ETD Collection for University of Texas, El Paso

Development of a high pressure optically accessible combustor and shear coaxial injector

Christopher David Navarro — Wed, 21 Nov 2012 10:14:20 PST

A trend in the last decade in the field of propulsion and rocketry is leaning toward the use of the combination of Liquid Methane and Liquid Oxygen as propellant fuels. This is in contrast with the earlier trend of using Hydrogen systems and toxic hypergolic systems. The Multi-Purpose Optically Accessible Combustor (MOAC) and Shear Coaxial injectors have been developed to investigate injector design and combustion research involving Oxygen and Methane propellants. The MOAC is intended for the experimentation and research of combustion of liquid and gaseous propellants. Development of the MOAC system and versatility to use a number of injector styles is discussed. Development of Shear Coaxial injectors common with Oxygen and Methane systems and geometric influences are discussed as well. Instrumentation critical to obtaining test data for analysis of the thermodynamic properties of both the propellants and the combustion chamber are detailed. Optical instrumentation associated with the MOAC system is thoroughly described to identify the characteristics of the spray and combustion dynamics. Finally, testing parameters will be explained as well as a summary of initial test results concluded from initial testing.^

The impact of decadal land cover change on the global warming potential of Beringian Arctic tundra

David Hwei-Len Lin — Fri, 26 Oct 2012 10:45:16 PDT

The goal of this study is to (1) determine how land cover in the Beringian Arctic changed in the last half century; (2) assess what biophysical properties control peak growing season land-atmosphere CO₂ and CH₄ exchange in multiple landscapes and land cover classes in Beringia; and (3) model how decadal land cover change in Beringia has altered peak growing season CO₂ and CH₄ exchange and global warming potential. ^ Using a campaign-style, snapshot sampling approach sixteen sites were visited in ten different landscapes throughout the Beringian Arctic between 2005 and 2008. Sites represented a broad range of arctic terrestrial ecosystems, and data collection included CO₂ exchange, CH₄ exchange, and a number of biophysical and spectral properties for the purpose of spatial scaling and model development. For seven landscapes, ground-truthed land cover maps were created from recent high-resolution Quickbird imagery. Using conservative assumptions regarding land cover change, modern land cover maps were used as baselines for the development of historic high-spatial-resolution land cover maps derived from aerial photography and declassified military imagery dating back to 1948. Using these multi-temporal coverages, trends in decade time scale land cover change were determined for each study landscape. Within Alaska, drier landscapes and open water cover classes expanded whereas wet vegetated land cover classes decreased in area. For Russian landscapes, shrub dominated land cover expanded wherever these were present and land cover generally shifted towards an expanse of wetter landscape vegetation types. ^ Multiple regression models were developed using field data. These were able to effectively predict CO₂ and CH₄ flux (R² = 0.70 and 0.66 respectively) for a range of vegetation types and landscapes at multiple locations in the Beringian Arctic. Originating from measurements taken during the snapshot sampling campaign, the models were relatively simple, spatially scalable models whose input parameters could be derived from automated ground and aerial/satellite based observation platforms. The effectiveness of these models suggests that predicting the GWP of landscapes across Beringia many multiple landscapes may only require the measurement of simple ecosystem measures and given the variety of landscapes within this study, these relationships may extend to other parts of the Arctic as well. ^ Ecosystem fluxes were then spatially extrapolated over the multi-temporal land cover maps to determine the impact of land cover change on CO₂ and CH₄ flux. Using the global warming potential (GWP) metric, we calculated the global warming potential of these landscapes in CO₂ equivalents (CO₂e). Results suggest all landscapes were historic net sinks of carbon and remain net sinks of CO₂e. Four of the seven sites appeared to become weaker sinks, while the remaining three sites became stronger sinks of CO₂e. Decadal changes in CO₂ and CH₄ flux as well as global warming did not appear to have any geographic associations. When the effect of land cover change on NDVI was calculated, most landscapes displayed a change in NDVI consistent with regional aggregations measured at coarse spatial scales (i.e. an increase for Alaskan landscapes, except for the Barrow and Atqasuk sites, and a decrease for Russian landscapes). ^ These findings build on the current understanding of the relationship between ecosystem structural structure and function change and draw attention to the importance of understanding how their spatio-temporal variation can affect global warming potential over decadal time scales. Findings also suggest that using simple set measurements within a network of automated sensors could allow the development of a cost-efficient network for monitoring fluxes. In the process of building ecosystem flux models, the novel snapshot-sampling approach developed in this study demonstrates the capacity for fast and efficient sampling of large areas in combination with remote sensing platforms. The simple models and capacities demonstrated here would benefit the future development of an integrated Arctic observing network. (Abstract shortened by UMI.)^

