Digital Commons Network^™

Synthesis, Optical Spectroscopy And Laser Potential Of Pyrylium Tosylates, Jung Jae Koh, Christina Inbok Lee, Mihaela Alexa Ciulei, Haesook Han, Pradip Kumar Bhowmik, Vladimir Kartazaev, Swapan Kumar Gayen

Chemistry and Biochemistry Faculty Research

Safe and inexpensive methods for synthesis of a series of four substituted 2,4,6-triphenylyrylium tosylate salts with different substituents are reported. The synthesis methods use p-toluenesulfonic acid monohydrate instead of conventional acid catalysts including perchloric acid or boron trifluoride diethyl etherate that pose explosion danger and difficult storage problems, respectively. The chemical structures of these salts were established using FTIR, 1H and 13C NMR spectroscopic techniques and elemental analysis. Thermogravimetric analysis (TGA) showed that these salts have good thermal stability, and differential scanning calorimetry (DSC) analysis showed that they have lower melting transitions than the corresponding tetrafluoroborate and perchlorate salts. Solutions …

The Origin Of The Prompt Emission For Short Grb 170817a: Photosphere Emission Or Synchrotron Emission?, Yan-Zhi Meng, Jin-Jun Geng, Bin-Bin Zhang, Jun-Jie Wei, Di Xiao, Liang-Duan Liu, He Gao, Xue-Feng Wu, En-Wei Liang, Yong-Feng Huang, Zi-Gao Dai, Bing Zhang

Physics & Astronomy Faculty Research

The first gravitational-wave event from the merger of a binary neutron star system (GW170817) was detected recently. The associated short gamma-ray burst (GRB 170817A) has a low isotropic luminosity (~1047 erg s−1) and a peak energy E p ~ 145 keV during the initial main emission between −0.3 and 0.4 s. The origin of this short GRB is still under debate, but a plausible interpretation is that it is due to the off-axis emission from a structured jet. We consider two possibilities. First, since the best-fit spectral model for the main pulse of GRB 170817A is a cutoff power law …

The Allowed Parameter Space Of A Long-Lived Neutron Star As The Merger Remnant Of Gw170817, Shunke Ai, He Gao, Zi-Gao Dai, Xue-Feng Wu, Ang Li, Bing Zhang, Mu-Zi Li

Physics & Astronomy Faculty Research

Due to the limited sensitivity of the current gravitational wave (GW) detectors, the central remnant of the binary neutron star (NS) merger associated with GW170817 remains an open question. In view of the relatively large total mass, it is generally proposed that the merger of GW170817 would lead to a short-lived hypermassive NS or directly produce a black hole (BH). There is no clear evidence to support or rule out a long-lived NS as the merger remnant. Here, we utilize the GW and electromagnetic (EM) signals to comprehensively investigate the parameter space that allows a long-lived NS to survive as …

Deep Learning For Link Prediction In Dynamic Networks Using Weak Estimators, Carter Chiu, Justin Zhan

Computer Science Faculty Research

Link prediction is the task of evaluating the probability that an edge exists in a network, and it has useful applications in many domains. Traditional approaches rely on measuring the similarity between two nodes in a static context. Recent research has focused on extending link prediction to a dynamic setting, predicting the creation and destruction of links in networks that evolve over time. Though a difficult task, the employment of deep learning techniques have shown to make notable improvements to the accuracy of predictions. To this end, we propose the novel application of weak estimators in addition to the utilization …

Impact Of Upstream Chlorination On Filter Performance And Microbial Community Structure Of Gac And Anthracite Biofilters, Glen Andrew De Vera, Daniel Gerrity, Mitchell Stoker, Wilbur Frehner, Eric C. Wert

Civil and Environmental Engineering and Construction Faculty Research

Drinking water filters may be operated to promote or deter biological activity through upstream oxidant addition. While there are several water quality benefits from biofiltration, microbial growth in biofilters warrants further investigation. In this study, routine monitoring detected target DNA sequences for Naegleria fowleri in source water and Acanthamoeba spp. in source water and biofilter effluent, triggering further microbial community characterization. Full-scale anthracite and granular activated carbon (GAC) filters receiving chlorinated waters were compared in terms of effluent water quality (i.e., turbidity and particle counts), biological activity (i.e., adenosine triphosphate (ATP)), and the composition of the microbial community (i.e., 16S/18S …

On The Radio Detectability Of Circumplanetary Discs, Zhaohuan Zhu, Sean M. Andrews, Andrea Isella

