Digital Commons Network^™

On The Development Of Computational Methods To Help In Performing Medical Physics Tasks Leveragin The Portal Dosimetry Application, Enea Rrokaj

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this project is to build software that can programmatically analyze dosimteric images and reduce the QA time when performing gamma analysis at varying test criteria and evaluating the results of the Winston-Lutz test. The application leverages the Eclipse Scripting API (ESAPI) within the Eclipse Treatment planning system of Varian Medical Systems. The Portal Dosimetry Application of Eclipse is used to collect the image pixels. The pixels are then displayed in a Windows Presentation Foundation using Microsoft Visual Studio and C#.

The purpose of the Gamma Index pass rates software is to benchmark the Portal Dosimetry Application by …

Prokaryotic Diversity And Aqueous Geochemistry Of Subsurface Environments Of The Death Valley Regional Flow System, Joshua David Sackett

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation summarizes over four years of effort towards the completion of a Ph.D. in Biological Sciences. The work presented in this document covers a broad range of topics, but a central unifying theme is prokaryotic life in the continental subsurface. The work presented in each chapter relied heavily on cultivation-independent methods for assessing prokaryotic communities, including prokaryotic community structure reconstruction from high-throughput sequencing of 16S rRNA gene libraries and single-cell genome analysis of novel uncultivated bacteria.

Chapter 2 examines the aqueous geochemistry and prokaryotic diversity of Devils Hole, a cavernous limnocrene and sole natural habitat for the critically endangered …

Calculation Of Access Charge For High Speed Rail Xpresswest Of Nevada, Sameeksha Sapkota

UNLV Theses, Dissertations, Professional Papers, and Capstones

XpressWest is a High Speed Rail (HSR) system that plans to connect Las Vegas with California at Palmdale. It will utilize the railway network of the California High Speed Rail (CAHSR) to connect Las Vegas with California destinations that include Los Angeles and San Francisco. For sharing the railway network of CAHSR, XpressWest will pay certain charge known as an access charge. The access charge is the fee paid by the train operator to the infrastructure owner for the addition of trains in a track. There are several access charge systems in the world. However, there is no study that …

Studies Of Inner-Shell Chemistry Of Mercury Based Compounds At Extreme Conditions, Sarah Schyck

UNLV Theses, Dissertations, Professional Papers, and Capstones

It has been theoretically predicted that when mercury difluoride (HgF2) is pressurized to above 50 GPa in the presence of molecular fluorine, it will most likely transform into mercury tetrafluoride (HgF4), thus mercury will behave as a transition element at high pressure. However, there is no experimental evidence verifying this prediction yet. To begin with, the crystalline properties of pure HgF2 at high pressure were not experimentally established. In this thesis, the high pressure structural properties of HgF2 are investigated by means of synchrotron X-ray powder diffraction. Our results reveal that the predicted, ambient cubic structure of HgF2 with the …

Application Of Machine Learning Techniques In Credit Card Fraud Detection, Ronish Shakya

UNLV Theses, Dissertations, Professional Papers, and Capstones

Credit card fraud is an ever-growing problem in today’s financial market. There has been a rapid increase in the rate of fraudulent activities in recent years causing a substantial financial loss to many organizations, companies, and government agencies. The numbers are expected to increase in the future, because of which, many researchers in this field have focused on detecting fraudulent behaviors early using advanced machine learning techniques. However, the credit card fraud detection is not a straightforward task mainly because of two reasons: (i) the fraudulent behaviors usually differ for each attempt and (ii) the dataset is highly imbalanced, i.e., …

Effect Of Curing Conditions On Mechanical Properties And Durability Of Concrete, Edgar Lazaro Salas-Borrero

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents the results for three different concrete mix designs with compression strengths of 4500 psi. The experiment was conducted in the Las Vegas area during the summer, from August 16th to October 12th, 2018, where temperatures and relative humidity was recorded daily, three times a day. In total, 135 concrete specimens (4” x 8”) were taken on site and were subjected to five different curing conditions.

