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Title: SPACECRAFT LOADS PREDICTIONVIA SENSITIVITY ANALYSIS AND OPTIMIZATION.
Creator: braswell, tom, CATBAS, NECATI, University of Central Florida
Abstract / Description: Discrepancies between the predicted responses of a finite element analysis (FEA) and reference data from test results arise for many reasons. Some are due to measurement errors, such as inaccurate sensors, noise in the acquisition system or environmental effects. Some are due to analyst errors precipitated by a lack of familiarity with the modeling or solver software. Still others are introduced by uncertainty in the governing physical relations (linear versus non-linear behavior), boundary...
Show moreDiscrepancies between the predicted responses of a finite element analysis (FEA) and reference data from test results arise for many reasons. Some are due to measurement errors, such as inaccurate sensors, noise in the acquisition system or environmental effects. Some are due to analyst errors precipitated by a lack of familiarity with the modeling or solver software. Still others are introduced by uncertainty in the governing physical relations (linear versus non-linear behavior), boundary conditions or the element material/geometrical properties. It is the uncertainty effects introduced by this last group that this study seeks to redress. The objective is the obtainment of model improvements that will reduce errors in predicted versus measured responses. This technique, whereby measured structural data is used to correct finite element model (FEM) errors, has become known as "model updating". Model updating modifies any or all of the mass, stiffness, and damping parameters of a FEM until an improved agreement between the FEA data and test data is achieved. Unlike direct methods, producing a mathematical model representing a given state, the goal of FE model updating is to achieve an improved match between model and test data by making physically meaningful changes. This study replaces measured responses by reference output obtained from a FEA of a small spacecraft. This FEM is referred to as the "Baseline" model. A "Perturbed" model is created from this baseline my making prescribed changes to the various component masses. The degree of mass variation results from the level of confidence existing at a mature stage of the design ii iii cycle. Statistical mean levels of confidence are assigned based on the type of mass of which there are three types: •Concentrated masses – nonstructural, lumped mass formulation (uncoupled) •Smeared masses – nonstructural mass over length or area, lumped mass formulation (uncoupled) •Mass density – volumetric mass, lumped mass formulation (uncoupled) A methodology is presented that accurately predicts the forces occurring at the interface between the spacecraft and the launch vehicle. The methodology quantifies the relationships between spacecraft mass variations and the interface accelerations in the form of sensitivity coefficients. These coefficients are obtained by performing design sensitivity /optimization analyses while updating the Perturbed model to correlate with the Baseline model. The interface forces are responses obtained from a frequency response analysis that runs within the optimization analysis. These forces arise due to the imposition of unit white noise applied across a frequency range extending up to 200 hertz, a cut-off frequency encompassing the lift-off energy required to elicit global mass response. The focus is on lift-off as it is characterized by base excitation, which produces the largest interface forces.
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Date Issued: 2007
Identifier: CFE0001733, ucf:47305
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001733

Title: THE EFFECTS OF STIMULUS MOTION ON CONTRAST SENSITIVITY: DYNAMIC SENSITIVITY FUNCTIONS.
Creator: Zavod, Merrill, Rinalducci, Edward, University of Central Florida
Abstract / Description: Static Visual Acuity (SVA) has been called into question for some time as a measure of overall visual system function and as a predictor of performance on real-life tasks requiring vision (i.e., operating an automobile). Specifically, it has been pointed out that the targets employed in most SVA testing (high contrast, stationary letters) are an insufficient analog to actual targets encountered in everyday activities, which are often in motion and/or of less-than-perfect contrast. In addition...
Show moreStatic Visual Acuity (SVA) has been called into question for some time as a measure of overall visual system function and as a predictor of performance on real-life tasks requiring vision (i.e., operating an automobile). Specifically, it has been pointed out that the targets employed in most SVA testing (high contrast, stationary letters) are an insufficient analog to actual targets encountered in everyday activities, which are often in motion and/or of less-than-perfect contrast. In addition, the size-threshold methodology typically used to measure SVA is incongruent with current theories of a multi-channel visual system. Dynamic Visual Acuity (DVA) and Contrast Sensitivity have been suggested as alternatives to SVA, but while each mitigates specific weaknesses of the SVA measure, neither addresses the shortcomings completely. Traditional DVA measures employ moving targets, but these targets are usually of perfect contrast and a size-threshold methodology is used to specify acuity levels. Contrast Sensitivity employs a contrast-threshold methodology and allows measurement of specific visual channels, but stationary targets are utilized. The present study combined the DVA and Contrast Sensitivity measures in an effort to retain the unique qualities of each while addressing their shortcomings, resulting in a more detailed picture of the human visual system and functioning than has yet been possible. By measuring contrast sensitivity to targets at a set of spatial frequencies spanning the human "window of visibility" and under conditions of motion representative of that encountered in everyday activities, it was hoped that a more powerful predictor of actual visual performance would be created. In addition, normative data was established for two separate age populations, in the hopes of learning more about specific changes that occur to the visual system during the aging process. Indeed, several effects and interactions among the three main variables (spatial frequency, velocity, age) were uncovered, which appears to indicate that the new test may provide more information about the visual system than DVA or contrast sensitivity by themselves. The ramifications of this effort to human factors and visual performance research are discussed along with recommendations for the continuation and application of this line of research.
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Date Issued: 2004
Identifier: CFE0000293, ucf:46210
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000293

