Texas Tech University

Permanent URI for this collectionhttps://hdl.handle.net/2249.1/35893

Texas Technological College formally became Texas Tech University to reflect its growth into a diverse university with law and engineering schools, graduate school and an honors college. The university’s enrollment includes approximately 28,000 students. This collection contains the theses and dissertations produced at Texas Tech University.


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Now showing 1 - 20 of 16000
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    Counseling for wellness: A case study of wellness counseling groups
    (2013-05) Berry, Jeremy; Hendricks, Bret; Crews, Charles R.; Duemer, Lee S.
    This dissertation outlined a need within the research for investigating issues salient in the lives of the aging population, and the need for identifying an understanding of the use of a wellness counseling model with the aging population. The content of the group counseling sessions within this study utilized the Wheel of Wellness model for counseling. As the aging population continues to expand, it in increasingly important that the counseling field continues to explore new treatment models and continues to work to understand the various issues that may be important to this population. The literature review in this dissertation focused on the developmental aspects of aging that are experienced and the use of group counseling with the aging population. The methods section of this qualitative study utilized grounded theory (Glaser, 1998), and was a case study format. A group of adults over 65 took part in 12 weekly group counseling sessions implementing a wellness model of counseling, specifically the Wheel of Wellness. The sessions were recorded using audio equipment and then analyzed using thematic coding procedures and NVIVO 10 software to aid in the coding procedure. Participants were also interviewed prior to the counseling experience to gauge understanding of the model and its components and to highlight initial interest in the model. In addition, each participant was interviewed following the groups to discuss their interest in the group process, counseling, and wellness. The counselor's experiences working with a wellness model and the aging population was also explored. Limitations of this study were also discussed. The results of the study indicated the following themes: Change and adaptations, family and traditions, loneliness and isolation, control over choices, healthcare needs, education, fear and loss, acceptance and growth, death and dying, community and support, spiritual connectivity, and the importance of humor. In conclusion, increased awareness of the thought, feeling, emotions, and behaviors of the aging population, as well as increased awareness of their reception to counseling and specific models of counseling such as wellness counseling, will promote advocacy and social justice within the population. In addition, such awareness may aid in helping counselors become more effective in working with the population, and will help counselor education programs in preparing counselors to work within this population. Group counseling using wellness as a counseling model appeared to be effective within this population, and allowed the group members to take an active interest in their treatment and to understand the relationships between various aspects of their lived experiences and their overall health and well-being. Future research should explore wellness counseling within the aging population in individual counseling and the circumplex relationship of the components of the Wheel of Wellness.
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    The viscoelastic properties of thin films
    (2013-05) Wang, Jin Hua; McKenna, Gregory B.; Vaughn, Mark W.; Weeks, Brandon L.; Quitevis, Edward L.
    There is a considerable interest in studying material properties at micro-, nanometer size scale. Thin films exhibit significant different behaviors from that of bulk systems. Both liquid dewetting technique and particle embedment method have been used to investigate viscoelastic properties of thin films. The liquid dewetting technique which uses liquid as substrate is a direct mechanical method to study the viscoelastic properties of polymer (polystyrene (PS) and polycarbonate (PC)) thin films. Results show that the glass transition temperature (Tg) dependence for PS and PC thin films on liquid surface is more like the supported film rather than the freely standing film. Both Tg depression and film stiffening were observed when PS film thickness is less than 20 nm. No molecular weight effect was found for the dewetting behaviors of the PS films prior to the terminal flow regime, where the majority of the current work was carried out. For PC thin films, similar Tg was observed when film thickness is less than 35 nm. As the film thickness increases during the dewetting experiment, the present results show that the film dewetting process for the polymer/glycerol couple has to be described as a “non-isothermal” experiment. A numerical method is proposed to correct the experimental data to the “isothermal” and constant thickness condition. A novel temperature-step method has been described to direct obtain the Tg of thin films from the liquid dewetting measurement based on the liquid dewetting experiment is a “non-isothermal” experiment. Different from all of the previous methods in literature used to obtain the glass transition temperature of thin films, we can get polymer thin film glass transition temperature-thickness dependence only from one sample within a single experiment by change operating temperature steps. Two liquids (glycerol and 1-Butyl-3-methylimidazolium trifluoromethanesulfonate) have been chosen to study the liquid substrate effects on polymer thin film dewetting behaviors by this temperature-step mehod. It was found that PS thin film dewet faster on glycerol than that on ionic liquid and its Tg has a stronger film thickness dependence compared to PS thin film on ionic liquid. A sub-micron particle embedment technique has been used to determine the shear modulus of 1, 2-dipalmitoyl-Sn-glycero-3-phosphotidylcholine (DPPC) lipid multibilayers by two different particles (PS particle and silica particle) from atomic force microscope (AFM). Methods used to determine particle size has been discussed and results show that AFM might be the best way to obtain particle size in the present work. The standard JKR model was used to relate the shear modulus of the lipid multibilayer films with the particle embedment depths. The so-determined modulus of the DPPC is consistent with the reported literature values for DPPC, while silica particles give more reliable results compare to polystyrene particles which has a small amount of surfactant in the sample.
