Digital Commons Network^™

Characterization Of High Resolution Range And Doppler Chaotic Ladar, Berenice Verdin

Open Access Theses & Dissertations

Compared to high range resolution radar systems, chaotic LADAR (laser detection and ranging) has the potential of providing an increase in range-Doppler resolution by several orders of magnitude.

The purpose of this project is to determine system parameters and signal processing schemes required to build a high resolution chaotic LADAR. Specifically, the LADAR is based on a semiconductor laser that generates a wideband chaotic signal via optical feedback. The behavior of the laser output is modeled by changing the control parameters of the delay differential equations that dictate the behavior of the laser output. Depending on the feedback level and …

Using Chromium Stable Isotopes To Monitor Chromium Reactive Transport: Oxidation Experiments And Field Studies, Alejandro Villalobos Aragon

Open Access Theses & Dissertations

Chromium (Cr) is a common contaminant found at a number of sites globally. Cr sources can be either anthropogenic or natural. Cr occurs in nature in two valences, with Cr(VI) being carcinogenic, more toxic and mobile than Cr(III). Reduction of Cr(VI) to Cr(III) is a common remediation strategy, but monitoring Cr reduction using only concentration and speciation analyses is a difficult endeavor because concentrations can be affected by dilution and advection in addition to reduction. Cr isotopes are fractionated during reduction processes, so monitoring isotopic changes in Cr may be a faster and more effective way to monitor reduction. This …

By-Product Synergy In The Textile Industry: Indigo Waste Recovery In The Denim Finishing Process, Dennis Wambuguh

Open Access Theses & Dissertations

Textile dyeing effluents present a substantial environmental problem, primarily because such effluents contain high concentrations of waste dyes, dye-products, and variable salts. The stonewashing process for the degradation of blue indigo to create a `faded' look in blue denim results in high concentrations of indigo dye waste in the resulting effluent and because indigo is very difficult to decompose biologically, the effluent ends up in the environment, raising aesthetic concerns and damaging the integrity of the rceiving streams. Wastewater containing indigo is characterized by a moderate amount of chemical oxygen demand (COD), pH, suspended solids, dissolved solids and a dark …

Exploring Poly(Ethylene Glycol) As A Suitable Material For Peripheral Nerve Regeneration Scaffolds Manufactured By Stereolithography, Nubia Zuverza

Open Access Theses & Dissertations

One of the challenges in tissue engineering is to have spatial and temporal control over the biological elements within a scaffold used to guide regeneration for example of transected nerves. Some of the physical and chemical characteristics to regulate include incorporation of bioactive domains and release of chemical signals. This study presents the use of stereolithography (SL) to incorporate localized domains for cell adhesion in addition to include releasable nerve growth factor (NGF) in the process of building poly(ethylene glycol)diacrylate (PEGda) hydrogel scaffolds. Besides providing sites for cell attachment, an ideal nerve guidance conduit (NGC) should be able to release …

The Tower Clock 2009, Tower Clock

Tower Clock Yearbooks

No abstract provided.

Silica Removal From Brine By Using Ion Exchange, Carlos R. Acevedo

Open Access Theses & Dissertations

Local governments have been forced to look for additional water sources to satisfy the ever increasing demand for fresh water. Very often, the new water sources such as the underground water in continental territories have high salt content. Currently, reverse osmosis technology (RO) is one of the most common processes for water desalination. However, this process is limited by high silica and salt concentrations in water. At high concentrations silica clogs the membranes used in the RO process, reducing their life and increasing operational costs. In this study, quaternary ammonium resins and sulfonic acid resins were used to remove silica …

Multi-Objective Network Reliability Optimization Using Evolutionary Algorithms, Franciso Oswaldo Aguirre

Open Access Theses & Dissertations

This work presents a new multiple objective evolutionary algorithm to solve three well known network reliability allocation problems considering different conflicting objectives to be optimized simultaneously. The new algorithm is applied in the design of a telecommunication network that is formed for several stations or nodes interconnected by telecommunication links or paths. The problem presented in this work involves finding which links to activate in order to obtain connectivity in the nodes. The number of nodes that need to be connected depends of the case that is being evaluated. The three network reliability problems considered are: all-terminal, k-terminal, and two-terminal. …

Microstructure And Electrical Performance Of Sputter-Deposited Hafnium Oxide (Hfo2) Thin Films, Brandon Adrian Aguirre

Open Access Theses & Dissertations

Hafnium oxide (HfO2) based dielectrics have been currently considered as the possible replacements for the traditional gate-oxide (SiO2) of the complementary metal-oxide semiconductor (CMOS) devices. The high dielectric constant, wide band gap, and thermal stability in contact with Si make HfO2 a potential material for application in CMOS devices. The performance of HfO2 as a gate oxide material, however, depends on its quality and interface structure with Si. In this work, HfO2 thin films have been deposited by rf sputtering onto Si(100) substrates under varying growth temperatures (Ts). The objective of the work is to understand the growth and microstructure …

Effect Of Air Addition On Plasma-Based Reforming Of Methane And Propane, Atul Vitthalrao Ambhore

Open Access Theses & Dissertations

No abstract provided.