Title: SILICON-SENSITIZED ERBIUM EXCITATION IN SILICON-RICH SILICA FOR INTEGRATED PHOTONICS.
Creator: Savchyn, Oleksandr, Kik, Pieter, University of Central Florida
Abstract / Description: It is widely accepted that the continued increase of processor performance requires at least partial replacement of electronic interconnects with their photonic counterparts. The implementation of optical interconnects requires the realization of a silicon-based light source, which is challenging task due to the low emission efficiency of silicon. One of the main approaches to address this challenge is the use of doping of silicon based matrices with optical centers, including erbium ions....
Show moreIt is widely accepted that the continued increase of processor performance requires at least partial replacement of electronic interconnects with their photonic counterparts. The implementation of optical interconnects requires the realization of a silicon-based light source, which is challenging task due to the low emission efficiency of silicon. One of the main approaches to address this challenge is the use of doping of silicon based matrices with optical centers, including erbium ions. Erbium ions incorporated in various hosts assume the trivalent state (Er3+) and demonstrate a transition at 1.54 μm, coinciding with optical transmission windows in both silicon and silica. Due to the low absorption cross-section and discrete energy levels of the Er3+ ion, indirect excitation is necessary. In late 90s it was demonstrated that the incorporation of excess silicon in erbium-doped silica results in strong erbium sensitization, leading to an increase of the effective absorption cross-section by orders of magnitude. The sensitization was considered to occur via silicon nanocrystals that formed at high annealing temperatures. While a large increase of the absorption cross-section was demonstrated, the incorporation of Si nanocrystals was found to result in a low concentration of excited erbium, as well as silicon related free-carrier absorption. The focus of this dissertation is the investigation of the nature of the sensitization mechanism of erbium in silicon-rich silica. The results presented in the dissertation demonstrate that erbium in silicon-rich silica is predominantly excited by silicon-excess-related luminescence centers, as opposed to the commonly considered silicon nanocrystals. This is a remarkable conclusion that changes the view on the exact origin of erbium sensitization, and that resolves several technical challenges that exist for nanocrystal-based sensitization. The work shows that the density of indirectly excited erbium ions is significantly larger in samples without silicon nanocrystals (annealed at T < 1000oC) as opposed to samples with silicon nanocrystals (annealed at T > 1000oC). The density of indirectly excited erbium ions, defining the maximum achievable gain, was demonstrated to be approximately excitation wavelength independent, while the effective erbium absorption cross-section was shown to significantly depend on the excitation wavelength. The excitation mechanism of erbium by luminescence centers was shown to be fast (< 30 ns) and capable of erbium sensitization to different energy levels. This multilevel nature of erbium excitation was demonstrated to result in two different mechanisms of the excitation of the first excited state of erbium: fast (< 30 ns) direct excitation by the luminescence centers, and slow (> 2.3 μs) excitation due to the relaxation of erbium ions excited into higher energy levels to the first excited state. Based on photoluminescence studies conducted in the temperature range 15 - 300K it was shown that the relaxation efficiency of erbium from the second excited state to the first excited state (responsible for the slow excitation mechanism) is temperature independent and approaches unity. The relative stability of the optical properties demonstrated in the temperature range 20 - 200oC, implies that relatively stable optical gain can be achieved under realistic on-chip operating conditions. The optimum Si excess concentration corresponding to the highest density of sensitized Er3+ ions is shown to be relatively insensitive to the presence of Si nanocrystals and is ~ 14.5 at.% and ~ 11.5 at.% for samples without and with Si nanocrystals respectively. The presented results and conclusions have significant implications for silicon photonics and the industrial application of Er-doped SiO2. The work shows that in order to sensitize erbium ions in silicon-rich silica there is no need for the presence of silicon nanocrystals, and consequently lower fabrication temperatures can be used. More importantly, the results strongly suggest that higher gain values can be acquired in samples annealed at lower temperature (without silicon nanocrystals) as compared to samples annealed at high temperatures (with silicon nanocrystals). In addition, the maximum gain is predicted to be relatively independent of excitation wavelength, significantly relaxing the requirements on the pump source. Based on the experimental results it is predicted that relatively stable performance of erbium-doped silicon-rich silica is possible up to typical processor operating temperatures of ~ 80 - 90oC making it a viable material for on-chip devices. The results suggest that low temperature annealed erbium-doped silicon-rich silica is a preferable material for on-chip photonic devices as compared with its high temperature annealed counterpart.
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Date Issued: 2010
Identifier: CFE0003312, ucf:48492
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003312

Title: EFFECTS OF GHRKO VISCERAL FAT TRANSPLANT OF INSULIN SIGNALING.
Creator: Bennis, Mohammed, Masternak, Michal, University of Central Florida
Abstract / Description: Insulin sensitivity has been positively correlated with a healthy and extended lifespan, while insulin resistance, decreased insulin sensitivity, has been linked to aging and is the main indicative of type 2 diabetes. Growth Hormone Receptor/ Binding Protein Knockout mice (GHRKO), although obese, are characterized by high insulin sensitivity and a prolonged lifespan. Due to the absence of growth hormone receptors (GHR), growth hormone (GH) is unable to activate its downstream pathway....
Show moreInsulin sensitivity has been positively correlated with a healthy and extended lifespan, while insulin resistance, decreased insulin sensitivity, has been linked to aging and is the main indicative of type 2 diabetes. Growth Hormone Receptor/ Binding Protein Knockout mice (GHRKO), although obese, are characterized by high insulin sensitivity and a prolonged lifespan. Due to the absence of growth hormone receptors (GHR), growth hormone (GH) is unable to activate its downstream pathway. Interestingly, the secretory activity of visceral fat in GHRKO mice is altered stimulating insulin sensitivity. In this study, we transplanted normal (N) mice with GHRKO visceral fat pads to determine the role of visceral fat developed with the absence of GH signaling on the insulin-signaling pathway in animals with physiologically normal GH action. We found that the visceral fat transplant (VFT) helped the normal mice gain the beneficial effects of fat developed in the absence of GH and caused improvement of their whole body insulin sensitivity when comparing with sham-operated mice and with mice that received visceral fat from N animals. In presented study, RT-PCR was used to determine the levels of hepatic mRNA expression between three experimental groups including Normal-sham mice (N-S), normal mice transplanted with visceral fat from normal animals (N-N), and normal mice receiving visceral fat from GHRKO mice (N-KO). Additionally, Western Blot and ELISA were used to determine the level of total and phosphorylated proteins. By studying the effect of visceral fat transplant from GHRKO or N mice on the whole body insulin signaling in N male mice, and testing different genes expression and proteins quantification, we can shed light on the mechanism by which white adipose tissue (WAT) regulates whole body insulin sensitivity and longevity as well as understanding the role of WATs in development of diabetes and the process behind insulin resistance.
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Date Issued: 2015
Identifier: CFH0004781, ucf:45372
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004781

Title: GENERATION RATED X: PERSONALITY TRAITS, SEXUAL ATTITUDES, AND THE EFFECTS OF SEXUALLY EXPLICIT MEDIA ON ATTRACTION AMONG MEN.
Creator: Eckstein, H. Christopher, White, Grace, University of Central Florida
Abstract / Description: Previous research has indicated that exposure to pornography, or sexually explicit media (SEM), can lead married men to express a stronger desire for sexual intimacy (Staley & Prause, 2013). However, SEM exposure has also resulted in decreased physical attractiveness ratings among men evaluating their spouses (Kenrick, et al., 1989). Only a small amount of research has investigated the effects of SEM on attraction among unmarried males. The current study examined the effects of SEM in a...
Show morePrevious research has indicated that exposure to pornography, or sexually explicit media (SEM), can lead married men to express a stronger desire for sexual intimacy (Staley & Prause, 2013). However, SEM exposure has also resulted in decreased physical attractiveness ratings among men evaluating their spouses (Kenrick, et al., 1989). Only a small amount of research has investigated the effects of SEM on attraction among unmarried males. The current study examined the effects of SEM in a sample of 108 heterosexual, undergraduate males. Participants evaluated pictures of 15 unknown women�s faces for physical attractiveness. They were then exposed to five minutes of SEM, after which they re-evaluated the same 15 faces for attractiveness. This study also examined the association between Big Five personality traits and self-reported sexual attitudes. The relations between sexual attitudes and the effects of SEM exposure were also explored. Counter to the expected hypothesis, results indicated an increase in attractiveness ratings after SEM exposure, demonstrating a sensitization rather than a desensitization effect on attraction. The Big Five Extraversion trait significantly predicted increases in attractiveness ratings after SEM exposure. Personality was also a significant predictor of sexual attitudes in relation to the socio-sexual orientation facets of behavior and attitude, which constitute the number of casual and changing sex partners and attitudes towards uncommitted sex, respectively. Additional research is necessary to replicate and confirm novel findings in this study.
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Date Issued: 2016
Identifier: CFH2000071, ucf:45542
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000071

