Digital Commons Network^™

Pattern-Based Downscaling Of Snowpack Variability In The Western United States, Nicolas Gauthier, Kevin J. Anchukaitis, Bethany Coulthard

Geoscience Faculty Research

The decline in snowpack across the western United States is one of the most pressing threats posed by climate change to regional economies and livelihoods. Earth system models are important tools for exploring past and future snowpack variability, yet their coarse spatial resolutions distort local topography and bias spatial patterns of accumulation and ablation. Here, we explore pattern-based statistical downscaling for spatially-continuous interannual snowpack estimates. We find that a few leading patterns capture the majority of snowpack variability across the western US in observations, reanalyses, and free-running simulations. Pattern-based downscaling methods yield accurate, high resolution maps that correct mean and …

Combined Application Of 4d Bim Schedule And An Immersive Virtual Reality On A Modular Project: Unlv Solar Decathlon Case, Rajarshi Ghimire, Seungtaek Lee, Jin O. Choi, Jin-Yeol Lee, Yong-Cheol Lee

Civil and Environmental Engineering and Construction Faculty Research

The use of a 4D schedule as technological advancement has brought significant improvement to the planning and execution of construction projects, through visualizing step-wise construction progress, following a sequence of pre-planned activities, and finalizing a baseline schedule with necessary changes. Moreover, the application of immersive virtual reality (IVR) to create an interactive 4D BIM schedule of a planned structure has made it possible to create a detailed plan of any construction project. Because of these benefits, the use of 4D schedules and immersive virtual reality in the construction industry has increased, leading to improved planning and execution. However, past studies …

Effect Of Heat Treatment On Microstructure And Hardness Of A Worn Rail Repaired Using Laser Powder Deposition, Ershad Mortazavian, Zhiyong Wang, Hualiang Teng

Mechanical Engineering Faculty Research

The frequent replacement of worn rails on tracks brings an immense economic burden on the railroad industry, and also causes significant interruptions to railroad operation. Restoration of worn rails via laser powder deposition (LPD) can considerably reduce the associated maintenance costs. This study was focused on the use of LPD to repair the worn profile of a standard U.S. rail. The microstructure of the 304L stainless steel deposits with a minimum hardness of 85 HRB was composed of austenite, δ-ferrite, and sigma. Micropores were dispersed throughout the deposit, and microcracks were found at the rail-deposition interface. The pearlitic rail substrate …

Two Modes Of Game-Based Learning For Middle School Mathematics, Micah Stohlmann

Teaching and Learning Faculty Research

Game-based learning has received more focus as a way to engage students and increase interest in mathematics. Game-based learning should be integrated with effective practices for teaching mathematics, though these is a need for further research on effective implementation models. The purpose of this article is to describe two modes of game-based learning that are aligned with National Council of Teachers of Mathematics effective practices for teaching mathematics including multiple representation and meaningful discourse. Examples will be discussed from the implementation of game-based learning in a Saturday Science, Technology, Engineering and Mathematics (STEM) program for middle school students offered at …

Pyxtal_Ff: A Python Library For Automated Force Field Generation, Howard Yanxon, David Zagaceta, Binh Tang, David S. Matteson, Qiang Zhu

Physics & Astronomy Faculty Research

We present PyXtal_FF—a package based on Python programming language—for developing machine learning potentials (MLPs). The aim of PyXtal_FF is to promote the application of atomistic simulations through providing several choices of atom-centered descriptors and machine learning regressions in one platform. Based on the given choice of descriptors (including the atom-centered symmetry functions, embedded atom density, SO4 bispectrum, and smooth SO3 power spectrum), PyXtal_FF can train MLPs with either generalized linear regression or neural network models, by simultaneously minimizing the errors of energy/forces/stress tensors in comparison with the data from ab-initio simulations. The trained MLP model from PyXtal_FF is interfaced with …

The Relationship Between Spatial Ability And The Conservation Of Matter In Middle School, Merryn Cole, Jennifer Wilhelm, Briana Marie-Mcknight Vaught, Corinne Fish, Hailey Fish

Teaching and Learning Faculty Research

Research has shown that spatial ability plays a key role in understanding STEM (Science, Technology, Engineering, and Mathematics) content, including chemistry. Conservation of Matter (CoM) is an essential but challenging topic for chemistry students of all ages to grasp; it is often taught in a way where students memorize it but do not learn what it means conceptually. This research explored the relationship between understanding spatial ability and conceptual understanding of CoM in middle school students. CoM was examined in two ways using the Conservation of Matter Assessment (CoMA): through questions on conservation of atoms and the conservation of mass. …

We Will Chaos Into Three(Lines): Be(Com)Ing Writers Of Three Through (Re)Etymologizing “Write”, Rebecca Christ, Tara Gutshall Rucker, Candace Kuby

Taboo: The Journal of Culture and Education

No abstract provided.