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    The role of Nek2 and TRF1 in mitotic perturbations: Potential implications for breast cancer treatment
    (2013-05) Lee, Jaehyung; Gollahon, Lauren; Rodgers, Brenda E.; Butler, Boyd; Thomas, Jeffrey; Zhang, Kai
    Although the anti-cancer drugs paclitaxel and doxorubicin are commonly used to treat many solid tumors, their effectiveness is highly variable due to tumor cell resistance. Therefore, it is important to find mechanisms that can be targeted to increase the sensitivity of cancer cells to current chemotherapy agents. NIMA related kinase 2 (Nek2), a serine/threonine kinase, is emerging as an important oncogene because of its regulatory role in multiple mitosis-related events including timing of mitotic entry, chromatin condensation, spindle organization and cytokinesis. Thus, regulation of the Nek2 expression levels may prove important as a target for cancer treatment. In order to determine the potential of Nek2 as a viable anti-cancer target that increases drug sensitivity, the triple negative breast cancer cell lines MDA-MB-231 and MDA-MB-468 were used. The approach design utilized was to pretreat the cells with small interfering RNA (siRNA) and antisense oligonucleotides (ASOs) against Nek2, and then expose them to various concentrations of paclitaxel and doxorubicin. Results demonstrated that drug susceptibility in these pre-treated cells was dramatically increased compared with either agent alone. FACS results showed that apoptosis was induced in siRNA or ASO pretreated. Furthermore, Nek2 knockdown worked synergistically with paclitaxel and doxorubicin by inhibition of cell proliferation. Hence, results suggest that these drugs in combination with Nek2 depletion may improve the sensitivity of breast cancer cells to chemotherapy treatments. To understand how Nek2 affects cancer development caused by chromosomal instability, the relationship between Nek2 and telomeric repeat binding factor 1 (TRF1) was investigated. TRF1 not only regulates telomere length, but is also associated with cell cycle regulation. Nek2 depleted cells lead to centrosome separation failure while Nek2 overexpression results in premature centrosome separation. While it has been shown in mice that TRF1 interacts directly with Nek2, the interactions and correlations between Nek2 and TRF1 in human cells are far from clear. In this study, the results showed that mitotic aberrations through Nek2 overexpression require TRF1. Kinase assay results demonstrate that Nek2 directly binds to and phosphorylates TRF1 in vitro and in vivo at multiple sites. Nek2 overexpression MCF 7 and MDA-MB-231 breast cancer cells resulted in increased numbers of centrosomes and multinucleated cells, ultimately leading to cytokinetic failure and aneuploidization. Furthermore, TRF1 depletion by siRNA prevented Nek2-induced unaligned chromosomes during metaphase. Concurrent Nek2 overexpression and TRF1 depletion showed that cells with  2 centrosomes restored cytokinetic failure and chromosome instability similar to controls. Therefore, I propose that TRF1 is required for overexpressed Nek2 to trigger abnormal mitosis and chromosomal instability. Taken together, overexpression of the Nek2 in breast cancer suggests that inhibition of Nek2 beneficially interferes with the cancer proliferation. Furthermore, combinational treatments involving Nek2 depletion in conjunction with anti-cancer drugs could potentially be developed as a cancer inhibitor. Therefore, Nek2’s contribution to cancer development may serve as a new starting point to exploit as a therapeutic target.
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    The value of credit bearing internships for students, employers and institutions of higher education
    (2013-05) Shindell, Robert; Taylor, Colette M.; Burley, Hansel E.; Wetherbe, James C.
    A well-educated workforce is critical for the economic development and success of this country (Kazis et al., 2007; Symonds, 2005). Colleges and universities are being challenged to demonstrate effective ways this is contributing to the development of a successful workforce. Although many in academe believe that experiential education is a good thing for students as they make the transition to the world-of-work, there is relatively little research regarding how this benefit the individual student’s development. Internships, one form of experiential education, have been designated high-impact educational practices by many colleges and universities throughout the United States, because they bestow substantial educational benefits to the students who participate in them (Kuh, 2008; O’Neill, 2010). The study purpose to determine the “value” of credit bearing internships for college students. This archival study examined data from approximately 27,500 undergraduates from 298 colleges and universities throughout the United States who were surveyed between September and December 2011.