Title: THE EFFECT OF CHEMICAL FRAGRANCES ON CHILD HEALTH AND DEVELOPMENT.
Creator: Gilton, Katie, Waldrop, Julee, University of Central Florida
Abstract / Description: The American public is bombarded with chemically fragranced products every day, typically in combination with each other. These products can include cosmetics, perfumes, detergents, air fresheners, soaps, and deodorants. Contained in these fragranced products are chemicals that can be harmful to child health and development. Many articles have been published examining the chemicals found in fragranced products and the effects that these chemicals can have on the human body. This integrated...
Show moreThe American public is bombarded with chemically fragranced products every day, typically in combination with each other. These products can include cosmetics, perfumes, detergents, air fresheners, soaps, and deodorants. Contained in these fragranced products are chemicals that can be harmful to child health and development. Many articles have been published examining the chemicals found in fragranced products and the effects that these chemicals can have on the human body. This integrated literature review examines empirical evidence related to the health and safety of particular chemicals used in these products. Nurses need to be aware of the actual and potential harms from the chemicals used in the self-regulating cosmetic industry and can advocate for public policies that promote a safer environment, therefore protecting the health and wellbeing of children.
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Date Issued: 2011
Identifier: CFH0003835, ucf:44771
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0003835

Title: ONE TEACHER'S JOURNEY THROUGH CREATING CULTURALLY-SENSITIVE INSTRUCTIONAL MATERIAL FOR VILLAGE AND ORPHANED STUDENTS IN SIERRA LEONE.
Creator: Shearhod, Jesica, Biraimah, Karen, University of Central Florida
Abstract / Description: My first experience teaching, in Sierra Leone in July of 2010, is where I realized that most elementary students were illiterate and lacked the foundational skills in order to learn how to read. I decided to return the following year in May of 2011 to undertake a project to provide culturally-sensitive literacy materials for village and orphaned children in the form of storybooks. The school site for this thesis is Children of the Nations (COTN) which is a school of 98 orphaned and 1,488...
Show moreMy first experience teaching, in Sierra Leone in July of 2010, is where I realized that most elementary students were illiterate and lacked the foundational skills in order to learn how to read. I decided to return the following year in May of 2011 to undertake a project to provide culturally-sensitive literacy materials for village and orphaned children in the form of storybooks. The school site for this thesis is Children of the Nations (COTN) which is a school of 98 orphaned and 1,488 village students that range from 4years-20 years of age. The titles of the two books produced by this thesis are: What's Up and ABC's of Sierra Leone. These books are culturally relevant to the students who helped in creating them and includes pictures and words that students can identify. This study will 1) provide insights into history and literacy development issues of Sierra Leone from the perspective of a Western educator; 2) examine modern factors affecting literacy development; 3) describe my teaching experience in Sierra Leone with multiage children learning English; and 4) explore the notion of creating culturally-sensitive instructional materials for village and orphan students in Sierra Leone.
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Date Issued: 2012
Identifier: CFH0004188, ucf:44817
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004188

Title: A Comprehensive Assessment of Vehicle-to-Grid Systems and Their Impact to the Sustainability of Current Energy and Water Nexus.
Creator: Zhao, Yang, Tatari, Omer, Oloufa, Amr, Mayo, Talea, Zheng, Qipeng, University of Central Florida
Abstract / Description: This dissertation aims to explore the feasibility of incorporating electric vehicles into the electric power grid and develop a comprehensive assessment framework to predict and evaluate the life cycle environmental, economic and social impact of the integration of Vehicle-to-Grid systems and the transportation-water-energy nexus. Based on the fact that electric vehicles of different classes have been widely adopted by both fleet operators and individual car owners, the following questions...
Show moreThis dissertation aims to explore the feasibility of incorporating electric vehicles into the electric power grid and develop a comprehensive assessment framework to predict and evaluate the life cycle environmental, economic and social impact of the integration of Vehicle-to-Grid systems and the transportation-water-energy nexus. Based on the fact that electric vehicles of different classes have been widely adopted by both fleet operators and individual car owners, the following questions are investigated: 1. Will the life cycle environmental impacts due to vehicle operation be reduced? 2. Will the implementation of Vehicle-to-Grid systems bring environmental and economic benefits? 3. Will there be any form of air emission impact if large amounts of electric vehicles are adopted in a short time? 4. What is the role of the Vehicle-to-Grid system in the transportation-water-energy nexus? To answer these questions: First, the life cycle environmental impacts of medium-duty trucks in commercial delivery fleets are analyzed. Second, the operation mechanism of Vehicle-to-Grid technologies in association with charging and discharging of electric vehicles is researched. Third, the feasible Vehicle-to-Grid system is further studied taking into consideration the spatial and temporal variance as well as other uncertainties within the system. Then, a comparison of greenhouse gas emission mitigation of the Vehicle-to-Grid system and the additional emissions caused by electric vehicle charging through marginal electricity is analyzed. Finally, the impact of the Vehicle-to-Grid system in the transportation-water-energy nexus, and the underlying environmental, economic and social relationships are simulated through system dynamic modeling. The results provide holistic evaluations and spatial and temporal projections of electric vehicles, Vehicle-to-Grid systems, wind power integration, and the transportation-water-energy nexus.
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Date Issued: 2017
Identifier: CFE0007300, ucf:52153
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007300

Title: The Reproducibility and Validity of Using the Dmax Method to Predict Physical Working Capacity at Fatigue Threshold.
Creator: Riffe, Joshua, Stout, Jeffrey, Hoffman, Jay, Fukuda, David, University of Central Florida
Abstract / Description: Although the original (ORG) physical working capacity at fatigue threshold (PWCFT) assessment has demonstrated strong reliability and sensitivity to training and/or nutritional interventions, limitations may exist regarding the method of PWCFT estimation. However, a relatively new mathematical method, called Dmax, has been shown to be objective and reliable when estimating metabolic and neuromuscular fatigue thresholds. To date, however, no study has examined whether the Dmax method for...
Show moreAlthough the original (ORG) physical working capacity at fatigue threshold (PWCFT) assessment has demonstrated strong reliability and sensitivity to training and/or nutritional interventions, limitations may exist regarding the method of PWCFT estimation. However, a relatively new mathematical method, called Dmax, has been shown to be objective and reliable when estimating metabolic and neuromuscular fatigue thresholds. To date, however, no study has examined whether the Dmax method for estimating the work rate at PWCFT is similar to the ORG method. PURPOSE: The purpose of this study is to evaluate the reliability and validity of the Dmax-EMG method for estimating and tracking changes in PWCFT. METHODS: In the reproducibility study, 11 men (age: 21.9 (&)#177; 1.37 years; height: 175.6 (&)#177; 8.65 cm; body mass: 82.1 (&)#177; 13.92 kg) completed two incremental exercise tests (GXT) to exhaustion on nonconsecutive days. In the validity study, 11 active men (age: 23.4 (&)#177; 3.0 years; height: 177.9 (&)#177; 7.8 cm; body mass: 80.9 (&)#177; 10.7 kg) and 10 active women (age: 22.3 (&)#177; 3.1 years; height: 166.6 (&)#177; 9.5 cm; body mass: 62.8 (&)#177; 8.7 kg) volunteered to perform 12 sessions of high-intensity interval training (HIIT) over 4-weeks along with a pre- and post-training GXT to compare the Dmax to the ORG method of estimating PWCFT. RESULTS: The reproducibility study revealed no significant differences between the first (181.5 (&)#177; 29.2 W) and second (181.9 (&)#177; 26.18 W) GXT trials (p = 0.87). In addition, ICC3,1 resulted in 0.949 with an SEM of 6.28 W and a MD of 17.41 W. In the cross-validation, the CE between actual and predicted PWCFT was not statistically different at pre (-6.7 W; p (>) 0.05) or post (-7.2 W; p (>) 0.05). Pre (r = 0.87) and post (r = 0.84) validity coefficients were considered very strong and the pre and post TE PWCFT values were 30.8 W and 32.5 W, respectively. Wide limits of agreement were calculated in the Bland-Altman analyses (pre: -68.36 to 54.93 W; post: -57.77 to 72.06 W) with no significant biases in both pre (-6.7 (&)#177; 30.8 W; p = 0.330) and post (-7.2 (&)#177; 32.5 W; p = 0.325). In addition, 95.2% and 100% participants fell within (&)#177;1.96 standard deviations of the mean difference for pre and post, respectively. CONCLUSION: Results of the study suggest that the Dmax method is both a reproducible and a valid method to estimate PWCFT when compared to the ORG method in young men.
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Date Issued: 2016
Identifier: CFE0006168, ucf:51155
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006168