Supporting Novice Application Users In Learning By Trial And Error And Using Help, Oscar Daniel Andrade

Open Access Theses & Dissertations

This thesis examines three related topics in analyzing user preferences for troubleshooting application usability problems and the kinds of issues that influence such preferences. The goal of this thesis is to propose (1) ways in which users can be supported to learn to use applications and (2) a model to rewrite help such that users are able to adapt its contents dynamically.

The consensus of documentation research is that users rarely use help, usually preferring to muddle through. To increase use of help, tutorials for novice users could be changed from guided presentations toward using the application's help system. To …

Laminar Burning Velocities Of Gas Mixtures, Vishwanath Reddy Ardha

Open Access Theses & Dissertations

In this study, burning velocities of hydrogen-carbon monoxide (H2-CO) mixtures, which are primary constituents of syngas fuels, are measured. The effect of different burner systems, H2 concentration, and different measurement techniques on the burning velocities of H2-CO mixtures is also discussed. The burning velocities of H2-CO mixtures increase with the increase in H2 content in the mixture. When compared with different burner systems using different methods, the burning velocity data almost coincide in the lean condition, but at rich condition the data stray away from each other. The burning velocities of actual syngas compositions (based on different sources of coal) …

Symbiotic Effects Of The Fungus Glomus Sp. On Chromium(Iii), Chromium(Vi), And Lead(Ii) Uptake By Mesquite (Prosopis Sp.): A Novel Method To Remediate Heavy Metals, Jack A. Arias

Open Access Theses & Dissertations

The indiscriminate disposal of lead (Pb) and chromium (Cr) containing wastes has resulted in a detrimental impact on environmental health. Lead and Cr are in the EPA priority list due to their degree of toxicity on humans, animals, plants, and other living organisms. The removal of toxic wastes involves technologies that are expensive, sometimes incomplete, and could represent health hazards. In addition, site restoration after contaminant removal encompasses time and technological resources. Phytoremediation, the use of plants alone or associated with microorganisms, represents a potentially cost-effective option in the long term management of contaminated sites. Various plants known as "hyperaccumulators" …

Salsola Kali (Tumbleweed): A Possible Biomonitoring Device For The Detection Of Airborne Heavy Metals, Tenoch Benitez

Open Access Theses & Dissertations

Vehicular congestion generates particulate matter and contaminants such as lead, cadmium, copper, chromium, nickel, and zinc which have been detected in the U.S.-Mexico border region. To overcome the inconvenience of expensive sampling techniques, scientists started to assess air quality by using bioindicator plants, a technique called biomonitoring. Biomonitoring is an inexpensive and environmentally friendly approach to determine inorganic contaminants at trace levels. The purpose of this project was to determine the effectiveness of tumbleweed (Salsola kali) plants, sprayed with chelating agents, as a passive monitoring device to determine the possible presence of heavy metals in the ambient air around international …

Third Grade Students' Challenges And Strategies To Solving Mathematical Word Problems, Elizabeth Bernadette

Open Access Theses & Dissertations

This project explores the difficulties and challenges that third grade students face solving mathematical word problems. Three students were asked to be participants and share their knowledge on this topic as well as their work. After extensive interviews it was concluded that the challenges of mathematical word problems include but are not limited to the level of reading comprehension, conceptual understanding of mathematical concepts, and the belief that math is a compilation of computations and unexplainable procedures. The participants provided insight as to what strategies are helpful to students. These strategies include group discussion on problem solving strategies, self-assessment, incorporating …

Uptake Of Pahs And Metals By Plants In Arid Environment, Zarhelia Carlo

Open Access Theses & Dissertations

Study of plant uptake of PAHs with the concurrent presence of metals in laboratory conditions was done with the aim to resemble specific combinations of natural environment. Toxicological response of seedlings was tested to define treatment conditions or possible interferences. The levels of PAHs and metals in the treatments were set up to have no toxic effect on plant growth. The complexity of concurrent contamination was demonstrated in a laboratory with soil. No visual differences were observed among various dose treatments of Cu and Zn with organics three PAHs, Phenanthrene (Phen), Acetoanthrancene, and Benzo(a)pyrene (BaP). The metal analysis by ICP/OES …

Real-Time Image-Based Motion Detection Using Color And Structure, Manali Chakraborty

