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Assessing the Potential for Magmatic Sulfides within Southwestern Laurentia Large Igneous Province
No full textThe ~1.1 Ga magmatism of the Southwestern Laurentia Large Igneous Province (SWLLIP) generated a series of mafic-ultramafic sheets, sills, and dikes emplaced within Mesoproterozoic sedimentary units and older crystalline basement rock throughout the southwest United States and northern Mexico. This large igneous province (LIP) event remains enigmatic in identifying the processes that generated this magmatism. In addition, potential links to the contemporaneous magmatism of North America\u27s magmatic Ni-Cu-platinum group element (PGE) mineralized Mid-Continent Rift (MCR) LIP to the northeast of the SWLLIP remain unclear. The contemporaneous 1.1 Ga MCR LIP event hosts economically viable magmatic sulfide deposits in the Duluth Complex in Minnesota and elsewhere, providing further incentive to understand the links between the LIP events as well as independently assessing the mineral exploration potential for magmatic sulfide deposit formation within the SWLLIP. This study aims to further our knowledge of the petrogenesis of the SWLLIP and the potential of this magmatic event to host magmatic sulfide mineralization.
Whole-rock geochemical and Pt, Pd, and Au data have been obtained for 52 SWLLIP samples from California, Arizona, and New Mexico, allowing an initial assessment of the petrogenesis, magmatic sulfide fertility, sulfide saturation status, and crustal contamination of magmas of the SWLLIP to be assessed. All these factors are critical in determining the potential for this LIP to host magmatic Ni-Cu-PGE sulfide mineralization. Two suites have been identified within the SWLLIP that define two distinct magmatic pulses during the LIP event: a potentially prospective (from a magmatic sulfide viewpoint) tholeiitic suite and a seemingly unprospective alkaline suite. The tholeiitic suite has undepleted chalcophile element samples, demonstrating that the magmas that formed the suite were derived from a fertile mantle source region with sufficient partial melting to generate chalcophile-undepleted magmas. Furthermore, some tholeiitic samples within this suite are depleted in chalcophile elements and are crustally contaminated, suggesting that the magmas assimilated country rocks and became sulfur-saturated before emplacement. This process is crucial in most magmatic Ni-Cu-PGE mineralizing systems elsewhere and within the SWLLIP-generated immiscible sulfide melts deposited elsewhere within the system. This indicates the magmatic sulfide prospectivity of intrusions with this tholeiitic suite within the SWLLIP. In comparison, alkaline SWLLIP suite samples are uniformly depleted in chalcophile elements and display varying degrees of crustal contamination that do not contain sufficient sulfides, inferring they are unfertile. These unfertile melts were generated by low degree partial melting of the mantle and did not become sulfur saturated before emplacement. Overall, this research indicates that exploration for magmatic sulfides within the SWLLIP should focus on intrusions and sections of the LIP with affinities to the tholeiitic suite. The transitional alkaline suite is likely unprospective of chalcophile elements from an exploration viewpoint. This geochemical dataset allows for comparison between the two distinct pulses of magmatism in the SWLLIP and the MCR magmatism, particularly the mafic magmatism associated with the Duluth Complex, which is suggestive of a single plume under the North American craton
Utilizing the Multi-Theory Model to Explain the Fruits and Vegetables Consumption of Asian American, Native Hawaiian, and Pacific Islander College Student
No full textThe benefits of fruits and vegetables have been well documented. Studies show that adequate consumption of fruits and vegetables can reduce the risk of many chronic diseases. However, many adults are consuming well below the recommended levels of fruits and vegetables (F&V) (\u3c 5 cups daily). The transitional period from adolescence to young adulthood is an important time for the promotion of maintaining healthy dietary habits and lifestyles, as most health behaviors learned during this time may persist into later life. While there are numerous studies on the dietary behaviors in other populations, the existing literature on dietary behaviors among Asian Americans, Native Hawaiians, and Pacific Islanders (AANHPIs) is limited. Therefore, this study aimed to utilize the Multi-Theory Model (MTM) for health behavior change to explain the intention of initiating and sustaining fruits and vegetables among AANHPI college students in the U.S. that express and do not express consuming the daily cups of fruits and vegetables. Using a quantitative cross-sectional survey, data was collected from AANHPI college students over the age of 18 who are currently enrolled at a college or university in the U.S., using a 43-item questionnaire. Multiple regression models were used to analyze data. Of the 436 participants, 54.4% (n=237) reported not consuming the recommended daily five cups of F&V. Two MTM initiation constructs, behavioral confidence (b=0.119,