For each concrete mix design, three concrete samples (4” x 8”) were taken and submitted for each curing condition, resulting in 45 cylinders for each concrete mix design. The same number of …

Design And Analysis Of First And Second Order K-Delta-1-Sigma Modulators In Multiple Fabrication Processes, Shada Sharif

UNLV Theses, Dissertations, Professional Papers, and Capstones

Analog to digital converters (ADC) are an important category of electronic circuits that are required in order to convert real-world analog signals into the digital domain. One of the main trade-offs in ADC design is between data conversion speed and resolution. Delta Sigma ADCs are commonly used for high precision data conversion of low bandwidth signals such as those found in audio, industrial and biomedical applications. A major disadvantage of traditional Delta Sigma ADC architectures is that they have limited signal bandwidth and are not suited for high speed applications such as communication systems. The continuous time K-Delta-1-Sigma (KD1S) modulator …

Surface Resistivity For Concrete Quality Assurance, Stanley Tat

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal of this study was to determine the effectiveness of SRT for concrete quality assurance and to evaluate the relationship between SRT and the three chloride ion ingress methods currently used by various State DOTs. Additionally, the influence of binder type and content, concrete age, and water-to cementitious materials ratio on the experimental results were also examined.

In this study, Type V Portland and three SCMs; namely fly ash, slag, and silica fume were used. Fine and coarse, aggregates were supplied by a local quarry. To evaluate the transport properties of the studied concretes, RMT, RCPT, and ACT were …

Estimation Of The Parameters In A Spatial Regressive-Autoregressive Model Using Ord's Eigenvalue Method, Sajib Mahmud Mahmud Tonmoy

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, we study one of Ord's (1975) global spatial regression models.

Ord considered spatial regressive-autoregressive models to describe the interaction

between location and a response variable in the presence of several covariates. He also

developed a practical estimation method for the parameters of this regression model

using the eigenvalues of a weight matrix that captures the contiguity of locations.

We review the theoretical aspects of his estimation method and implement it in the

statistical package R.

We also implement Ord's methods on the Columbus, Ohio, crime data set from the

year 1980, which involves the crime rate of …

Biodegradable And Biocompatible Silk Fibroin For Optical Applications, Corey Bryce Malinowski

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study presents nanopatterned silk fibroin films that were fabricated using soft lithography and nanoimprinting to replicate patterns from diffraction gratings. These film’s optics were analyzed based on their light scattering potential as well as their transmittance and transmission haze using a laser light, spectrometer, and UV-Vis spectrophotometer, respectively. The patterned fibroin films all displayed similar light scattering patterns to their master patterns with some transmission haze. When using the spectrometer to measure samples, those made without any nanostructure displayed transmission of 90% and over, while those with patterns depended on the structure used. The denser a structure, like the …

Case Study: Armenian And Cuban Ethnic Interest Groups In American Foreign Policy, Harry H. Terzian

UNLV Theses, Dissertations, Professional Papers, and Capstones

Current academic research has moved away from comparative models as a mechanism by which to assess and understand socio-political as well as historical phenomena. In addition, comparative analysis when it comes to addressing ethnic lobbies is almost nonexistent within contemporary research. This work implements a comparative framework and as a result has unlocked a new approach when addressing ethnic advocacy organizations. The purpose of this research is to assess and document the history and impact of both Armenian and Cuban ethnic interest groups within the United States. Specifically, focusing upon the Armenian National Committee of America and the Cuban American …

Cfd Modeling Of Smoke Movement In An Atrium, Robin Wu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this paper is to better understand the behavior of smoke movement in an atrium. Thus gives first responders and civilians in and out of building a better understanding

With the advancements of modern technology, computers and softwares make simulation models possible such as fire models to simulate fire and smoke movements. In this paper, a computational fluid dynamic (CFD) software Fire Dynamic Simulator (FDS) is used to conduct a series of atrium tests to investigate the effectiveness of smoke exhaust systems. FDS solves the Navier-Stokes equations appropriate for low speed flows (Ma < 0.3) with an emphasis on smoke, heat transport and CO2 concentrations from fires. The default turbulence model used in FDS simulation is the Large Eddy Simulation (LES), which is the solution of Navier-Stokes equations at low speed.