Title: Electrical, Optical and Chemical Properties of Organic Photo Sensitve Materials.
Creator: Shi, Zheng, Liao, Yi, Kolpashchikov, Dmitry, Ye, Jingdong, Zou, Shengli, Su, Ming, University of Central Florida
Abstract / Description: Light as a (")green(") source of energy has become increasingly attractive throughout the past century and has shown versatility for the application of activating chemical reactions. Compared with traditional energy sources, it provides a more direct, selective and controllable method. My PhD study was focused on the study of photochemistry of organic materials in two different systems. The first system is regarding reversible photoacids which generate protons on irradiation. With the aim of...
Show moreLight as a (")green(") source of energy has become increasingly attractive throughout the past century and has shown versatility for the application of activating chemical reactions. Compared with traditional energy sources, it provides a more direct, selective and controllable method. My PhD study was focused on the study of photochemistry of organic materials in two different systems. The first system is regarding reversible photoacids which generate protons on irradiation. With the aim of systematically studying these novel types of long lived photoacids, a series of photoacids was designed, synthesized and whose chemical mechanism was thoroughly investigated. This type of photoacid changes from a weak acid to a strong acid with a pH change of several units, which achieves nearly complete proton dissociation upon visible light irradiation. The whole process is reversible and the half-life of the proton-dissociation state is long enough to be used in many applications. Besides fundamental studies, different applications based on this type of photoacids were also completed. An esterification reaction was catalyzed and the volume of a pH-sensitive polymer was altered due to the large amount of photo generated protons from this photoacid. A reversible electrical conductivity change of polyaniline (PANI) was also achieved by doping with this reversible photoacid. In order to induce a large conductivity increase, an irreversible photoacid generator (PAG) was embedded in a novel PANI/PAG/PVA novel composition. In this system, Poly (vinyl alcohol) (PVA) forms a hydrogen-bonding network to facilitate proton transfer between the PAG and PANI. A final electrical conductivity of 10-1 S cm-1 was successfully achieved after irradiation. The second system in which I explored photochemistry of organic molecules concerns Photo-retro-Diels-Alder (PrDA) reactions and a variety of Diels-Alder (DA) adducts were designed for these studies. UV light was used to trigger the retro-Diels-Alder reactions. Quantum yield of each DA adducts was investigated. This revealed that the photo-reactivity of this process depends on the electron-donating ability of the diene and the electron-withdrawing ability of the dienophile component. Mechanistic studies of this PrDA reaction reveal that a charge-separated intermediate is generated from a singlet excited state. This was applied to an unsaturated cyclic ?-diketones (DKs), which underwent PrDA reactions and generated anthracene derivatives and carbon monoxide (CO), which itself plays profound and important roles in biological systems. These unsaturated cyclic ?-diketones (DKs) encapsulated in micelles are effective CO-releasing molecules (CORMs) and are capable of carrying and releasing CO in cellular systems. This novel type of organic CORMs has potentially low toxicity and generates fluorescence, which provides a useful tool for the study of the biological functions of CO.
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Date Issued: 2013
Identifier: CFE0005114, ucf:50748
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005114

Title: Immuno-PCR detection of Lyme borreliosis.
Creator: Halpern, Micah, Ballantyne, John, Cunningham, Glenn, Fookes, Barry, University of Central Florida
Abstract / Description: Lyme borreliosis, more commonly referred to as Lyme disease, is the fastest growing zoonotic disease in North America with approximately 30,000 confirmed cases and 300,000 estimated infections per year. In nature, the causative agent of Lyme disease, the bacterium Borrelia burgdorferi, cycles between Ixodes sp. ticks and small mammals. Humans become infected with Lyme disease after being bitten by an infected tick. The primary indicator of a Borrelia burgdorferi infection is a bull's eye rash...
Show moreLyme borreliosis, more commonly referred to as Lyme disease, is the fastest growing zoonotic disease in North America with approximately 30,000 confirmed cases and 300,000 estimated infections per year. In nature, the causative agent of Lyme disease, the bacterium Borrelia burgdorferi, cycles between Ixodes sp. ticks and small mammals. Humans become infected with Lyme disease after being bitten by an infected tick. The primary indicator of a Borrelia burgdorferi infection is a bull's eye rash typically followed by flu-like symptoms with treatment consisting of a 2-4 week course of antibiotics. If not treated, later stages of the disease can result in arthritis, cardiovascular and neurological symptoms. Diagnosis of Lyme disease is challenging and currently requires a complex laboratory diagnostic using indirect detection of host-generated antibodies by a two-tiered approach consisting of an enzyme linked immunosorbent assay (ELISA) followed by IgM and IgG immunoblots. Although two-tier testing has provided an adequate approach for Lyme disease diagnosis, it has weaknesses including subjective analysis, complex protocols and lack of reagent standardization. Immuno-PCR (iPCR) is a method that combines ELISA-based detection specificity with the sensitivity of PCR signal amplification and has demonstrated increased sensitivity for many applications such as detection of disease biomarkers but has yet to be applied for diagnosis of Lyme disease.Herein, using iPCR and recombinant B. burgdorferi antigens, an assay for both the direct and the indirect detection of Lyme disease was developed and demonstrated improved sensitivity for detection of B. burgdorferi antibodies using a murine model. Moreover, we present evidence using human Lyme disease patient serum samples that iPCR using both multiple antigens and a unique single hybrid antigen is capable of achieving increased sensitivity and specificity compared to existing methodology. These data represent the first demonstration of iPCR for Lyme disease diagnosis and support the replacement of two-tier testing with a more simplified and objective approach.
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Date Issued: 2013
Identifier: CFE0005346, ucf:50470
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005346