A Case for the Caldecott: Librarians Tell the Story
No full textWith the weight and hype being put into winning these “heavy medals” as referred to by School Library Journal Blog (Mroczek-Bayci, 2023) plus the rising conflicts centered around book banning across the nation, how are school librarians selecting these titles, specifically the Caldecott winners, when adding them to their library collections? Are librarians utilizing Book Industry and Standards and Communications (BISAC) codes to aid in their curation or are they following the masses and clicking the add to cart and purchasing button, or is there another means of decision making happening? This study was guided by a qualitative narrative methodological approach (Polkinghorne, 1995). The purpose of this study was twofold. First, I wanted to better understand how school librarians make curation decisions centered on books for their collection, specifically related to incorporating Caldecott Medal winning titles. Second, I wanted to determine how if librarians’ selection decisions were centered on elements of Culturally Relevant Pedagogy as defined by Ladson-Billings (1995, 2014), Culturally Sustaining Pedagogy as defined by Paris (2012) and Critical Librarianship (Drabinski, 2019)
Performance Effects of Dissociated Hydrogen in Nuclear Thermal Propulsion Engines
No full textNuclear thermal propulsion (NTP) research considers hydrogen dissociation as negligible to design and analysis of propulsion engines. This study reintroduces chemically reacting flow to NTP engine analysis for investigation of the dissociation effect on engine performance. A first-principles approach observes the basic chemical mechanism and reaction within the high-speed, high-temperature NTP flow to baseline expected atomic hydrogen levels and validate equilibrium. A surface reaction study looks into hydrogen absorption through dissociation and its effect on the boundary layer, and bulk flow. For total performance, the resulting dissociated flow is analyzed through nozzle expansion and performance metrics calculated.
All historic reactor inlet conditions can be assumed to be at equilibrium for atomic hydrogen values at, or below, 1% and remain at equilibrium until approximately 1600 K. Beyond this temperature, all reactors operated in non-equilibrium at worst conditions of sonic velocity, with one reactor operating as low as 51% of equilibrium but converged toward equilibrium at the outlet. All historic NTP reactors correlated with equilibrium at reactor outlet within 82%. Hydrogen dissociation is present in all historic NTP reactors, but all atomic hydrogen levels were below 0.5% molar fraction of total concentration when considering bulk flow temperatures and any speed up to the sonic speed.
Historic reactors demonstrate that similar NTP systems must consider non-equilibrium near the outlet above 1600 K as well as if the flow is disrupted from trace amounts below 1600 K. Highest core exit temperatures contains the highest dissociated atomic hydrogen while highest operating pressures cause the reactor to closely follow equilibrium. Reactor inlets that contain less than 1% molar fraction atomic hydrogen can be assumed to reach equilibrium by the reactor outlet.
NTP reactors contain a notable crossflow velocity near the reactor outlet due to the absorption of hydrogen into the NTP cladding material. Tungsten is selected as the cladding of choice due to concerning indications of high hydrogen penetration rates in molybdenum-tungsten (Mo-W) alloy. Zirconium carbide (ZrC) was rejected due to its historic issues with mass loss and carbon chemical reaction but proves to be a promising future candidate. The effects of the boundary layer were in questions as crossflow velocity reached 80 mm/s into NTP cladding resembling a form of wall suction. The absorption of hydrogen has a small effect on the thermal boundary layer. This demonstrated that the fluid mechanics of NTP reactors must consider the surface reaction of dissociated hydrogen flow in design and optimization of NTP engines. A follow-on computational fluid dynamics (CFD) looked closely at the boundary layer effects, assuming wall transpiration of hydrogen and provide the most accurate velocity and mass flow rates exiting the reactor and entering the chamber.
A 2-D axisymmetric computational fluid dynamics (CFD) model of the KIWI 4BE nuclear reactor provided the highest quality of chamber conditions for NTP. Atomic hydrogen was found to double over simple 1-D assumptions assuming equilibrium, equilibrium conditions, and assuming centerline temperature. For the KIWI 4BE model, 0.7% molar fraction of atomic hydrogen entered the NTP “Chamber” accompanied by a significant velocity decrement of 7% less than non-chemically reacting assumptions. The thermal profile changes appear relatively insignificant while the “1/7th” turbulent velocity profile was not accurate and needs further update. Analysis of zirconium carbide indicated that hydrogen absorption maybe greatly suppressed but further operational conditions are needed for testing. Further computations were completed in 1-D rocket nozzle expansion to fully understand the performance effect.
