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Pages
- Title
- Explicit Feedback Within Game-Based Training: Examining the Influence of Source Modality Effects on Interaction.
- Creator
-
Goldberg, Benjamin, Bowers, Clint, Cannon-Bowers, Janis, Kincaid, John, McDaniel, Thomas, Sottilare, Robert, University of Central Florida
- Abstract / Description
-
This research aims to enhance Simulation-Based Training (SBT) applications to support training events in the absence of live instruction. The overarching purpose is to explore available tools for integrating intelligent tutoring communications in game-based learning platforms and to examine theory-based techniques for delivering explicit feedback in such environments. The primary tool influencing the design of this research was the Generalized Intelligent Framework for Tutoring (GIFT), a...
Show moreThis research aims to enhance Simulation-Based Training (SBT) applications to support training events in the absence of live instruction. The overarching purpose is to explore available tools for integrating intelligent tutoring communications in game-based learning platforms and to examine theory-based techniques for delivering explicit feedback in such environments. The primary tool influencing the design of this research was the Generalized Intelligent Framework for Tutoring (GIFT), a modular domain-independent architecture that provides the tools and methods to author, deliver, and evaluate intelligent tutoring technologies within any training platform. Influenced by research surrounding Social Cognitive Theory and Cognitive Load Theory, the resulting experiment tested varying approaches for utilizing an Embodied Pedagogical Agent (EPA) to function as a tutor during interaction in a game-based environment. Conditions were authored to assess the tradeoffs between embedding an EPA directly in a game, embedding an EPA in GIFT's browser-based Tutor-User Interface (TUI), or using audio prompts alone with no social grounding.The resulting data supports the application of using an EPA embedded in GIFT's TUI to provide explicit feedback during a game-based learning event. Analyses revealed conditions with an EPA situated in the TUI to be as effective as embedding the agent directly in the game environment. This inference is based on evidence showing reliable differences across conditions on the metrics of performance and self-reported mental demand and feedback usefulness items. This research provides source modality tradeoffs linked to tactics for relaying training relevant explicit information to a user based on real-time performance in a game.
Show less - Date Issued
- 2013
- Identifier
- CFE0004850, ucf:49696
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004850
- Title
- THE RELATIONSHIP BETWEEN GENRE CHOICE OF MUSIC AND ALTRUISTIC BEHAVIOR.
- Creator
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Hippler, Christine, Whitten, Shannon, University of Central Florida
- Abstract / Description
-
ABSTRACT Extensive research has documented the relationship between listening to certain genres of music and negative effects on social behavior such as aggressive and antisocial behavior. The present study explored whether there are genres of music associated with altruism. Altruistic behavior is defined as behavior that is consistently more caring, helpful, considerate of other's feelings, and self- sacrificing. These behaviors promote our ability to thrive as a community. Yet, few studies...
Show moreABSTRACT Extensive research has documented the relationship between listening to certain genres of music and negative effects on social behavior such as aggressive and antisocial behavior. The present study explored whether there are genres of music associated with altruism. Altruistic behavior is defined as behavior that is consistently more caring, helpful, considerate of other's feelings, and self- sacrificing. These behaviors promote our ability to thrive as a community. Yet, few studies have addressed the relationship between music and altruism. Data was collected from 608 college students who completed a self-report altruism scale, music preference measure, the Marlowe Crowne social desirability scale, and a demographic information form in order to see if there is a relationship between choice of music and altruism. A multiple hierarchal regression analysis found music genre choice accounted for 15.9 percent of variance in self-reported altruism. Significant, positive correlations emerged also between altruism and several music genres including alternative, country, classical, and emo.
Show less - Date Issued
- 2011
- Identifier
- CFH0003820, ucf:44753
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0003820
- Title
- Nonlinear dynamic modeling, simulation and characterization of the mesoscale neuron-electrode interface.