Title: REJECTION IN THE JOB SELECTION PROCESS: THE EFFECTS OF INFORMATION & SENSITIVITY.
Creator: Yonce, Clayton, Fritzsche, Barbara, University of Central Florida
Abstract / Description: Most people will experience rejection in the job selection process. Rejection from job opportunities is often issued via a letter from a hiring manager. These letters elicit reactions from applicants who may, in turn, have less favorable self perceptions and less favorable perceptions of the organization from which the applicant was rejected. Numerous research articles have been published that deal with delivering notification of selection and/or rejection to applicants in the job selection...
Show moreMost people will experience rejection in the job selection process. Rejection from job opportunities is often issued via a letter from a hiring manager. These letters elicit reactions from applicants who may, in turn, have less favorable self perceptions and less favorable perceptions of the organization from which the applicant was rejected. Numerous research articles have been published that deal with delivering notification of selection and/or rejection to applicants in the job selection process. However, relatively few use a realistic laboratory design to obtain results. This study examined the effects of sensitivity and information in notifications of rejection when applicants are rejected in the job selection process. A more realistic laboratory design was used to increase the psychological fidelity of the job selection situation. One hundred forty undergraduate students participated in this study. Participants were told to imagine that they were graduate school applicants. Then, the participants completed a fake graduate school admissions test and received notification of rejection from a fake graduate school. Participants were assigned to conditions (letters varying in sensitivity and information type) randomly and the participants completed a post-notification of rejection survey that captured their self and organizational perceptions. Additionally, moderating variables were explored.
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Date Issued: 2005
Identifier: CFE0000877, ucf:46654
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000877

Title: A NEW THEORY AND MEASURE OF ETHICAL WORK CLIMATE: THE PSYCHOLOGICAL PROCESS MODEL (PPM) AND THE ETHICAL CLIMATE INDEX (ECI).
Creator: Arnaud, Anke, Schminke, Marshall, University of Central Florida
Abstract / Description: ABSTRACT With this dissertation I developed a new theory and measure of ethical work climate (EWC). Currently, there exists one dominant theory and measure of EWC developed by Victor and Cullen (1988, 1987). Even though researchers have identified problems with this theory, such as inconsistencies with regard to its limited theoretical scope and troubling psychometric properties, it is the most widely utilized framework for conceptualizing and testing EWC. Therefore, I propose to develop an...
Show moreABSTRACT With this dissertation I developed a new theory and measure of ethical work climate (EWC). Currently, there exists one dominant theory and measure of EWC developed by Victor and Cullen (1988, 1987). Even though researchers have identified problems with this theory, such as inconsistencies with regard to its limited theoretical scope and troubling psychometric properties, it is the most widely utilized framework for conceptualizing and testing EWC. Therefore, I propose to develop an improved theory and measure of EWC, one capable of addressing some of the principle shortcomings of earlier efforts. Building on Rest's (1986, 1979) "Four-Component" model of individual-level ethical decision-making and behavior, I specify four dimensions of EWC necessary for the emergence of ethical behavior: collective moral sensitivity, collective moral judgment, collective moral motivation, and collective moral character. I developed a multidimensional instrument capable of capturing each of these dimensions at the climate level. I anticipate that this theory and instrument will allow researchers to understand EWCs and their impact on attitudes and behaviors more effectively than previous approaches. Chapter 1 reviews the organizational climate and culture literatures, so as to gain a comprehensive understanding of the organizational climate construct in general and how it differs from organizational culture in particular. Chapter 2 includes a review and evaluation the EWC literature. This helped to identify opportunities and suggestions for a new theory and measure of EWC. Chapter 3 describes the development of the new theory of EWCs, the Psychological Process Model, with propositions for future research. Chapter 4 informs about the development of the Ethical Climate Index, the measure used to assess the new theory of EWCs. It describes 3 studies that were used to construct the Ethical Climate Index to measure the ethical work climate dimensions of collective moral sensitivity (12-items), collective moral judgment (10-items), collective moral motivation (8-items), and collective moral character (6-items). Study 1 and 2 resulted in parsimonious and reliable scales for each one of the four dimensions. Results of the 3rd study support convergent and discriminant validity for each one of the scales and suggest that the ECI is a valid and reliable predictor of ethical and unethical behavior. Implications and suggestions for the use of this measure in future research is discussed.
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Date Issued: 2006
Identifier: CFE0000918, ucf:46740
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000918

Title: AN INVERSE ALGORITHM TO ESTIMATE THERMAL CONTACT RESISTANCE.
Creator: Gill, Jennifer, Kassab, Alain, University of Central Florida
Abstract / Description: Thermal systems often feature composite regions that are mechanically mated. In general, there exists a significant temperature drop across the interface between such regions which may be composed of similar or different materials. The parameter characterizing this temperature drop is the thermal contact resistance, which is defined as the ratio of the temperature drop to the heat flux normal to the interface. The thermal contact resistance is due to roughness effects between mating surfaces...
Show moreThermal systems often feature composite regions that are mechanically mated. In general, there exists a significant temperature drop across the interface between such regions which may be composed of similar or different materials. The parameter characterizing this temperature drop is the thermal contact resistance, which is defined as the ratio of the temperature drop to the heat flux normal to the interface. The thermal contact resistance is due to roughness effects between mating surfaces which cause certain regions of the mating surfaces to loose contact thereby creating gaps. In these gap regions, the principal modes of heat transfer are conduction across the contacting regions of the interface, conduction or natural convection in the fluid filling the gap regions of the interface, and radiation across the gap surfaces. Moreover, the contact resistance is a function of contact pressure as this can significantly alter the topology of the contact region. The thermal contact resistance is a phenomenologically complex function and can significantly alter prediction of thermal models of complex multi-component structures. Accurate estimates of thermal contact resistances are important in engineering calculations and find application in thermal analysis ranging from relatively simple layered and composite materials to more complex biomaterials. There have been many studies devoted to the theoretical predictions of thermal contact resistance and although general theories have been somewhat successful in predicting thermal contact resistances, most reliable results have been obtained experimentally. This is due to the fact that the nature of thermal contact resistance is quite complex and depends on many parameters including types of mating materials, surface characteristics of the interfacial region such as roughness and hardness, and contact pressure distribution. In experiments, temperatures are measured at a certain number of locations, usually close to the contact surface, and these measurements are used as inputs to a parameter estimation procedure to arrive at the sought-after thermal contact resistance. Most studies seek a single value for the contact resistance, while the resistance may in fact also vary spatially. In this thesis, an inverse problem (IP) is formulated to estimate the spatial variation of the thermal contact resistance along an interface in a two-dimensional configuration. Temperatures measured at discrete locations using embedded sensors appropriately placed in proximity to the interface provide the additional information required to solve the inverse problem. A superposition method serves to determine sensitivity coefficients and provides guidance in the location of the measuring points. Temperature measurements are then used to define a regularized quadratic functional that is minimized to yield the contact resistance between the two mating surfaces. A boundary element method analysis (BEM) provides the temperature field under current estimates of the contact resistance in the solution of the inverse problem when the geometry of interest is not regular, while an analytical solution can be used for regular geometries. Minimization of the IP functional is carried out by the Levenberg-Marquadt method or by a Genetic Algorithm depending on the problem under consideration. The L-curve method of Hansen is used to choose the optimal regularization parameter. A series of numerical examples are provided to demonstrate and validate the approach.
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Date Issued: 2005
Identifier: CFE0000748, ucf:46582
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000748