The Occurrence Of Rocky Habitable-Zone Planets Around Solar-Like Stars From Kepler Data, Steve Bryson, Michelle Kunimoto, Ravi K. Kopparapu, Jeffrey L. Coughlin, William J. Borucki, David Koch, Victor Silva Aguirre, Christopher Allen, Geert Barentsen, Natalie M. Batalha, Travis Berger, Alan Boss, Lars A. Buchhave, Christopher J. Burke, Douglas A. Caldwell, Jennifer R. Campbell, Joseph Catanzarite, Hema Chandrasekaran, William J. Chaplin, Jessie L. Christiansen, Jørgen Christensen-Dalsgaard, David R. Ciardi, Bruce D. Clarke, William D. Cochran, Jessie L. Dotson, Laurance R. Doyle, Eduardo Seperuelo Duarte, Edward W. Dunham, Andrea K. Dupree, Michael Endl, James L. Fanson

Physics & Astronomy Faculty Research

We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define η⊕ as the HZ occurrence of planets with radii between 0.5 and 1.5 R⊕ orbiting stars with effective temperatures between 4800 and 6300 K. We find that η⊕ for the conservative HZ is between... (See article for full abstract).

X-Spec: A 70 Ev To 15 Kev Undulator Beamline For X-Ray And Electron Spectroscopies, Lothar Weinhardt, Ralph Steininger, Dagmar Kreikemeyer-Lorenzo, Stefan Mangold, Dirk Hauschild, David Batchelor, Thomas Spangenberg, Clemens Heske

Chemistry and Biochemistry Faculty Research

X-SPEC is a high-flux spectroscopy beamline at the KIT (Karlsruhe Institute of Technology) Synchrotron for electron and X-ray spectroscopy featuring a wide photon energy range. The beamline is equipped with a permanent magnet undulator with two magnetic structures of different period lengths, a focusing variable-line-space plane-grating monochromator, a double-crystal monochromator and three Kirkpatrick-Baez mirror pairs. By selectively moving these elements in or out of the beam, X-SPEC is capable of covering an energy range from 70 eV up to 15 keV. The flux of the beamline is maximized by optimizing the magnetic design of the undulator, minimizing the number of …

3d Numerical Simulation-Based Targeting Of Skarn Type Mineralization Within The Xuancheng-Magushan Orefield, Middle-Lower Yangtze Metallogenic Belt, China, Xunyu Hu, Xiaohui Li, Feng Yuan, Simon M. Jowitt, Alison Ord, Rui Ye, Yue Li, Wenqiang Dai, Xiangling Li

Geoscience Faculty Research

Recent exploration has identified a series of Cu-Mo skarn deposits within the Xuancheng-Magushan orefield. The orefield forms part of the Nanling-Xuancheng mining district, which is located within the Middle-Lower Yangtze River Metallogenic Belt (MLYRMB) of central-eastern China. However, this area contains thick and widespread unprospective sedimentary cover sequences that have impeded traditional approaches to mineral exploration. This study presents the results of 3D numerical simulation modeling that identifies possible mineral exploration targets within the entire Xuancheng-Magushan orefield. This modeling enables the identification of unexplored areas with significant exploration potential that are covered by thick sedimentary sequences that cannot be easily …

Two New Finite Element Schemes And Their Analysis For Modeling Of Wave Propagation In Graphene, Jichun Li

Mathematical Sciences Faculty Research

© 2020 The Author(s) In this paper, we investigate a system of governing equations for modeling wave propagation in graphene. Compared to our previous work (Yang et al., 2020), here we re-investigate the governing equations by eliminating two auxiliary unknowns from the original model. A totally new stability for the model is established for the first time. Since the finite element scheme proposed in Yang et al. (2020) is only first order in time, here we propose two new schemes with second order convergence in time for the simplified modeling equations. Discrete stabilities inheriting exactly the same form as the …

Validation Of Novel Obstructive Sleep Apnea Treatment With Silicone Gel Experimental Models, Dustin Walter Burd