Physics & Astronomy Faculty Research

Discs around young planets, so-called circumplanetary discs (CPDs), are essential for planet growth, satellite formation, and planet detection. We study the millimetre and centimetre emission from accreting CPDs by using the simple α disc model. We find that it is easier to detect CPDs at shorter radio wavelengths (e.g. λ ≲ 1 mm). For example, if the system is 140 pc away from us, deep observations (e.g. 5 h) at ALMA Band 7 (0.87 mm) are sensitive to as small as 0.03 lunar mass of dust in CPDs. If the CPD is around a Jupiter mass planet 20 au away …

Grb 120729a: External Shock Origin For Both The Prompt Gamma-Ray Emission And Afterglow, Li-Ye Huang, Xiang-Gao Wang, Weikang Zheng, En-Wei Liang, Da-Bin Lin, Shi-Qing Zhong, Hai-Ming Zhang, Xiao-Li Huang, Alexi V. Filippenko, Bing Zhang

Physics & Astronomy Faculty Research

Gamma-ray burst (GRB) 120729A was detected by Swift/BAT and Fermi/GBM, and then rapidly observed by Swift/XRT, Swift/UVOT, and ground-based telescopes. It had a single long and smooth \gamma-ray emission pulse, which extends continuously to the X-rays. We report Lick/KAIT observations of the source, and make temporal and spectral joint fits of the multiwavelength light curves of GRB 120729A. It exhibits achromatic light-curve behavior, consistent with the predictions of the external shock model. The light curves are decomposed into four typical phases: onset bump (Phase I), normal decay (Phase II), shallow decay (Phase III), and post-jet break (Phase IV). The spectral …

Gamma-Ray Burst Jet Breaks Revisited, Xiang-Gao Wang, Bing Zhang, En-Wei Liang, Rui-Jing Liang, Da-Bin Lin, Jing Li, Long Li

Physics & Astronomy Faculty Research

Gamma-ray Burst (GRB) collimation has been inferred with the observations of achromatic steepening in GRB light curves, known as jet breaks. Identifying a jet break from a GRB afterglow light curve allows a measurement of the jet opening angle and true energetics of GRBs. In this paper, we re-investigate this problem using a large sample of GRBs that have an optical jet break that is consistent with being achromatic in the X-ray band. Our sample includes 99 GRBs from 1997 February to 2015 March that have optical and, for Swift GRBs, X-ray light curves that are consistent with the jet …

Five Years Of Video-Based Assessment Data: Lessons From A Teacher Education Program, Peter D. Wiens, Matthew D. Gromlich

Teaching and Learning Faculty Research

Teacher education programs are under considerable pressure to evaluate their effectiveness in training new teachers. Over the last several decades there have been repeated calls for more systematic research on preservice teacher preparation programs. One institution has heeded this call, using the Video Assessment of Interactions and Learning (VAIL: Jamil, Sabol, Hamre, & Pianta, 2015) to annually assess teacher noticing of teacher student interactions in preservice teachers. While there was no significant difference in first-test and last-test VAIL scores, VAIL scores were shown to be related to final college GPA. Additionally, there was a difference in student effort on the …

Formation Of Evolved Rocks At Gale Crater By Crystal Fractionation And Implications For Mars Crustal Composition, Arya Udry, Esteban Gazel, Harry Y. Mcsween Jr.

Geoscience Faculty Research

The recent discovery of some ancient evolved rocks in Gale crater by the Curiosity rover has prompted the hypothesis that continental crust formed in early Martian history. Here we present petrological modeling that attempts to explain this lithological diversity by magma fractionation. Using the thermodynamical software MELTS, we model fractional crystallization of different Martian starting compositions that might generate felsic igneous compositions like those analyzed at Gale crater using different variables, such as pressure, oxygen fugacities, and water content. We show that similar chemical and mineralogical compositions observed in Gale crater felsic rocks can readily be obtained through different degrees …

Variations In Institutional Review Board Processes And Consent Requirements For Trauma Research: An East Multicenter Survey, Jeffry Nahmias, Areg Grigorian, Scott Brakenridge, Randeep S. Jawa, Daniel N. Holena, John Varujan Agapian, Brandon Bruns, Paul J. Chestovich, Bruce Chung, Jonathan Nguyen, Carl I. Schulman, Kristan Staudenmayer, Rachel Dixon, Jason W. Smith, Andrew C. Bernard, Jose L. Pascual

School of Medicine Faculty Research

Oversight of human subject research has evolved considerably since its inception. However, previous studies identified a lack of consistency of institutional review board (IRB) determination for the type of review required and whether informed consent is necessary, especially for prospective observational studies, which pose minimal risk of harm. We hypothesized that there is significant inter-institution variation in IRB requirements for the type of review and necessity of informed consent, especially for prospective observational trials without blood/tissue utilization. We also sought to describe investigators’ and IRB members’ attitudes toward the type of review and need for consent. Eastern Association for the …