Identifying the antecedents of moral conviction

Katherine R. G White — Fri, 26 Oct 2012 10:45:15 PDT

Our understanding of how moral attitudes influence behavior has been greatly expanded by recent research on moral conviction, but little has been done to identify factors that contribute to the formation of moral conviction. The primary purpose of the present research was therefore to identify antecedents to moral conviction. Across two studies, three potential antecedents were identified - reliance on the Harm moral foundation, personal relevance, and attitude intensity. In study 1 (N = 469), high individual reliance on the Harm moral foundation predicted stronger moral conviction. In study 2 (N = 460), high personal relevance and greater attitude intensity predicted stronger moral conviction. Study 2 also tested three separate hypotheses forwarded by the Integrated Theory of Moral Conviction (ITMC) – the universality, objectivity, and emotion hypotheses. While results offered support for the objectivity and emotion hypotheses, support for the universality hypothesis was equivocal. Future research is required to determine the mechanism by which personal relevance increases moral conviction and the directional links between emotion and moral conviction.^

The bonds of a common faith: Catholicism, marriage, and the making of borders in nineteenth-century Paso del Norte

Jamie Matthew Starling — Fri, 26 Oct 2012 10:45:14 PDT

The Roman Catholic Church occupied a central place in life in the U.S.-Mexican borderlands as it governed interpersonal relationships, marriage, and family law from the Spanish colonial period until the 1860s and 1870s. This project examines the role of this church in Paso del Norte (present-day Ciudad Juárez, Chihuahua and El Paso, Texas) as a social institution that regulated domestic life against the backdrop of dramatic political, economic, cultural, and ecological transformations. The central sources for this study are the marriage records of the Parish of Guadalupe. This church emerged as a Franciscan Mission for the indigenous Manso people in the seventeenth century and became a secular parish of the Diocese of Durango in the eighteenth century. ^ In the nineteenth century, the parish experienced many of the processes that defined the United States-Mexican borderlands on an intimate level; Mexican independence and attempts to forge a republic, military conflicts between Mexico and the United States, the emergence of long-distance trade networks, the growth of Euro-American settlement, and industrialization. One of the most significant changes the parish experienced was the imposition of a new boundary in 1848. However, Guadalupe, as the seat of the Vicariate of Paso del Norte, retained its authority over adjacent parts of Texas and New Mexico. For nearly three decades after the U.S.-Mexico War, Catholics who lived north of the border continued to be baptized, married, and buried by an institution that remained under Mexican leadership. Ultimately, the arrival of a wave of settlers who sought to "Americanize" the borderlands brought an end to a Mexican church hierarchy that extended north of the border. ^

Professional learning communities as a critical structure for ELL schooling

Miguel Angel Serrano — Fri, 26 Oct 2012 10:45:14 PDT

Nationally, English language learners (ELLs) have underperformed in making the grade on standards set by the U.S. Department of Education. National data indicate that ELLs are performing lower (National Center for Education Statistics, 2011). ELLs are likely to perform less well on state assessments and drop-out rates are higher than their English speaking peers (Ballantyne, Sanderman & Levy, 2008). Current school practices lack a comprehensive knowledge base as to how to prepare ELLs to be academically successful. With the advent of No Child Left Behind (NCLB), educators have to demonstrate annual language and academic gains for English Language Learners (ELLs) with greater accountability than ever before. Further understanding of learning English and learning in English is necessary. This study focused on Borderland High School that did not meet the academic standards for ELLs as set by NCLB. In its efforts to improve the academic performance of ELLs, the school identified professional learning communities (PLCs) as their strategy to address this challenge. PLCs involve teachers and administrators coming together to work on improving student performance in schools. This research utilized team learning as its theoretical framework. Team learning is one the five disciplines that indicate that learning in teams happen when colleagues work together towards a common goal (Senge, 1990). ^ Four guiding research questions determined which variables of the PLC had the greatest impact on the academic performance of ELLs. A mixed methods study examined Borderland High School's 2007 reform efforts to determine if PLCs and their variables led to ELL achievement. The quantitative research phase indicated the academic literacy variable in the PLC to be correlated to and a predictor of academic success for ELLs in the area of Reading. In comparison, the research showed that for non-ELLs the academic literacy variable in the PLC to be correlated and a predictor of success in the area of Mathematics. The multiple regression model indicated GPA to be a predictor of success for non-ELLs on the Mathematics TAKS exam. In addition, this phase also showed that PLCs were a predictor of the overall academic success of students at Borderland High School. The research also revealed that the teacher planning variable showed a positive relationship with the PLC as whole. ^ The qualitative research phase examined both student and teacher perspectives. In this phase, the student perspective showed that the academic literacy variable of the PLC supported ELL academic performance at Borderland High School. From the teacher perspective, the teacher collaboration and planning variables of the PLC proved to be critical in supporting the academic literacy of ELLs. ^

