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Multi-Resolution Spatio-Temporal Change Analyses Of Hydro-Climatological Variables In Association With Large-Scale Oceanic-Atmospheric Climate Signals, Kazi Ali Tamaddun

UNLV Theses, Dissertations, Professional Papers, and Capstones

The primary objective of the work presented in this dissertation was to evaluate the change patterns, i.e., a gradual change known as the trend, and an abrupt change known as the shift, of multiple hydro-climatological variables, namely, streamflow, snow water equivalent (SWE), temperature, precipitation, and potential evapotranspiration (PET), in association with the large-scale oceanic-atmospheric climate signals. Moreover, both observed datasets and modeled simulations were used to evaluate such change patterns to assess the efficacy of the modeled datasets in emulating the observed trends and shifts under the influence of uncertainties and inconsistencies. A secondary objective of this study was to …

Preparation And Evaluation Of Uranium Alloys Based On Burnup, Andrew Jonathan Swift

UNLV Theses, Dissertations, Professional Papers, and Capstones

Next generation fast reactor designs utilizing metallic fuel are being developed as an alternative fuel cycle option in an effort to reduce carbon emissions. Historically, oxide fuels have been the industry standard, but interest in metallic fuel systems has grown considerably due to their thermal conductivity, fissile atom density, inherent safety, and ability to reach progressively higher burnups. Chemical complexity of metallic fuel systems increase as a function of burnup from fission product ingrowth and associated fuel cladding chemical interactions (FCCI) brought on by elemental redistribution and phase formation. To date, the most extensive operational study for metallic fuel was …

Creative Self-Efficacy: Students In General Education, With Learning Disabilities, And With Gifts And Talents, Jennifer Elaine Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

Creative self-efficacy is the belief in one’s own ability to be creative. It is a component of creativity and is vital for future success. Within the construct of creative thinking, four areas of creative thinking (i.e., fluency, flexibility, elaboration, and originality) have been suggested.

The purpose of this study was to investigate the perception of creative self-efficacy in third, fourth, and fifth grade students in general education, with learning disabilities, and with gifts and talents in terms of fluency, flexibility, elaboration, and originality. Along with educational sub-type and grade level, an exploration of the relationship of gender and ethnicity were …

Assessing Simulated Transmissivity In Numerical Flow Models Of Complex Hydrogeology, Afan Tarar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accurately extracting a meaningful transmissivity, a target value within one order of magnitude of field estimates, in numerical models poses a significant challenge when modeling complex groundwater systems. Aquifer transmissivity is directly proportional to the aquifer thickness and the estimated aquifer hydraulic conductivity. In complex geologic conditions (especially in fractured systems) with multiple heterogeneous and anisotropic hydrogeologic units, transmissivity can vary over several orders of magnitude.

To extract a meaningful value of transmissivity from a numerical model, a simple five-layer MODFLOW model was constructed. Each layer in the model was assigned a fixed hydraulic conductivity and thickness. The model simulates …

The Effects Of Injury On Running Status And Gait Biomechanics, Kristyne Wiegand

UNLV Theses, Dissertations, Professional Papers, and Capstones

Over the past several decades, endurance running has grown steadily as a popular form of physical activity. Running is easily accessible, does not require expensive equipment, and can be performed without specific skill training. Individuals who run also experience health benefits like increased cardiovascular health and reduced risk of all-cause morbidity. Despite these benefits, running is also associated with high rates of musculoskeletal injury. Although researchers have attempted to identify injury risks and mitigate the incidence of running injury, there is still no consensus as to why runners become injured. Research has also attempted to identify biomechanical movement patterns that …

An Analysis Of Postmastectomy Breast Reconstruction Due To Breast Cancer In Nevada And The United States From 2008-2013, Jenna Webb

UNLV Theses, Dissertations, Professional Papers, and Capstones

Background: In the United States, female breast cancer was the leading cause of new cancer cases from 2011-2015. Since the Women’s Health and Cancer Act of 1998 (WHCRA), the federal government mandates employee and private health insurance providers to cover breast reconstruction if they cover mastectomies. Postmastectomy breast reconstruction (PBR) rates increased after the WHCRA, but these rates have remained relatively low throughout recent years. Objective: The objective of this study was to determine factors associated with women having PBR due to breast cancer in Nevada and the United States from 2008 to 2013. Methods: Using two HCUP database, NIS …

