Motivation Among Women Studying For The Ged: A Preregistered Study, Amanda Dawn Kennedy

Graduate Theses and Dissertations

Adult women with Attention Deficit Hyperactivity Disorder (ADHD) and mood disorders, such as anxiety and depression, represent an understudied and underserved demographic within educational research, particularly among those pursuing nontraditional academic pathways, such as obtaining the high school equivalency diploma (i.e., GED). Despite the well-documented challenges associated with ADHD and mood disorders, including difficulties with motivation, executive functioning, and emotional regulation, little research has examined how these factors influence women’s persistence and success in adult education settings. Understanding the unique experiences of this population is essential for developing targeted support systems that enhance learning outcomes and academic achievement. This study …

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Measuring The Impact Of Ged Preparation On Ged Testing Outcomes, Matthew Utz Aug 2025

Measuring The Impact Of Ged Preparation On Ged Testing Outcomes, Matthew Utz

Graduate Theses and Dissertations

This quantitative study investigates the relationship between participation in GED preparation programs and GED test outcomes among adult learners at a single Adult Basic Education (ABE) center located in an urban area of a south-central U.S. state. Recognizing the significance of the GED as an alternative credential to a traditional high school diploma, the research examines how instructional hours and structured preparation correlate with students’ final scores in mathematics, English language arts, social studies, and science. The study also describes the demographic characteristics of the learners, including gender, race, and age groups, and analyzes their performance on the Test of …

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Navigating Stigma And Privacy: Health-Related Communication Among Bangladeshi Women, Nazmul Shajib Aug 2025

Navigating Stigma And Privacy: Health-Related Communication Among Bangladeshi Women, Nazmul Shajib

Graduate Theses and Dissertations

Women in Bangladesh often silently bear the burden of stigma tied to their bodies, minds, and societal roles. This study examines the coping strategies women use to manage health-related stigma and their privacy while facing issues like reproductive health, mental health, and postpartum challenges. The study was conducted by utilizing in-depth interviews with 17 Bangladeshi women. Stigma Management Communication Theory (SMC) and Communication Privacy Management Theory (CPM) are the two frameworks that guided the study. The findings of the study reveal that stigma often silences women and threatens their social identities, and women feel that having a health problem means …

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End Times: American Mortality, Death Materiality, And Social Death In The 1990s, Jordan A. Savage Aug 2025

End Times: American Mortality, Death Materiality, And Social Death In The 1990s, Jordan A. Savage

Graduate Theses and Dissertations

The United States in the 1990s was marked by pervasive representations of death in popular culture. As death imagery became increasingly visible in entertainment, there was a growing detachment from the embodied, biological realities of death, a tension intensified by the ongoing AIDS crisis. This project explores how death is politicized and how decisions about who lives and dies are shaped by power. I draw on a constellation of theoretical frameworks that collectively illuminate the operations of state-sanctioned death and social abandonment. These include Michel Foucault’s concept of biopolitics, which examines the management of life by state power; Giorgio Agamben’s …

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A Grounded Theory Investigation Of The Experiences Of Rehabilitation Administrators, Counselors, And Supervisors Providing Services To Women With Disabilities Experiencing Intimate Partner Violence, Dana Posey Aug 2025

A Grounded Theory Investigation Of The Experiences Of Rehabilitation Administrators, Counselors, And Supervisors Providing Services To Women With Disabilities Experiencing Intimate Partner Violence, Dana Posey

Graduate Theses and Dissertations

Abstract There is a noticeable gap in the literature as it relates to how rehabilitation and disability service providers have worked with women with disabilities who have experienced intimate partner violence. To address the dearth of knowledge, a qualitative grounded theory study was conducted with 12 rehabilitation administrators, counselors, and supervisors regarding their experiences providing services to women with disabilities who have been in or are in an intimate partner violence relationship. Semi-structured interviews were administered, recorded, and transcribed verbatim in an ongoing manner throughout the process. As data was collected, it was analyzed using NVIVO 15, which is a …

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The Influence Of Retail Display Conditions On Ground Beef Quality And Palatability, Sarah Lynn Shoup Aug 2025

The Influence Of Retail Display Conditions On Ground Beef Quality And Palatability, Sarah Lynn Shoup

Graduate Theses and Dissertations

The objectives of these studies were to evaluate the impact of retail display case type and muscle type on meat quality attributes, including color, lipid oxidation, texture, and volatile compound profiles, as well as to assess economic implications based on retail color degradation. Case type effects were further evaluated by considering environmental factors such as temperature, air velocity, and relative humidity and their influence on the shelf life of beef patties. An economic analysis was also conducted to estimate the value of patties based on a* (redness) scores at different points during retail display. In Study 1, differences in L* …