The impact of national culture on cost of equity capital in cross-listed firms

Kathy F Otero — Fri, 26 Oct 2012 10:45:13 PDT

This study examines the GLOBE cultural dimensions of institutional collectivism, in-group collectivism, uncertainty avoidance, and power distance to evaluate the impact of national culture on cost of equity capital for firms cross-listing on two stock exchanges. In addition to evaluating the direct effect of culture on cost of equity capital, the study examines the moderating effect of national culture on impact of the political/regulatory environment and disclosure on cost of equity capital. Limited support was found for both the direct effect and the moderating effect of national culture on cost of equity capital.^

Assessing cortical electrophysiologic and behavioral activity in individuals with aphasia and participants with no brain damage responding to spoken sentence length messages

Patricia Lara — Fri, 26 Oct 2012 10:45:12 PDT

In this study, six individuals with aphasia and twelve participants with no brain damage responded to spoken sentence length messages using a modified version of the Revised Token Test (McNeil & Prescott, 1978) while cortical activation was recorded using event related potentials (ERP). ERP is a non-invasive imaging procedure that measures cortical activation reflected in the electrical activity that is produced at the level of the cortex in response to internal or external stimulus. ^ Participants were presented with a visual display that provided eight different token arrangements per trial that were displayed on the computer screen. Spoken messages that increased in length and grammatical complexity were presented via speakers. Participants were instructed to listen to the spoken message and respond by touching the visual choice that matched the spoken message on a touch screen for a total of 90 trials. ^ The task of semantic processing may be reflected in the latency and peak amplitude of the N400 ERP component. This component has been reported to reflect the processing of single spoken words in participants with no brain damage and individuals with aphasia (Friederici et al., 1999; Handy, 2005; Luck, 2005; Rugg & Coles, 1997). The N400 ERP component has not been well investigated in the processing of spoken sentence length messages in individuals with aphasia. ^ In order to investigate the mechanisms involved in the auditory comprehension of spoken sentence length messages, we need to identify where in that temporal process the individual is processing the message. Since ERP can be time locked to a specific event, it seems reasonable to use ERP to investigate the temporal characteristics of auditory comprehension of sentence length messages.^ The present study compared the performance of individuals with aphasia and participants with no brain damage responding to spoken sentence length messages. The results show that the two groups performed differently in regards to correct response rate. The individuals with aphasia made more error responses than did the participants with no brain damage. The participants with no brain damage showed reduced accuracy as the complexity of the sentence increased while the individuals with aphasia maintained the same performance throughout the test. No statistically significant difference was found between the individuals with aphasia and the participants with no brain damage for the mean latency and amplitude of the P300 and N400 components. However, upon visual examination of the ERP waveforms, the individuals with aphasia exhibited longer ERP latencies of the N400 and the P300 than the participants with no brain damage. In addition, the individuals with aphasia displayed slightly increased amplitudes for the P300 ERP component. Furthermore, the cortical activation patterns between the two groups were different. The non-brain damaged individuals displayed some degree of activation in the left frontal electrodes for the N400 component while the individuals with aphasia exhibited activation in the frontal and right temporal electrodes with some degree of activation exhibited in the left temporal electrodes. Furthermore, the individuals with aphasia exhibit high areas of activation throughout the cortex for the P300 suggesting that the individuals with aphasia were recruiting all cortical areas available to them to compensate for damage to localized areas. The participants with no brain damage displayed activation in the frontal, right and left temporal electrodes. Cortical activation was also exhibited in the parietal electrodes consistent with the literature that suggests that the P300 is elicited primarily in the parietal electrodes.^ The nature of activation also differed across the duration of each sentence in each of the two groups of participants. The individuals with aphasia showed reduced attentional activity at the start of each trial and an increased latency and reduced amplitude when processing the spoken message. The participants with no brain damage showed quicker attentional response to the onset of each trial and a shorter latency and increased amplitude when processing the sentence. ^ The implication of this study is that the individuals with aphasia processed spoken sentence length messages different from participants with no brain damage. Their attentional response was delayed and they required added processing time, but obtained a moderate degree of correct response rate.^