- Creator
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Thakore, Vaibhav, Hickman, James, Mucciolo, Eduardo, Rahman, Talat, Johnson, Michael, Behal, Aman, Molnar, Peter, University of Central Florida
- Abstract / Description
-
Extracellular neuroelectronic interfacing has important applications in the fields of neural prosthetics, biological computation and whole-cell biosensing for drug screening and toxin detection. While the field of neuroelectronic interfacing holds great promise, the recording of high-fidelity signals from extracellular devices has long suffered from the problem of low signal-to-noise ratios and changes in signal shapes due to the presence of highly dispersive dielectric medium in the neuron...
Show moreExtracellular neuroelectronic interfacing has important applications in the fields of neural prosthetics, biological computation and whole-cell biosensing for drug screening and toxin detection. While the field of neuroelectronic interfacing holds great promise, the recording of high-fidelity signals from extracellular devices has long suffered from the problem of low signal-to-noise ratios and changes in signal shapes due to the presence of highly dispersive dielectric medium in the neuron-microelectrode cleft. This has made it difficult to correlate the extracellularly recorded signals with the intracellular signals recorded using conventional patch-clamp electrophysiology. For bringing about an improvement in the signal-to-noise ratio of the signals recorded on the extracellular microelectrodes and to explore strategies for engineering the neuron-electrode interface there exists a need to model, simulate and characterize the cell-sensor interface to better understand the mechanism of signal transduction across the interface. Efforts to date for modeling the neuron-electrode interface have primarily focused on the use of point or area contact linear equivalent circuit models for a description of the interface with an assumption of passive linearity for the dynamics of the interfacial medium in the cell-electrode cleft. In this dissertation, results are presented from a nonlinear dynamic characterization of the neuroelectronic junction based on Volterra-Wiener modeling which showed that the process of signal transduction at the interface may have nonlinear contributions from the interfacial medium. An optimization based study of linear equivalent circuit models for representing signals recorded at the neuron-electrode interface subsequently proved conclusively that the process of signal transduction across the interface is indeed nonlinear. Following this a theoretical framework for the extraction of the complex nonlinear material parameters of the interfacial medium like the dielectric permittivity, conductivity and diffusivity tensors based on dynamic nonlinear Volterra-Wiener modeling was developed. Within this framework, the use of Gaussian bandlimited white noise for nonlinear impedance spectroscopy was shown to offer considerable advantages over the use of sinusoidal inputs for nonlinear harmonic analysis currently employed in impedance characterization of nonlinear electrochemical systems. Signal transduction at the neuron-microelectrode interface is mediated by the interfacial medium confined to a thin cleft with thickness on the scale of 20-110 nm giving rise to Knudsen numbers (ratio of mean free path to characteristic system length) in the range of 0.015 and 0.003 for ionic electrodiffusion. At these Knudsen numbers, the continuum assumptions made in the use of Poisson-Nernst-Planck system of equations for modeling ionic electrodiffusion are not valid. Therefore, a lattice Boltzmann method (LBM) based multiphysics solver suitable for modeling ionic electrodiffusion at the mesoscale neuron-microelectrode interface was developed. Additionally, a molecular speed dependent relaxation time was proposed for use in the lattice Boltzmann equation. Such a relaxation time holds promise for enhancing the numerical stability of lattice Boltzmann algorithms as it helped recover a physically correct description of microscopic phenomena related to particle collisions governed by their local density on the lattice. Next, using this multiphysics solver simulations were carried out for the charge relaxation dynamics of an electrolytic nanocapacitor with the intention of ultimately employing it for a simulation of the capacitive coupling between the neuron and the planar microelectrode on a microelectrode array (MEA). Simulations of the charge relaxation dynamics for a step potential applied at t = 0 to the capacitor electrodes were carried out for varying conditions of electric double layer (EDL) overlap, solvent viscosity, electrode spacing and ratio of cation to anion diffusivity. For a large EDL overlap, an anomalous plasma-like collective behavior of oscillating ions at a frequency much lower than the plasma frequency of the electrolyte was observed and as such it appears to be purely an effect of nanoscale confinement. Results from these simulations are then discussed in the context of the dynamics of the interfacial medium in the neuron-microelectrode cleft. In conclusion, a synergistic approach to engineering the neuron-microelectrode interface is outlined through a use of the nonlinear dynamic modeling, simulation and characterization tools developed as part of this dissertation research.