The compartment tested was 9 …

College Access And African American Males: An Instrumental Case Study On The Impact Of Postsecondary Educators And Educational Leaders On Secondary Students With Postsecondary Educational Aspirations, Kimberly L. Williams

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study examined the college access experiences of successful African American males. Postsecondary education is critical for economic and social stability; however, African American males from families with low socioeconomic status have been operating in educational systems that keeps them on the margins. Many African American males report strong postsecondary educational aspirations early in their educational careers, but they encounter microaggressions that leave them feeling like outsiders-within. This study examined African American males’ college access experiences as they successfully transitioned through the K-16 educational pipeline. Further, their experiences in their role (s) as postsecondary educators or postsecondary educational leaders working …

Air Pollution Related Asthma Inpatient Hospital Admission In The Las Vegas Valley, Joshua Allen Jensen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Asthma is a chronic respiratory condition characterized by inflammation in the lungs that causes airflow to be restricted. In Southern Nevada’s Las Vegas Valley, the natural basin geography causes air pollutants to accumulate. Research has linked air pollution with worsening asthma symptoms. The goal of this study was to determine the non-linear lagged relationship between Asthma Related Inpatient Hospital Admissions (ARIHA) and the Environmental Protection Agency’s (EPA) criteria air pollutants in the Las Vegas Valley using hospital and pollution monitoring station data. Overall, a statistically significant increased RR of ARIHA between 7 and 13 days after exposure to PM2.5 24-hour …

Novice Versus Expert Algebraic Problem-Solving Strategies: An Eye Tracking Approach, Krystal Kamekona-Mendoza

UNLV Theses, Dissertations, Professional Papers, and Capstones

Algebra continues to be an important point along the educational spectrum. It is often the point at which we see a deviation of educational trajectories for those who are interested in pursuing additional math and science courses and those who are not. Understanding how college algebra students perform is a crucial step in further understanding the difficulties that students often encounter, as well as understanding other potential factors that may contribute to their performance. The novice/expert paradigm is one way to examine performance differences. While existing literature indicates that novices and experts perceive, sort, and solve problems differently across a …

Using Design Science Research To Develop A Conceptual Solution For Improving Knowledge Sharing In A Virtual Workspace, Lata Koneru

UNLV Theses, Dissertations, Professional Papers, and Capstones

Enhancements in technology have resulted in significant changes to day-to-day operations of organizations in the present day. One especially noteworthy change is the alteration in the nature of teams from being co-located, with face-to-face interaction, to virtual, with the involvement of information and communication technologies (ICT) to facilitate communication. This change in team character has had a downstream impact on a key element of an organization’s competitive edge, namely knowledge.

Overall, there is consensus that knowledge is a crucial facet of the competitive edge of an organization. Consequently, knowledge management, knowledge sharing, and organizational learning are essential components of an …

Fluid Structure Interaction Study Of The Obstructive Sleep Apnea And Surgical Treatment Using Suture-Patch Device On The Patient’S Tongue, Yang Liu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Up to 14% of the U.S. population is estimated to have obstructive sleep apnea (OSA) related to obesity, and there is increased incidence occurring worldwide. While treatment with continuous positive airway pressure (CPAP) resolves airway obstruction, patient compliance is relatively low. Alternative interventions are available to treat OSA patients; however, their outcomes have had variable results. For example, current technologies have demonstrated an inability to define and treat the specific anatomical site(s) causing the obstruction, resulting in suboptimal modifications of the airway and poor control of OSA.

In the current study, a three-dimensional (3-D) fluid-structure interaction (FSI) numerical simulation has …

How Instruction, Math Anxiety, And Math Achievement Affect Learning A Novel Math Task: Evidence For Better Instruction, Amy Jane Mcauley

UNLV Theses, Dissertations, Professional Papers, and Capstones

The primary goal of this paper is to test how math anxiety, achievement, and instruction affect learning a novel math task. Currently, most research measures achievement and math anxiety on previously learned tasks. A two-part study was proposed to measure the effects of math anxiety on learning modular arithmetic (MA), a novel math task that involves subtraction and division. Participants of varying degrees of anxiety and achievement were randomly assigned to either a specific or vague instruction condition. Participants were either taught how to solve the task or given minimal information about how to solve the task. Before moving on, …