Open Access Theses & Dissertations

Motion detection is an important problem in computer vision and has multiple applications in the real world, including surveillance-related activities, gaming, and human-robot interactions. These systems need to be robust enough to handle fluctuations in light intensity and other external factors like noise and compression artifacts. In this thesis a method is proposed for detecting the regions of motion from a video sequence in real time. The main idea of this work is to detect motion based on both structure and color. Structure-based detection is carried out using information from the Census Transform computed on gradient images obtained with Sobel …

Introduction To Pseudo-Ordered Groups, Maria Dolores Cruz

Open Access Theses & Dissertations

We will give a definition, examples and basic properties of pseudo-ordered groups. These generalize partially-ordered groups. The pseudo-ordered groups have a compatible pseudo-order relation that may lack transitivity. Unlike partially-ordered groups, our groups can be finite and still admit a non-trivial pseudo-order. We will show necessary and sufficient conditions for a group to have a compatible pseudo-order. We also consider maximal pseudo-orders. We give a definition of a pseudo chain induced by a pseudo-order and characterize all pseudo chains on the group $\mathbb {Z}_{n}.$ We will calculate the number of non-isomorphic pseudo-orders on $\mathbb {Z}_{n}$ for $ n < 24.$

Ms.Ms., Amanda Elvira Cuellar

Open Access Theses & Dissertations

In this paper, the idea that Shakespeare's Caesar is just as Shavian as Shaw's representation of Julius Caesar is explored. In addition, an examination of the characteristics of the Life Force that prevail in Caesar and Cleopatra is presented. I compare these characteristics to the qualities described in Shakespeare's play. Ultimately, both rulers employ the power of the Life Force which exemplifies each man's genius.

Art In A New Light: Design And Assessment Of Illuminants To Reduce Photochemical Degradation Of Works Of Art, Monica Fabiola Delgado

Open Access Theses & Dissertations

The purpose of this research is to design the best lighting that will minimize long term photochemical degradation of Old Master Drawings and/or other works of art, while maintaining the patron's appreciation of the object's color and detail. The present approach is a technological refinement to the basic underlying earlier work on fluorescent lighting by W. A. Thornton, W.A. at General Electric1. Thin-film dielectric, multi-coating technology is used to create filters that eliminate ultraviolet light, near infrared light and significant unnecessary parts from the visible spectrum, thus maximizing the reduction in photochemical degradation, while maintaining optimal color rendering. Three interference …

Latina Sorority Involvement And The College Experience: Social And Academic Impact, Darilis Garcia-Mcmillian

Open Access Theses & Dissertations

Membership in a Latina-based sorority communicates messages to sisters as well as the university community. These messages usually reflected the goals and principles of the organization which is often what attracts women to join. Once they are part of the sorority their affiliation impacts their college experience. This study looks at the effect Greek membership has on participants' social and academic lives. Through narrative analysis the women's responses were examined to understand their perceptions of how joining Delta Tau Lambda Sorority impacted their college experience. The human and rhetorical agency of members was examined through their survey responses. Their experiences …

Prenatal Physical Activity Patterns And Determinants In An Urban Ecuadorian Population, Erika Gonzalez Beltran

Open Access Theses & Dissertations

Background & Significance. Evidence has accumulated over the past two decades suggesting that healthy pregnant women who engage in regular moderate physical activity (PA) may reduce their risk for certain adverse pregnancy and postnatal health outcomes. The U.S. Department of Health and Human Services (DHHS)/Centers for Disease Control and Prevention (CDC) recently issued the 2008 Physical Activity Guidelines for Americans which recommends at least 150 minutes/week of moderate-intensity aerobic PA for pregnant women. The American College of Obstetricians and Gynecologists (ACOG, 2002) recommends 30 min of moderate-intensity PA, specified as derived from recreational or leisure activities on most or all …

The Relation Of Alcohol Expectancies To Alcohol Consumption And Alcohol-Related Problems Among College Students, Michelle Nicholle Greco

Open Access Theses & Dissertations

The purpose of the present study was to examine the relationships among positive and negative alcohol expectancies and alcohol consumption and alcohol-related problems in a sample of Hispanic, predominantly Mexican-American, college students. It was hypothesized that positive expectancies would be positively related to alcohol consumption and alcohol-related problems and that negative expectancies would be negatively related to alcohol consumption and alcohol related problems. Little is known and understood about the role of positive and negative expectancies in Hispanic college students and even less is known about how expectancies relate to alcohol related problems in this population.