Show less - Date Issued
- 2012
- Identifier
- CFE0004797, ucf:49718
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004797
- Title
- DIFFRACTION STUDIES OF DEFORMATION IN SHAPE MEMORY ALLOYS AND SELECTED ENGINEERING COMPONENTS.
- Creator
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RATHOD, CHANDRASEN, Vaidyanathan, Raj, University of Central Florida
- Abstract / Description
-
Deformation phenomena in shape memory alloys involve stress-, temperature-induced phase transformations and crystallographic variant conversion or reorientation, equivalent to a twinning operation. In near equiatomic NiTi, Ti rich compositions can exist near room temperature as a monoclinic B19' martensitic phase, which when deformed undergoes twinning resulting in strains as large as 8%. Upon heating, the martensite transforms to a cubic B2 austenitic phase, thereby recovering the strain and...
Show moreDeformation phenomena in shape memory alloys involve stress-, temperature-induced phase transformations and crystallographic variant conversion or reorientation, equivalent to a twinning operation. In near equiatomic NiTi, Ti rich compositions can exist near room temperature as a monoclinic B19' martensitic phase, which when deformed undergoes twinning resulting in strains as large as 8%. Upon heating, the martensite transforms to a cubic B2 austenitic phase, thereby recovering the strain and exhibiting the shape memory effect. Ni rich compositions on the other hand can exist near room temperature in the austenitic phase and undergo a reversible martensitic transformation on application of stress. Associated with this reversible martensitic transformation are macroscopic strains, again as large as 8%, which are also recovered and resulting in superelasticity. This work primarily focuses on neutron diffraction measurements during loading at the Los Alamos Neutron Science Center at Los Alamos National Laboratory. Three phenomena were investigated: First, the phenomena of hysteresis reduction and increase in linearity with increasing plastic deformation in superelastic NiTi. There is usually a hysteresis associated with the forward and reverse transformations in superelastic NiTi which translates to a hysteresis in the stress-strain curve during loading and unloading. This hysteresis is reduced in cold-worked NiTi and the macroscopic stress-strain response is more linear. This work reports on measurements during loading and unloading in plastically deformed (up to 11%) and cycled NiTi. Second, the tension-compression stress-strain asymmetry in martensitic NiTi. This work reports on measurements during tensile and compressive loading of polycrystalline shape-memory martensitic NiTi with no starting texture. Third, a heterogeneous stress-induced phase transformation in superelastic NiTi. Measurements were performed on a NiTi disc specimen loaded laterally in compression and associated with a macroscopically heterogeneous stress state. For the case of superelastic NiTi, the experiments related the macroscopic stress-strain behavior (from an extensometer or an analytical approach) with the texture, phase volume fraction and strain evolution (from neutron diffraction spectra). For the case of shape memory NiTi, the macroscopic connection was made with the texture and strain evolution due to twinning and elastic deformation in martensitic NiTi. In all cases, this work provided for the first time insight into atomic-scale phenomena such as mismatch accommodation and martensite variant selection. The aforementioned technique of neutron diffraction for mechanical characterization was also extended to engineering components and focused mainly on the determination of residual strains. Two samples were investigated and presented in this work; first, a welded INCONEL 718 NASA space shuttle flow liner was studied at 135 K and second, Ti-6Al-4V turbine blade components were investigated for Siemens Westinghouse Power Corporation. Lastly, also reported in this dissertation is a refinement of the methodology established in the author's masters thesis at UCF that used synchrotron x-ray diffraction during loading to study superelastic NiTi. The Los Alamos Neutron Science Center is a national user facility funded by the United States Department of Energy, Office of Basic Energy Sciences, under Contract No. W-7405-ENG-36. The work reported here was made possible by grants to UCF from NASA (NAG3-2751), NSF CAREER (DMR-0239512), Siemens Westinghouse Power Corporation and the Space Research Initiative.
Show less - Date Issued
- 2005
- Identifier
- CFE0000723, ucf:46608
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000723
- Title
- THE IMPACT OF MEDITATION AND MINDFULNESS IN THE ELEMENTARY CLASSROOM: A REVIEW OF RESEARCH LITERATURE ACROSS FIVE DISCIPLINES.