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    Toxicity of cadmium quantum dots compared to cadmium and zinc ions in zebrafish (Danio rerio) and water flea (Daphnia pulex)
    (2013-05) Tang, Song
    Recent advances in the ability to manufacture and manipulate materials at the nanoscale have led to increased production and use of many types of nanomaterials in diverse areas. Nanocrystaline semiconductors (Quantum dots; QDs) are small, long-lived fluorescent nanocrystals composed of a core of semiconductor material (e.g. cadmium selenide, zinc sulfide) and shells or dopants of other elements. Often, the continuously increased uses of QDs come increased appearance of in the aqueous environments, and then can be toxic to aquatic organisms and poses significant ecological risks. However, the toxicological impacts of heavy metal constituted QDs on aquatic species are largely unknown, especially at the molecular level. Moreover, it is crucial to determine whether the toxicity of metallic QDs is quantitative or mechanistically different than that of soluble metal components. The aim of this study was to compare the toxicities of ionic cadmium (Cd) and zinc (Zn) and Cd- and Zn-containing QDs at both in vitro via zebrafish liver cells (ZFL) and in vivo through Daphnia pulex. Our results revealed that (1) ionic Cd2+ was more toxic than Zn2+, and the general trend of toxicity of QDs was determined to be CdTe > CdSe/ZnS or InP/ZnS; (2) smaller QDs showed greater toxicity than larger QDs; (3) both Cd2+ and CdTe QDs exposure led to an accumulation of Cd, an increased formation of intracellular reactive oxygen species (ROS), and an induction of DNA strand breaks; (4) CdTe QDs exposure induced expression patterns of metal response, stress defense, and DNA repair genes in a manner similar to that of Cd2+ exposure, while CdSe/ZnS or InP/ZnS QDs altered gene expression in a manner very different from that of the corresponding Cd or Zn salts; and (5) nucleotide excision repair (NER) repair capacity were inhibited with Cd2+ but not with CdTe. The adverse cellular effects caused by acute exposure of QDs might be mediated through differing mechanisms than those resulting from Cd2+ toxicity, and studying the effects of the ionic form may be not enough to explain QD toxicities in aquatic organisms.
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    The relationship between teachers’ self-efficacy beliefs and parental involvement practices: A multi-method study
    (2013-05) Krizman, Charlotte; Siwatu, Kamau O.; Coward, Fanni; Lan, William
    This study was designed to explore the relationship between teachers’ self-efficacy beliefs and their use of family involvement practices. Bandura’s concept of self-efficacy and Epstein’s typology of family involvement provided the theoretical framework for examining this relationship. The study employed both quantitative and qualitative data collection methods, justifying a two-phase sequential multi-methods study. In the first phase of the study, self-reporting instruments were used to discover the nature of the relationship between teacher self-efficacy, teacher’s family involvement self-efficacy, and the teacher’s use of family involvement practices. Teacher self-efficacy and family involvement self-efficacy were measured, respectively, using the Teacher’s Sense of Efficacy Scale and the Family Involvement Teacher Efficacy Scale. Family involvement practices were self-recorded using the Teacher’s Family Involvement Practices Survey. In the second phase of the research, qualitative data was collected via interviews with a purposeful sample of teachers to further investigate the relationship between the two constructs. Participants in the study included 49 teachers from three different school districts along Mississippi’s Gulf Coast region. Of those that participated, eight agreed to provide qualitative data in a follow-up interview. The findings of the research indicate that a moderately strong relationship exists between teaching self-efficacy and the use of parental involvement practices. In other words, higher levels of teaching self-efficacy were associated with more frequent use of parental involvement practices. Teaching self-efficacy in student engagement and instructional strategies were significantly associated to teaching self-efficacy. The research findings also revealed that communication is by far the most frequently used parental involvement practice. Other practices were largely neglected, which may be due to a variety of reasons, such as lack of appropriate training in the various methods available for parental involvement; variables within the school atmosphere that make parental involvement difficult, and logistical obstacles that teachers face as they try to involve parents. Finally, despite having been significantly established in previous studies, the relationship between teacher family involvement self-efficacy and the use of parental involvement practices was not found to be significant with this study. The instrumentation used in this study may play a role in this phenomenon and should be considered carefully before employing it in future research.
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    A radiative model for determining plasma dissociation using vacuum ultraviolet self-absorption spectroscopy
    (2013-05) Laity, George; Neuber, Andreas A.; Krompholz, Hermann G.; Hatfield, Lynn H.; Frank, Klaus
    This manuscript documents the first five years of collective knowledge gained from the Texas Tech University research program to study the emission and subsequent re-absorption of vacuum ultraviolet radiation present during the initiation of nano-second plasma discharges generated at atmospheric pressure. The initial experimental study resulted in direct observation of vacuum ultraviolet radiation produced by an open transient plasma at atmospheric pressure for the first time in the available literature. Upgrades to the spectral instrumentation enabled more efficient measurement of vacuum ultraviolet radiation for the wavelength range 115 - 135 nm, allowing for enhanced resolution in the recording of emission line profiles. A direct consequence of this effort was the conception of a passive optical diagnostic for measuring the absolute number density of atoms in the discharge plasma: the vacuum ultraviolet self-absorption spectroscopy (VUV-SAS) technique. An integral piece of this technique is a radiative transfer simulation for calculating the radiation trapping physics inside the plasma channel volume, executed in the MATLAB® environment and accelerated via GPU resources using the NVIDIA® CUDA architecture. The combination of experimental and modeling approaches resulted in successful demonstration of the VUV-SAS diagnostic for N2/H2 plasmas at atmospheric pressure, where spatially resolved N and H atom densities on the order 10^17 cm^-3 were observed without an invasive laser absorption diagnostic. Through approximation of the quasi-contiguous Stark broadening of H atoms in the discharge plasma, spatially resolved electron densities on the order 10^18 cm^-3 were observed along the plasma channel. All measured quantities are validated through detailed discussion of the relevant physics concerning the fast ionization shockwave characteristic to the inception of spark discharge plasmas. Finally, the extended VUV-SAS technique was successful in demonstrating the measurement of N and O atom densities present in air discharge plasmas, thereby finding practical application for a variety of future pulsed power laboratory experiments.