Planet-Driven Spiral Arms In Protoplanetary Disks. I. Formation Mechanism, Jaehan Bae, Zhaohuan Zhu

Physics & Astronomy Faculty Research

Protoplanetary disk simulations show that a single planet can excite more than one spiral arm, possibly explaining the recent observations of multiple spiral arms in some systems. In this paper, we explain the mechanism by which a planet excites multiple spiral arms in a protoplanetary disk. Contrary to previous speculations, the formation of both primary and additional arms can be understood as a linear process when the planet mass is sufficiently small. A planet resonantly interacts with epicyclic oscillations in the disk, launching spiral wave modes around the Lindblad resonances. When a set of wave modes is in phase, they …

Planet-Driven Spiral Arms In Protoplanetary Disks. Ii. Implications, Jaehan Bae, Zhaohuan Zhu

Physics & Astronomy Faculty Research

We examine whether various characteristics of planet-driven spiral arms can be used to constrain the masses of unseen planets and their positions within their disks. By carrying out two-dimensional hydrodynamic simulations varying planet mass and disk gas temperature, we find that a larger number of spiral arms form with a smaller planet mass and a lower disk temperature. A planet excites two or more spiral arms interior to its orbit for a range of disk temperatures characterized by the disk aspect ratio $0.04\leqslant {(h/r)}_{p}\leqslant 0.15$, whereas exterior to a planet's orbit multiple spiral arms can form only in cold disks …

Introduction To A Resources Special Issue On Criticality Of The Rare Earth Elements: Current And Future Sources And Recycling, Simon M. Jowitt

Geoscience Faculty Research

The rare earth elements (REE) are vital to modern technologies and society and are amongst the most important of the critical elements. This special issue of Resources examines a number of facets of these critical elements, current and future sources of the REE, the mineralogy of the REE, and the economics of the REE sector. These papers not only provide insights into a wide variety of aspects of the REE, but also highlight the number of different areas of research that need to be undertaken to ensure sustainable and secure supplies of these critical metals into the future.

Using Empirical Recurrence Rates Ratio For Time Series Data Similarity, Moinak Bhaduri, Justin Zhan

Computer Science Faculty Research

Several methods exist in classification literature to quantify the similarity between two time series data sets. Applications of these methods range from the traditional Euclidean type metric to the more advanced Dynamic Time Warping metric. Most of these adequately address structural similarity but fail in meeting goals outside it. For example, a tool that could be excellent to identify the seasonal similarity between two time series vectors might prove inadequate in the presence of outliers. In this paper, we have proposed a unifying measure for binary classification that performed well while embracing several aspects of dissimilarity. This statistic is gaining …

Provenance And Paleogeography Of The 25-17 Ma Rainbow Gardens Formation: Evidence For Tectonic Activity At Ca. 19 Ma And Internal Drainage Rather Than Throughgoing Paleorivers On The Southwestern Colorado Plateau, Melissa A. Lamb, L. Sue Beard, Malia Dragos, Andrew D. Hanson, Thomas A. Hickson, Mark Sitton, Paul J. Umhoefer, Karl E. Karlstrom, Nelia Dunbar, William Mcintosh

Geoscience Faculty Research

The paleogeographic evolution of the Lake Mead region of southern Nevada and northwest Arizona is crucial to understanding the geologic history of the U.S. Southwest, including the evolution of the Colorado Plateau and formation of the Grand Canyon. The ca. 25–17 Ma Rainbow Gardens Formation in the Lake Mead region, the informally named, roughly coeval Jean Conglomerate, and the ca. 24–19 Ma Buck and Doe Conglomerate southeast of Lake Mead hold the only stratigraphic evidence for the Cenozoic pre-extensional geology and paleogeography of this area. Building on prior work, we present new sedimentologic and stratigraphic data, including sandstone provenance and …

Employability Skills And Trends In The Outdoor Power And Equipment Industry, Antoine J. Alston, Ryan Anderson, Chastity W. English, Dexter B. Wakefield

Journal of Research in Technical Careers

The Power, Structural and Technical Systems (PST) Career Pathway is one of eight within the Agriculture, Food, and Natural Resources Career Cluster; this pathway provides the curriculum that includes outdoor power equipment content. The perceived workforce readiness and skills needed in this pathway and related future trends were analyzed for entry-level jobs within the outdoor power equipment industry. The respondents expressed concern with being able to find qualified entry-level employees. Respondents indicated that the major skill categories of interpersonal skills, communication skills, computer skills, character skills, technical competency, and their corresponding subskills, were important for entry-level employment. The respondents indicated …