This study was a …

Reanalysis Of Some Effects Of The Mutual Exclusivity Constraint And Their Operation In Bilingual Children, Marina Kalashnikova

Open Access Theses & Dissertations

This study investigates the operation of the Mutual Exclusivity constraint in two groups of three-year-old children: monolingual Spanish speakers and bilingual Spanish-English speakers. Previous research has yielded controversial findings regarding the differences in the intra-lingual level operation of the constraint in monolingual and bilingual children. This investigation sheds light on the conflicting outcomes of previous studies by proposing that non-linguistic cognitive and processing abilities may account for the effects attributed to the constraint and that there may be observable differences in monolingual and bilingual children in the development of some--but not all--of these abilities. Although, this study yielded no significant …

Revision Of The Ant Genus Crematogaster (Hymenoptera: Formicidae) In North America, Cynthia Ellen Morgan

Open Access Theses & Dissertations

The natural history of thirty-eight species of the genus Crematogaster in North America has been discussed and distribution of specimens mapped. A dichotomous key to the workers of these species has been developed. I hypothesized that the species richness is not as great as previously thought in North America. A taxonomic review of these species has been made with the following changes:

Crematogaster cerasi Fitch 1855 senior synonym of C. browni Buren1968.

C. coarctata Mayr 1870 senior synonym of C. californica Emery 1895, C. mormonum

Emery 1895 and C. colei Buren1968.

C. depilis Wheeler 1919 senior synonym of C. larreae …

Development Of The Video Suggestibility Scale For Children: Spanish-Language Version, Claudia Ornelas

Open Access Theses & Dissertations

This study examined the psychometric properties of a Spanish version of the Video Suggestibility Scale (VSSC). A cross-cultural validation with a sample of 3-5 year old Spanish speaking children was performed to evaluate its psychometric properties (N = 79). The development of the VSSC Spanish language version (VSSC-S) is described. The new version was created using the translation-back-translation process to increase the instrument‟s equivalence. Internal consistencies were satisfactory. Construct validity was assessed by using factor analysis and the Varimax procedure. As expected, the VSSC-S items loaded on two separate factors. Overall, results suggest that the VSSC-S taps into similar constructs …

Electric Power Distribution Optimization Using Evolutionary Algorithms, Sowmya Parimi

Open Access Theses & Dissertations

In the present research, a new evolutionary algorithm is developed to solve the component allocation problem in electricity distribution systems. The problem addresses the upgrade/design of an electricity distribution system with the objective of minimizing expected system downtime subject to cost and repair time constraints. The algorithm is tested on the Dual Element Spot Network (DESN) configuration which is one of the most commonly used configurations by the power industry. This algorithm is demonstrated with two examples.

Geography Of Pestecide Exposure In The Lower Valley (El Paso County, Texas), Critina Solis Sanchez

Open Access Theses & Dissertations

Previous studies using GIS have been used to understand the demographics of particular areas of a city and the risks associated with living there. In the Lower Valley (Socorro, Clint, and San Elizario) area of El Paso County (TX), there has been a rapid growth in population. This increase in growth has led to this project about the types of pesticides used in farms and if they are creating possible health risks for people living in this area and which populations are most at risk. To determine population risk, I use existing GIS information, specifically a USDA aerial photograph taken …

Deterring Bonds: Why She Can't Leave., Yolanda Cora Seidler

Open Access Theses & Dissertations

Is it always true that the marriage bonds nurture love?

Domestic violence knows np boundaries it happens everywhere it touches everyone, regardless of age, income, level of education, occupation, race/ethnicity, and religious belief. For this study, because of its unique characteristics, the military community was selected. Some of its differences with the civil community as well as its response to victims, protection, rights, and the offenders accountability are discussed.

Hip Hop Rhetoric: Relandscaping The Rhetorical Tradition, Roberto Jose Tinajero Ii

Open Access Theses & Dissertations

This dissertation is a rhetorical analysis of hip hop music and culture. Chapter 1 focuses on adding hip hop rhetoric to the discussion and terrain of rhetoric and writing studies and to the rhetorical tradition. Chapter 2 uses the rhetorical notion of kairos to discuss the ethos of hip hop culture and discourse. Chapter 3 uses hip hop rhetoric to discuss the tensuous-solidarity between Latinos and African Americans. Chapter 4 focuses on Latino/Borderland Hip Hop and discusses the multi-consciousness of Latino identity. Chapter 5 focuses on Christiian religious imagery in gangsta rap music. There is also a short conclusion.

Survey Research On Communication And Language For English Language Learners And Native English Speakers Enrolled In A College Course On Statistical Literacy, Maria Guadalupe Valenzuela

Open Access Theses & Dissertations

The purpose of this study was to examine in what ways language is a factor that affects the learning process of students in an introductory statistics class. This research used a questionnaire survey instrument called: CLASS, Communication, Language And Statistics Survey that was applied to a total of 137 college students from a large southwestern public university, 83 of these students were self-identified as native English speakers (NOELL) and 53 were self-identified as English learner speakers (ELL) and one was dropped. This research found that in statistical instruction, there are some particular differences in behavior and learning process in the …