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    Visfatin, retinol binding protein-4, and vaspin concentrations in plasma and different tissues and their relationship to insulin resistance in morbidly obese subjects
    (2013-05) Goktas, Zeynep; Wang, Shu; Boylan, Lee M.; Reed, Debra; Shen, Chwan-Li; SanFrancisco, Susan
    The purpose of this study was to measure visfatin, vaspin, and retinol binding protein-4 (RBP-4) gene expression levels and protein concentrations in subcutaneous, omental, and mesenteric adipose tissue, liver, muscle tissue, and plasma in severely obese patients and to investigate the relationship between these proteins and insulin resistance markers. Thirty eight morbidly obese (BMI ≥40) subjects had the subcutaneous, omental, and mesenteric adipose, liver, and muscle tissues and blood samples taken at the time of Roux-en-Y surgeries. Visfatin, vaspin and RBP-4 gene expressions were measured by Real Time PCR, and their protein concentrations were measured with ELISA kits (Adipogen, Korea). Subjects were divided into three groups as normal (n=13), pre-diabetic (n=12) and diabetic (n=13) according to blood HbA1c levels. Results were analyzed using ANOVA and Pearson correlation with p <0.05 being significant. Visfatin gene expression levels were significantly lower in subcutaneous adipose tissue in all three diabetic classification groups. Omental visfatin expression levels were positively correlated with blood HbA1c levels (r = 0.351) and Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR) (r = 0.401). Livers (23.1 ± 8.53 ng/mg protein) and muscle tissues (9.9 ± 8.74 ng/mg protein) had the highest and lowest visfatin protein concentrations, respectively. Omental visfatin protein concentrations were positively correlated with HOMA-IR (r=0.456) and blood HbA1c (r=0.481). Livers had the highest RBP-4 expression levels. Omental RBP-4 expression levels were positively correlated with HOMA-IR (r=0.355 ) and blood glucose levels (r=0.454). Livers (11621 ± 1033.5 ng/mg protein) had the highest RBP-4 protein concentrations, and mesenteric (339.4 ± 47.78 ng/mg protein) had the lowest concentrations. RBP-4 protein concentrations in omental were positively correlated with blood glucose levels (r = 0.363). Omental vaspin expression levels were positively correlated with blood HbA1c levels. Livers (2.19 ± 0.34 ng/mg protein) and mesenteric adipose tissues (0.36 ± 0.16 ng/mg protein) had the highest and lowest vaspin protein concentrations, respectively. Mesenteric vaspin protein concentrations were positively correlated with HOMA-IR, blood glucose, and HbA1c levels. In conclusion, visfatin, vaspin, and RBP-4 might play important roles in insulin resistance. Higher concentrations of visfatin and RBP-4 in omental adipose tissues and vaspin in mesenteric adipose tissues were associated with higher levels of insulin resistance. The correlations of visfatin, vaspin, and RBP-4 with insulin resistance are tissue-dependent. Further studies are needed to investigate the underlying mechanisms of these inflammatory factors in insulin resistance.
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    Biomechanics of slips and falls in the elderly: Effects of restricted arm motion on recovery strategies
    (2013-05) Jayadas, Aditya; Smith, James L.; Hsiang, Simon M.; Patterson, Patrick E.; Boros, Rhonda L.; James, Roger C.