Algorithmic aspects of analysis, prediction, and control in science and engineering: Symmetry-based approach

Jaime Nava — Fri, 26 Oct 2012 10:45:12 PDT

Algorithms are extremely important in science and engineering. One of the main objectives of science is to predict future events; this usually requires sophisticated algorithms. Once we are able to predict future events, a natural next step is to influence these events, i.e., to control the corresponding systems; control also usually requires complex algorithms. To be able to predict and control a system, we need to have a good description of this system, so that we can use this description to analyze the system's behavior and extract the desired prediction and control algorithms from this analysis. ^ A typical prediction is based on the fact that we observed similar situations in the past; we know the outcomes of these past situations, and we expect that the future outcome of the current situation will be similar to these past observed outcomes. In mathematical terms, similarity corresponds to symmetry, and similarity of outcomes — to invariance. ^ Because symmetries are ubiquitous and useful, we will show how symmetries can be used in all classes of algorithmic problems of sciences and engineering: from analysis to prediction to control. Specifically, we show how the symmetry-based approach can be used in the analysis of real-life systems, in the algorithmics of prediction, and in the algorithmics of control.^

The orientation curriculum in a community college: An interpretive approach

Patricia A Gutierrez-Hartell — Fri, 26 Oct 2012 10:45:11 PDT

This study focused on curriculum used in a community college orientation program classroom where most of the students were Hispanic. Curriculum for the purpose of student orientation has become an essential tool for increasing student retention rates at institutions of higher education (Hendel, 2007; National Research Council Publications, 2009). While the objectives of orientation courses and their curricula have been documented, not much is known about how these objectives unfold in classrooms, particularly in classrooms serving Hispanic students. ^ Qualitative inquiry was the basis for my study. I relied on an ethnographic approach to conduct research that involved gathering data by observing the routine ways in which people make sense of their everyday life (Spindler & Spindler, 1987). Given that I was interested in what and how a professor and students produced as a local version of an orientation course curriculum, how they enacted the curriculum in practice, and with what outcomes, qualitative inquiry using an ethnographic approach was appropriate for my study. ^ To gain an understanding of the meaning imposed on curriculum in a particular classroom, I examined the three layers that constituted the curriculum in total: the formal curriculum, the enacted curriculum, and the experienced curriculum (Glatthorn, Boschee & Whitehead, 2005; Mendez, 2006; Page, 1991). What the curriculum says should be taught and how it gets taught in the classroom along with what the student hears, learns, and creates are almost always very different things (Sizer, 1999).^

Raman and infrared study of electrospun PLLA/PCL nanofiber blends for use in tissue engineering

Jose Luis Enriquez Carrejo — Fri, 26 Oct 2012 10:45:10 PDT

Recently, the biomedical engineering field has developed at a very fast pace as improved techniques and materials become available to promote its growth. Consequently, the research in polymeric biomaterials has been highly stimulated by this trend. The goal of the current research is to demonstrate the usefulness of the Raman scattering, Raman mapping, and infrared absorption spectroscopies to tissue engineering, by spectroscopically characterizing blends of PLLA and PCL polymers, which were prepared by electrospinning with and without cell addition. The proposed use of these blends is as primary biomaterials in biodegradable scaffolds used in tissue engineering. Both Raman and infrared absorption spectra showed a direct relation between the relative intensities of the characteristic molecular vibrations of the individual polymers with their concentrations in each blend. The confocal Raman mapping of the samples that were prepared by co-electrospinning allowed direct visualization of different polymeric fibers. These images not only reveal the microstructural characteristics of each polymer, but they are also in good agreement with the Raman scattering results. Furthermore, by performing Raman mapping inside a single fiber, the homogeneity of the polymeric mixture can be visualized. These results demonstrate the existence of sub-domains of non-interacting polymers. The broadening of the cell characteristic peak at 1661 cm^-1 observed in the Raman spectra of the blends seeded with C2C12 myoblasts, could be an indication of cell attachment onto the scaffolds. ^

In the spirit of liberation: Race, governmentality, and the de-colonial politics of the Original Rainbow Coalition of Chicago

