Digital Commons Network^™

Two-Dimensional Dynamics Model Of The Lower Limb To Include Viscoelastic Knee Ligaments, Eduardo Granados

Theses and Dissertations - UTB/UTPA

A dynamic, 2D, anatomical knee joint model has been developed to simulate knee reactions to external input forces. A deformable contact area approach is used to find contact forces and moments, and a method of applying nonlinear viscoelastic ligament strain rate response was also developed and implemented on the model to account for the effects of viscoelasticity on the ligament fibers. The ligaments were then tested for various deficiencies to identify their effects on the natural frequency of the knee. Internal knee forces from ligaments, muscles, and contacting surfaces are modeled and then numerically found for different exercises. Static and …

Two Dimensional Inverse Dynamics Model Of Human Knee Dynamics During The Moderate Squat Exercise, Ricardo Gomez Jr.

Theses and Dissertations - UTB/UTPA

The purpose of this research is to investigate the internal forces on the human knee joint during moderate squat exercise. An inverse dynamics, two dimensional, anatomic dynamic knee model is developed. The model describes the motion in the sagittal plane of human leg, and includes tibia, femur, ligamentous knee structures, tendons and muscles. The software package Matlab is used to solve the inverse dynamics model. Numerical simulations are conducted for walking (the stance phase of the gait cycle) in order to validate the model, and for moderate squatting in order to predict ligament, contact and muscle forces during this exercise.

Zeros Of Cubic Eisenstein Series, Sahak D. Sandragorsian

Theses and Dissertations - UTB/UTPA

This thesis provides a detailed exposition and extension of the work of F. K. C. Rankin and Swinnerton-Dyer on the location of the zeros of Eisenstein series for SL(2,Z). Exact values of the zeros in special cases will be given in terms of modular functions. Analogous new results on zeros of cubic Eisenstein series will be presented.

The Impact Of Information Quality Awareness On Users' Behaviors Toward Information Quality Practices, Javier Flores

Theses and Dissertations - UTB/UTPA

Healthcare organization rely more on electronic information to optimize most of their processes. Additional information sources and more diverse information increase the relevance and importance of information quality (IQ). The quality of information needs to be improved to support a more efficient and reliable utilization of information systems (IS). This improvement can only be achieved through the implementation of initiatives followed by most users across the organization. The purpose of this study is to develop a model related to how awareness of IS users about IQ issues would affect their actual practices toward IQ initiatives. It is posited that users’ …

Investigation Of Slective Laser Melting Of Mecanically Alloyed Metastable Al5fe2 Powder, Hugo Montiel

Theses and Dissertations - UTB/UTPA

Selective Laser Melting (SLM), an Additive Manufacturing (AM) technology, enables the production of complex structured metal products. Aluminum alloys are used in SLM as high-strength lightweight materials for weight reduction in structural components. Previous investigations report high laser powers (300 W) and slow scanning speeds (500 mm/s) to process aluminum alloys under SLM. This research investigates the SLM processing of Al-Fe alloy by utilizing metastable Al5Fe2 powder system produced by mechanical alloying. Metastable systems are thermodynamically activated with internal energy that can generate an energy shortcut when processing under SLM. The optimum laser power, scan speeds and scan distances were …

High Precision Optical Cavity Length And Width Measurements Using Double Modulation, A. Staley, D. Hoak, A. Effler, K. Izumi, S. Dwyer, K. Kawabe, E. J. King, Malik Rakhmanov, R. L. Savage, D. Sigg

Physics & Astronomy Faculty Publications

We use doubly phase modulated light to measure both the length and the linewidth of an optical resonator with high precision. The first modulation is at RF frequencies and is set near a multiple of the free spectral range, whereas the second modulation is at audio frequencies to eliminate offset errors at DC. The light in transmission or in reflection of the optical resonator is demodulated while sweeping the RF frequency over the optical resonance. We derive expressions for the demodulated power in transmission, and show that the zero crossings of the demodulated signal in transmission serve as a precise …

Measuring Infrared Surface Brightness Fluctuation Distances With Hst Wfc3: Calibration And Advice, Joseph B. Jensen, John P. Blakeslee, Zachary Gibson, Hyun Chul Lee, Michele Cantiello, Gabriella Raimondo, Nathan Boyer, Hyejeon Cho