    Slip and fall accidents pose a serious threat to elderly individuals. Several researchers, over the past few decades, have successfully quantified different gait parameters pertaining to the biomechanics of slips and falls to help reduce the incidence of slip and fall accidents in the elderly. However, a comprehensive understanding of mechanisms including strategies used by the elderly for recovery during a slippery perturbation under different arm restriction conditions is still lacking. This research study investigated gait patterns in young and elderly individuals, in terms of proactive and reactive strategies that individuals used to reduce their likelihood of a fall related injury during a slippery perturbation under different arm restriction conditions. In addition to the gait parameters, the strength capabilities of the lower extremities of young and elderly individuals were also explored. Lastly, a logistic regression equation was developed to predict falls and recoveries. The study did help identify successful strategies used for recovery under different arm restriction conditions. In addition, unsuccessful reactive movements that resulted in falls were also pointed out. Proactive strategies identified including reduced step length, walking velocity, heel contact velocity and foot floor angle were used by both younger and older individuals when they knew the floor was slippery. Reduced step length, foot floor angle and walking velocity were also noted when one or two arms of individuals were restricted. In terms of age, more elderly individuals fell when compared to younger individuals. Several other variables including average sliding heel velocity, peak sliding heel deceleration and separation between whole body center of mass and sliding heel also showed differences for age. Significant differences were noted not only between older and younger individuals but also between fallers and non-fallers in terms of the recovery effort. Variables including average sliding heel velocity, maximum and minimum differences between the upper body center of mass (UBCOM) and the lower body center of mass (LBCOM) showed differences between fallers and non-fallers. In terms of arm restriction, both young and older individuals showed significant differences in maximum wrist velocities for the different arm restriction conditions. Differences in maximum velocities between the WBCOM and heel when comparing the no-arm and two-arm restriction, and also the no-arm and one-arm conditions were also found. In terms of strength, knee and ankle torques were found to be significantly higher for younger individuals when compared to elderly individuals. The leg collapse that was observed which resulted in falls was an additional indicator of poor strength in the elderly. The primary contribution to elderly gait literature and the biomechanics of slips and falls through this study was the development of a novel method through the exploration of UBCOM-LBCOM dynamics during recovery effort from a slippery perturbation under different arm restriction conditions. In terms of findings, the study did show that individuals were able to recover better when their arms were not restricted. The study did also show that the elder fallers were unable to ‘catch up’ by moving their trunk (and UBCOM) quickly to keep up with the sliding heel (and the LBCOM. On the other hand, younger non-fallers were able to have a higher difference in velocities between the UBCOM and LBCOM, and still ‘catch up’ successfully. Thus, the study of UBCOM-LBCOM dynamics might be useful in better understanding elderly slips and falls.
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    Latino Males' Perceptions of Their k-12 School Experiences
    (2013-05) Calderon, Gloria; Aguirre-Muñoz, Zenaida; Price, Margaret A.; Munoz, Juan S.
    The Latino male high school dropout rate is one of the most pressing and least researched aspects of the dropout crisis in the United States. Dropping out of high school prior to graduation probably has one of the most negative impacts on the work prospects of these young men as well as the future of their families and the well-being of their communities. Although there are many studies that address Latino high school dropout rates, there is limited data focusing on male Latino perceptions of ways their schooling experiences may influence their academic decisions. This study examines Latino male dropouts’ perceptions of their K-12 school experiences and explores how these experiences might have an effect on their decision to drop out of school.
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    Queens of the South Plains: Collected oral histories of drag queens living in Lubbock, TX
    (2013-05) Ballard, Katy; Check, Ed; Akins-Tillett, Future; Ortega, Francisco; Peaslee, Robert M.; Sharp, Elizabeth A.
    In my dissertation research, Queens of the South Plains: Collected Oral Histories of Drag Queens Living in Lubbock, Texas, I am collecting oral histories of five Lubbock, Texas performance artists who participate or have participated in local drag queen shows and culture: Thomas Mims, Devon Nicole, and Damion Davis, Audrianna Guillen, and Chris Wheeler. I utilize oral histories because no other institutional histories exist. Academically, there is a large amount of research on drag histories in metropolitan areas and on non-metropolitan lesbian, gay, bisexual, transgender, transsexual, questioning, queer and intersexed (LGBTQ) lives, but there is very little, if any, research that connects these two fields of study. Since the early 1990s, there has been a small but growing body of literature and art documenting rural and non-metropolitan spaces and lives. However, other than the collected interviews of two rural drag queens in the documentary film Small Town Gay Bar scant literature exists on drag queens in rural areas. In this study, I conduct face-to-face interviews with five subjects that I document through audio recordings using a semi-structured interview format. In addition to the five subjects/performers, I conduct supplemental interviews of people involved in the subjects’ lives to gain a broader perspective of small city drag culture in Lubbock as a non-metropolitan setting. The literature review of urban drag queen cultures and rural queer lives is juxtaposed against the contexts and invisible histories of the lives of drag queens in rural/non-metropolitan settings. This research is a small step in bridging the gap in academic research connecting drag queen culture and research on rural and non-metropolitan LGBTQ lives.
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    Local implementation of the AcieveTexas college and career initiative as reported by Texas high school counselors
    (2013-05) Walker, Jodi K.; Alexander, Karen L.; Couch, Sue; Stout, Betty L.; Davis, Kim
    The purpose of the study was to understand the high school counselor’s perception of the integration of the AchieveTexas College and Career Initiative at the local level, determine how much time high school counselors spent on the four components of the Texas Comprehensive Developmental Guidance program (including AchieveTexas), and identify the perceptions of success and barriers within the implementation process. In the summer of 2012, perceptions of high school counselors of the local implementation of AchieveTexas in Regions 13 and 20 in Texas on their campuses were examined using an online survey. These regions were targeted because their districts had offered and/or received professional development for counselors regarding the local implementation of AchieveTexas. High school counselors reported that successful outcomes for implementation of AchieveTexas included increased enrollment in Career and Technical Education (CTE) courses (67.9%), increased number of applications for admission to postsecondary institutions (64.2%), and increased graduation rates (62.3%). Barriers to implementation of the AchieveTexas initiative included lack of time and/or information and counselor to student ratios. Overall, the successful implementation of AchieveTexas requires “buy-in” of principals, counselors, teachers, parents, and the surrounding community. Findings of the study suggest that the AchieveTexas initiative is a tool to guide local districts to implement career clusters on their local campus and help students acquire college and career readiness skills that will benefit them in their future. AchieveTexas requires collaboration at various levels to achieve this goal.