Title: Identification and Functional Characterization of a Long Non-coding RNA associated with Prostate Cancer.
Creator: Hasan, Md Faqrul, Chakrabarti, Ratna, Zhao, Jihe, Zhang, Shaojie, University of Central Florida
Abstract / Description: Prostate cancer is the most common cancer in men in the western world. Although early stage prostate cancer is treatable late stage, more specifically, metastatic and drug resistant prostate cancers are mostly incurable. The failure of current treatments obligates the research community to explore novel areas in prostate cancer biology and find better therapeutic targets. Emerging evidences show that non-coding RNAs specifically long non-coding RNAs (lncRNAs) play regulatory roles in various...
Show moreProstate cancer is the most common cancer in men in the western world. Although early stage prostate cancer is treatable late stage, more specifically, metastatic and drug resistant prostate cancers are mostly incurable. The failure of current treatments obligates the research community to explore novel areas in prostate cancer biology and find better therapeutic targets. Emerging evidences show that non-coding RNAs specifically long non-coding RNAs (lncRNAs) play regulatory roles in various cellular processes and are frequently dysregulated in cancer including prostate cancer. These aberrantly expressed lncRNAs mostly with unexplored genetic information may drive cancer progression. Previous studies done in our laboratory showed a tumor suppressor role of a cluster of small non-coding RNAs or microRNA (miRNA) miR-17-92a in PC-3 prostate cancer cells. To learn the underlying mechanism, transcriptome analysis with or without expression of miR-17-92a was conducted in our laboratory. RNA-sequencing data analysis identified reduced expression of a set of lncRNAs and oncogenes, and up regulation of several tumor suppressor genes upon expression of miR-17-92a cluster miRNAs. One of the down regulated intergenic lncRNAs, PAINT (Prostate Cancer Associated Intergenic Non-coding Transcript) (LINC00888), was selected for determining its functional role in prostate cancer. TCGA and GEO profiles analyses revealed up regulation of PAINT in prostate tumors with higher Gleason Scores, in highly aggressive metastatic prostate cancer cell lines, and upon androgen deprivation therapy of prostate cancer cells. This observation was supported by our studies on expression analysis of PAINT in prostate tumor tissues using RNA in-situ hybridization in tissue microarrays (TMA) containing tissues from different stages of prostate cancer and normal prostate tissues, which showed higher expression of PAINT in prostate cancer tissues compared to normal tissues. Furthermore, late stage (stage III and stage IV) prostate tumors showed significant overexpression of PAINT compared to early stage (stage II) prostate cancer tissues. We examined the functional relevance of PAINT in promoting tumor progression next using different prostate cancer cell lines. Silencing of PAINT using siRNAs showed decreased cell proliferation, reduced S-phase progression and activation of pro-apoptotic proteins PARP and Caspase-3. Silencing of PAINT also showed decreased cell migration and increased expression of the epithelial marker, E-cadherin while reduced expression of mesenchymal markers Slug and Vimentin. Ectopic expression of PAINT reversed the effects observed upon silencing of PAINT. Increased cell proliferation, cell cycle progression and cell migration were noted in prostate cancer cells overexpressing PAINT. Additionally, cancer promoting phenotype such as larger colony formation and higher expression of mesenchymal marker Slug, was detected upon overexpression of PAINT. Our study also determined the therapeutic benefit of inhibition of expression showing an increased sensitivity of metastatic prostate cancer cells to the chemotherapeutic agent docetaxel (DTX) and selective Aurora kinase inhibitor VX-680. Taken together, our study establishes an oncogenic function of PAINT, its clinical relevance as a marker for advanced stage prostate cancer and its potential as a therapeutic target for metastatic prostate cancer.
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Date Issued: 2019
Identifier: CFE0007466, ucf:52681
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007466

Title: Heat Transfer in a Coupled Impingement-Effusion Cooling System.
Creator: Miller, Mark, Kapat, Jayanta, Deng, Weiwei, Gordon, Ali, University of Central Florida
Abstract / Description: The efficiency of air-breathing gas turbine engines improves as the combustion temperature increases. Therefore, modern gas turbines operate at temperatures greater than the melting temperature of hot-gas-path components, and cooling must be introduced in order to maintain mechanical integrity of those components. Two highly effective techniques used in modern designs for this purpose are impingement cooling and use of coolant film on hot-gas-path surface introduced through discrete film or...
Show moreThe efficiency of air-breathing gas turbine engines improves as the combustion temperature increases. Therefore, modern gas turbines operate at temperatures greater than the melting temperature of hot-gas-path components, and cooling must be introduced in order to maintain mechanical integrity of those components. Two highly effective techniques used in modern designs for this purpose are impingement cooling and use of coolant film on hot-gas-path surface introduced through discrete film or effusion holes. In this study, these two mechanisms are coupled into a single prototype cooling system. The heat transfer capability of this system is experimentally determined for a variety of different geometries and coolant flow rates.This study utilizes Temperature Sensitive Paint (TSP) in order to measure temperature distribution over a surface, which allowed for local impingement Nusselt number, film cooling effectiveness, and film cooling heat transfer enhancement profiles to be obtained. In addition to providing quantitative heat transfer data, this method allowed for qualitative investigation of the flow behavior near the test surface. Impinging jet-to-target-plate spacing was varied over a large range, including several tall impingement scenarios outside the published limits. Additionally, both in-line and staggered effusion arrangements were studied, and results for normal injection were compared to full coverage film cooling with inclined- and compound-angle injection. Effects of impingement and effusion cooling were combined to determine the overall cooling effectiveness of the system.It is shown that low impingement heights produce the highest Nusselt number, and that large jet-to-jet spacing reduces coolant flow rate while maintaining moderate to high heat transfer rates. Staggered effusion configurations exhibit superior performance to in-line configurations, as jet interference is reduced and surface area coverage is improved. Coolant to mainstream flow mass flux ratios greater than unity result in jet blow-off and reduced effectiveness. The convective heat transfer coefficient on the film cooled surface is higher than a similar surface without coolant injection due to the generation of turbulence associated with jet-cross flow interaction.
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Date Issued: 2011
Identifier: CFE0004140, ucf:49042
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004140