UNLV Theses, Dissertations, Professional Papers, and Capstones

Predictive modeling to increase treatment success rates for surgical procedures is becoming more common in the scientific community. For obstructive sleep apnea (OSA), modeling has been predominately performed using computers as opposed to experimental models. Computer simulation saves time by eliminating the need to fabricate complex experimental models but comes at the expense of insight gained through physical observations made in real time. Experimental models for studying OSA are needed to validate computational work, provide perspective on anatomical scale and demonstrate complex deformations in real time. This work addresses prior hurdles in experimental model fabrication with a novel process using …

Vibration Overtone Hyperpolarizability Measured For H2 Using Electric Field Induced Second Harmonic Generation, Rachel Ellis

UNLV Theses, Dissertations, Professional Papers, and Capstones

The vibrational contribution to the second hyperpolarizability (γ) of gas phase H2 was measured using electric field induced second harmonic generation. Measurements were made for the pure vibrational 3-0 Q(J) overtone transitions (v=0,J → v’=3,J for J = 0,1,2,3). Measured intensities were found to be 4-14% larger than ab initio calculations. The first chapter of this thesis provides an introduction to nonlinear optics, second harmonic generation, and the tensor nature of hyperpolarizabilities. The second chapter provides theoretical expressions for γ and relevant static and Raman polarizabilities. The third chapter covers the experimental design and electric field induced second harmonic generation. …

Light Conditions During Desiccation And Rehydration Impact The Recovery Of Cultured Timmiella Crassinervis, Sotodeh Ebrahimi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many terrestrial mosses of xeric environments experience excess light during extended periods of desiccation. While dry or hydrated, excess light energy can lead to formation of reactive oxygen species and photoinhibition (e.g. damage to Photosystem II) which affects photosynthetic stress and efficiency. This study aimed to determine the effect of duration dry and light intensity (PAR) on cultured shoots of the chaparral moss Timmiella crassinervis, as well as to elucidate the optimal rehydration light conditions for this species. I hypothesized that 1) mosses exposed to higher light intensities during desiccation would incur more damage upon rehydration than those exposed to …

Tectonic Evolution Of The Tucki Mountain Metamorphic Core Complex, Southeastern California: Evidence For Late Cretaceous Extension Within The Sevier-Laramide Orogen, William Killey Barba

UNLV Theses, Dissertations, Professional Papers, and Capstones

The exhumation of Cordilleran metamorphic core complexes from mid-crustal depths in the western U.S. Basin and Range Province has been classically associated with Cenozoic extension. However, recent studies reveal that extensional tectonic exhumation of numerous metamorphic core complexes initiated during the Late Cretaceous. New geologic mapping and structural analysis integrated with geochronology and thermochronology data provide evidence for a Late Cretaceous extensional shear zone, previously interpreted as Miocene in age, within the Tucki Mountain metamorphic core complex on the western flank of Death Valley, California. The shear zone occurs within the immediate footwall of the Miocene-Pliocene Tucki Mountain detachment fault …

Using The Critical Mathematics Pedagogical Framework To Teach Adult Basic Education Learners: A Transformative Convergent Parallel Mixed Methods Study, Matthew D. Gromlich

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal of this study was to design and implement curricula in the Adult Basic Education classroom that aligned to the Critical Mathematics Pedagogical Framework. Specifically, this study assessed if ABE students’ mathematics anxiety and mathematics self-efficacy ware affected by curricula that aligns to the Critical Mathematics Pedagogical Framework. Using a transformative convergent parallel mixed methods study, this study showed that students taught using CMPF-based lessons specifically reflected on their own attitudes towards mathematics self-efficacy, mathematics anxiety, number positioning, and the need for societal change around mathematical concepts. Both quantitative and qualitative data were analyzed to highlight student reflections and …

Fast Neutron Assay Of Elemental Content Of Bulk Samples, Calder Emerson Lane

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this research was to analyze the capabilities of fast neutrons in the detection and analysis of various isotopes in bulk samples. The deuterium-tritium (DT) fusion reaction generates highly penetrating, high-energy (14.1-MeV) neutrons which induce nuclear reactions in irradiated targets. Neutrons and gamma rays are generated in these reactions. Emitted gamma rays are characteristic of the emitter; the gamma spectrum enables stoichiometric identification of the assayed samples. Neutron backscattering can also be used for identification of the elemental composition of the sample.