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    Experimental and computation study of protein interactions with lipid nanodomains
    (2013-05) Qiu, Liming; Cheng, Kelvin K.; Vaughn, Mark W.; Sanati, Mahdi; Khare, Rajesh; Quitevis, Edward L.
    Protein lipid interactions are significantly relevant to understanding of a wide variety of biological phenomena in general. In particular, human beta-amyloid protein is closely related to the pathogenesis of Alzheimer's disease. Due to its high propensity to self-aggregate, beta-amyloid protein is difficult to study with experiments. Molecular dynamics simulations is capable of providing atomistic details of the protein lipid interactions; therefore, is an important theoretical tool to investigate these subtle interactions and offer insights to the pathogenesis of Alzheimer's disease. In this dissertation, I studies the protein lipid interactions with several systems with different lipid composition and protein conformations. I developed computational tools to quantitatively analyze lipid perturbations due to protein interactions, since it is commonly believed that the neurotoxicity of beta-amyloid protein is through perturbation of the lipid membrane. I discovered that for the case of a beta-amyloid dimer on the surface of lipid bilayers, the perturbation effect of protein is correlated to the degree of disorder of the protein in term of its secondary structure. Meanwhile, for a system where a beta-amyloid protein was partially inserted into the bilayer, the protein insertion rate was regulated by both the secondary structure of the protein and the lipid environment. Especially, a scaling relation between the insertion rate and degree of disorder was found. Even though molecular dynamics simulations is a powerful tool in studying atomistic protein lipid interactions, it is not efficient in sampling the free energy landscape of the system; hence results are biased by the initial structure of the system. I developed a multiscale molecular simulation scheme to increase the efficiency in free energy landscape sampling by switching the system between different spatial resolutions, i.e., atomistic and coarse-grain representations of the system. Using this method, I discovered a novel protein lipid orientation, which has implications in understanding the biochemical pathway of the protein as well as developing therapeutic interventions. Finally, I also developed a Monte Carlo method to estimate molecule volumes accurate to atomistic scale. This method is directly applicable to lipid membrane system with heterogeneous components including proteins; it is a useful tool for not only investigating protein lipid interactions but also calibration of force field parameters for classical molecular dynamics simulations.
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    Reactions of aluminum with halogen containing oxides
    (2013-05) Farley, Cory; Pantoya, Michelle; Long, Kevin; Christopher, Gordon; Berg, Jordan M.; Bhattacharya, Sukalyan
    Due to increasing threats of biological attacks, new methods for the neutralization of spore forming bacteria are currently being examined. Thermites may be an effective method to produce high temperature reactions, and some compositions such as aluminum (Al) and iodine pentoxide (I2O5) also have biocidal properties. This study examines the thermal degradation behavior of I2O5 mixed with micron and nanometer scale aluminum (Al) particles. Differential scanning calorimetry (DSC) and thermo-gravimetric (TG) analyses were performed in an argon environment on both particle scales revealing a non-reaction for micron Al and a complex multistep reaction for the nanometer scale Al. Results show that upon I2O5 decomposition, iodine ion adsorption into the alumina shell passivating Al particles is the rate controlling step of the Al-I2O5 reaction. This pre-ignition reaction is unique to nano-Al mixtures and attributed to the significantly higher specific surface area of the nanometric Al particles which provide increased sites for I- sorption. A similar pre-ignition reaction had previously been observed with fluoride ions and the alumina shell passivating Al particles. Composite energetic materials comprised of nanoparticle fuel and oxidizer can exhibit high flame propagation speeds on the order of 1000m/s when burning in an unconfined environment. In particular, halogen based formulations such as aluminum and iodine pentoxide have received significant attention due to both high flame speeds and biocidal properties. Studies have attributed high flame speeds to convective influences within a reaction driving the heat forward in a pressure wave accelerating ignition of unburned powders. This study examines factors contributing to convective flows such as gas and heat generation and their relationship to the measured flame speed as well as fundamental chemical kinetics influencing the observed flame speeds. The goal is to understand parameters directly related to high flame speeds in halogen containing composites. Results show a direct correlation between apparent activation energy and flame speed indicating that flame speed is directly influenced by chemical kinetics. For this reason, the intermediate chemistry associated with Al and iodine species was examined to identify chemical influences accelerating flame speeds. Ab initio quantum chemical calculations of gas-phase reactions resolve key exothermic intermediate reactions contributing toward the kinetics of the fastest burning mixtures. Condensed phase density functional theory calculations of Al2O3/I2O5 interfaces resolved adsorption/desorption properties. This study examines the effect of atmospheric oxygen concentration (4 or 93% oxygen) on energy propagation of nanometric aluminum with copper oxide (Al+CuO), iron oxide (Al+Fe2O3), calcium iodate (Al+Ca(IO3)2), and iodine pentoxide (I2O5). In all cases energy propagation was examined in terms of flame speed and higher in the high oxygen environments. However, the convectively driven mixtures showed a smaller percent increase in flame speeds. This behavior is attributed to the increased availability of oxygen as a result of solid oxidizer thermal decomposition at lower temperatures. The slower Al+Fe2O3 reaction showed greater increases in flame speed attributed to early stage reactions involving atmospheric oxygen that promote oxide decomposition and faster flame speeds. A predictor based on solid oxidizer thermal decomposition and flame speed was developed to evaluate the sensitivity of a reaction to atmospheric oxygen concentration.