Antonio R Lopez — Fri, 26 Oct 2012 10:45:10 PDT

The Original Rainbow Coalition was a revolutionary alliance established in Chicago in early 1969 by the Illinois Chapter of the Black Panther Party, the Young Lords Organization, and the Young Patriots. The alliance connected one of the largest Black Panther chapters in the country with its headquarters in the heart of North Lawndale, to militant organizations in other outcast communities of the city. In Uptown, the Young Patriots were rooted in almost a decade of grassroots efforts that aimed to organize poor people in a community that featured a large population of southern whites who migrated to Chicago. And in Lincoln Park, the Young Lords had evolved from a street organization involved in the ethnic conflicts of the neighborhood to a political organization that defended against the blatant removal of the working-class Puerto Rican residents from the area. Witnessing harsh realities of poverty, police terror, and displacement, the Young Patriots and Young Lords were the first to embrace the Panther's politics of working-class solidarity and community service. ^ In contrast to scholars that examine radical coalitions of the late sixties through ethnic histories of community formation, or through the lens of the black freedom struggle during the long civil rights era, this dissertation centers the history of racialized governmentality in Chicago to explain the formation and political significance of the Original Rainbow Coalition. Tracing the evolution of state racism in Chicago from the period of Indian Removal to the War on Poverty era, it demonstrates that a sophisticated strategy of racialized governmentality developed in Chicago following the Great Depression. Due to profound histories of "inter-racial" solidarity at the point of production during the 1930s, this study reveals that a neo-liberal political milieu was consolidated in Chicago in the following decades, and that state capitalism increasingly thrived upon the racialization of poverty, the incitement of racial consciousness, and the preservation of segregated spaces of poverty and despair in the city. ^ Utilizing a comparative and transnational framework to evaluate racial politics in Chicago during the post-Great Depression era, this dissertation argues that the oppositional consciousness that mobilized the Original Rainbow Coalition derived from the historically specific material conditions maintained by a neo-liberal state in Chicago. In this light, this study contends that the Original Rainbow Coalition was a calculated political tactic that undermined the post-racial politics that buttressed the legitimacy of state power in Chicago, and disrupted ideas of racial essentialism that circulated at the grassroots level and worked to paralyze social change. Furthermore, due to their de-colonial politics of solidarity and the political effectiveness of their community service programs, the Black Panthers, Young Lords, and Young Patriots were criminalized as gangs and endured state sanctioned acts of police terror, legal harassment, and the horrific political assassination of Chairman Fred Hampton -- one of the most powerful advocates of revolutionary working-class solidarity at the time.^

The private business of Porfirio Diaz and the early modernization of Mexico, 1876--1911

Jorge Humberto Jimenez-Munoz — Fri, 26 Oct 2012 10:45:09 PDT

Porfirio Díaz came to power in 1876 and ruled Mexico for over three decades. This period has been known as the Porfiriato. Mexico's economy became part of the modern global market and the country experienced a process of industrialization, the rise of foreign trade, the expansion of communications, and the emergence of new social classes. These series of economic and social transformations have been linked with the country's early modernization. ^ My dissertation contributes new insights into Mexico's process of modernization and shows how this transformation brought the rise of an entrepreneurial class under Porfirio Díaz guidance and leadership. My dissertation lends transparency to the role of Porfirio Díaz as an entrepreneur, and examines the diversified enterprises that Díaz promoted, founded and developed while in power. My work details the incorporation of Díaz companies and partnerships, and lays out a system of corruption with conflicts of interest, the use of privileged information for personal gain, the privatization of policymaking and quid pro quo arrangements that bolstered Díaz's entrepreneurial career. My dissertation shows that Díaz used and abused power for personal gain, concentrating power in the presidency, manipulating legislation to his favor, facilitating the emergence of a hierarchical, loyal and privileged elite, and expanding foreign businesses in the country .^

