Physical Sciences and Mathematics Commons^™

Photoelectic Driven Decomposition Of Uracil Via Hard X-Ray Irradiation, Trimaan Malik

UNLV Theses, Dissertations, Professional Papers, and Capstones

Radiation damage into biological samples creates substantial challenges across a wide range of fields, from biochemistry to materials science. This comprehensive study investigates the effects of x-ray irradiation on uracil, the only nucleobase exclusive to Ribonucleic acid (RNA), to understand how doping with 10% (by mass) of specific powdered elements impacts the sustained radiation damage. The experiments were conducted at the Brockhouse Undulator Beamline of the Canadian Light Source synchrotron. Virgin and doped uracil samples were irradiated with hard x-rays, above their respective absorption edges, and studied with x-ray diffraction to compare their decomposition behaviors. The Uracil reflections on the …

Dynamical Studies Of Misaligned Circumbinary Disks, Ian C. Rabago

UNLV Theses, Dissertations, Professional Papers, and Capstones

Binary stars are common outcomes of the star formation process, with nearly half of Sun-like stars forming as part of a binary pair. The presence of a second star adds additional complexity and dynamical effects to the planet formation process in the surrounding circumbinary disk. In this work, I investigate the behavior of a circumbinary disk using hydrodynamic modeling, specifically in the case where the disk is misaligned to the binary orbital plane. Around eccentric binaries, highly inclined disks can align themselves perpendicular to the binary orbital plane. These "polar disks'' can produce vortices and spiral arms when the disk …

Simulation And Design Of Ion Traps Using The Method Of Fundamental Solutions, Trevor Taylor

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis I apply the numeric method, the Method of Fundamental Solutions (MFS), to solve for the fields create by ion traps in various configurations, such as quadrupole ion traps, linear ion traps, toroidal ion traps, and toroidal surface ion traps. The traps are then designed to maximize desired qualities such as minimization of their anharmonicity, and their ability to shuttle ions. A particular focus will be on the toroidal surface ion trap, as well as its ability to shuttle ions. This trap is planned for future experiments involving measurement of the electron Electric Dipole Moment.

Understanding Disk Substructures With 3d Self-Consistent Thermodynamics, Shangjia Zhang

UNLV Theses, Dissertations, Professional Papers, and Capstones

Protoplanetary disks are birthplaces of planets. The past decade witnessed a great advance- ment in disk observations by Atacama Large Millimeter Array (ALMA) and extreme adaptive optics (ExAOs). Hundreds of disks have been observed at high angular resolutions and revealed rich substructures (e.g., gaps/rings) at midplane and atmosphere, at least part of which are per- turbed by planets. Deep understanding of disk physics has a great potential to unveil more young planets from substructures and distinguish those that are not caused by planets. I worked on con- straining young planet populations using planet-disk interaction simulations and substructures and self-consistent treatment …

Redirection Of Current In A Dense Plasma Focus, Rocky Gonzalez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Mission Support & Test Services (MSTS) reports that significant amounts of energy needed for generating high energy neutrons is lost within a Dense Plasma Focus between its pinch-end of the anode stalk and at its base near the insulating sleeve. It is their mission and the goal of this research effort to both experimentally and theoretically study current redirection in a DPF during and after pinch dynamics. It is hypothesized that current redirection, due to restrike, behind the dynamic sheath of a dense plasma focus will result in a measurable change in the magnetic field along the longitudinal axis …

Collaborative Deep Reinforcement Learning For Solving Multi-Objective Vehicle Routing Problems, Yaoxin Wu, Mingfeng Fan, Zhiguang Cao, Ruobin Gao, Yaqing Hou, Guillaume Sartoretti

Research Collection School Of Computing and Information Systems

Existing deep reinforcement learning (DRL) methods for multi-objective vehicle routing problems (MOVRPs) typically decompose an MOVRP into subproblems with respective preferences and then train policies to solve corresponding subproblems. However, such a paradigm is still less effective in tackling the intricate interactions among subproblems, thus holding back the quality of the Pareto solutions. To counteract this limitation, we introduce a collaborative deep reinforcement learning method. We first propose a preference-based attention network (PAN) that allows the DRL agents to reason out solutions to subproblems in parallel, where a shared encoder learns the instance embedding and a decoder is tailored for …

Deep Reinforcement Learning Guided Improvement Heuristic For Job Shop Scheduling, Cong Zhang, Zhiguang Cao, Wen Song, Yaoxin Wu, Jie Zhang