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    The food safety knowledge level of certified food managers who attended two self-selecting training courses
    (2013-05) Payton, Larry; Brashears, Michael T.; Burris, Scott; Dooley, Kimberly; Lindner, James
    The foodservice industry is dependent on millions of employees daily to ensure proper and safe food handling of food products consumed by the general public. The State of Texas requires food establishments’ management or person in charge be trained in food protection. For this inquiry, the researcher studied the knowledge level gained by food mangers from two food companies and two certification courses. There were 90 food service operations that participated in the study. The data was collected through the use of a food safety knowledge test instrument. The scope of the study was to explore the level of food safety knowledge of two self-selected certified food managers in Texas. Sixty-five percent (65.6%) of the certified food managers were certified by course A and 34.4% were certified by course B. The researcher explored two educational theories that are often utilized in the agricultural education discipline. Adult education and training programs in agriculture should use appropriate and effective instructional methods. Creswell and Martin (1993) inferred a linkage between adult education and instructional design as it related to agriculture. This study explored the phenomenon regarding certified food manager training courses and knowledge level through certification. In agricultural education, lives are affected through education and training. Trede and Wade (1993) suggested that agricultural education helps people improve their lives through an educational process using scientific knowledge. The participants’ knowledge test scores were as follows: course A (n=59) 72.9% and course B (n=31) 69.0%. The resulting t-test was determined to the knowledge test score of course A and course B, and proved not to be statistically significant at an alpha level .05. Thus, the researcher concluded instructional design and adult learning theory did not have an impact on the knowledge level of participants as a result of the two self-selected courses for certified food manager training in this study. Food safety knowledge of participants who spoke English or Korean as their native languages were analyzed closely as they represented the largest population of the participants. Korean as a native language represented the largest group at 45.6% of the population. English as a native language represented the second largest group at 43.3% of the population. Certified Food Manager Training is offered in these languages throughout Texas. Differences were found within the participants’ native or first languages. The certified food managers who identified as English and Korean native or first language resulted a statistically significant comparison when analyzed via independent t-test. The researcher recommends further research on affects of native language on certified food manager training. This research study discusses potential improvements that may be implemented in future research for certified food management training. The scope of this study utilized two self selected courses that were available to the participating certified food managers. For example, the Food Safety Knowledge Test instrument which was developed specifically for the scope of this research. Although this instrument was only used once it served as a suitable tool for this research project and could serve as a guide for the development of future research instruments. The researcher suggests that future researchers consider utilizing a tested and established research instrument. A study with a broader scope including courses supported by other National and State level accreditation organization as well as increasing the number of participant; may yield additional findings.
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    Essays on the economics of agriculture and energy in Texas
    (2013-05) Liu, Bing; Benson, Aaron G.; Auld, Dick L.; Malaga, Jaime; Johnson, Phillip N.; Williams, Ryan B.
    This dissertation is a collection of economic analyses of current agriculture and energy situation in Texas. Considering the current Texas natural resources, these three essays focus on alternative crops that can be introduced into Texas to realize local environmental and societal benefits. The first section presents an assessment of the life-cycle energy and GHG emission impacts associated with winter safflower seed-derived biodiesel to determine its suitability as an energy crop on the Texas High Plains. Winter safflower is considered a potential feedstock for biodiesel production that can be grown on the Texas High Plains. It requires fewer inputs in terms of irrigation and fertilizer than current irrigated crops, and could be grown on semi-arid or marginal land. In addition, this study identifies the factors that have the greatest impact on GHG emissions and the likelihood that winter safflower would be adopted by farmers on the High Plains. Finally, in order to analyze farmers’ planting decisions corresponding to different carbon policies, a production function of safflower and GHG emissions is developed, and a profit maximization model is used to evaluate possible incentives to change behavior. The second section established an econometric supply/demand simulation and forecast model of U.S. corn to quantify the effects of key exogenous variables on the corn supply and demand relationships. The model parameters were estimated through a system of simultaneous equations using the three-stage least squares (3SLS) method, based on annual time-series data from1981 to 2011. Then this model was validated using the Theil’s inequality coefficient. The validated model is expected to forecast a baseline and simulate impacts of plausible scenarios for key exogenous variables in the future. The third section focuses on a new crop, guar, which is considered suitable to be grown on the Texas High Plains to help local farmers to increase revenue. Guar gum is highly valuable and sought after as an ingredient from small quantities in numerous food products to large scale uses in oil field services. Traditionally, much of the guar consumed in the U.S. is imported from India. However, the U.S. energy companies are seeking for stable domestic supply of guar to meet oil field demands. Production contracts are seen as effective methods for maintaining a steady supply of high quality guar seed for processors to ensure their production goals. This current study examined different contract choices that farmers could face in a certain guar production contract. A principle-agent model was established to simulate the incentives inherit in guar production contracts. Specifically, we conducted a choice-based experiment to observe producers’ preferences over different contract attributes. The results of this survey are expected to reveal the value producers place on the different attributes. Finally, the ultimate goal of this study is to determine an efficient contract that will attract sufficient producer participation to ensure a steady supply of high quality guar seed.