Physics & Astronomy Faculty Publications

We present new calibrations of the near-infrared (near-IR) surface brightness fluctuation (SBF) distance method for the F110W (J110) and F160W (H160) bandpasses of the Wide Field Camera 3 Infrared Channel (WFC3/IR) on the Hubble Space Telescope. The calibrations are based on data for 16 early-type galaxies in the Virgo and Fornax clusters observed with WFC3/IR and are provided as functions of both the optical (g475-z850 ) and near-infrared (J110-H160) colors. The scatter about the linear calibration relations for the luminous red galaxies in the sample is approximately 0.10 mag, corresponding to a statistical error of 5% in distance. Our results …

High Precision Optical Cavity Length And Width Measurements Using Double Modulation, A. Staley, D. Hoak, A. Effler, K. Izumi, S. Dwyer, K. Kawabe, E. J. King, Malik Rakhmanov, R. L. Savage, D. Sigg

Physics & Astronomy Faculty Publications

We use doubly phase modulated light to measure both the length and the linewidth of an optical resonator with high precision. The first modulation is at RF frequencies and is set near a multiple of the free spectral range, whereas the second modulation is at audio frequencies to eliminate offset errors at DC. The light in transmission or in reflection of the optical resonator is demodulated while sweeping the RF frequency over the optical resonance. We derive expressions for the demodulated power in transmission, and show that the zero crossings of the demodulated signal in transmission serve as a precise …

Undiagnosed Diabetes And Pre-Diabetes In Health Disparities, Susan P. Fisher-Hoch, Kristina Vatcheva, Mohammad H. Rahbar, Joseph B. Mccormick

School of Mathematical & Statistical Sciences Faculty Publications

Globally half of all diabetes mellitus is undiagnosed. We sought to determine the extent and characteristics of undiagnosed type 2 diabetes mellitus and pre-diabetes in Mexican Americans residing in the United States. This disadvantaged population with 50% lifetime risk of diabetes is a microcosm of the current pandemic. We accessed baseline data between 2004 and 2014 from 2,838 adults recruited to our Cameron County Hispanic Cohort (CCHC); a two-stage randomly selected 'Framingham-like' cohort of Mexican Americans on the US Mexico border with severe health disparities. We examined prevalence, risk factors and metabolic health in diagnosed and undiagnosed diabetes and pre-diabetes. …

Particle Dynamics In The Rising Plume At Piccard Hydrothermal Field, Mid-Cayman Rise, Margaret L. Estapa, John A. Breier, Chris R. German

School of Earth, Environmental, & Marine Sciences Faculty Publications

Processes active in rising hydrothermal plumes, such as precipitation, particle aggregation, and biological growth, affect particle size distributions and can exert important influences on the biogeochemical impact of submarine venting of iron to the oceans and their sediments. However, observations to date of particle size distribution within these systems are both limited and conflicting. In a novel buoyant hydrothermal plume study at the recently discovered high-temperature (3988C) Piccard Hydrothermal Field, Mid- Cayman Rise, we report optical measurements of particle size distributions (PSDs). We describe the plume PSD in terms of a simple, power-law model commonly used in studies of upper …

The Relationships Between Managerial Metacognition, Total Quality Management, And A Firm's Sustainable Competitive Advantages: An Empirical Investigation Based On Structural Equation Modeling Analysis, Young Sik Cho

Theses and Dissertations - UTB/UTPA

The purpose of this study is to explore how managerial metacognition has an influence on the effective implementation of total quality management (TQM) and the creation of a firm’s sustainable competitive advantages (P) by using the lens of Resource-Based View (RBV). In particular, this study conceptualized the existing TQM framework by two sub-constructs, technical quality management (TQ) and behavioral quality management (BQ) practices, and newly proposed the sequential relationship of 'TQ→BQ→P' based on the premise of the RBV. In addition, through post-hoc analysis, this study tested the mediation effect of a firm's TQ practices on the relationship between managerial metacognition …

Species Identification And Habitat Assessment Of The South Texas Siren, Taylor C. Lafortune

Theses and Dissertations - UTB/UTPA

At least one species of siren is endemic to the Rio Grande Valley of Texas, yet very little is known about the populations of the region. Texas Parks and Wildlife refers to the populations of Siren spp. in South Texas as the “South Texas siren (large form Siren sp. 1),” and recognizes these populations as a threatened species, yet their current population status remains unclear. The species identification of the South Texas siren has been hampered by similarity in morphology across species, and by the lack of complete siren genetic sequences in the NCBI GenBank database. In addition to species …