Research Collection School Of Computing and Information Systems

Recent studies in using deep reinforcement learning (DRL) to solve Job-shop scheduling problems (JSSP) focus on construction heuristics. However, their performance is still far from optimality, mainly because the underlying graph representation scheme is unsuitable for modelling partial solutions at each construction step. This paper proposes a novel DRL-guided improvement heuristic for solving JSSP, where graph representation is employed to encode complete solutions. We design a Graph-Neural-Network-based representation scheme, consisting of two modules to effectively capture the information of dynamic topology and different types of nodes in graphs encountered during the improvement process. To speed up solution evaluation during improvement, …

Lake Mead: A Living Museum, Marley Salveter

UNLV Theses, Dissertations, Professional Papers, and Capstones

Lake Mead, the largest man-made water project in the nation and a prolific source of electricity, irrigation, and recreation for much of the western population, is currently experiencing a drastic transformation. Amid the ongoing water crisis parching the west, the once overflowing reservoir is consistently shrinking, descending into depths historically uncharted.While serving as a bleak demonstration of climate change’s effects, the body of water is simultaneously assuming an alternative role that may be less apparent to the public. As water levels decline, Lake Mead is actively metamorphosing into a “Living Museum”, by gradually unveiling previously submerged artifacts. As a result, …

Australian Non-Perennial Rivers: Global Lessons And Research Opportunities, Margaret Shanafield, Melanie Blanchette, Edoardo Daly, Naomi Wells, Ryan M. Burrows, Kathryn Korbel, Gabriel C. Rau, Sarah Bourke, Gresley Wakelin-King, Aleicia Holland, Timothy Ralph, Gavan Mcgrath, Belinda Robson, Keirnan Fowler, Martin S. Andersen, Songyan Yu, Christopher S. Jones, Nathan Waltham, Eddie W. Banks, Alissa Flatley, Catherine Leigh, Sally Maxwell, Andre Siebers, Nick Bond, Leah Beesley, Grant Hose, Jordan Iles, Ian Cartwright, Michael Reid, Thiaggo De Castro Tayer, Clément Duvert

Research outputs 2022 to 2026

Non-perennial rivers are valuable water resources that support millions of humans globally, as well as unique riparian ecosystems. In Australia, the Earth's driest inhabited continent, over 70% of rivers are non-perennial due to a combination of ancient landscape, dry climates, highly variable rainfall regimes, and human interventions that have altered riverine environments. Here, we review Australian non-perennial river research incorporating geomorphology, hydrology, biogeochemistry, ecology, and Indigenous knowledges. The dominant research themes in Australia were drought, floods, salinity, dryland ecology, and water management. Future research will likely follow these themes but must address emerging threats to river systems due to climate …

Optimizing Ic Engine Efficiency: A Comprehensive Review On Biodiesel, Nanofluid, And The Role Of Artificial Intelligence And Machine Learning, Manzoore E. M. Soudagar, Sagar Shelare, Deepali Marghade, Pramod Belkhode, Mohammad Nur-E-Alam, Tiong S. Kiong, S. Ramesh, Armin Rajabi, Harish Venu, T. M. Yunus Khan, M. A. Mujtaba, Kiran Shahapurkar, M. A. Kalam, I. M. R. Fattah

Research outputs 2022 to 2026

Transportation and power generation have historically relied upon Internal Combustion Engines (ICEs). However, because of environmental impact and inefficiency, considerable research has been devoted to improving their performance. Alternative fuels are necessary because of environmental concerns and the depletion of non-renewable fuel stocks. Biodiesel has the potential to reduce emissions and improve sustainability when compared to diesel fuel. Several researchers have examined using nanofluids to increase biodiesel performance in internal combustion engines. Due to their thermal and physical properties, nanoparticles in a host fluid improve engine combustion and efficiency. This comprehensive review examines three key areas for improving ICE efficiency: …

El Nino Prediction At 1- And 3- Year Lead Times Driven By The Western North Pacific Precursor And Their Impacts, Krishna Borhara

All Graduate Theses and Dissertations, Fall 2023 to Present

The El Niño–Southern Oscillation (ENSO) is a climate variability characterized by fluctuations in the atmospheric and upper ocean conditions of the tropical Pacific Ocean that result in either warmer- or colder-than-average sea surface temperatures (SST) in the tropical eastern Pacific. These changes cause variations in weather and climate in distant locations through large-scale atmospheric circulation patterns. These variations often manifest in form of adverse effects or extremes such as heat waves, droughts, or floods, making efforts towards improving ENSO prediction critical in mitigating its impact on various sectors. This dissertation focuses on how interactions between the atmosphere and ocean in …