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Freezing And Shipping Optimization To Increase Quality And Profitability Of Meat E-Commerce, Paul Olaoluwaniyi Dahunsi Aug 2025

Freezing And Shipping Optimization To Increase Quality And Profitability Of Meat E-Commerce, Paul Olaoluwaniyi Dahunsi

Graduate Theses and Dissertations

Freezing remains one of the most reliable methods for preserving meat quality and extending shelf life. However, quality deterioration can still occur due to structural and biochemical changes activated during freezing, thawing, and distribution. Since the COVID-19 pandemic, consumers’ preference for bulk purchasing and online meat shopping has increased, raising questions about the best strategies to balance both quality maintenance and profitability. This thesis aimed to evaluate two key stages where frozen beef is most vulnerable to quality degradation: consumer-level freezing and post-purchase shipping. The objectives were (1) to determine the effects of product size and subsequent consumer freezing practices …

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The Black Bombers Of Ghana: Sport, Nation-Building And Pan-Africanism, 1958 To The 21st Century, Kenneth Tagoe Aug 2025

The Black Bombers Of Ghana: Sport, Nation-Building And Pan-Africanism, 1958 To The 21st Century, Kenneth Tagoe

Graduate Theses and Dissertations

Ghana’s Amateur Boxing Team, known as the Black Bombers, has impacted the country’s political and socio-economic development since its formation in 1958. This thesis argues that amateur boxing was one of the sports that Kwame Nkrumah, Ghana’s first president, used to promote nation-building and, more broadly, a Pan-African agenda. The team’s success in international competitions has widely projected Ghana's sporting reputation and reinforced the Pan-African principles of Black pride and excellence in the global athletics arena, and beyond. This thesis traces the origins of amateur boxing and the formation of the Black Bombers, the squad’s participation in international athletics events …

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A Multicomponent Microneedle Patch For The Delivery Of Meloxicam For Veterinary Applications, Katherine Alejandra Miranda Munoz Aug 2025

A Multicomponent Microneedle Patch For The Delivery Of Meloxicam For Veterinary Applications, Katherine Alejandra Miranda Munoz

Graduate Theses and Dissertations

Veterinary medicine requires innovative drug delivery strategies to enhance therapeutic efficacy while minimizing stress and handling. This dissertation explores the development and application of biodegradable microneedle patches for the transdermal delivery of meloxicam in livestock, offering a minimally invasive alternative to traditional administration methods. The research investigates the fabrication and characterization of microneedles using polyvinyl alcohol, collagen, and chitosan blends, demonstrating their mechanical strength, biocompatibility, and ability to facilitate sustained drug release. In vitro and in vivo evaluations confirm effective skin penetration, dissolution, and localized drug delivery. Pharmacokinetic studies highlight anatomical site-dependent variations in drug absorption, emphasizing the need for …

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End Times: American Mortality, Death Materiality, And Social Death In The 1990s, Jordan A. Savage Aug 2025

End Times: American Mortality, Death Materiality, And Social Death In The 1990s, Jordan A. Savage

Graduate Theses and Dissertations

The United States in the 1990s was marked by pervasive representations of death in popular culture. As death imagery became increasingly visible in entertainment, there was a growing detachment from the embodied, biological realities of death, a tension intensified by the ongoing AIDS crisis. This project explores how death is politicized and how decisions about who lives and dies are shaped by power. I draw on a constellation of theoretical frameworks that collectively illuminate the operations of state-sanctioned death and social abandonment. These include Michel Foucault’s concept of biopolitics, which examines the management of life by state power; Giorgio Agamben’s …

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Firm Disclosures And Retail Investor Behavior: The Role Of Information Type, Disagreement, And Social Networks, Hansol Yoon Aug 2025

Firm Disclosures And Retail Investor Behavior: The Role Of Information Type, Disagreement, And Social Networks, Hansol Yoon

Graduate Theses and Dissertations

This paper examines whether disclosure characteristics–specifically hard versus soft information–influence disagreement among retail investors, whether due to differences in information sets or interpretation, and how such disagreement subsequently affects trading volume. Using a sample of 85,050 earnings conference calls and StockTwits disagreement data from 2010 to 2021, I find that hard information (i.e., earnings figures) is negatively associated with investor disagreement, while soft information (i.e., forward-looking statements) is positively associated with it. Further analysis reveals that the disclosure characteristics impact trading activity only indirectly, through their influence on investor disagreement. Additionally, I examine the moderating role of social network centrality, …

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Impact Of Lighting Wavelength On Broiler Behavior, Health, And Performance, Angela Perretti Aug 2025

Impact Of Lighting Wavelength On Broiler Behavior, Health, And Performance, Angela Perretti