Title: INTERACTION BETWEEN SECONDARY FLOW AND FILM COOLING JETS OF A REALISTIC ANNULAR AIRFOIL CASCADE (HIGH MACH NUMBER).
Creator: Nguyen, Cuong, Kapat, Jayanta, University of Central Florida
Abstract / Description: Film cooling is investigated on a flat plate both numerically and experimentally. Conical shaped film hole are investigated extensively and contribute to the current literature data, which is extremely rare in the open public domain. Both configuration of the cylindrical film holes, with and without a trench, are investigated in detail. Design of experiment technique was performed to find an optimum combination of both geometrical and fluid parameters to achieve the best film cooling...
Show moreFilm cooling is investigated on a flat plate both numerically and experimentally. Conical shaped film hole are investigated extensively and contribute to the current literature data, which is extremely rare in the open public domain. Both configuration of the cylindrical film holes, with and without a trench, are investigated in detail. Design of experiment technique was performed to find an optimum combination of both geometrical and fluid parameters to achieve the best film cooling performance. From this part of the study, it shows that film cooling performance can be enhanced up to 250% with the trenched film cooling versus non-trenched case provided the same amount of coolant. Since most of the relevant open literature is about film cooling on flat plate endwall cascade with linear extrusion airfoil, the purpose of the second part of this study is to examine the interaction of the secondary flow inside a 3D cascade and the injected film cooling jets. This is employed on the first stage of the aircraft gas turbine engine to protect the curvilinear (annular) endwall platform. The current study investigates the interaction between injected film jets and the secondary flow both experimentally and numerically at high Mach number (M=0.7). Validation shows good agreement between obtained data with the open literature. In general, it can be concluded that with an appropriate film coolant to mainstream blowing ratio, one can not only achieve the best film cooling effectiveness (FCE or η) on the downstream endwall but also maintain almost the same aerodynamic loss as in the un-cooled baseline case. Film performance acts nonlinearly with respect to blowing ratios as with film cooling on flat plate, in the other hand, with a right blowing ratio, film cooling performance is not affect much by secondary flow. In turn, film cooling jets do not increase pressure loss at the downstream wake area of the blades.
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Date Issued: 2010
Identifier: CFE0003546, ucf:48944
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003546

Title: ALL-OPTICAL REGENERATION FOR PHASE-SHIFT KEYED OPTICAL COMMUNICATION SYSTEMS.
Creator: Croussore, Kevin, Li, Guifang, University of Central Florida
Abstract / Description: All-optical signal processing techniques for phase-shift keyed (PSK) systems were developed theoretically and demonstrated experimentally. Nonlinear optical effects in fibers, in particular four-wave mixing (FWM) that occurs via the ultra-fast Kerr nonlinearity, offer a flexible framework within which numerous signal processing functions can be accomplished. This research has focused on the regenerative capabilities of various FWM configurations in the context of processing PSK signals. Phase...
Show moreAll-optical signal processing techniques for phase-shift keyed (PSK) systems were developed theoretically and demonstrated experimentally. Nonlinear optical effects in fibers, in particular four-wave mixing (FWM) that occurs via the ultra-fast Kerr nonlinearity, offer a flexible framework within which numerous signal processing functions can be accomplished. This research has focused on the regenerative capabilities of various FWM configurations in the context of processing PSK signals. Phase-preserving amplitude regeneration, phase regeneration, and phase-regenerative wavelength conversion are analyzed and demonstrated experimentally. The single-pump phase-conjugation process was used to regenerate RZ-DPSK pulse amplitudes with different input noise distributions, and the impact on output phase characteristics was studied. Experiments revealed a limited range over which amplitude noise could effectively be suppressed without introduction of phase noise, particularly for signals with intensity pattern effects. Phase regeneration requires use of phase-sensitive amplification (PSA), which occurs in nonlinear interferometers when the pump and signal frequencies are degenerate (NI-PSA), or in fiber directly through single-stage (degenerate) or cascaded (non-degenerate) FWM processes. A PSA based on a Sagnac interferometer provided the first experimental demonstration of DPSK phase and amplitude regeneration. The phase-regenerative capabilities of the NI-PSA are limited in practice by intrinsic noise conversion (amplitude to phase noise) and to a lesser extent by the requirement to modulate the pump wave to suppress stimulated Brillouin scattering (SBS). These limitations are relaxed in novel materials with higher SBS thresholds and nonlinearities. Degenerate FWM provides PSA in a traveling-wave configuration that intrinsically suppresses the noise conversion affecting the NI-PSA, while providing stronger phase-matched gain. Experiments confirmed superior phase-regenerative behavior to the NI-PSA with simultaneous reduction of amplitude noise for NRZ-DPSK signals. Phase-regenerative wavelength conversion (PR-WC) provides the regenerative properties of PSA at a new wavelength, and was proposed and demonstrated for the first time in this research. The parallel implementation of two FWM processes, phase-conjugation and frequency conversion, provides two idlers which exhibit interesting and useful regenerative properties. These were investigated theoretically and experimentally. Ideal phase-regenerative behavior is predicted when the contributing FWM processes are equally phase-matched, which can be maintained over any interaction length or wavelength shift provided the pump powers are properly adjusted. Depleted-pump regime PR-WC provides simultaneous phase and amplitude regeneration. Experiments confirmed regenerative behavior for wavelength shifts of the idlers up to 5 nm. Two techniques for phase regeneration of 4-level PSK signals were developed and evaluated. The first is based on parallel operation of PSAs suitable for processing 2-level PSK signals, where phase projection and regeneration are combined to recover the input data. Analysis of this scheme outlined the conditions required for effective phase regeneration and for practical implementation using known PSAs. A novel process based on FWM (parallel phase-conjugation followed by PSA) was developed and analyzed, and demonstrated using numerical simulations. These studies provide a basis for further work in this area.
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Date Issued: 2007
Identifier: CFE0001923, ucf:47473
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001923

Title: CHARACTERIZATION OF POLYETHERIMIDE UNDER STATIC, DYNAMIC, AND MULTIPLE IMPACT CONDITIONS.
Creator: Zuanetti, Bryan, Gordon, Ali, University of Central Florida
Abstract / Description: The application of polymers in robust engineering designs is on the rise due to their excellent mechanical properties such as high fracture toughness, specific strength, durability, as well as, thermal and chemical resistances. Implementation of some advanced polymeric solids is limited due to the lack of available mechanical properties. In order for these materials to endure strenuous engineering designs it is vital to investigate their response in multiple loading rates and conditions. In...
Show moreThe application of polymers in robust engineering designs is on the rise due to their excellent mechanical properties such as high fracture toughness, specific strength, durability, as well as, thermal and chemical resistances. Implementation of some advanced polymeric solids is limited due to the lack of available mechanical properties. In order for these materials to endure strenuous engineering designs it is vital to investigate their response in multiple loading rates and conditions. In this thesis, the mechanical response of polyethermide (PEI) is characterized under quasi-static, high strain rate, and multiple impact conditions. Standard tension, torsion, and compression experiments are performed in order to distinguish the multi-regime response of PEI. The effects of physical ageing and rejuvenation on the quasi-static mechanical response are investigated. The strain softening regime resulting from strain localization is eliminated by thermal and mechanical rejuvenation, and the advantages of these processes are discussed. The dynamic fracture toughness of the material in response to notched impact via Charpy impact test is evaluated. The high strain-rate response of PEI to uniaxial compression is evaluated at rates exceeding 104/s via miniaturized Split Hopkinson Pressure Bar (MSHPB), and compared to the quasi-static case to determine strain-rate sensitivity. The elastic response of the aged material to multiple loading conditions are correlated using the Ramberg-Osgood equation, while the elastoplastic response of rejuvenated PEI is correlated using a both the Ramberg-Osgood equation and a novel model. The strain-rate sensitivity of the strength is found to be nominally bilinear and transition strains are modeled using the Ree-Erying formulation. Finally, multiple impact experiments are performed on PEI using the MSHPB and a model is proposed to quantify damage as a result of collision.
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Date Issued: 2013
Identifier: CFH0004531, ucf:45166
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004531