Sustainable Fertilizer Management Practices For Container Nursery Production, Saroj Burlakoti

All Graduate Theses and Dissertations, Fall 2023 to Present

Growing nursery plants in containers requires a timely supply of mineral nutrients for optimum growth. However, there is a misconception among growers that the application of higher doses of fertilizers hastens plant growth; instead, it can lead to runoff and leaching loss of nutrients. Reducing fertilizer application while sustaining healthy plants can not only negate environmental consequences but also save fertilizer costs. For example, two ground covers, Lysimachia nummularia (creeping jenny, moneywort) and Vinca minor 'Bowles' (periwinkle), can be grown for three months by applying 6 mg/L of phosphorus (P) as reduction of P to single application of 6 mg/L …

Achieving Responsible Anomaly Detection, Xiao Han

All Graduate Theses and Dissertations, Fall 2023 to Present

In the digital transformation era, safeguarding online systems against anomalies – unusual patterns indicating potential threats or malfunctions – has become crucial. This dissertation embarks on enhancing the accuracy, explainability, and ethical integrity of anomaly detection systems. By integrating advanced machine learning techniques, it improves anomaly detection performance and incorporates fairness and explainability at its core.

The research tackles performance enhancement in anomaly detection by leveraging few-shot learning, demonstrating how systems can effectively identify anomalies with minimal training data. This approach overcomes data scarcity challenges. Reinforcement learning is employed to iteratively refine models, enhancing decision-making processes. Transfer learning enables the …

Cost-Risk Analysis Of The Ercot Region Using Modern Portfolio Theory, Megan Sickinger

Master's Theses

In this work, we study the use of modern portfolio theory in a cost-risk analysis of the Electric Reliability Council of Texas (ERCOT). Based upon the risk-return concepts of modern portfolio theory, we develop an n-asset minimization problem to create a risk-cost frontier of portfolios of technologies within the ERCOT electricity region. The levelized cost of electricity for each technology in the region is a step in evaluating the expected cost of the portfolio, and the historical data of cost factors estimate the variance of cost for each technology. In addition, there are several constraints in our minimization problem to …

The Impact Of Ai On Ux: Challenges And Opportunities, Susan Stephanie Wells

Theses

Integrating artificial intelligence (AI) in user experience (UX) design is reshaping the field of UX, offering new opportunities and challenges for designers. This thesis project explores the multifaceted relationship between AI and UX design, focusing on the challenges, opportunities, and skills demanded of UX designers in the age of AI. Through a review of academic research and real-world experiences, this project studies the impact of AI on web design processes, UX testing, and data analysis. Key findings highlight the transformative potential of AI in enhancing user experiences, from suggesting website structures to facilitating UX testing and data analysis.

Comparative analysis …

Remnant Polarization And Structural Arrangement In P(Vdf-Trfe) Electrospun Fiber Meshes Affect Osteogenic Differentiation Of Human Mesenchymal Stromal Cells, Bahareh Azimi, Massimiliano Labardi, Mohammad Sajad Sorayani Bafqi, Teresa Macchi, Claudio Ricci, Veronica Carnicelli, Lorenzo Scarpelli, Istiak Hussain, Francesca Matino, Mohammed Uddin

Physics and Astronomy Faculty Publications and Presentations

Highlights

• The type of solvent had noticeable effects on morphology and piezoelectric properties of P(VDF-TrFE) electrospun fibers.

• Using MEK as a solvent and specific environmental conditions led to the obtainment of surface nanopores.

• Uniaxially aligned fibers exhibited higher β phase and mechanical properties than random ones.

• Randomly oriented fibers had higher remnant piezoelectric properties (Vout, d31 piezoelectric coefficient) than aligned ones.

• Human mesenchymal stem cells cultured on randomly oriented fibers showed an accelerated osteogenic differentiation.

Abstract

Many tissues and cells are influenced by mechano-electric stimulation, thus the application of piezoelectric materials has recently received considerable attention in tissue engineering. …

Elasticity Of Orders In Quadratic Rings Of Integers, Jared Kettinger

All Theses

This project explores elasticity in quadratic rings of integers, specifically, those of the form Z[pω] where p is a rational prime which remains prime in Z[w]. For these rings, we establish an upper bound on the elasticity which is attained in many cases. We also prove that this upper bound is an equality in the case when the ring of integers is a unique factorization domain. During this process, we also prove theorems about the class group of quadratic rings of integers and develop a useful method for calculating a constant similar to the Davenport constant.