This work had three objectives. The first objective was to develop a computational technique to model …

Synthesis, X-Ray Absorption, And X-Ray Diffraction Spectroscopy Studies Of Uranium Based Heavy Fermion Systems, Vahe Mkrtchyan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Heavy fermion systems have attracted a great deal of interest since the discovery of the phenomenon in the 1970s. Over the past 35 years, the research in this field revealed a variety of unprecedented properties that the conventional theoretical framework considered conflicting or impossible. The subset of intermetallic compounds containing rare earth and actinide elements is of special interest, as these materials exhibit a range of exotic properties associated with 4f or 5f electrons. A thorough examination of the reports in the literature indicates a delicate interplay between the competing ground states, giving rise to anomalous properties including non-Fermi liquid …

A Nevanlinna-Type Counting Function And Pullback Measure, John Nguyen

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this dissertation, we introduce a Nevanlinna-type counting function, $M_{\varphi, \alpha}$. We show that $M_{\varphi, \alpha}$ is subharmonic and continuous on $\theset$ by exhibiting certain properties of the logarithmic potential of the associated pullback measure of two-dimensional Lebesgue measure on $\mathbb{D}$. Different identities of $M_{\varphi, \alpha}$ are presented. A change-of-variable formula calculates precisely the weighted Bergman norms of composition functions in terms of $M_{\varphi, \alpha}$. Certain estimates involving $M_{\varphi, \alpha}$ and the associated pullback measure on Carleson windows and semi-disks are demonstrated. For weighted Bergman space $A^2_\alpha$, we characterize orthogonal self-maps and give the Hilbert Schmidt norm of $C_\varphi$.

A Fortified Extension Of The Aes And Its Implementation, Ashby Mullin

UNLV Theses, Dissertations, Professional Papers, and Capstones

With the advancement of quantum computing (QC), the integrity of cryptography has been called into question. For example, two QC algorithms have been developed that can break asymmetric encryption (i.e., Grover’s, Shor’s), which also poses a threat to symmetric encryption. Asymmetric encryption efforts addressing this threat include lattice-based cryptography, which uses lattice problems to reduce efficiency of cryptanalysis. Symmetric encryption security can be bolstered by increasing the key length, allowing for additional permutations a key could have; known as keyspace. This thesis seeks to expand the keyspace of symmetric encryption in order to create more possibilities. This fortification to the …

Association Between White Matter Hyperintensities, Cortical Thinning, And Clinical Outcomes In Mild Traumatic Brain Injury, Thomas Helmut Knoblauch

UNLV Theses, Dissertations, Professional Papers, and Capstones

Traumatic Brain Injury (TBI) is a global health challenge, with over 4.6 million confirmed cases annually in North America alone. Mild traumatic brain injuries (mTBIs) are the most common and make up approximately 81% of all TBI diagnoses worldwide [1]. Studies indicate that 10–15% of patients suffer from trauma induced symptoms (i.e. headache, loss of balance, cognitive impairments, fatigue, and mental health/affective disorders) as far as 1 year post injury [2]. Prediction and management of these post-traumatic sequalae is complicated by a lack of symptom associated neuroimaging findings. In spite of a “prominent distribution” of frontotemporal WMHs in pediatric subjects …

A Nomological Network Analysis Of Innovation In Hospitality Education And Industry, Robert H. Rippee

UNLV Theses, Dissertations, Professional Papers, and Capstones

The development of a theory of innovation for hospitality innovation finds heightened importance due to the COVID-19 Pandemic that has unleashed a devastating and sustained disruption on global hospitality and tourism. The problem for research is that the industry lacks a taxonomy for research on innovation in hospitality. This study addresses the gap in understanding the nomological relationship between innovation constructs and the observable manifestations of innovation in the hospitality industry. This study used an emergent basic qualitative design of a phenomenon through data collected in three phases. Two large samples of literature and a series of focus groups comprised …

A Combined Approach To Evaluating Student Engagement In A Virtual Laboratory Environment, Aster Sigel

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study measured student engagement with galvanic skin response (GSR) using a one group randomized pretest–posttest design in a science, technology, engineering, and mathematics (STEM) learning environment to develop effective intervention strategies for engaging students in STEM learning experiences. Student engagement is a multi-dimensional interrelated construct, consisting of emotional, behavioral, and cognitive components, and varies in different subjects and learning environments. Student engagement in higher education is associated with academic achievement, retention, and graduation. In this study, the emotional, behavioral, and cognitive engagement data of 30 college students were obtained using self-report surveys, observation and physiological data, which was recorded …