- Creator
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Routhier-Martin, Kayli, Killingsworth Roberts, Sherron, University of Central Florida
- Abstract / Description
-
Mindfulness meditation programs, benefits, and outcomes were examined through research previously conducted and published by professionals within five differing disciplines: health and wellness, psychology, elementary education, exceptional education, and medicine. The goal was to find common themes within the differing disciplines in order to gather information about the effectiveness of a mindfulness meditation program to be used in an elementary classroom. In this thesis, the chapter of...
Show moreMindfulness meditation programs, benefits, and outcomes were examined through research previously conducted and published by professionals within five differing disciplines: health and wellness, psychology, elementary education, exceptional education, and medicine. The goal was to find common themes within the differing disciplines in order to gather information about the effectiveness of a mindfulness meditation program to be used in an elementary classroom. In this thesis, the chapter of Health and Wellness is a review of literature that tells the benefits found within meditators, which are not found within non-meditators. The chapter of Psychology explains the social-emotional needs of students, the causes of stress and anxieties amongst students, and the benefits that meditation provides in order to counter the negative effects of stress, anxiety, poverty, etc. The chapter of Elementary Education reviews research literature on the existing mindfulness meditation programs within the United States. This chapter also describes the implementation of such a program in an elementary school, as well as the documented data of the outcomes of the programs. The chapter of Exceptional Education is a review of the research literature on the benefits mindfulness meditation has on students with exceptionalities, such as specific learning disabilities, attention deficit hyperactivity disorder, and autism spectrum disorder. The chapter of Medicine is a retelling of previously published scholarly articles that list the neurological benefits of meditation, and also references the negative side effects to the currently prescribed medications that are being used in the treatment of ADHD.
Show less - Date Issued
- 2015
- Identifier
- CFH0004877, ucf:45424
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004877
- Title
- CLAIMS OF MISTAKEN IDENTITY:AN EXAMINATION OF U.S. TELEVISION FOOD COMMERCIALS AND THE ADULT OBESITY ISSUE.
- Creator
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Delgado, Cristina, DeLorme, Denise, University of Central Florida
- Abstract / Description
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Obesity is one of the major public health issues in the United States, often regarded as part of a global crisis. Companies invest billions of dollars each year towards television advertising campaigns aimed at convincing audiences how their ground-breaking discovery 'battles the bulge' or somehow offers an increased health benefit. This study examined how advertisers presented health-related claims, including health and nutrient-content claims, in U.S. adult-targeted television food...
Show moreObesity is one of the major public health issues in the United States, often regarded as part of a global crisis. Companies invest billions of dollars each year towards television advertising campaigns aimed at convincing audiences how their ground-breaking discovery 'battles the bulge' or somehow offers an increased health benefit. This study examined how advertisers presented health-related claims, including health and nutrient-content claims, in U.S. adult-targeted television food commercials. The claims were compared to FTC, FDA, and USDA laws, regulations, and recommendations. A content analysis of food advertising was conducted of commercials from major and cable network programs broadcast during prime-time in the first quarter of 2009. The majority of claims match current regulations when compared to Federal references. The results show that Nutrient and Wellness claims were the most frequently cited. The type of benefit, Healthy Eating, emerged almost 3 times more than any other benefit type. This is also similar to those results which suggest advertisers' intentions were to promote overall wellness in their content delivery. As such, the Wellness Approach was identified and conceptualized, leading towards full development of a Wellness Effect theory. Implications and future research opportunities are discussed on both a theoretical and practical level.
Show less - Date Issued
- 2009
- Identifier
- CFE0002565, ucf:48260
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002565
- Title
- THE RELATIONSHIP OF 10TH-GRADE DISTRICT PROGRESS MONITORING ASSESSMENT SCORES TO FLORIDA COMPREHENSIVE ASSESSMENT TEST SCORES IN READING AND MATHEMATICS FOR 2008-2009.