Merits Of Creating A Revised Cte National Research Agenda For 2020, Jeanea M. Lambeth, Richard M. Joerger, Jack Elliot

Journal of Research in Technical Careers

This article promotes the idea that clearly focused scholarly inquiry needs direction developed through a collaborative and informative process. The authors propose that the National CTE Research Agenda adopted in 2008 should be revised and updated to reflect the contemporary issues and policies of the career and technical education profession. The aim of this discussion is to propose a systematic research approach with the potential to influence policy for career and technical education. The challenge for our profession will be to create a united and informed agenda that will transform policy, promote innovation in scholarly endeavors, and foster improved outcomes …

A Dramatistic Analysis Of Nevada's Controversy Over Solar Net Metering Incentive Policies, Robert S. Burgy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Utilizing a dramatistic rhetorical lens (Burke, 1945), this project examines Nevada’s 2015-2017 public controversy to decide whether or not to implement solar net metering incentives. By examining communication surrounding The Public Utility Commission of Nevada (PUCN), NV Energy, and SolarCity, this thesis analyzes the underlying social orientations contained within the controversy’s discourse. This thesis examines how the environment was left out of solar energy discourse in favor of economic reasoning. Nevada’s solar controversy is an important component of humanity’s unending conversation about our relationship to the environment and an important case study to develop our understanding of public controversy.

Advancing Community Detection Using Keyword Attribute Search, Sanket Chobe

UNLV Theses, Dissertations, Professional Papers, and Capstones

As social network structures evolve constantly, it is necessary to design an efficient mechanism to track the influential nodes and accurate communities in the networks. The attributed graph represents the information about properties of the nodes and relationships between different nodes, hence, this attribute information can be used for more accurate community detection. Current techniques of community detection do not consider the attribute or keyword information associated with the nodes in a graph. In this thesis, I propose a novel ideal of online community detection using a technique of keyword search over the attributed graph. First, the influential attributes are …

Petrology And Geochemistry Of The Enriched Poikilitic Shergottite Northwest Africa 10169: Insight Into The Martian Interior, Logan Matthew Combs

UNLV Theses, Dissertations, Professional Papers, and Capstones

The martian meteorite Northwest Africa (NWA) 10169 is classified as a new member of the geochemically enriched poikilitic shergottites, based on mineral composition, Lu-Hf isotope systematics, and rare earth element (REE) composition. Akin to other poikilitic shergottites, it shows a similar bimodal texture to other enriched and intermediate poikilitic shergottites. In addition, olivine and pyroxene in the poikilitic zone have higher Mg#’s (Mg/Mg+Fe) than those in the interstitial areas, suggesting that the poikilitic texture represents early-stage crystallization, opposed to late-stage non-poikilitic crystallization. Calculated fO2 values are reduced (FMQ -2.3 ± 0.23) within the poikilitic texture, and more oxidized (FMQ -1.07 …

Motor Impairments In Children With Autism: Insight Into The Complexity Of The Disorder, Jeffrey Douglas Eggleston

UNLV Theses, Dissertations, Professional Papers, and Capstones

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder which has seen an increasing prevalence rate in recent decades. Currently, the diagnostic criteria for the disorder evaluate a multitude of social communication and interactions, in a variety of contexts, and restricted or repetitive behavioral patterns (stereotyped movement, resistance to changes in routines, restricted interests, and hyper- or hypo-reactivity to sensory stimulus). Furthermore, ASD severity is based upon the marked severity of the above described impairment and they must also fall within one of three potential categories: 1) symptoms being present in early development, although potentially not manifested fully; 2) the …

Modeling Impaired Hippocampal Neurogenesis After Radiation Exposure, Kapukotuwa Walawwe Sidath Chathuranga Kapukotuwa

UNLV Theses, Dissertations, Professional Papers, and Capstones

The birth of neuronal cells from neuronal stem cells is known as neurogenesis, and the granular cell layer of the dentate gyrus of hippocampus is one of the two regions in the brain this process occurs. Cognitive damages following radiation therapy for brain cancers in both children and adults have been linked to impairment of neurogenesis in the hippocampus. Studies followed using mice and rats as model animals have shown impairment in neurogenesis process following exposure to radiation. Obtaining experimental data for radiation-induced changes in neurogenesis in humans is very difficult. Model was developed and applied to mouse data previously; …

Examining The Influence Of Executive Resources And Mathematical Abilities On Framing Biases, Gabriel Allred

