Digital Commons Network^™

The Effect Of Heat Generation In The Railroad Bearing Thermoplastic Elastomer Suspension Element On The Thermal Behavior Of Railroad Bearing Assembly, Oscar Osvaldo Rodriguez

Theses and Dissertations

Understanding the internal heat generation of the railroad bearing elastomer suspension element during operation is essential to predict its dynamic response and structural integrity, as well as to predict the thermal behavior of the complete railroad bearing assembly including the bearing adapter. The latter is essential for sensor selection and placement within the adapter (e.g., typical temperature sensors have operating ranges of up to 125°C or 257°F). The internal heat generation is a function of the loss modulus, strain, and frequency. Based on experimental studies, estimations of internally generated heat within the thermoplastic elastomer pad were obtained. The calculations show …

The Taming Of The Bull, Mark Zavala

Theses and Dissertations

This work is an original manuscript composed of fictional vignettes compiled together to produce an interconnected novel. The works includes the effects, issues, and culture that encompass the borderland of the Rio Grande Valley. The young protagonist experiences loss, isolation, self-realization, friendship, and the importance of family and friends, all within the context of the unique culture of south Texas.

Carbon Nanotube Yarn Based Dye Sensitized Solar Cells With Enhanced Electron/Hole Pair Recombination Prevention Characteristics, Glenn E. Grissom

Theses and Dissertations

Carbon nanotube yarn based solar cells (CNTYSCs) show promise in a variety of applications such as military and smart fabrics. We use a highly aligned and interwoven Carbon nanotube yarn (CNTY) for the working electrode (WE) and counter electrode (CE), to create a flexible super strong, conductive, and photo active surface for the support of a calcined TiO2 nano-solution and macro-solution deposition as a base for added functionalizations of a dye-sensitized solar cell (DSSC) that is able to maintain its flexibility and integrity. The CNT fiber based solar cells have power conversion ability that is independent of the direction of …

Covering A Ball By Smaller Balls, Alexey Glazyrin

School of Mathematical & Statistical Sciences Faculty Publications

We prove that, for any covering of a unit d-dimensional Euclidean ball by smaller balls, the sum of radii of the balls from the covering is greater than d. We also investigate the problem of finding lower and upper bounds for the sum of powers of radii of the balls covering a unit ball.

Extraction Of Metazoan Meiofauna From Muddy Deep-Sea Samples: Operator And Taxon Effects On Efficiency, Melissa Rohal, David Thistle, Erin E. Easton

School of Earth, Environmental, & Marine Sciences Faculty Publications

Deep-sea metazoan meiofaunal specimens are usually extracted from muddy samples by centrifugation in a fluid in which meiofauna tend to float and sediment particles tend to sink. Although the procedure is in common use, its efficiency has seldom been examined. The study reported here showed that well-trained operators extracted metazoan meiofauna with efficiencies that were different enough to be a concern in quantitative studies. Therefore, samples should be assigned to operators in a stratified-random manner. In the course of these studies, both operators also extracted individuals of the common nematode family Desmoscolecidae significantly less efficiently than other nematode families, a …

Magnetic Polymer Composite As A Thermosensitive Agent For Induced Hyperthermia, Nareg Ohannesian

Theses and Dissertations

Polyetheretherketone (PEEK) - magnetite (Fe3O4) blended compounds were produced by high speed vibration milling of PEEK-Fe 3O4 powders exposed to hexane and heated to the melting point (~350 °C) to form the homogeneous magnetic polymer composite, which provided a uniform dispersion of magnetite with low agglomerations in the polymer matrix. Polymer composite with 10 wt.% of magnetite displayed a magnetic saturation of 8 emu/g, tensile strength of 60 MPa and Young’s modulus of 4.4 GPa. Biotoxicity assessment was conducted via in vitro assay. The composite did not induce any adverse reactions, permitting use in medical applications. This study develops analytical …