Influence Of The Atlantic Inflow On Trace Metal Enrichments In Sediments And Particulate Matter Of The Nw Alboran Sea (Sw Mediterranean), Albert Palanques, Pere Puig, Pere Masqué, Enrique Isla

Research outputs 2022 to 2026

Trace metal contents and fluxes in downward particulate matter and dated sediment cores of the NW Alboran Sea are analysed in this study with the aim of assessing the role of the Atlantic inflow on their transport. Increases in Zn, Cu and Pb were detected in downward particulate matter collected by sediment traps after river flooding events and after the Aznalcollar mining spill. Their arrival coincided within the recently estimated time range for river particles discharged into the Gulf of Cádiz to reach the Alboran Sea, indicating that their transfer is enhanced during events of increased river inputs of contaminated …

The Influence Of Methyl Orange On The Co2-Brine Wettability Of Organic-Acid-Aged Calcite Samples: Implications For Co2 Geo-Storage, Fatemah Alhammad, Mujahid Ali, Nurudeen Yekeen, Muhammad Ali, Mohammadreza Kamali, Stefan Iglauer, Alireza Keshavarz

Research outputs 2022 to 2026

The underground storage of CO2 in a depleted carbonate formation is a suitable method for limiting its anthropogenic release and minimize global warming. The rock wettability is an essential factor controlling the mechanisms of CO2 trapping and its containment safety in the geo-storage formation. The geo-storage rock contains innate organic acids which alters the wettability of the rock surface from the hydrophilic condition to the hydrophobic state, thus reduce the CO2 storage capacity. In this study, methyl orange which is a toxic dye that is generally released into environment was used as wettability modifier to change the wettability of stearic …

Experiment Development And Validation Of A Granular Jamming Robotic Gripper, Jacob R. Dowd

UNLV Theses, Dissertations, Professional Papers, and Capstones

A granular jamming gripper (GJG) is widely known as a Universal Gripper because of the wide range of objects that it can grasp and the simplicity of control, design, and manufacturing. Despite multitude of research improving the GJG, here, we focus on the base version of the GJG and attempt to glean the range of objects that it may reliably grasp. Despite the limited range of objects, which were a sphere, rectangular prism, and cylinder, we gleaned geometric properties as it relates to successful and unsuccessful grasping. This was based on the two types of testing: push and pull testing …

An Examination Of The Teaching And Learning Of Resonance In General Chemistry I And Organic Chemistry I Using Variation Theory, Sabrina Barakat

UNLV Theses, Dissertations, Professional Papers, and Capstones

Resonance is a fundamental chemistry concept first introduced to students in General Chemistry I, reintroduced in Organic Chemistry I, and then utilized throughout other higher-level chemistry courses. A molecule or ion can be said to exhibit resonance when it can be represented by two or more chemical structures (i.e., Lewis structures) that differ only in their arrangement of electrons. In other words, resonance represents the electronic structure of a molecule or ion when a single Lewis structure does not adequately depict the true distribution of electrons. The molecule or ion is best represented as a combination of all of the …

Assessing The Potential For Magmatic Sulfides Within Southwestern Laurentia Large Igneous Province, Thomas J. Boes

UNLV Theses, Dissertations, Professional Papers, and Capstones

The ~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's 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 …

Investigating Controls On Temporal And Spatial Variation Of Dissolved Uranium At Springs In Horn Creek Drainage, Grand Canyon National Park, Arizona, Usa, Collin Davidson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Groundwater is a critical resource in the Grand Canyon, providing water to local communities, millions of annual visitors, and ecosystems. One major concern for this critical resource is the potential for uranium contamination in conjunction with uranium mining efforts. Upper Horn Bedrock Spring (UHB) in the Horn Creek drainage of the Grand Canyon sits below the oldest uranium mine in the region, Orphan Lode mine. UHB spring contains the highest concentration of dissolved uranium in the region, eclipsing the Maximum Contaminant Level (MCL) set by the USEPA by an order of magnitude on average. This research and recent collaboration with …

Error Estimates For A Mixed Finite Element Method For The Maxwell's Transmission Eigenvalue Problem, Chao Wang, Jintao Cui, Jiguang Sun

Michigan Tech Publications, Part 2

In this paper, we analyze a numerical method combining the Ciarlet-Raviart mixed finite element formulation and an iterative algorithm for the Maxwell's transmission eigenvalue problem. The eigenvalue problem is first written as a nonlinear quad-curl eigenvalue problem. Then the real transmission eigenvalues are proved to be the roots of a non-linear function. They are the generalized eigenvalues of a related linear self-adjoint quad-curl eigenvalue problem. These generalized eigenvalues are computed by a mixed finite element method. We derive the error estimates using the spectral approximation of compact operators, the theory of mixed finite element method for quad-curl problems, and the …

Exploring The Coronal Magnetic Field With Galactic Cosmic Rays: The Sun Shadow Observed By Hawc, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, K. P. Arunbabu, D. Avila Rojas, R. Babu, Et Al.