Graduate Theses and Dissertations

Lighting influences broiler production, health, and behavior. Due to their advanced visual system, avian species perceive a wide spectrum of light. The objective of this study was to investigate the effects of white (W, 350 to 780 nm) blue (B, 450 nm), and green (G, 560 nm) light on broiler production, processing performance, activity, fear, stress, blood cell profiles, tibiotarsi (tibia) morphology, and depth perception. Day-of-hatch by-product chicks from a Cobb 500 female line (N=600) were randomly assigned to 12 pens (N=4 treatment replicates). Body weight and feed consumption were recorded on day (D) 0, 14, 28, and 41, and …

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Small Angle X-Ray Scattering Studies Of Collagenase H Mutant, Colh-E416q, Madelyn Millsap Aug 2025

Small Angle X-Ray Scattering Studies Of Collagenase H Mutant, Colh-E416q, Madelyn Millsap

Graduate Theses and Dissertations

Collagenase H (ColH) from Hathewaya histolytica plays a central role in collagen degradation through endopeptidase and carboxytripeptidase reactions. To better understand how its domain architecture supports these functions, we examined the solution structure of a catalytically inactive mutant, ColH-E416Q, using small-angle X-ray scattering (SAXS). The E416Q mutant is catalytically inactive because the glutamate residue at position 416, which normally functions as a general acid/base during catalysis, is replaced by glutamine—an amide that cannot donate or accept protons effectively, thus disabling the proton transfer steps essential for peptide bond hydrolysis. SAXS results indicate that the E416Q substitution leaves overall domain architecture …

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Cotton Yield And Tissue-Potassium Response To Potassium Fertilization, Maria Paula Ramos Do Prado Aug 2025

Cotton Yield And Tissue-Potassium Response To Potassium Fertilization, Maria Paula Ramos Do Prado

Graduate Theses and Dissertations

Potassium (K) deficiency is a common yield-limiting factor in cotton (Gossypium hirsu tum L.) production across the U.S. Cotton Belt. Adequate fertilizer-K management is paramount to ensure optimum plant growth and development, minimizing yield losses. Currently, fertilizer K recommendations for cotton in Arkansas are derived from expected yield responses of other crops, with no calibrated fertilizer-K rates or critical tissue-K concentrations defined to maxim ize crop yield. Our research objectives were i) to investigate cotton yield response and fiber qual ity to K fertilization on soils with different K availability; ii) to correlate relative yield with tis sue-K concentrations at …

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Effect Of Dietary Tryptophan Supplementation And Heat Stress On Pasture Broiler Welfare And Performance, Jaelen Matthew Cherry Aug 2025

Effect Of Dietary Tryptophan Supplementation And Heat Stress On Pasture Broiler Welfare And Performance, Jaelen Matthew Cherry

Graduate Theses and Dissertations

Pasture-raised broiler chickens face temperature extremes that can threaten welfare. In the study, we evaluated whether a 0.26 % tryptophan-supplemented diet (T) improved heat stress (HS) resilience in Ross-708 broilers raised on pasture. At D14, birds began the T or remained on the control diet (C) and were moved outdoors. On D20 and 41, half of each group underwent six-hour HS; the remainder stayed under thermoneutral (TN) conditions. Weekly body weight, feed intake on D20 and D41 were recorded, and fear was measured using the Tonic Immobility (TI) test. Neither diet nor HS affected body weight. However, tryptophan supplementation resulted …

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Minor League: The Journey To The Show, Collin Anderson Aug 2025

Minor League: The Journey To The Show, Collin Anderson

Graduate Theses and Dissertations

When thinking about the path an athlete takes to get to the major leagues, many think of the same process: High School, College, Professional. However, the professional level includes is more than just the MLB or NBA that people would assume. Almost all professional U.S. sports leagues have a minor league system associated with them that nearly all players pass through at one point or another. Through the lens of a documentary, this portion in an athlete’s journey will be spotlighted to show what these leagues do for them, how they help them improve, and how they prepare them to …

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Strain Induced Quantum Emitters In Monolayer Wse₂: Fabrication And Characterization Of Dimple Dot Devices, Garrett Maxwell Kitterman Aug 2025

Strain Induced Quantum Emitters In Monolayer Wse₂: Fabrication And Characterization Of Dimple Dot Devices, Garrett Maxwell Kitterman

Graduate Theses and Dissertations

Strain induced defects in monolayer tungsten diselenide (WSe₂) give rise to localized exciton funnels, offering a promising approach for the development of tunable quantum emitters. The quantum devices fabricated for this thesis used a modified dimple dot geometry, in which nano indentation creates a strain profile on the monolayer WSe₂. This allows for the funneling of excitons to a confined region. These strain induced funnels enable localized emission from single excitons in WSe₂. Device fabrication was carried out through mechanical exfoliation, dry transfer, and electron beam lithography of Cr/Au gates on a SiO₂ substrate. These devices were then characterized using …