Development Of A Dna Barcoding Reference Library For Identification Of Medicinal Plant Materials Used In The Rio Grande Valley Of Texas: A Representative Case Study Using Arnica (Asteraceae), Hector G. Aguilar De Alba

Theses and Dissertations - UTB/UTPA

DNA barcoding is a technique that uses a short DNA fragment to identify a specimen to the species level. This technique is essential in situations where a lack of distinguishing morphological characteristics makes identification impossible. In the Río Grande Valley a variety of herbal supplements are cheap, readily available and sold as “Arnica” with no information to identify the contents. The appearance of dried and shredded material suggests that a variety of plant species are involved, belonging to the family Asteraceae. Arnica montana, also part of Asteraceae, is found in Europe and has anti-inflammatory properties used to externally treat bruises …

Approximate Analysis Solution Of Burgers-Kdv Equation, Hani Aldirawi

Theses and Dissertations - UTB/UTPA

In this thesis, we study the Two-Dimensional Burgers-Kortewege-de Vries(2D-BKdV) equation by analyzing the equivalent Abel equation, which indicates that under some particular conditions, the 2D-BKdV equation has a unique bounded traveling wave solution. By using the theorem of contractive mapping, a traveling wave solution to the 2D-BKdV equation is expressed explicitly.

Effect Of Instruction And Textbook Adoption Procedures On Kindergarten Students' Learning Of The Concept Of Rectangle, Francisco Rivera

Theses and Dissertations - UTB/UTPA

The purpose of this study was to produce scientific knowledge about the ability of kindergarten children to learn the correct mathematical concept of rectangle. The subjects of this study were kindergarten children in a public school district whose population had a large proportion of Hispanic and economically disadvantaged children. A Solomon Four-Group Design as described by Campbell and Stanley (1963) was used. Both the control and experimental groups received instruction using a district adopted curriculum. A description of how the district's curriculum addressed the concept of rectangle was included in the results. The experimental group received additional instruction using a …

Iron-Mediated Stabilization Of Soil Carbon Amplifies The Benefits Of Ecological Restoration In Degraded Lands, Lucas C. R. Silva, Timothy A. Doane, Rodrigo S. Correa, Vinicius Valverde, Engil Isadora Pujol Pereira, William R. Horwath

School of Earth, Environmental, & Marine Sciences Faculty Publications

Recent observations across a 14‐year restoration chronosequence have shown an unexpected accumulation of soil organic carbon in strip‐mined areas of central Brazil. This was attributed to the rapid plant colonization that followed the incorporation of biosolids into exposed regoliths, but the specific mechanisms involved in the stabilization of carbon inputs from the vegetation remained unclear. Using isotopic and elemental analyses, we tested the hypothesis that plant‐derived carbon accumulation was triggered by the formation of iron‐coordinated complexes, stabilized into physically protected (occluded) soil fractions. Confirming this hypothesis, we identified a fast formation of microaggregates shortly after the application of iron‐rich biosolids, …

A Study On Hispanic College Students' Mathematics Anxiety, Study Habits, And Academic Performances On Mathematics, Luis M. Fernandez

Theses and Dissertations - UTB/UTPA

Mathematics anxiety has been described as a feeling of apprehension, fear, tension, and discomfort when confronted with mathematics. Mathematics anxiety has also been shown to interfere with mathematics performance; therefore, for our research we investigated what portions of individuals seem to suffer higher levels of mathematics anxiety and to what extent they are affected by it. We also investigated the study habits of the students and how these affect their mathematics anxiety levels and overall mathematics performance. Our data was obtained from Hispanic undergraduate students (n=405) who took Elementary Algebra (Math 1300), Intermediate Algebra (Math 1334), College Algebra (Math 1340) …

Modification Of Traffic-Related Respiratory Response By Asthma Control In A Population Of Car Commuters, Maria C. Mirabelli, Rachel Golan, Roby Greenwald, Amit U. Raysoni, Fernando Holguin, Priya Kewada, Andrea Winquist, W Dana Flanders, Jeremy A. Sarnat

School of Earth, Environmental, & Marine Sciences Faculty Publications

Background: Effects of traffic-related exposures on respiratory health are well documented, but little information is available about whether asthma control influences individual susceptibility. We analyzed data from the Atlanta Commuter Exposure study to evaluate modification of associations between rush-hour commuting, in- vehicle air pollution, and selected respiratory health outcomes by asthma control status.