UNLV Theses, Dissertations, Professional Papers, and Capstones

The finding that the presentation of a choice (i.e., either as a loss or a gain) can affect and bias our willingness to engage in risk is one of the paramount findings of behavioral economics. First discussed by Tversky and Kahneman (1981), the framing effect demonstrates that when given two choices framed as a loss, we tend to become risk seeking. However, when the exact same outcome is presented as a gain, we become risk averse, choosing the more conservative option, regardless of the actual expected value. The effect is not limited to general research samples but has been demonstrated …

Static And Dynamic Quantitative Microbial Risk Assessment Of Potable Reuse Paradigms, Erfaneh Amoueyan

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years, potable reuse applications have become more common due to population growth and increased water demand, especially in communities with limited or variable water resources. However, there are concerns about potential exposure to pathogens and chemical compounds in treated wastewater. Therefore, advanced wastewater treatment processes are of paramount importance in any potable reuse system. The overall aim of this study was to develop and implement static and dynamic QMRAs to compare public health risk in various potable reuse scenarios. Cryptosporidium, norovirus, adenovirus, and Salmonella were chosen as the target pathogens. The research evaluated the performance of full advanced …

Before And After Her Body, Shannon Austin

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis, titled Before and After Her Body, is a full-length poetry manuscript submitted for completion of the Master of Fine Arts – Creative Writing Program. This collection delves into several interconnected themes, including gender, the female body, myth, legacy, and time. Broken into three main sections, these poems build from an examination of women as physical bodies to an exploration of women in conversation with other women and with themselves.

In these poems, characters from myth and popular culture blend with the persona of the narrator, who is at once an observer and a participant, discovering her own tradition …

Holocene Climate Evolution Of Continental Western Eurasia Constrained By Stable-Isotope And Cation Geochemistry Of U-Th-Dated Speleothems And Meteogenic Travertine, Jonathan Lloyd Baker

UNLV Theses, Dissertations, Professional Papers, and Capstones

Reliable reconstructions of global and regional climate during the Holocene (11,700 years ago to present) are vital to constraining the natural range of climate variability and testing state-of-the-art models, which seek to forecast the near- and long-term impact of anthropogenic greenhouse forcing. Much of continental Eurasia is still underrepresented, however, in geological proxy reconstructions of Holocene climate variability, and the vast majority of paleoclimate data only reflect conditions during peak summer months (JJA) or the growing season. The paucity of winter proxy data has therefore been cited as a possible explanation for the current mismatch between geological proxy-based and climate-model …

Bi-Directional Testing For Change Point Detection In Poisson Processes, Moinak Bhaduri

UNLV Theses, Dissertations, Professional Papers, and Capstones

Point processes often serve as a natural language to chronicle an event's temporal evolution, and significant changes in the flow, synonymous with non-stationarity, are usually triggered by assignable and frequently preventable causes, often heralding devastating ramifications. Examples include amplified restlessness of a volcano, increased frequencies of airplane crashes, hurricanes, mining mishaps, among others. Guessing these time points of changes, therefore, merits utmost care. Switching the way time traditionally propagates, we posit a new genre of bidirectional tests which, despite a frugal construct, prove to be exceedingly efficient in culling out non-stationarity under a wide spectrum of environments. A journey surveying …

The Combined Effect Of Photovoltaic And Electric Vehicle Penetration On Conservation Voltage Reduction In Distribution System, Narayan Bhusal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Global conditions over the past dozen years have led to an expanded appetite for renewable energy sources: The diminishing fossil fuel supply, the political instability of countries producing these fossil fuels, the ever-more destructive effects of global warming, and the lowering of costs for renewable energy technologies have made countries around the world reconsider their sources of energy. The proliferation of photovoltaic (PV) systems especially has surged dramatically with the decreasing initial costs for installation, and increasing government support in the form of renewable energy portfolios, feed-in-tariffs,

tax incentives, etc. Furthermore, electric vehicles (EV) are also becoming widespread due to …

Development Of Chemical Separation Methods Using Transition Metals For Nuclear Forensic And Medicinal Applications, Lucas Peter Boron-Brenner

UNLV Theses, Dissertations, Professional Papers, and Capstones

Insufficient data exists on the effects of prompt fast neutron activation on metals found commonly in nuclear devices and the urban environment. Different metals such as Ti, Au, Fe, and Cu were activated using the Flattop Criticality Benchmark at the Device Assembly Facility on the Nevada Test Site using a known neutron spectrum and flux to determine a baseline cross section value. Cross section information gathered from these neutron activation measurements could provide information that helps government and law enforcement agencies to correctly trace the origin of a nuclear device’s fuel or component features.

Based on activation products produced in …