Three essays on share price misvaluation

Mohammad Aminul Karim — Fri, 26 Oct 2012 10:45:09 PDT

This doctoral dissertation examines the measurement and identification of share price misvaluation using two prominent models. It also examines the role of equity misvaluation in the context of a number of corporate events. The first essay examines abnormal returns surrounding the announcement of stock splits and how this return is related to equity misvaluation and/or growth options of the firm. I find that overvalued firms have lower abnormal returns than undervalued firms and high-growth firms have higher abnormal returns than low-growth firms. Moreover, undervalued firms perform better than overvalued firms in the long run. I conclude that in the short run the market is able to distinguish, at least partially, between valid and false split signals and eventually corrects itself in subsequent years. My second essay examines the role of advertising and the method of payments in mergers or acquisitions. I find that stock-based acquirers have a higher advertising intensity in the pre-merger year when compared with cash-based acquirers and stock-based acquirers are more overvalued than cash-based acquirers prior to the merger. Moreover, managerial ownership in the acquiring firm is positively related to pre-merger advertising intensity where the method of payment is the acquirers' own equity. My third essay compares the Residual Income Model (RIM) by Ohlson [1995. Earnings, book values and dividends in equity valuation. Contemporary Accounting Research 11, 661–687] and the Rhodes-Kropf, Robinson, and Viswanathan model [2005.Valuation waves and merger activity: The empirical evidence. Journal of Financial Economics 77, 561–603]. These two models are used to detect misvaluation. Using publicly traded US firms I find that the Rhodes-Kropf et al. (2005) model is more consistent with theoretical predictions of misvaluation surrounding corporate events such as seasoned equity offerings (SEOs) and open market share repurchases. ^

A study of WO3 and W0.95Ti0.05O 3 thin films using comparative spectroscopy

James Heyward Howard — Fri, 26 Oct 2012 10:45:08 PDT

Tungsten oxide (WO₃) is important and well-studied in materials science, particularly for sensor applications. In this research work, we consider the innovation of adding Ti to thin films of this material. Since the characteristics of any such material are strongly dependent on the conditions and methods used in its deposition, the main objective of this project is to provide a detailed spectroscopic characterization by Raman scattering, infrared absorption, and X-ray photoelectron spectroscopy (XPS) of WO₃ and of W_0.95Ti_0.05O₃. This characterization will be based on comparison of the morphology and composition of WO₃-based thin films, grown by radio frequency magnetron reactive sputtering at substrate temperatures varied from room temperature (RT) to 500 ºC. In the W_0.95Ti_0.05O₃ thin films, our Raman data reveal a phase transformation from a monoclinic WO₃ structure to an orthorhombic or tetragonal configuration, based on peak shifts of WO₃ W-O-W stretching modes from 806 and 711 cm^-1, to 793 and 690 cm^-1, respectively. In addition, Ti-doped WO₃ films require higher growth temperatures to attain crystalline microstructure than do pure WO₃ films. XPS data indicate a reduced WO_3-x stoichiometry at the surface of the doped material, with W⁶⁺ and W⁵⁺ tungsten oxidation states present. This observation could easily be related to the existence of a different structural phase of this material, corroborating the Raman measurements.^

Applications of density functional theory in materials science and engineering

Manuel Alvarado — Fri, 26 Oct 2012 10:45:07 PDT

Density Functional Theory (DFT) is a powerful tool that can be used to model various systems in materials science. Our research applies DFT to two problems of interest. First, an organic/inorganic complex dye system known as a Mayan pigment is modeled to determine chemical binding sites, verifying each model with physical data such as UV/Vis spectra. Preliminary studies on palygorskite-based mayan pigments (mayacrom blue, mayacrom purple) show excellent agreement with experimental studies when using a dimer dye geometry binding with tetrahedrally-coordinated aluminum impurity sites in palygorksite. This approach is applied to a sepiolite-based organic/inorganic dye system using thioindigo attached to a tetrahedral aluminum impurity site with an additional aluminum impurity site in close proximity to the binding site. As a second application of DFT, various grain orientations in β-Sn are modeled under imposed strains in order to calculate elastic properties of this system. These calculations are intended to clarify discrepancies in published, experimental crystal compliance values.^

Investigation on a gas-solid fluidized bed hydrodynamics using a non-intrusive technology to visualize flow field