Michigan Tech Publications, Part 2

Galactic cosmic rays (GCRs) are charged particles that reach the heliosphere almost isotropically in a wide energy range. In the inner heliosphere, the GCR flux is modulated by solar activity so that only energetic GCRs reach the lower layers of the solar atmosphere. In this work, we propose that high-energy GCRs can be used to explore the solar magnetic fields at low coronal altitudes. We used GCR data collected by the High-Altitude Water Cherenkov observatory to construct maps of GCR flux coming from the Sun’s sky direction and studied the observed GCR deficit, known as Sun shadow (SS), over a …

Weighted Ehrhart Theory: Extending Stanley's Nonnegativity Theorem, Esme Bajo, Robert Davis, Jesús A. De Loera, Alexey Garber, Sofía Garzón Mora, Katharina Jochemko, Josephine Yu

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

We generalize R. P. Stanley's celebrated theorem that the h∗-polynomial of the Ehrhart series of a rational polytope has nonnegative coefficients and is monotone under containment of polytopes. We show that these results continue to hold for weighted Ehrhart series where lattice points are counted with polynomial weights, as long as the weights are homogeneous polynomials decomposable as sums of products of linear forms that are nonnegative on the polytope. We also show nonnegativity of the h∗-polynomial as a real-valued function for a larger family of weights.

We generalize R. P. Stanley's celebrated theorem that the h ⁎ -polynomial of …

A Comparative Analysis Of Field Electron Emission From Carbon Black Embedded Within Insulated Copper Hollowed Wires And Glass Tubes, Hatem A. Al-Braikat, Ahmad M D Jaber, Adel M. Abuamr, Mazen A. Madanat, Aseel A. Al-Jbarart, M-Ali H. Al-Akhras, Marwan S. Mousa

Karbala International Journal of Modern Science

In this study, two different methods are used to investigate carbon black as a cold field electron emitter. The first method is to incorporate carbon black into a specially designed insulated copper hollowed wire. The wire has a cup-shaped structure created by electrochemical etching. The second method involves the incorporation of carbon black into narrow glass tubes. A Comparative analyses is carried out to evaluate the effectiveness of each method. To evaluate the performance of the samples, the current-voltage characteristics will be examined using field electron microscopes. This analysis will provide an understanding of the emission of the carbon black …

Learning To Teach About Climate Justice And Social Justice In Science Methods, Mindy J. Chappell

Northwest Journal of Teacher Education

In November, the Editors of NWJTE sat down for a conversation with Dr. Mindy J. Chappell, a Science Teacher Educator in the College of Education at Portland State University. Dr. Chappell’s passions include developing teachers who are prepared to disrupt normative science ideologies and provide young people with science instruction that encourages and empowers them to be leaders in their communities. She engages in arts-based educational science research through the methodology of Ethnodance (a term she coined). She places young people and their lived experiences at the heart of her work.

Feminist Political Ecology In The Classroom, Ella J. Yeigh

Northwest Journal of Teacher Education

As the effects of climate change are being felt more frequently, discussions on how to combat such a massive issue are increasingly prevalent. Finding solutions to the climate crisis requires an understanding of how mainstream economic systems have led to the climate crisis and using these same principles to get out of the climate crisis is misguided. Economic actions have inherent value biases that have real political effects. Feminist Political Ecology (FPE) as a theoretical model presents a better understanding of how values that are inherent in economic models such as reliance on efficiency, markets, and continual economic growth have …

Philosophy In Science: Can Philosophers Of Science Permeate Through Science And Produce Scientific Knowledge?, Thomas Pradeu, Maël Lemoine, Mahdi Khelfaoui, Yves Gingras

Presidential Fellows Articles and Research

Most philosophers of science do philosophy ‘on’ science. By contrast, others do philosophy ‘in’ science (PinS), that is, they use philosophical tools to address scientific problems and to provide scientifically useful proposals. Here, we consider the evidence in favour of a trend of this nature. We proceed in two stages. First, we identify relevant authors and articles empirically with bibliometric tools, given that PinS would be likely to infiltrate science and thus to be published in scientific journals (‘intervention’), cited in scientific journals (‘visibility’), and sometimes recognized as a scientific result by scientists (‘contribution’). We show that many central figures …