Calculation of the changing atomic hydrogen level requires a chemical analysis throughout nozzle expansion. NASA Chemical Equilibrium Analysis Application provides the tools to complete this analysis. The specific impulse is found for the chemically reacting flow and nonchemically reacting flow cases and compared. The specific impulse demonstrates the superior efficiency of the KIWI B4E engine over liquid engines. Despite reduced velocity and increased atomic hydrogen, the chemically reacting flow model produced a slight increase in specific impulse of 0.9% over the non-chemically reacting flow model. Modeling of NTP engines will underestimate the engine performance if chemically reacting flow is not considered
Removal of Permethrin and Bifenthrin Insecticides from Runoff Water by Activated Carbon Adsorption
No full textAmong the hundreds of pesticides and insecticides, pyrethroids-particularly permethrin and bifenthrin, have become very popular due to their high toxicity to insects and low toxicity to humans, leading to extensive use in both agriculture and urban areas. Pyrethroids have no discharge limits because of this, leading to a negative impact on surrounding ecosystems due to their high toxicity to fish and aquatic life. Due to their low solubility and long half-lives, they are prominent in the environment long after application with a high potential for getting transported in runoff water to nearby water bodies. In this study, DSR-C reactivated carbon from Calgon Carbon was tested as an adsorbent for permethrin and bifenthrin from deionized water. Pyrethroid samples were extracted from water by liquid-liquid extraction and analyzed using a UV-vis spectrophotometer. Isotherm data was best represented by the Langmuir model suggesting single-layer adsorption with an adsorption capacity of 149 mg/g for permethrin and 0.822 mg/g for bifenthrin. Permethrin adsorption was studied further in solutions containing 200 mg/L of sulfate and 10 mg/L of nitrogen, phosphorus, and potassium fertilizer nutrients to simulate realistic agricultural runoff conditions. Across all three water matrices used (DI water, 10 mg/L N-P-K, and 200 mg/L sulfate), kinetic data for permethrin adsorption was best represented by the pseudo-second order kinetic model with similar kinetic rates and equilibrium capacities. Isotherm data represented by the Langmuir model resulted in an average adsorption capacity of 155 ± 39 mg/g across three different water matrices. Adsorption with DSR-C is an effective treatment process for permethrin in agricultural runoff water
Effectiveness of a Virtual Simulation Program as a Novel Approach to Improve Clinical Judgment in Prelicensure Nursing Students
No full textProblem: Limited clinical placement opportunities for practicing decision-making skills have widened the academic-practice gap. Research shows a disturbing decline in entry-level competency among newly graduated registered nurses. Innovative strategies like virtual patient simulation may foster decision-making skills and prepare prelicensure nursing students for practice. However, research is lacking in examining virtual patient simulation (VPS) as an effective approach for developing clinical judgment in prelicensure nursing students. The American Association for Academic Nursing has determined that clinical judgment is an essential nursing attribute. Moreover, the National Council of State Boards of Nursing developed the Next Generation National Council Licensure Exam based on a clinical judgment model. Identifying effective novel teaching strategies is imperative for nursing programs to prepare nursing students for entry-level practice.Methodology: The study guided by the Tanner Clinical Judgment Model, integrating the three learning domains (cognitive, affective, and psychomotor), was used as the conceptual framework for the virtual simulation intervention. This quasi-experimental study with repeated measures mixed design examined the effectiveness of VPS in acquiring clinical judgment compared to high-fidelity mannequin simulation (HFMS). The study also investigated the efficacy of virtual patient simulation as a primer for HFMS using the Lasater Clinical Judgment Rubric among third-year Bachelor of Nursing prelicensure students, controlling for previous experiences in Healthcare and Virtual Technology and Age. Participants were assigned to the control group (n = 48) and received three HFMS scenarios, and the intervention group (n = 46) received three VPS, followed by three HFMS scenarios. Repeated measures using the Lasater Clinical Judgment Rubric measured clinical judgment at pretest (T1) and posttest (T2) for the HFMS (control group) and pretest (T1) and posttests (T2 and T3) for the VPS (intervention) group. Results: Mixed ANCOVA and mixed MANCOVA examined the differences in the change of self-perceived clinical judgment total scale score and subscale scores, respectively, from pretest to posttest between the HFMS and VPS groups. Statistical analyses were performed using an alpha level of .05. The mixed ANCOVA showed the interaction effect of Time by study group for the self-perceived clinical judgment total scale score was not significant for either group between T1 and T2 (p = .33) and between T1 and T3 (p = .12). The interaction effect of Time by study group using mixed MANCOVA for the self-perceived clinical judgment subscale scores were also not significant between T1 and T2 (p = .54) and between T1 and T3 (p = .65). The results indicated that both groups showed similar increases over time for the self-perceived clinical judgment total scale and subscale scores between HFMS and VPS among third-semester pre-licensure nursing students. Discussion: The findings showed that the self-perceived clinical judgment total scale and subscale scores improved across the repeated measures, and students benefited from HFMS, VPS, and combined simulation approaches. Both approaches were similarly effective in fostering students’ clinical judgment development. Implications: Virtual patient simulation is as effective as high-fidelity mannequin simulation and offers nursing programs another learning approach for promoting clinical judgment among prelicensure nursing students