Rashedul Hasan Sarker MD. — Fri, 26 Oct 2012 10:44:50 PDT

The biggest challenge for 21^st century is to fulfill global energy demand and at the same time reduce detrimental impact on environment. Gasification technology can meet the requirement and also reduce emission without compromising its performance. In coal gasification, instead of burning coal completely a partial combustion takes place with presence of steam and limited amount of oxygen. In this controlled environment a chemical reaction takes place and produces a mixture of clean synthetic gas. Gas-solid fluidized bed is one type of gasification technology. During gasification mixing behavior of solid (coal) and gas and their flow pattern very complicated to understand. Many attempts have taken in laboratory scale to understand bed hydrodynamics with spherical particle whereas in actual coal are non-spherical. Considering this issue an attempt has taken to investigate fluidized bed behavior using different ranges non-spherical particles and spherical particle as well. Different parameters are controlled during investigation like particle size, bed height, bed diameter and particle shape. Particles used from 355 µm to 1180 µm, bed diameter varied from 2 cm to 7 cm, two fluidized bed with diameter 3.4 cm and 12.4 cm, spherical and non-spherical shape particles were taken into consideration for investigation. Pressure drop was measured with increasing superficial gas velocity. The velocity required to start fluidize the particle is called minimum fluidization velocity. Minimum fluidization velocity is one of the most important parameter to design and optimize gas-solid fluidized bed performance. This minimum fluidization velocity was monitored during investigation with changing factors that affect this velocity. From investigation it has been found that minimum fluidization velocity is independent on bed height for both spherical and non-spherical particles, it decrease with decreasing particle size and it also decrease with decreasing bed diameter. Shadow sizing a non-intrusive technology is also used to visualize flow field inside fluidized bed in dilute section for both spherical and non-spherical particles and also detect the particle size.^

Evaluation of protection induced by DNA vaccine candidate against Leishmania mexicana in BALB/c mice model

Rosina Rodarte — Fri, 26 Oct 2012 10:44:50 PDT

Background and Significance. The only immunizing intervention shown to be effective for preventing human cutaneous leishmaniasis is Leishmanization (LZ), but is not currently recommended due to a small number of complications, such as non-healing lesions, and cases of immunosuppression following LZ. First generation and second generation vaccines are difficult to standardize from cultured parasites. Third generation vaccines using DNA are one of the most promising new developments in vaccination strategies. The introduction of DNA plasmids into the cells of living hosts has the potential to lead to the generation of both humoral and cellular immune responses and protective immunity. DNA vaccination provides specificity, stability, safety, and a cost advantage. ^ A leishmaniasis vaccine should optimally be composed of several molecules in order to attack the survival mechanism of the parasite. This is because Leishmania parasites have multiple molecules allowing them to enter the host cells and attack the body. For this study, the molecules selected were biopterin transporter (BT), intracellular adhesive molecules (ICAMs), ORFF, and Amastin. Biopterin Transporter is a potential growth promoter of Leishmania parasites. Cell adhesion molecules (ICAMs) allow the survival of the parasite inside the cell. The ORFF gene is reported to induce partial protection against challenge with L. donovani. The Amastin family plays a role in adjusting the cytoplasmic pH allowing the survival of Leishmania parasites inside the cells. For the present study, the BT, ICAM, ORFF, and Amastin antigens were assembled in the pVAX backbone as a bicistronic plasmid in order to examine the poly-antigen vaccination approach. The ability of these molecules to induce immunity and protection was evaluated using a murine model. ^ Study Objectives. The two major objectives of this experimental phase 0 trial were: (1) to characterize the immune response induced by the DNA vaccine candidate against L. mexicana infection in a murine model, and (2) to determine the efficacy of the DNA vaccine candidate in immunized BALB/c mice challenged with virulent L. mexicana promastigotes. ^ Hypothesis. It was hypothesized that the use of a cocktail DNA vaccine would induce protection against L. mexicana infection in BALB/c mice by promoting the activation of protective Th1-related cytokines and decreasing the progression of the disease at infected footpad sites. ^ Methodology. The experimental design used 29, six-week old BALB/c female mice. The experimental and control groups were housed under identical environmental conditions. The mice were randomized to one of the six experimental or control groups. The three experimental groups were immunized with 100µL of pVAX-BT-ICAM, 100µL of pVAX-ORFF-Amastin, or 100µL of pVAX-BT-ICAM plus pVAX-ORFF-Amastin. The negative control groups were injected with 100µL PBS or 100µL of pVAX. Three weeks after their last immunization, the experimental and control groups were challenged subcutaneously in the left hind footpad with 40µL of 1 x 10⁶ stationary phase virulent L. mexicana promastigotes (LV4 strain). The development of footpad lesions at the infection site was measured weekly for eight weeks. Quantitative Real Time Polymerase Chain Reactions (QRT-PCR) assays were run to quantify gene expression of Th1 indicators (Interleukin-2, Tumor Necrosis Factor-α, and Interferon-γ) and Th2 (Interleukin-4) indicator. The data were analyzed using descriptive and bivariate statistical techniques. ^ Results. A partial protection and Th1 immune response was suggested in the experimental group receiving the pVAX-BT-ICAM plus pVAX-ORFF-Amastin vaccine candidate. This group had the smallest mean footpad lesion ( x = 0.465 ± 0.10). There was found statistically significant reduction in footpad thickness when this group was compared to the other experimental groups [pVAX-BT-ICAM (P = 0.000) or pVAX-ORFF-Amastin (P = 0.032)] and to the negative controls [PBS (P = 0.032) or pVAX (P = 0.015)]. The group vaccinated with pVAX-BT-ICAM plus pVAX-ORFF-Amastin had a Th1 cytokine profile (high levels of IL-2, TNF-α, and IFN-γ) which is associated with immune protection against L. mexicana. However, there was also an increased IL-4 expression. For this group, no statistically significance differences were found between this group cytokine profiles (P = 0.376 ). ^ Conclusion. Only the pVAX-BT-ICAM-I plus pVAX-ORFF-Amastin vaccine formulation provided partial protection in BALB/c mice. This vaccine formulation was able to decrease parasite burden better than single bicistronic plasmids at the end of the eight-week follow-up period. The lymphocytes of the group vaccinated with pVAX-BT-ICAM-I plus pVAX-ORFF-Amastin had a predominant Th1 immune response by showing higher levels of IFN--γ, TNF-α, and IL-2. However, this protective cytokine profile was reduced by the presence of IL-4 which correlates to a partial protection observed after the eight-week follow-up. Hence, in order to successfully attack L. mexicana, the vaccine must be composed of several antigens. (Abstract shortened by UMI.) ^