The Processj C++ Runtime System And Code Generator, Alexander Christian Thomason

UNLV Theses, Dissertations, Professional Papers, and Capstones

ProcessJ is a modern Process-Oriented language that builds on previous work from other languages like occam and occam-pi. However, the only readily-available runtime system is built on top of the Java Virtual Machine (JVM). This is not a choice made intentionally, but simply out of a lack of other implementations -- until now. This thesis introduces the new C++-based runtime system for ProcessJ, coupled with a new C++ code generator for the ProcessJ compiler. This thesis later examines the implementation details of the runtime system, including the components that make it up. We also examine the ability to cooperatively schedule …

Microbe-Mineral Interactions During Exceptional Fossil Preservation, Stromatolite Formation, And Desert Varnish Growth, Michael Strange

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Ediacaran to Cambrian Deep Spring Formation consists of mixed carbonate-siliciclastic strata which contain an increasingly complex and biogeographically important biota. Past investigations of the Deep Spring Formation at Mt. Dunfee, Nevada, explored the highly diverse microbialite reefs consisting of a wide range of stromatolite morphologies which exerted significant control on local sedimentation and topography. Early investigations also documented the biomineralizing metazoan Cloudina (an Ediacaran index fossil). However, recent exploration of the area has resulted in the discovery of several new metazoan fossil communities consisting of a diverse assemblage of Ediacaran soft-tissue tubicolous vermiforms (tube fossils) similar to Cloudina. The …

Initial Measurements On The Effect Of Stress On P- And S-Wave Velocities In Olivine, Taryn Traylor

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is well known that elasticity is a key physical property in the determination of the structure and composition of the Earth and provides critical information for the interpretation of seismic data. This study investigates the stress-induced variation in elastic wave velocities, known as the acoustoelastic effect, in San Carlos olivine. A recently developed experimental ultrasonic acoustic system, the Directly Integrated Acoustic System Combined with Pressure Experiments (DIASCoPE), was used with the D-DIA multi-anvil apparatus to transmit ultrasonic sound waves and collect the reflections. We use the DIASCoPE to obtain longitudinal (P) and shear (S) elastic wave velocities from the …

Shakespeare’S As You Like It And James Cameron’S Avatar: Reharmonizing Society With Nature, Erin Rebecca Turner

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shakespeare’s As You Like It is a comedy whose main character, Rosalind, is forced out of her home among the upper caste of society through no fault of her own, but because of an issue with her father. She moves into the pastoral unknown disguised as a man to avoid the issues that come traveling as a woman, outside the protection of the home. Along the way, she finds pleasure with the power she holds as a man. She is heard when she speaks as a man and she is given access to knowledge she would not be given as …

An Exploration Of The Numeracy Skills Required For Safe, Quality Nursing Practice, Anna Wendel

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study was to explore the numeracy skills required for safe, quality nursing practice. Using a descriptive mixed methods design, this study answered two research questions: 1) What numeracy skills do nurses perceive as important for providing safe, quality nursing care in the first three years of practice? 2) How do nurses incorporate numeracy skills into daily patient care during the first three years of practice? Early career nurses from a not-for-profit health care organization in the mid-Atlantic region of the United States (n=109) responded to an online survey tool developed by the student investigator that ranked …

Equivalences Of Determinacy Between Levels Of The Borel Hierarchy And Long Games, And Some Generalizations, Katherine Aimee Yost

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis will be primarily focused on directly proving that the determinacy of Borel games in X^ω is equivalent to the determinacy of certain long open games, from a fragment of ZFC that’s well-known to be insufficient to prove Borel determinacy. The main theorem is a level by level result which shows the equivalence between determinacy of open games in a long tree, [Υ^α], and determinacy of Σ_0^α games in X^ω. In Chapter 9, we mimic the proof used in our main theorem to show that the determinacy of clopen games in the product space X^ω × ω^ω is equivalent …

Developments Of Machine Learning Potentials For Atomistic Simulations, Howard Yanxon

UNLV Theses, Dissertations, Professional Papers, and Capstones

Atomistic modeling methods such as molecular dynamics play important roles in investigating time-dependent physical and chemical processes at the microscopic level. In the simulations, energy and forces, sometimes including stress tensor, need to be recalculated iteratively as the atomic configuration evolves. Consequently, atomistic simulations crucially depend on the accuracy of the underlying potential energy surface. Modern quantum mechanical modeling based on density functional theory can consistently generate an accurate description of the potential energy surface. In most cases, molecular dynamics simulations based on density functional theory suffer from highly demanding computational costs. On the other hand, atomistic simulations based on …