Motivation And Gesture In Foreign And Second Language Development: A Sociocultural Study Of Chinese Learners Of English, Lixian Tian

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation study investigated motivation as related to goal-directed activity and gesture awareness as well as their interplay in second and foreign language development in different English as a foreign language (EFL) and English as a second language (ESL) contexts. This study included four groups of Chinese learners of English. The first EFL group consisted of college students in China learning English without intention of studying abroad (G1) and the second EFL group in China included Chinese learners of English who were learning English to prepare to study abroad (G2). Participants in the first ESL group were living and studying …

The Affective Perceptual Model: Enhancing Communication Quality For Persons With Pimd, Jadin Tredup

UNLV Theses, Dissertations, Professional Papers, and Capstones

Methods for prolonged compassionate care for persons with Profound Intellectual and Multiple Disabilities (PIMD) require a rotating cast of import people in the subjects life in order to facilitate interaction with the external environment. As subjects continue to age, dependency on these people increases with complexity of communications while the quality of communication decreases. It is theorized that a machine learning (ML) system could replicate the attuning process and replace these people to promote independence. This thesis extends this idea to develop a conceptual and formal model and system prototype.

The main contributions of this thesis are: (1) proposal of …

Exploring The Utility Of Mindfulness In The Elementary School Classroom, Sarah M. Wells

UNLV Theses, Dissertations, Professional Papers, and Capstones

Current evidence supporting the efficacy of mindfulness training in the K-12 setting is quite limited. In addition there is a lack of theory that is committed explicitly to explaining how a direct mindfulness-achievement effect might appear. This study builds a promising foundation for helping address this gap in the existing literature. Framed within the context of a limited source model of self-regulation, academic achievement and perceptions of third, fourth, and, fifth graders participating in a 3-week mindfulness training program were examined across variables of executive control, and emotional regulation. Mindfulness training produced observed emotional and cognitive benefits, including increased executive …

Generalized And Higher Dimensional Apollonian Packings, Daniel Lautzenheiser

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, we show that circle, sphere, and higher dimensional sphere packings may

be realized as subsets of the boundary of hyperbolic space, subject to certain symmetry

conditions based on a discrete group of motions of the hyperbolic space. This leads to

developing and applying counting methods which admit rigorous upper and lower bounds on

the Hausdorff (or Besikovitch) dimension of the residual set of several generalized Apollonian

circle packings. We find that this dimension (which also coincides with the critical exponent

of a zeta-type function) of each packing is strictly greater than that of the Apollonian

packing, supporting …

Adaptive And Supertwisting Adaptive Spacecraft Orbit Control Around Asteroids, Keum W. Lee, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

This paper addresses the development of control systems for the orbit control of spacecraft around irregularly shaped rotating asteroids with uncertain parameters. The objective is to steer the spacecraft along prescribed orbits. First, a nonlinear adaptive law for orbit control was designed. This was followed by the design of a supertwisting adaptive (STWA) control system. In the closed-loop system, which includes the adaptive law or the STWA law, all the signals remain bounded, and the trajectory tracking error asymptotically converges to zero for any initial condition. Finally, under the assumption of boundedness of the derivative of the uncertain functions of …

Non-Isobaric Thermal Instability, Tim Waters, Daniel Proga

Physics & Astronomy Faculty Research

Multiphase media have very complex structure and evolution. Accurate numerical simulations are necessary to make advances in our understanding of this rich physics. Because simulations can capture both the linear and nonlinear evolution of perturbations with a relatively wide range of sizes, it is important to thoroughly understand the stability of condensation and acoustic modes between the two extreme wavelength limits of isobaric and isochoric instability as identified by Field. Partially motivated by a recent suggestion that large non-isobaric clouds can "shatter" into tiny cloudlets, we revisit the linear theory to survey all possible regimes of thermal instability. We uncover …

Cloud Coalescence: A Dynamical Instability Affecting Multiphase Environments, Tim Waters, Daniel Proga

Physics & Astronomy Faculty Research

Mass and size distributions are the key characteristics of any astrophysical object, including the densest clumps comprising the cold phase of multiphase environments. In our recent papers, we showed how individual clouds of various sizes form and evolve in active galactic nuclei. In particular, we showed that large clouds undergo damped oscillations as a response to their formation process. Here we follow up this investigation, addressing how different size clouds interact. We find that smaller clouds become trapped in the advective flows generated by larger clouds. The explanation for this behavior leads to a rather remarkable conclusion: even in the …