The topology of statistical convergence

Khdiga K Tabib — Fri, 26 Oct 2012 10:44:49 PDT

A sequence {x_n} is said to be statistically convergent to ℓ provided that "almost all" of the values of { x_n} are arbitrarily close to ℓ. One can also define what is meant by statistical limit point, statistical limit superior, statistical limit inferior of a sequence and so forth and thus create a theory of convergence that includes ordinary convergence. In this work we investigate all these concepts and prove some new results. We also introduce a topology defined by this new convergence which we call statistical topology. Then we prove that both the statistical topology and the regular topology are identical. ^

Coping as a mediator between proximity to violence in Juarez, and PTSD symptoms among college students attending a university on the Texas -- Mexico border

Francis J Reyes — Fri, 26 Oct 2012 10:44:49 PDT

The present study directly examined whether proximity to ongoing violence might lead to symptoms of Post-Traumatic Stress Disorder (PTSD) in a sample of students attending a border university less than a mile from the US Mexico border. Exposure to violence is a common cause of PTSD symptomology. Prior research in the region suggests that ongoing traumatic stress due to the violence in Juarez is associated with increased PTSD symptomology. Because coping skills are thought to protect individuals from PTSD the Transactional Model of Stress and Coping (Lazarus & Folkman, 1984) guided the study. The purpose of this study was to examine the relationship between proximity to violence in Juarez and PTSD symptoms in a sample of college students (N = 244) attending a border university with large Hispanic enrollment. Secondarily, this study examined the role of coping strategies in mediating this relationship. In addition to assessing proximity to violence in Juarez, the present study also assessed how people were coping with stress in their lives. Proximity to violence, as expected, positively correlated with PTSD symptoms. The best model fit to the study data was one in which avoidance coping was represented as a latent variable underlying the use of specific coping strategies, and proximity to violence was represented as a latent variable underlying proximity items. Using this model allowed us to account for 34% of the variance in PTSD symptoms in this sample. Results from this study are another example of how experiencing community violence and/or having close friends and family who are affected by violence may be associated with increased PTSD symptoms. Implications for future research and programs are discussed.^

Domestic violence, border control measures, and its effects on the immigrant population in the border region

Heryca Serna — Fri, 26 Oct 2012 10:44:48 PDT

Domestic violence is a serious issue that can be predominantly challenging for undocumented immigrants to surpass given their citizenship status in the country. Immigrant victims of domestic violence, in particular, are in a foreign country exposed to an unknown language, culture, and legal system, as well as being isolated from family, friends, or any other possible support systems. Due to these circumstances immigrant victims of domestic violence rarely leave their homes largely due to mistrust for law enforcement and service agencies. Limitations to recovery for undocumented immigrant women have substantial social and political consequences. The objective of this research is to investigate how border control measures affect the recovery of undocumented immigrants who are victims of domestic violence. The study analyzes variables that affect immigrant survivors of domestic violence specifically in the border region specifically, the immigration status of the abusive partner, perceptions of rights, actual interactions with local and federal law enforcement, obstacles and facilitations for recovery from domestic violence.^