Methods: Between 2009 and 2011, 39 adults participated in Atlanta Commuter Exposure, and each conducted two scripted rush-hour highway commutes. In-vehicle particulate components were measured during all commutes. Among adults with asthma, we evaluated asthma control by questionnaire and spirometry. Exhaled nitric oxide, forced expiratory volume in …

Alternative Restoration Treatments To Maximize Growth And Survival Of Tamaulipan Thornscrub Species During Seeding Establishment, Jennifer Lynn Vela

Theses and Dissertations - UTB/UTPA

Anthropogenic activities that destroy, degrade, or fragment terrestrial ecosystems have long-lasting detrimental impacts on ecosystem function, services, and biodiversity. The Tamaulipan thornscrub ecoregion of south Texas and northeastern Mexico has sustained considerable loss, degradation, and fragmentation due land conversion for agriculture, urbanization, and introduction of invasive flora and fauna. In an attempt to restore habitat for endangered and migratory animals, United States Fish and Wildlife Service has undertaken a large-scale thornscrub revegetation effort in south Texas. The goal of this study was to develop effective restoration techniques to promote growth and survival of Tamaulipan thornscrub species during seedling establishment. Beginning …

The Effects Of Math Anxiety On Consumer Price Perception And Purchase Decision, Peter Andersen

Theses and Dissertations - UTB/UTPA

Mathematics anxiety is an emotional state resulting in a negative reaction to numerical information and math problems. Therefore, it has been studied by education research to explain its effects on academic performance. However, the marketing literature has failed to notice the role of math anxiety in consumer behavior. As retailers offer various price promotions to increase product sales, buyers need to compare prices and calculate the final price after sales. The success of promotions depends on the way that the sellers frame the promotions, as consumers may react to promotions that offer gains differently than those that reduce their loss. …

Evaluation Of Control Strategies For The Spread Of Citrus Greening, Vicente Valle Martinez

Theses and Dissertations - UTB/UTPA

Huanglongbing, also known as citrus greening, is a vector-based disease in citrus (with no cure known to date) that has drastically affected the citrus production in Florida in less than a decade and has been recently detected in Texas and California. In this paper, an epidemic model of the spatial spread of the disease is implemented among commercial and residential groves by taking into consideration the diffusion patterns of the psyllid vectors. A system of differential equations resembling one for malaria infection in humans is derived to evaluate different control methods such as quarantine, treatment, removal, foliar treatment, and pest …

Double Compact Objects. Iii. Gravitational-Wave Detection Rates, Michal Dominik, Emanuele Berti, Richard O'Shaughnessy, Ilya Mandel, Krzysztof Belczynski, Christopher Fryer, Daniel E. Holz, Tomasz Bulik, Francesco Pannarale

Physics & Astronomy Faculty Publications

The unprecedented range of second-generation gravitational-wave (GW) observatories calls for refining the predictions of potential sources and detection rates. The coalescence of double compact objects (DCOs)—i.e., neutron star–neutron star (NS–NS), black hole–neutron star (BH–NS), and black hole–black hole (BH–BH) binary systems—is the most promising source of GWs for these detectors. We compute detection rates of coalescing DCOs in second-generation GW detectors using the latest models for their cosmological evolution, and implementing inspiral-merger-ringdown gravitational waveform models in our signal-to-noise ratio calculations. We find that (1) the inclusion of the merger/ringdown portion of the signal does not significantly affect rates for NS–NS …

Lateral Dispersal And Foraging Behavior Of Entomopathogenic Nematodes In The Absence And Presence Of Mobile And Non-Mobile Hosts, Harit K. Bal, Parwinder Grewal

School of Earth, Environmental, & Marine Sciences Faculty Publications

Entomopathogenic nematodes have been classified into cruisers (active searchers) and ambushers (sit and wait foragers). However, little is known about their dispersal and foraging behavior at population level in soil. We studied lateral dispersal of the ambush foraging Steinernema carpocapsae (ALL strain) and cruise foraging Heterorhabditis bacteriophora (GPS11 strain) from infected host cadavers in microcosms (0.05 m2) containing Wooster silt-loam soil (Oxyaquic fragiudalf) and vegetation in the presence or absence of non-mobile and mobile hosts. Results showed that the presence of a non-mobile host (Galleria mellonella larva in a wire mesh cage) enhanced H. bacteriophora dispersal for up …

Fatigue Life Estimation Of Modified Railroad Bearing Adapters For Onboard Monitoring Applications, Alexis Trevino, Arturo A. Fuentes, Constantine Tarawneh, Joseph Montalvo