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    Development of equivalent surcharge loads for the design of soil nailed segment of MSE/soil nail hybrid retaining walls based on results from full-scale wall instrumentation and finite element analysis
    (2013-05) Wei, Yiqing; Jayawickrama, Priyantha W.; Lawson, William D.; Senadheera, Sanjaya
    MSE/Soil Nail hybrid retaining walls have been used in cut/fill retaining systems recently. In this type of wall a MSE wall is constructed above an existing soil nail wall. Therefore, the soil nail wall portion of the hybrid wall system has much heavier surcharge than the normal one. The dissertation demonstrates the results of instrumentation and monitoring a MSE/Soil Nail hybrid retaining wall system. The innovative 2D finite element models were used to simulate the behavior of the hybrid retaining wall system, considering the soil nail ultimate pullout capacity and the effects of the construction phase. In order to evaluate the global FOS of the soil nail wall portion, the equivalent loads considering the vertical loads and horizontal loads of the MSE wall portion are presented by the results of the finite element analysis. The vertical load factor is 1.2 times of the self weight of the MSE wall. Meanwhile the horizontal load factors are in function of the soil nail pullout capacities. The instrumentation data and numerical analysis results are discussed below.
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    Do I stay or do I go? A mixed-methods study of factors of attrition as reported by leavers of secondary agriculture programs
    (2013-05) Lemons, Laura L.; Brashears, Michael T.; Burris, Scott; Meyers, Courtney; Price, Margaret A.
    Agricultural education has experienced a perpetual shortage of qualified agriculture teachers in secondary classrooms for decades. Teacher attrition has been identified as a contributing factor. This two-phase exploratory mixed-methods study sought to deepen the knowledge base regarding secondary agriculture teacher attrition. The first phase of this study was a qualitative case study. Semi-structured interviews were conducted with former secondary agriculture teachers in order to describe how they characterized their experience teaching agriculture and determine the reasons they perceived for exiting the profession. Data from the interviews was analyzed and used to develop an attrition risk assessment instrument, which was pilot tested to establish validity and reliability during the second phase of the study.
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    Building reflective learners: Using portfolios with elementary school students
    (2013-05) Lewis, Karla; Janisch, Carole; Akrofi, Amma; Johnson, Peggy
    This alternative dissertation presents two qualitative studies. These studies, conducted in the teacher/researcher’s classroom, focused on the use of portfolios with elementary school students. In the first study, the researcher examined the written reflections of the portfolio participants. Data collection included students’ written reflections generated in response to their selections of work to be included in the portfolio. In the second study, the research focused on the purpose of a portfolio as perceived by the participants. Data collection included interviews and artifacts of the portfolio. In both studies, the researcher kept a reflective journal to document the process of creating portfolios and students’ responses to their use. Results of the first study showed the written reflective language used by students did change over the course of the school year. This change was from more academic awareness to a more personal awareness of what they had accomplished and achieved, including a move from a short terse account to a longer more authentic description of the selected work. Results of the second study showed participants’ understood portfolios as a measure of their achievements. Positive feelings led to self-efficacy with portfolios. These outcomes suggest that elementary school students can grow in self-awareness and self-evaluation through a portfolio experience. Through explicit instruction in written reflection, even a young student's thinking can change and evolve and portfolios can serve as a form of alternative assessment.
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    An investigation of literature circles as a means to promote reading comprehension
    (2013-05) Medrano, Elsa; Janisch, Carole; Peggy, Johnson; Price, Margaret A.; Burley, Hansel E.
    This case study investigated how integrating comprehension strategies within a student centered instructional model such as Literature Circles improved reading comprehension. Research studies have indicated how students involved in Literature Circles have made greater gains in reading comprehension, felt empowered, and discovered how using a strategy helped them comprehend better. The study was conducted in a fifth grade classroom where Literature Circles were a part of daily reading instruction. Research questions centered on the instructional practices of the teacher and students’ perceptions of the instruction along with their personal responses in terms of reading achievement. Data collection included field notes from classroom observations, interviews with the teacher, and interviews with the fifth graders. Findings suggest that students have positive experiences with reading through the use of Literature Circles and they do increase in their ability to understand and use effective reading strategies in order to better comprehend. This study will contribute to the body of educational research in identifying teaching and learning strategies to respond to the literacy needs of students as well as develop best classroom practices specifically related to Literature Circles.
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