Title: Involvement of miRNAs in the Development of Androgen Independent Prostate Cancer.
Creator: Ottman, Richard, Chakrabarti, Ratna, Cole, Alexander, Khaled, Annette, Zervos, Antonis, University of Central Florida
Abstract / Description: Development of resistance to androgen deprivation therapy (ADT) is a major obstacle for the management of advanced prostate cancer. Therapies with androgen receptor (AR) antagonists and androgen withdrawal initially result in tumor regression but development of compensatory mechanisms including AR bypass signaling leads to tumor re-growth, independent of circulating androgens. The result is the emergence of castration resistant prostate cancer (CRPC), a highly morbid disease exhibiting...
Show moreDevelopment of resistance to androgen deprivation therapy (ADT) is a major obstacle for the management of advanced prostate cancer. Therapies with androgen receptor (AR) antagonists and androgen withdrawal initially result in tumor regression but development of compensatory mechanisms including AR bypass signaling leads to tumor re-growth, independent of circulating androgens. The result is the emergence of castration resistant prostate cancer (CRPC), a highly morbid disease exhibiting aberrant expression of many protein-coding and non-coding genes. Under the umbrella of non-coding RNAs is a class of small regulatory RNAs referred to as microRNAs (miRNAs). MicroRNAs are believed to function in the maintenance of cell homeostasis but are often differentially expressed in many different types of cancer including CRPC.In this study, the association of genome wide miRNA expression (1113 unique miRNAs) with development of resistance to ADT was determined. Androgen sensitive prostate cancer cells that progressed to ADT and AR antagonist Casodex (CDX) resistance upon androgen withdrawal and treatment with CDX were used. Validation of expression of a subset of 100 miRNAs led to identification of 43 miRNAs that are significantly altered during progression of cells to treatment resistance. A correlation of altered expression of 10 proteins targeted by some of these miRNAs in these cells was shown.Additionally, profiles of miRNA expressions in cancerous prostate tissues were created and compared with profiles of paired adjacent uninvolved areas of prostate tissue. Among the miRNAs identified from these analyses, a cluster of miRNAs, miR-17-92a, that is under-expressed in prostate tumors and in androgen independent prostate cancer cells was highlighted. The miR-17-92a cluster miRNAs are transcribed from a polycistronic transcription unit C13orf25 that generates six mature miRNAs: miR-17, miR-18a, miR-19a, miR-19b, miR-20a and miR-92a, and is commonly de-regulated in many cancers. In this research, the expression of miR-17-92a miRNAs was found to be reduced in cancerous prostate tissues when compared to uninvolved areas and also in aggressive prostate cancer cells. Restoration of expression of all members of miR-17-92a cluster showed decreased expression of cell cycle regulatory proteins cyclin D1 and SSH1; as well as LIMK1 and FGD4 of the RhoGTPase signaling pathway. Expression of miR-17-92a miRNAs caused decreased cell proliferation, reduced activation of AKT and MAP kinases, delayed tumorigenicity and reduced tumor growth in animals. Additionally, miR-17-92a miRNA expression inhibited EMT via reduced cell migration and expression of mesenchymal markers while elevating expression and surface localization of the epithelial marker e-cadherin. Expression of miR-17-92a miRNAs improved sensitivity of androgen dependent LNCaP104-S prostate cancer cells to the Androgen Receptor antagonist bicalutamide (CDX), AKT inhibitor MK-2206 2HCl, and docetaxel. Androgen refractory PC-3 cells also showed increased sensitivity to docetaxel, MK-2206 2HCl, and Aurora kinase inhibitor VX680 upon ectopic expression of miR-17-92a cluster miRNAs. In conclusion, dynamic alterations in miRNA expression occur early on during androgen deprivation therapy and androgen receptor blockade. The cumulative effect of these altered miRNA expression profiles is the temporal modulation of multiple signaling pathways promoting survival and acquisition of resistance. These early events are driving the transition to castration resistance and cannot be studied in already developed CRPC cell lines or tissues. Notably, these data demonstrate a tumor suppressor effect of miR-17-92a cluster miRNAs in prostate cancer cells and restoration of expression of these miRNAs has a therapeutic benefit for both androgen-dependent and -independent prostate cancer cells. Furthermore, these results can be used as a prognostic marker of cancers with a potential to be resistant to ADT.
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Date Issued: 2016
Identifier: CFE0006697, ucf:52866
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006697

Adiabatic Film Cooling Effectiveness (2)	+ -
Experimental (2)	+ -
Film Cooling (2)	+ -
Pressure Sensitive Paint (2)	+ -
film cooling (2)	+ -

heat transfer (2)	+ -
sensitivity (2)	+ -
temperature sensitive paint (2)	+ -
Adolescents (1)	+ -
Attraction (1)	+ -
Behavioral Intention Battery (1)	+ -
Borrelia burgdorferi (1)	+ -
Boundary Layer (1)	+ -
CFD (1)	+ -
CRPC (1)	+ -
Classification (1)	+ -
Contact resistance (1)	+ -
Contrast Sensitivity (1)	+ -
Control chart pattern recognition (1)	+ -
Convective Heat Transfer (1)	+ -
Cost-sensitive learning (1)	+ -
Desensitization (1)	+ -
Dynamic Visual Acuity (1)	+ -
ELLs (1)	+ -
Electric Vehicles (1)	+ -
Electromyography (1)	+ -
English language learners (1)	+ -
Epithelial messenchymal transition (1)	+ -
Florida Association of School Psychologists (1)	+ -
Full-Coverage (1)	+ -

ETD Collection (24)	+ -
Honors Collection (5)	+ -

University of Central Florida (29)	+ -
Kapat, Jayanta (5)	+ -
Raghavan, Seetha (3)	+ -
Chakrabarti, Ratna (2)	+ -
Gordon, Ali (2)	+ -

Natsui, Gregory (2)	+ -
Vasu Sumathi, Subith (2)	+ -
, (1)	+ -
Arnaud, Anke (1)	+ -
Ballantyne, John (1)	+ -
Bennis, Mohammed (1)	+ -
Biraimah, Karen (1)	+ -
CATBAS, NECATI (1)	+ -
Calderon, Luisana (1)	+ -
Catbas, F. Necati (1)	+ -
Cole, Alexander (1)	+ -
Croussore, Kevin (1)	+ -
Cunningham, Glenn (1)	+ -
Deng, Weiwei (1)	+ -
Eckstein, H. Christopher (1)	+ -
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Gilton, Katie (1)	+ -
Halpern, Micah (1)	+ -
Hasan, Md Faqrul (1)	+ -

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