Mechanical Engineering Faculty Publications

This paper presents a study of the fatigue life (i.e. number of stress cycles before failure) of Class K cast iron conventional and modified railroad bearing adapters for onboard monitoring applications under different operational conditions based on experimentally validated Finite Element Analysis (FEA) stress results. Currently, freight railcars rely heavily on wayside hot-box detectors (HBDs) at strategic intervals to record bearing cup temperatures as the train passes at specified velocities. Hence, most temperature measurements are limited to certain physical railroad locations. This limitation gave way for an optimized sensor that could potentially deliver significant insight on continuous bearing temperature conditions. …

Einstein@ Home Discovery Of A Palfa Millisecond Pulsar In An Eccentric Binary Orbit, B. Knispel, A. G. Lyne, B. W. Stappers, P. C.C. Freire, P. Lazarus, B. Allen, C. Aulbert, O. Bock, S. Bogdanov, Fredrick Jenet

Physics & Astronomy Faculty Publications

We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3 Mo and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbital eccentricities …

Tracking Of Spall Deterioration On Tapered Roller Bearings, Amy Gonzalez, Constantine Tarawneh, Ping Hu, Joseph A. Turner, Brent Wilson

Mechanical Engineering Faculty Publications

Fatigue spall initiation is one of the major modes of premature bearing failure. The spall initiation is often exacerbated by the presence of impurities in the near-surface region (∼400 μm) of the bearing raceways. Once a spall initiates, it can propagate rapidly, leading to abnormal bearing operation and possible catastrophic failure if not detected early. Testing performed at the University of Texas-Pan American (UTPA) has focused on ultrasonically scanned tapered roller bearings found to have inclusion content within 400 μm of the surface of the raceways. These bearings undergo accelerated service life tests in which spall initiation is detected and …

Energy Harvesting Potential Of Terfenol-D For On-Board Bearing Health Monitoring Applications, Raul Estrada, Heinrich D. Foltz, Constantine Tarawneh, Rene Moreno

Electrical and Computer Engineering Faculty Publications

One of the limiting factors in on-board bearing health monitoring systems is the life of the batteries used to power the system. Thus, any device that can extend the life of the battery, or entirely replace it, is a notable improvement on any currently available systems. Existing on-board monitoring systems, not optimized for low power, are designed to run on approximately 300 mW of power. Current bearing health monitoring systems have proven effective with as few as one reading every four minutes. The environment under which railroad bearings operate is a harsh one, making most forms of energy harvesting very …

The Economics Of Counterfeiting, Elena Quercioli, Lones Smith

School of Economics and Finance Faculty Publications

We develop a strategic theory of counterfeiting as a multi-market large game. Bad guys choose whether to counterfeit, and what quality to produce. Opposing them is a continuum of good guys who select a costly verification effort. In equilibrium, counterfeiters produce better quality at higher notes, but verifiers try sufficiently harder that verification still improves. We develop a graphical framework for deducing comparative statics. Passed and counterfeiting rates vanish for low and high notes. Our predictions are consistent with time series and cross-sectional patterns in a unique data set assembled largely from the Secret Service

Professional Learning Communities And School Culture: A Case Of Study In District-Wide Implementation Of A Plc, Jaime Lopez

Theses and Dissertations - UTB/UTPA

The purpose of this study is to explore what influence a school district’s transformation to a PLC had on culture. In particular, the study examined what dimensions of a PLC are evident, how the district approached the change process, and its influence on student achievement. The methodology employed in this study is a Type 2 single-case study. Data regarding this district’s implementation of a PLC, and its influence on school culture was gathered via sources of evidence common in case study research; survey, documents, archival records, direct observations, and interviews. In summary, the findings suggest the following; (1) PLC work …

Bounded Rationality Alters The Dynamics Of Paediatric Immunization Acceptance, Tamer Oraby, Chris T. Bauch

School of Mathematical & Statistical Sciences Faculty Publications

Interactions between disease dynamics and vaccinating behavior have been explored in many coupled behavior-disease models. Cognitive effects such as risk perception, framing, and subjective probabilities of adverse events can be important determinants of the vaccinating behaviour, and represent departures from the pure “rational” decision model that are often described as “bounded rationality”. However, the impact of such cognitive effects in the context of paediatric infectious disease vaccines has received relatively little attention. Here, we develop a disease-behavior model that accounts for bounded rationality through prospect theory. We analyze the model and compare its predictions to a reduced model that lacks …