Variable Transition Time Inverters In A Digital Delay Line With Analog Storage For Processing Fast Signals And Pulses, James Kenton Mellott

UNLV Theses, Dissertations, Professional Papers, and Capstones

As the electronics industry moves forward there is an increasing need to process information faster and more accurately. High speed signals are used in scientific instrumentation, range finding devices, radar applications, and electro-optical interfaces. High-speed state of the art analog-to-digital converters are required to process these signals in real time. High frequency signals or very fast pulses are not able to be processed accurately due to either Nyquist-rate limitations or practical power consumption limits. For applications where signals are transient in nature and design size and power consumption are major factors, the proposed Variable Fast Transient Digitizer (VFTD) will be …

High Speed Fast Transient Digitizer Design And Simulation, Eric Clark Monahan

UNLV Theses, Dissertations, Professional Papers, and Capstones

In microelectronics, analog-to-digital converters (ADCs) are used as interfaces to convert analog inputs into discrete time or digital values that can be read via microcontrollers. As speed requirements and processing times in electronics continue to increase, high speed ADCs are increasingly critical components in the design of application-specific integrated circuits (ASICs). However, high speed ADCs introduce quantization error and are inefficient relative to size, cost, and power dissipation when compared to a High Speed Fast Transient Digitizer (HSFTD).

This thesis presents the design, layout, and simulation of a HSFTD designed to sample, in time at a fast rate, a high-speed …

Scheduling Two Machines With Dissimilar Costs, Madhurupa Moitra

UNLV Theses, Dissertations, Professional Papers, and Capstones

We consider two devices, which has states ON and OFF. In the ON state, the devices use their full power whereas in the OFF state the devices consume no energy but a constant cost is associated with switching back to ON. Such two devices are configured with different run and power-up costs on which a sequence of jobs must be processed. The object is to minimize the cost. Such systems are widely used to conserve energy, for example, to speed scale CPUs, to control data centers, or to manage renewable energy.

The problems are studied in the framework of online …

The Effect Of Instructors Training On Technology Adoption, Course Design, And Student Experiences: A Multiple Case Study Of Training Based On Tpack Or Quality Matters, Yvette Aqui

UNLV Theses, Dissertations, Professional Papers, and Capstones

The use of a Learning Management System (LMS) such as Blackboard Learn (Blackboard Learn, 2009) is a ubiquitous feature of the undergraduate experience. Despite its rapid increase in popularity and student demand for anytime, anywhere access to course materials, adoption of the LMS is slow and uneven. Some instructors also do not take advantage of some of the interactive tools in the LMS because it is complex in nature or they are unaware of the pedagogical affordances of the technology.

The purpose of this study was to explore the best ways to train faculty on how to use the LMS. …

Personality Patterns Of Students Who Make A Threat Of Targeted School Violence, Tawnya Michelle Ayim

UNLV Theses, Dissertations, Professional Papers, and Capstones

Although school shootings date back to the 1760’s (Dixon, 2005), recent attacks at schools in our country have raised awareness of school violence. This study investigates how students from one large school district responded to the personality pattern items on the Millon Adolescent Clinical Inventory, Second Edition after having made a threat to harm another student or staff member. Personality patterns were investigated in the overall sample, as well as within groups designated to be at a Low/Moderate risk level and High/Imminent risk level following a threat assessment. The minimal Differences between the sample for the current study and the …

The Influence Of Opponent Strategy And Psychopathic Traits On Point Gains And Cooperation In The Iterated Prisoner’S Dilemma, Mary Baggio

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Prisoner’s Dilemma game is a paradigm used to model and measure social cooperation. Uncooperative behavior may be one manifestation of the unstable interpersonal functioning in psychopathy. I investigated the effect of opponent strategy as well as psychopathic traits of fearless dominance (FD) and impulsive antisociality (IA) on cooperation rates and total and competitive point gains in a sample of 177 undergraduates playing long, finitely iterated Prisoner’s Dilemma games against computerized opponents who varied in their interpersonal styles from very harsh to very lenient. I analyzed rates of cooperation during each game, participants’ total points gained, and the difference in …

Efficient And Practical Composition Of Lock-Free Data Structures, Neha Bajracharya

UNLV Theses, Dissertations, Professional Papers, and Capstones

A concurrent data object is lock-free if it guarantees that at least one, among all concurrent operations, finishes after a finite number of steps. In other words, a lock free technique guarantees that some thread always makes progress. Lock-free data objects offer several advantages over their blocking counterparts, such as being immune to deadlocks and priority inversion, and typically provide high scalability and performance, especially in shared memory multiprocessor architectures.