The Local Theory For Regular Systems In The Context Of T-Bonded Sets, Mikhail M. Bouniaev, Nikolay Dolbilin

School of Mathematical & Statistical Sciences Faculty Publications

The main goal of the local theory for crystals developed in the last quarter of the 20th Century by a geometry group of Delone (Delaunay) at the Steklov Mathematical Institute is to find and prove the correct statements rigorously explaining why the crystalline structure follows from the pair-wise identity of local arrangements around each atom. Originally, the local theory for regular and multiregular systems was developed with the assumption that all point sets under consideration are (r,R)" role="presentation">(r,R) -systems or, in other words, Delone sets of type (r,R)" role="presentation">(r,R) in d-dimensional Euclidean space. In this paper, we will …

Simplification Of Eeg Signal Extraction, Processing, And Classification Using A Consumer-Grade Headset To Facilitate Student Engagement In Bci Research, Jesus D. Rodriguez

Theses and Dissertations

Brain-computer interfaces (BCIs) are an emerging technology that leverage neurophysiological signals as input to computing systems. By circumventing the reliance on traditional input methods (e.g., mouse and keyboard), BCIs show a promising alternative interaction modality for people with disabilities. Advances in BCI research have further inspired a range of novel applications, such as the use of neurophysiological signals as passive input (e.g., to detect and reduce operator workload when managing multiple machines). BCIs have also emerged as a tool for student engagement due to the intrinsic interdisciplinarity of the technology, which spans the fields of computer science, electrical engineering, neuroscience, …

Choline Supplementation Prevents A Hallmark Disturbance Of Kwashiorkor In Weanling Mice Fed A Maize Vegetable Diet: Hepatic Steatosis Of Undernutrition, Thaddaeus May, Kevin C. Klatt, Jacob Smith, Eumenia Castro, Mark Manary, Marie A. Caudill, Farook Jahoor, Marta L. Fiorotto

School of Medicine Publications

Hepatic steatosis is a hallmark feature of kwashiorkor malnutrition. However, the pathogenesis of hepatic steatosis in kwashiorkor is uncertain. Our objective was to develop a mouse model of childhood undernutrition in order to test the hypothesis that feeding a maize vegetable diet (MVD), like that consumed by children at risk for kwashiorkor, will cause hepatic steatosis which is prevented by supplementation with choline. A MVD was developed with locally sourced organic ingredients, and fed to weanling mice (n = 9) for 6 or 13 days. An additional group of mice (n = 4) were fed a choline supplemented MVD. Weight, …

Mobile Personal Health Monitoring For Automated Classification Of Electrocardiogram Signals In Elderly, Luis J. Mena, Vanessa G. Felix, Alberto Ochoa, Rodolfo Ostos, Eduardo Gonzalez, Javier Aspuru, Pablo Velarde, Gladys E. Maestre

School of Medicine Publications

Mobile electrocardiogram (ECG) monitoring is an emerging area that has received increasing attention in recent years, but still real-life validation for elderly residing in low and middle-income countries is scarce. We developed a wearable ECG monitor that is integrated with a self-designed wireless sensor for ECG signal acquisition. It is used with a native purposely designed smartphone application, based on machine learning techniques, for automated classification of captured ECG beats from aged people. When tested on 100 older adults, the monitoring system discriminated normal and abnormal ECG signals with a high degree of accuracy (97%), sensitivity (100%), and specificity (96.6%). …

Insights Into The Genetic Epidemiology Of Crohn's And Rare Diseases In The Ashkenazi Jewish Population, Manuel A. Rivas, Brandon E. Avila, Jukka Koskela, Hailiang Huang, Christine Stevens, Matti Pirinen, Talin Haritunians, Benjamin M. Neale, Mitja Kurki, John Blangero, Joanne E. Curran