Controlling Rotational Quenching Rates In Cold Molecular Collisions, James F.E. Croft, Balakrishnan Naduvalath

Chemistry and Biochemistry Faculty Research

The relative orientation and alignment of colliding molecules plays a key role in determining the rates of chemical processes. Here, we examine in detail a prototypical example: rotational quenching of HD in cold collisions with H2. We show that the rotational quenching rate from j = 2 → 0, in the v = 1 vibrational level, can be maximized by aligning the HD along the collision axis and can be minimized by aligning the HD at the so called magic angle. This follows from quite general helicity considerations and suggests that quenching rates for other similar systems can also be …

Second Repeating Frb 180814.J0422+73: Ten-Year Fermi-Lat Upper Limits And Implications, Yu-Han Yang, Bin-Bin Zhang, Bing Zhang

Physics & Astronomy Faculty Research

The second repeating fast radio burst source, FRB 180814.J0422+73, was detected recently by the CHIME collaboration. We use the ten-year Fermi Large Area Telescope archival data to place a flux upper limit in the energy range of 100 MeV−10 GeV at the position of the source, which is ~1.1 × 10−11 erg cm−2 s−1 for a six-month time bin on average, and ~2.4 × 10−12 erg cm−2 s−1 for the entire ten-year time span. For the maximum redshift of z = 0.11, the ten-year upper limit of luminosity is ~7.3 × 1043 erg s−1. We utilize these upper limits to …

Coherent Radio Emission From A Twisted Magnetosphere After A Magnetar-Quake, Weiyang Wang, Bing Zhang, Xuelei Chen, Renxin Xu

Physics & Astronomy Faculty Research

Magnetars are a class of highly magnetized, slowly rotating neutron stars, only a small fraction of which exhibit radio emission. We propose that the coherent radio curvature emission is generated by net charge fluctuations from a twist-current-carrying bundle (the j-bundle) in the scenario of magnetar-quake. Two-photon pair production is triggered, which requires a threshold voltage not too much higher than 109 V in the current-carrying bundle, and which can be regarded as the "open field lines" of a magnetar. Continued untwisting of the magnetosphere maintains change fluctuations, and hence coherent radio emission, in the progressively shrinking j-bundle, which lasts for …

Optimization Of Photocatalytic Degradation Of Acid Blue 113 And Acid Red 88 Textile Dyes In A Uv-C/Tio2 Suspension System: Application Of Response Surface Methodology (Rsm), Ali Saber, David E. James, Soroosh Mortazavian

Civil and Environmental Engineering and Construction Faculty Research

Textile industries produce copious amounts of colored wastewater some of which are toxic to humans and aquatic biota. This study investigates optimization of a bench-scale UV-C photocatalytic process using a TiO2 catalyst suspension for degradation of two textile dyes, Acid Blue 113 (AB 113) and Acid Red 88 (AR 88). From preliminary experiments, appropriate ranges for experimental factors including reaction time, solution pH, initial dye concentration and catalyst dose, were determined for each dye. Response surface methodology (RSM) using a cubic IV optimal design was then used to design the experiments and optimize the process. Analysis of variance (ANOVA) was …

Pacific Southwest United States Holocene Droughts And Pluvials Inferred From Sediment Δ18o (Calcite) And Grain Size Data (Lake Elsinore, California), Matthew E.C. Kirby, William Paul Patterson, Matthew Lachniet, James A. Noblet, Michael A. Anderson, Kevin Nichols, Judith Avila

Geoscience Faculty Research

Records of past climate can inform us on the natural range and mechanisms of climate change. In the arid Pacific southwestern United States (PSW), which includes southern California, there exist a variety of Holocene records that can be used to infer past winter conditions (moisture and/or temperature). Holocene records of summer climate, however, are rare from the PSW. In the future, climate changes due to anthropogenic forcing are expected to increase the severity of drought in the already water stressed PSW. Hot droughts are of considerable concern as summer temperatures rise. As a result, understanding how summer conditions changed in …

Alignment Of A Circumbinary Disc Around An Eccentric Binary With Application To Kh 15d, Jeremy L. Smallwood, Stephen H. Lubow, Alessia Franchini, Rebecca G. Martin