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Cultural Vibrations: Student Power, International Exchange, And Black America In Mai 1968, Noah Micheal Roberts Aug 2025

Cultural Vibrations: Student Power, International Exchange, And Black America In Mai 1968, Noah Micheal Roberts

Graduate Theses and Dissertations

Abstract This thesis examines the prominence of Black Americans in the 68’ student movement in France. May 68’ incorporated a diverse and global network of social movements and political organizations, and had a notable connection to the American student movement. Black Americans had formed a large expatriate community in France which overlapped with many of the transnational connections forged by the student movements of 68’. This community was extremely notable in the French public sphere for popular works of literature and music, but its political contributions have been minimized or understudied. By utilizing student accounts, state and organizational records, and …

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Rural Peer Helpers Speak: How One Program Makes A Difference, Misty S. Whisenhunt Aug 2025

Rural Peer Helpers Speak: How One Program Makes A Difference, Misty S. Whisenhunt

College of Education

The problem this mixed-methods convergent research study aimed to explore was the increasing incidence of rural high school students performing poorly academically, socially, and emotionally. This mixed-methods convergent research study aimed to examine one peer helper program as perceived by rural high school peer helpers. This research study aimed to answer the following research questions: (1) How do rural high school peer helpers perceive their experience as a peer helper? (2) What are the key elements of Thriveway’s Peer Helpers PLUS Program as perceived by rural high school peer helpers? (3) How effective is Thriveway’s Peer Helpers PLUS Program’s training …

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Cooling Climate Across Last Interglacial High Stands On San Salvador And Great Inagua, The Bahamas, Ian Winkelstern, Sierra Petersen, H. Allen Curran, Cecilie Phillips, Alex Quizon, Bosiljka Glumac, David Griffing Aug 2025

Cooling Climate Across Last Interglacial High Stands On San Salvador And Great Inagua, The Bahamas, Ian Winkelstern, Sierra Petersen, H. Allen Curran, Cecilie Phillips, Alex Quizon, Bosiljka Glumac, David Griffing

Geosciences: Faculty Publications

The last interglacial (LIG) is the last time global climate was about as warm as today, with global sea-levels several metres higher. The LIG probably had a re- duced latitudinal temperature gradient, with warmer poles and cooler tropics than today. Well-constrained records from low latitudes can test this overall model. We used bivalve shells sampled from six localities thought to expose the LIG age Cockburn Town Member of the Grotto Beach Formation on both San Salvador and Great Inagua Islands, The Bahamas. Previous work described two LIG depositional intervals: older ‘Reef I’ and younger ‘Reef II’, separated by a disconformity. …

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Kinematic Representations Of Viscoelastic Postseismic Deformation, John Loveless, Brendan J. Meade Aug 2025

Kinematic Representations Of Viscoelastic Postseismic Deformation, John Loveless, Brendan J. Meade

Geosciences: Faculty Publications

Abstract Following large earthquakes, viscoelastic stress relaxation may contribute to postseismic deformation observed at Earth's surface. Mechanical representations of viscoelastic deformation require a constitutive relationship for the lower crust/upper mantle material where stresses are diffused and, for non‐linear rheologies, knowledge of absolute stress level. Here, we describe a kinematic approach to representing
geodetically observed postseismic motions that does not require an assumed viscoelastic rheology. The core idea is to use observed surface motions to constrain time‐dependent displacement boundary conditions applied at the base of the elastic upper crust by viscoelastic motions in the lower crust/upper mantle, approximating
these displacements as …

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Mode Regulates Alternative Nitrogenase Expression In Themethanogen Methanosarcina Acetivorans, Melissa Chanderban, Daniel J. Lessner Aug 2025

Mode Regulates Alternative Nitrogenase Expression In Themethanogen Methanosarcina Acetivorans, Melissa Chanderban, Daniel J. Lessner

Biological Sciences Faculty Publications and Presentations

All methanogens that can fix nitrogen use molybdenum (Mo) nitrogenase. Some methanogens, including Methanosarcina acetivorans, also contain alternative vanadium- and iron-nitrogenases, encoded by the vnf and anf operons, respectively. These nitrogenases are produced when there is insufficient Mo to support Mo-nitrogenase activity. The factors that control the expression of the alternative nitrogenases in response to Mo availability are unknown in methanogens. Here we show that ModE is the regulator that represses transcription of the vnf and anf operons in M. acetivorans when cells are grown with Mo. CRISPRi repression of modE results in a significant increase in the transcription of …

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