School of Medicine Publications

As part of a broader collaborative network of exome sequencing studies, we developed a jointly called data set of 5,685 Ashkenazi Jewish exomes. We make publicly available a resource of site and allele frequencies, which should serve as a reference for medical genetics in the Ashkenazim (hosted in part at https://ibd.broadinstitute.org, also available in gnomAD at http://gnomad.broadinstitute.org). We estimate that 34% of protein-coding alleles present in the Ashkenazi Jewish population at frequencies greater than 0.2% are significantly more frequent (mean 15-fold) than their maximum frequency observed in other reference populations. Arising via a well-described founder effect approximately 30 …

Removal Of Chromium(Vi) And Chromium(Iii) Ions From Aqueous Solution Using Bio-Char Generated From Agricultural Waste Products, Diego Fernando Gonzalez

Theses and Dissertations

Heavy metals are one of the most persistent and prevalent contaminants in the aquatic environment. The removal of chromium from aqueous solution, especially in the hexavalent form is difficult. New technologies, techniques and/or new materials have been designed in order to effectively and efficiently remove chromium from the aqueous environment. The project focuses on the comparison of the effects of pH, time, temperature, binding capacity on bio-char’ generated from agricultural waste produces vs an amino modified derivative of the bio-char. Pineapple skins were dried, ground, sieved, and pyrolyzed to produce a bio-char material. The bio-char was analyzed using FTIR to …

Microwave-Assisted Ring-Opening Polymerization Of Poly(Ε-Caprolactone), Nancy Obregon

Theses and Dissertations

Poly(ϵ-caprolactone) (PCL) is a biodegradable polyester notorious by its promising properties and applications in the biomedical field. In this work, microwave-assisted ringopening polymerization (ROP) of ϵ-caprolactone (ϵ-CL) was performed. Stannous octoate [Sn(Oct)2] was used as catalyst with and without an alcohol initiator. The different initiators tested were glycerol, diethylene glycol (DEG) and poly(ethylene) glycol (PEG). Aiming to establish reaction parameters, the influence of different reaction times, temperatures, and monomer:initiator:catalyst ratios were examined. It was observed that the reaction was obtained and high molecular weight PCL was achieved successfully without an initiator. However, mixed results were obtained using an initiator. Products …

A Multiple Radar Approach For Automatic Target Recognition Of Aircraft Using Inverse Synthetic Aperture Radar, Carlos Pena-Caballero, Elifaleth Cantu, Jesus Rodriguez, Adolfo Gonzales, Osvaldo Castellanos, Angel Cantu, Megan K. Strait, Jae Son, Dong-Chul Kim

Computer Science Faculty Publications

Following the recent advancements in radar technologies, research on automatic target recognition using Inverse Synthetic Aperture Radar (ISAR) has correspondingly seen more attention and activity. ISAR automatic target recognition researchers aim to fully automate recognition and classification of military vehicles, but because radar images often do not present a clear image of what they detect, it is considered a challenging process to do this. Here we present a novel approach to fully automate a system with Convolutional Neural Networks (CNNs) that results in better target recognition and requires less training time. Specifically, we developed a simulator to generate images with …

The Rider (2018-04-30), Jesus Sanchez

The Rider Archives

Vol.3 No.28

The Green Bank Northern Celestial Cap Pulsar Survey. Ii. The Discovery And Timing Of 10 Pulsars, A. M. Kawash, M. A. Mclaughlin, Louis Percy Dartez, David Day, Anthony J. Ford, Jesus Hinojosa, Fredrick A. Jenet, Sean Leake, Grady Lunsford, Alberto Mata

Physics & Astronomy Faculty Publications

We present timing solutions for 10 pulsars discovered in 350 MHz searches with the Green Bank Telescope. Nine of these were discovered in the Green Bank Northern Celestial Cap survey and one was discovered by students in the Pulsar Search Collaboratory program during an analysis of drift-scan data. Following the discovery and confirmation with the Green Bank Telescope, timing has yielded phase-connected solutions with high-precision measurements of rotational and astrometric parameters. Eight of the pulsars are slow and isolated, including PSR J0930-2301, a pulsar with a nulling fraction lower limit of ∼30% and a nulling timescale of seconds to minutes. …