Physics & Astronomy Faculty Research

We analyse the evolution of a mildly inclined circumbinary disc that orbits an eccentric orbit binary by means of smoothed particle hydrodynamics (SPH) simulations and linear theory. We show that the alignment process of an initially misaligned circumbinary disc around an eccentric orbit binary is significantly different than around a circular orbit binary and involves tilt oscillations. The more eccentric the binary, the larger the tilt oscillations and the longer it takes to damp these oscillations. A circumbinary disc that is only mildly inclined may increase its inclination by a factor of a few before it moves towards alignment. The …

Capturing Heterogeneity Of Covariate Effects In Hidden Subpopulations In The Presence Of Censoring And Large Number Of Covariates, Farhad Shokoohi, Abbas Khalili, Masoud Asgharian, Shili Lin

Mathematical Sciences Faculty Research

The advent of modern technology has led to a surge of high-dimensional data in biology and health sciences such as genomics, epigenomics and medicine. The high-grade serous ovarian cancer (HGS-OvCa) data reported by The Cancer Genome Atlas (TCGA) Research Network is one example. The TCGA and other research groups have analyzed several aspects of these data. Here we study the relationship between Disease Free Time (DFT) after surgery among ovarian cancer patients and their DNA methylation profiles of genomic features. Such studies pose additional challenges beyond the typical big data problem due to population substructure and censoring. Despite the availability …

Generalized Warped Disk Equations, Rebecca G. Martin, Stephen H. Lubow, J. E. Pringle, Alessia Franchini, Zhaohuan Zhu, Stephen Lepp, Rebecca Nealon, C. J. Nixon, David Vallet

Physics & Astronomy Faculty Research

The manner in which warps in accretion disks evolve depends on the magnitude of the viscosity. ... See full text for complete abstract.

Dust Traps In The Protoplanetary Disk Mwc 758: Two Vortices Produced By Two Giant Planets?, Clement Baruteau, Marcelo Barraza, Sebastian Perez, Simon Casassus, Ruobing Dong, Wladimir Lyra, Sebastian Marino, Valentin Christiaens, Zhaohuan Zhu, Andres Carmona, Florian Debras, Felipe Alarcon

Physics & Astronomy Faculty Research

Resolved ALMA and VLA observations indicate the existence of two dust traps in the protoplanetary disc MWC 758. By means of two-dimensional gas+dust hydrodynamical simulations post-processed with three-dimensional dust radiative transfer calculations, we show that the spirals in scattered light, the eccentric, asymmetric ring and the crescent-shaped structure in the (sub)millimetre can all be caused by two giant planets: a 1.5-Jupiter mass planet at 35 au (inside the spirals) and a 5-Jupiter mass planet at 140 au (outside the spirals). The outer planet forms a dust-trapping vortex at the inner edge of its gap (at ∼85 au), and the continuum …

Long-Period Giant Companions To Three Compact, Multiplanet Systems, Sean M. Mills, Andrew W. Howard, Lauren M. Weiss, Jason H. Steffen, Howard Isaacson, Benjamin Fulton, Erik A. Petigura, Molly R. Kosiarek, Lea A. Hirsch, John H. Boisvert

Physics & Astronomy Faculty Research

Understanding the relationship between long-period giant planets and multiple smaller short-period planets is critical for formulating a complete picture of planet formation. This work characterizes three such systems. We present Kepler-65, a system with an eccentric (e = 0.28 ± 0.07) giant planet companion discovered via radial velocities (RVs) exterior to a compact, multiply transiting system of sub-Neptune planets. We also use precision RVs to improve mass and radius constraints on two other systems with similar architectures, Kepler-25 and Kepler-68. In Kepler-68 we propose a second exterior giant planet candidate. Finally, we consider the implications of these systems for planet …

Optimal Conditional Expectation At The Video Poker Game Jacks Or Better, Stewart N. Ethier, John J. Kim, Jiyeon Lee

UNLV Gaming Research & Review Journal

There are 134,459 distinct initial hands at the video poker game Jacks or Better, taking suit exchangeability into account. A computer program can determine the optimal strategy (i.e., which cards to hold) for each such hand, but a complete list of these strategies would require a book-length manuscript. Instead, a hand-rank table, which fits on a single page and reproduces the optimal strategy perfectly, was found for Jacks or Better as early as the mid 1990s. Is there a systematic way to derive such a hand-rank table? We show that there is indeed, and it involves finding the exact optimal …

Select Proceedings Of The 2nd Annual Graduate Student Conference: Games, Sins & Mafia, Samuel Gilpin, Carly Hunter, Jenessa Kenway, Alexander Valle, Jarret Keene

Graduate Student Conference

The four papers collected here were originally presented at the Second Annual Graduate Student Conference: "Games, Sins & Mafia." Hosted by the UNLV World Languages & Cultures department and the Organization of Vistas of Hispanic Studies, the conference took place on the UNLV campus on March 16, 2019. These proceedings feature three (at the time) graduate students and one undergraduate student from the UNLV English department. Taken as a whole, the proceedings explore the aesthetic, sociological, and philosophical concerns of a range of authors—William Faulkner, Juan Rulfo (Mexico), Roberto Harrison, and Clarice Lispector (Brazil).