Composition of data structures is a powerful approach to combine simple data structures to create more complex ones. It works as a building block for many advanced useful data structures. …

A Phenomenological Study On The Professional Development Of African American Male Administrators At Predominately White Post-~Secondary Institutions, Arnold Shmorn Bell

UNLV Theses, Dissertations, Professional Papers, and Capstones

As of today, African Americans continue to face a daunting endeavor when seeking to become executive administrative leaders at predominately White post-secondary institutions, even though, according to Tillman (2001), “Mentoring was identified as a technique to assist the professional advancement of African American faculty. In doing so, their numbers will increase at predominantly White institutions” (p. 295). Literature steadily indicates that mentorship contributes to one’s career development in the post-secondary environment. The influential aspects of mentorship on one’s professional development is supported by numerous studies that examines mentoring relationships across various academic disciplines and businesses in corporate America (Brown, 2005). …

The Roles Of Biophilic Attitudes And Auditory Stimuli Within Attention Restoration Theory, Jason B. Boggs

UNLV Theses, Dissertations, Professional Papers, and Capstones

Attention Restoration Theory indicates that interacting with nature allows one’s fatigued, directed attention to be restored. This effect has been documented and produced through directed interaction with nature, such as a walk in the park, as well as through indirect interactions (e.g., photographs). The current dissertation was designed to: 1) investigate whether and how biophilic attitudes affect the attention-restoring effects incurred from interactions with nature, and 2) extend the research on ART by assessing the impact of nature-related audio stimuli. A total of 184 participants completed an assessment of biophilic attitudes, engaged in attention fatiguing exercises, and participated in one …

Globalization And Cultural Flows: A Three-Article Dissertation Exploring Implications For Education And Culture In India, Dwight Edward Boucher

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation follows a three-article format to examine ways in which distinct manifestations of globalization have engaged and manipulated education in India as colonizing initiatives. The articles are interrelated and examine historical, societal, and individual stories related to colonial and global impositions of Western epistemological, economic, and educational forms in India. The introductory chapter outlines the broad implications of globalization and globalizing narratives, and it is intended to demonstrate that while globalization has the capacity to improve the quality and equitability of lives around the world, it also has the potential to serve as a hegemonic conduit for the continuation …

Conversational Movement Dynamics And Nonverbal Indicators Of Second Language Development: A Microgenetic Approach, Kristine Marie Bragg

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation study extends on current understandings of gesture and embodied interaction with the eco-social environment in second language development (SLD) while introducing new aspects of movement analysis through dynamical modeling. To understand the role of embodiment during learning activities, a second language learning task has been selected. Dyads consisting of a non-native English-speaking student and a native English-speaking tutor were video recorded during writing consultations centered on class assignments provided by the student. Cross-recurrence quantification analysis was used to measure interactional movement synchrony between the members of each dyad. Results indicate that students with varied English proficiency levels synchronize …

Mob-Ndr Kinase Signaling Components Are Required For Epithelial Tube Formation In The Drosophila Follicular Epithelium, Juan Carlos Duhart

UNLV Theses, Dissertations, Professional Papers, and Capstones

A major goal of developmental biology is to understand how a single fertilized cell can give rise to the many functional tissues and organs, of specific sizes and shapes, that make up the adult body plan. Over the last 25 years, developmental geneticists have uncovered much concerning the cell-to-cell communication systems that are necessary to build complex tissues and organs. For example, throughout development, cells communicate with their neighbors using specialized signaling molecules. These signals are instructive and provide “signal-receiving” cells with information about space and time. That is, signal-receiving cells “learn” precisely where they are located, and, how far …