Who Will Stay, Who Will Leave: Decision-Making Of Residents Living In Potential Hurricane Impact Areas During A Hypothetical Hurricane Event In The Rio Grande Valley, Dean Kyne, Arlett Sophia Lomeli, William Donner, Erika Zuloaga

Sociology Faculty Publications

The Rio Grande Valley (RGV) has been impacted by various hurricanes throughout history. While Hurricane evacuation has been studied extensively in other contexts, there is limited systematic research on the warning and response to a large-scale severe weather event in South Texas. This study attempts to understand the evacuation decision-making behavior of Southern residents in the event of a Hurricane making landfall over the Rio Grande Valley. The study uses an online survey questionnaire with 1060 participants: 275 students attending the University of Texas-Rio Grande Valley and the remaining 785 are members of the community. Throughout the course of the …

Using Restrictions To Accept Or Reject Solutions Of Radical Equations, Eleftherios Gkioulekas

School of Mathematical & Statistical Sciences Faculty Publications

The standard technique for solving equations with radicals is to square both sides of the equation as many times as necessary to eliminate all radicals. Because the procedure violates logical equivalence, it results in extraneous solutions that do not satisfy the original equation, making it necessary to check all solutions against the original equation. We propose alternative solution procedures that are rigorous and simple to execute where the extraneous solutions can be identified without verification against the original equation. In this article, we review previous literature, establish and illustrate rigorous solution procedures for radical equations of depth 1 (i.e. equations …

The Rider (2018-04-09), Jesus Sanchez

The Rider Archives

Vol.3 No.25

Full Issue Vol. 3 No. 1, Crosspol

Crosspol Journal

No abstract provided.

Re-Imagining Linguistic Competence And Teaching Towards Communicative Success In Transnational And Translingual Spaces Of Today's Global Reality, Maria Houston

Crosspol Journal

No abstract provided.

Utrgv Commencement – Spring 2018, The University Of Texas Rio Grande Valley

UTRGV Commencement Programs

No abstract provided.

Interactive Effects Of Hypoxia And Pcb Co-Exposure On Expression Of Cyp1a And Its Potential Regulators In Atlantic Croaker Liver, Md. Saydur Rahman, Peter Thomas

School of Earth, Environmental, & Marine Sciences Faculty Publications

Although marine and coastal environments which are contaminated with xenobiotic organic compounds often become hypoxic during the summer, the interactive effects of hypoxia and xenobiotic exposure on marine species such as teleost fishes remain poorly understood. The expression and activity of monooxygenase enzyme cytochrome P450-1A (CYP1A) in fishes are upregulated by exposure to polychlorinated biphenyls (PCBs), whereas they are down-regulated during hypoxia exposure. We investigated the interactive effects of hypoxia and PCB co-exposure on hepatic CYP1A expression in Atlantic croaker and on potential regulators of CYP1A. Croaker were exposed to hypoxia (1.7 mg/L dissolved oxygen), 3,3′,4,4′-tetrachlorobiphenyl (PCB 77, dose: 2 …

Mesoscale Effects On Carbon Export: A Global Perspective, Cheryl S. Harrison, Matthew C. Long, Nicole S. Lovenduski, Jefferson K. Moore