Examining the Risks and Resilience of Older Adults Living with HIV/AIDS: Qualitative Community-Based Participatory Research Studies in Southern Nevada
No full textSince the height of the HIV pandemic in the 1980s, medical interventions have significantly increased the life expectancy of people living with HIV/AIDS (PLWH) and made HIV/AIDS a livable, chronic health condition. Because of this, PLWH have been living longer lives and thriving with the help of HIV sector healthcare and service providers. However, with their longer life expectancy, older PLWH have been experiencing other health challenges. One such challenge is the risk of developing HIV-Associated Neurocognitive Disorder (HAND), which is a condition that affects up to 50% of PLWH at some point in their lifetime, with middle-aged and older PLWH being most at risk. In this three-paper dissertation, the awareness and knowledge of the specific risk of PLWH developing or experiencing neurocognitive challenges as they age as a result of HAND among relevant study participants (i.e., middle-age and older PLWH and their HIV sector providers) from Southern Nevada are examined and discussed in the first two papers. Looking beyond the risks aging PLWH face, the third paper of this three-paper dissertation takes on a more strengths-focused approach to examining the circumstances and experiences of study participants. It directs its attention to the inherent resilience of PLWH, specifically the resilience of middle-aged and older men who have sex with men (MSM) living with HIV/AIDS, the subpopulation of PLWH that has inarguably been impacted the most and the longest by HIV/AIDS since the global pandemic started in the 1980s
Modern Tools, Ancient Skills: An Attempted Dialogue between AI, Design and Traditional Craft
No full textThis study explores the integration of artificial intelligence (AI) tools in traditional craft practices, focusing on Guatemalan artisans. The research investigates how machine learning, specifically generative AI platforms like OpenAI’s DALL-E and Midjourney, can bridge the gap between traditional craftsmanship and contemporary design methods. Guatemalan artisans were trained to use these AI tools to generate design ideas, which were then translated into three-dimensional bronze door knockers. The study analyzes the impact of AI on the artisans\u27 workflow, creativity, and business, highlighting both the challenges and benefits. Results indicate that AI can streamline the design process and inspire new creative directions, while also raising concerns about potential over-reliance and the preservation of cultural heritage. The project underscores the importance of inclusive technological development and aims to promote a dialogue between traditional and modern design practices, contributing to the evolution of craft in a digital age
Top Tier 2.0: Community Partnerships
No full textCommunity Partnerships have a positive long-term impact on our local communities. UNLV leverages resources for the public good to advance the university and the communities it serves. The value of the university is demonstrated through collaboration and engagement with the community to provide expertise, service, and support.https://oasis.library.unlv.edu/top_tier_focus/1035/thumbnail.jp
Invertebrate Functional Diversity of Fossils From Arrow Canyon, Nevada
No full textPaleontology can be used to study how ecosystems evolve and respond to changes in the environment. Here we examine invertebrate fossils from the Pennsylvanian, a time period that ranged from 323.2 to 298.9 million years ago, which are preserved along the walls of Arrow Canyon (Nevada) in the Bird Spring Formation. We surveyed three sites within the canyon, and used data from the Paleobiology Database to create a list of taxa found on the canyon from this time interval. Although ecosystems have traditionally been studied using the composition of the ecosystem (the number of species), recent work has shown that functional structure may be more important to the health of an ecosystem. Therefore, here we examine functional diversity (the types of functions performed by all of the organisms in an ecosystem). Three functional traits were assigned to each taxon: tiering, feeding, and motility, using the Paleobiology Database and the scientific literature. We examined both how much of the functional space was filled, and how species were distributed within functional space using Functional Entities, unique combinations of functional traits. Brachiopods dominated the fossil samples, as the geologic setting favored the preservation of their shells. Other invertebrate phyla are represented, though their sample sizes are low. Further study on the functional diversity of the Bird Spring Formation may incorporate fossil data from other fossil localities to expand sample sizes at the genus level.https://oasis.library.unlv.edu/durep_podium/1055/thumbnail.jp