Charged Compact Binary Coalescence Signal And Electromagnetic Counterpart Of Plunging Black Hole–Neutron Star Mergers, Bing Zhang

Physics & Astronomy Faculty Research

If at least one of the members of a compact binary coalescence is charged, the inspiral of the two members would generate a Poynting flux with an increasing power, giving rise to a brief electromagnetic counterpart temporally associated with the chirp signal of the merger (with possibly a small temporal offset), which we term as the charged compact binary coalescence (cCBC) signal. We develop a general theory of cCBC for any mass and amount of charge for each member. Neutron stars (NSs), as spinning magnets, are guaranteed to be charged, so the cCBC signal should accompany all NS mergers. The …

The Potential Science And Engineering Value Of Samples Delivered To Earth By Mars Sample Return, David W. Beaty, Monica M. Grady, Harry Y. Mcsween, Elliot Sefton-Nash, B. L. Carrier, Francesca Altieri, Yuri Amelin, Eleonora Ammannito, Mahesh Anand, Liane G. Benning, Janice L. Bishop, Lars E. Borg, Dale Boucher, John R. Brucato, Henner Busemann, Kathleen A. Campbell, Andrew D. Czaja, Vinciane Debaille, David J. Des Marais, Michael Dixon, Bethany L. Ehlmann, Jack D. Farmer, David C. Fernandez-Remolar, Justin Filiberto, Jennifer Fogarty, Daniel P. Galvin, Y. S. Goreva, Lydia J. Hallis, Andrea Dawn Harrington, Elisabeth M. Hausrath, Chris D.K. Herd

Geoscience Faculty Research

Executive summary provided in lieu of abstract.

Changes In Snow Phenology From 1979 To 2016 Over The Tianshan Mountains, Central Asia, Tao Yang, Qian Li, Sajjad Ahmad, Hongfei Zhou, Lanhai Li

Civil and Environmental Engineering and Construction Faculty Research

Snowmelt from the Tianshan Mountains (TS) is a major contributor to the water resources of the Central Asian region. Thus, changes in snow phenology over the TS have significant implications for regional water supplies and ecosystem services. However, the characteristics of changes in snow phenology and their influences on the climate are poorly understood throughout the entire TS due to the lack of in situ observations, limitations of optical remote sensing due to clouds, and decentralized political landscapes. Using passive microwave remote sensing snow data from 1979 to 2016 across the TS, this study investigates the spatiotemporal variations of snow …

Kondo Signatures Of A Quantum Magnetic Impurity In Topological Superconductors, Rui Wang, Wei-Yi Su, Jian-Xin Zhu, Chin-Sen Ting, Hai Li, Changfeng Chen, Baigeng Wang, Xiaoqun Wang

Physics & Astronomy Faculty Research

We study the Kondo physics of a quantum magnetic impurity in two-dimensional topological superconductors (TSCs), either intrinsic or induced on the surface of a bulk topological insulator, using a numerical renormalization group technique. We show that, despite sharing the p+ip pairing symmetry, intrinsic and extrinsic TSCs host different physical processes that produce distinct Kondo signatures. Extrinsic TSCs harbor an unusual screening mechanism involving both electron and orbital degrees of freedom that produces rich and prominent Kondo phenomena, especially an intriguing pseudospin Kondo singlet state in the superconducting gap and a spatially anisotropic spin correlation. In sharp contrast, intrinsic TSCs support …

Fluorine Chemistry At Extreme Conditions: Possible Synthesis Of Hgf4, Michael G. Pravica, Sarah Schyck, Blake Harris, Petrika Cifligu, Eunja Kim, Brant Billinghurst

Physics & Astronomy Faculty Research

By irradiating a pressurized mixture of a fluorine-bearing compound (XeF2XeF2) and HgF2HgF2 with synchrotron hard x-rays ... (See full text for complete abstract)