School of Earth, Environmental, & Marine Sciences Faculty Publications

Carbon export from the surface to the deep ocean is a primary control on global carbon budgets and is mediated by plankton that are sensitive to physical forcing. Earth system models generally do not resolve ocean mesoscale circulation ((10–100) km), scales that strongly affect transport of nutrients and plankton. The role of mesoscale circulation in modulating export is evaluated by comparing global ocean simulations conducted at 1∘ and 0.1∘ horizontal resolution. Mesoscale resolution produces a small reduction in globally integrated export production (<2%); however, the impact on local export production can be large (±50%), with compensating effects in different ocean basins. With mesoscale resolution, improved representation of coastal jets block off-shelf transport, leading to lower export in regions where shelf-derived nutrients fuel production. Export is further reduced in these regions by resolution of mesoscale turbulence, which restricts the spatial area of production. Maximum mixed layer depths are narrower and deeper across the Subantarctic at higher resolution, driving locally stronger nutrient entrainment and enhanced summer export production. In energetic regions with seasonal blooms, such as the Subantarctic and North Pacific, internally generated mesoscale variability drives substantial interannual variation in local export production. These results suggest that biogeochemical tracer dynamics show different sensitivities to transport biases than temperature and salinity, which should be considered in the formulation and validation of physical parameterizations. Efforts to compare estimates of export production from observations and models should account for large variability in space and time expected for regions strongly affected by mesoscale circulation.

The Nanograv 11-Year Data Set: High-Precision Timing Of 45 Millisecond Pulsars, Zaven Arzoumanian, Adam Brazier, Sarah Burke-Spolaor, Sydney Chamberlin, Shami Chatterjee, Brian Christy, James M. Cordes, Neil J. Cornish, Fredrick A. Jenet, Jing Luo

Physics & Astronomy Faculty Publications

We present high-precision timing data over time spans of up to 11 years for 45 millisecond pulsars observed as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project, aimed at detecting and characterizing low-frequency gravitational waves. The pulsars were observed with the Arecibo Observatory and/or the Green Bank Telescope at frequencies ranging from 327 MHz to 2.3 GHz. Most pulsars were observed with approximately monthly cadence, and six high-timing-precision pulsars were observed weekly. All were observed at widely separated frequencies at each observing epoch in order to fit for time-variable dispersion delays. We describe our methods for …

Optimal Quantizers For Some Absolutely Continuous Probability Measures, Mrinal Kanti Roychowdhury

School of Mathematical & Statistical Sciences Faculty Publications

The representation of a given quantity with less information is often referred to as `quantization' and it is an important subject in information theory. In this paper, we have considered absolutely continuous probability measures on unit discs, squares, and the real line. For these probability measures the optimal sets of n-means and the nth quantization errors are calculated for some positive integers n.

Microwave-Induced Bismuth Nitrate-Impregnated Claymediated Novel Dinitration Of 9,10- Dihydrophenanthrene: A Precursor For New Heterocycles, Ram Naresh Yadav, Leonardo Salazar, Amrendra Kumar Singh, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

A facile method for the dinitration of 9, 10-dihydrophenanthrene using domestic microwave-induced bismuth nitrate-impregnated clay is developed.

Optimal Staged Self-Assembly Of General Shapes, Cameron Chalk, Eric M. Martinez, Robert Schweller, Luis Vega, Andrew Winslow, Tim Wylie

Computer Science Faculty Publications

We analyze the number of tile types t, bins b, and stages necessary to assemble n \times n squares and scaled shapes in the staged tile assembly model. For n \times n squares, we prove \mathcal{O}(\frac{\log{n} - tb - t\log t}{b^2} + \frac{\log \log b}{\log t}) stages suffice and \Omega(\frac{\log{n} - tb - t\log t}{b^2}) are necessary for almost all n. For shapes S with Kolmogorov complexity K(S), we prove \mathcal{O}(\frac{K(S) - tb - t\log t}{b^2} + \frac{\log \log b}{\log t}) stages suffice and \Omega(\frac{K(S) - tb - t\log t}{b^2}) are necessary to assemble a scaled version of S, for …

A Model For Donation Verification, Bin Fu, Fengjuan Zhu, John P. Abraham

Computer Science Faculty Publications

In this paper, we introduce a model for donation verification. A randomized algorithm is developed to check if the money claimed being received by the collector is (1 - ϵ)-approximation to the total amount money contributed by the donors. We also derive some negative results that show it is impossible to verify the donations under some circumstances.

The Rider (2018-03-19), Jesus Sanchez

The Rider Archives

Vol.3 No.23