- Creator
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Underwood, Marilyn, Taylor, Rosemarye, University of Central Florida
- Abstract / Description
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The focus of this research was to investigate the use of a district created formative benchmark assessment in reading to predict student achievement for 10th-grade students on the Florida Comprehensive Assessment Test (FCAT) in one county in north central Florida. The purpose of the study was to provide information to high school principals and teachers to better understand how students were performing and learning and to maximize use of the formative district benchmark assessment in order to...
Show moreThe focus of this research was to investigate the use of a district created formative benchmark assessment in reading to predict student achievement for 10th-grade students on the Florida Comprehensive Assessment Test (FCAT) in one county in north central Florida. The purpose of the study was to provide information to high school principals and teachers to better understand how students were performing and learning and to maximize use of the formative district benchmark assessment in order to modify instruction and positively impact student achievement. This study expanded a prior limited study which correlated district benchmark assessment scores to FCAT scores for students in grades three through five in five elementary schools in the targeted county. The high correlations suggested further study. This research focused on secondary reading, specifically in 10th grade where both state and targeted county FCAT scores were low in years preceding this research. Investigated were (a) the district formative assessment in reading as a predictor of FCAT Reading scores, (b) differences in strength of correlation and prediction among student subgroups and between high schools, and (c) any relationships between reading formative assessment scores and Mathematics FCAT scores. An additional focus of this study was to determine best leadership practices in schools where there were the highest correlations between the formative assessment and FCAT Reading scores. Research on best practices was reviewed, and principals were interviewed to determine trends and themes in practice. Tenth grade students in the seven Florida targeted district high schools were included in the study. The findings of the study supported the effective use of formative assessments both in instruction and as predictors of studentsÂÂÂÂÂÂ' performance on the FCAT. The results of the study also showed a significant correlation between performance on the reading formative assessment and performance on FCAT Mathematics. The data indicated no significant differences in the strength of correlation between student subgroups or between the high schools included in the study. Additionally, the practices of effective principals in using formative assessment data to inform instruction, gathered through personal interviews, were documented and described.
Show less - Date Issued
- 2010
- Identifier
- CFE0003214, ucf:48573
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003214
- Title
- Fabrication and Study of Graphene-Based Nanocomposites for Sensing and Energy Applications.
- Creator
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McInnis, Matthew, Zhai, Lei, Yestrebsky, Cherie, Zou, Shengli, Blair, Richard, Chen, Quanfang, University of Central Florida
- Abstract / Description
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Graphite is an allotrope of carbon made up of atomically thin sheets, each covalently bound together, forming a ?-conjugated network. An individual layer, called graphene, has extraordinary electrical, thermal and physical properties that provide the opportunity for innovating new functional composites. Graphene can be produced directly on a metallic substrate by chemical vapor deposition or by chemical oxidation of graphite, forming a stable aqueous suspension of graphene oxide (GO), which...
Show moreGraphite is an allotrope of carbon made up of atomically thin sheets, each covalently bound together, forming a ?-conjugated network. An individual layer, called graphene, has extraordinary electrical, thermal and physical properties that provide the opportunity for innovating new functional composites. Graphene can be produced directly on a metallic substrate by chemical vapor deposition or by chemical oxidation of graphite, forming a stable aqueous suspension of graphene oxide (GO), which allows for convenient solution processing techniques. For the latter, after thermal or chemical reduction, much of the properties of the starting graphene re-emerge due to the reestablishment of ?-conjugation. The ?-conjugated basal plane of graphene has been shown to influence the crystallization of ?-conjugated polymers, providing thermodynamically strong nucleation sites through the relatively strong ?-? interactions. These polymers can homocrystallize into 1-D filaments, but when nucleated from graphene, the orientation and geometry can be controlled producing hierarchical structures containing an electrical conductor decorated with wires of semi-conducting polymer. The resulting structures and crystallization kinetics of the conjugated polymer, poly(3-hexylthiophene-2,5-diyl) (P3HT) nucleated by graphene was studied. Further, field-effect transistors were developed using graphene as both the electrodes and the polymer crystallization surface to directly grow P3HT nanowires as the active material. This direct crystallization technique lead to higher charge mobility and higher on-off ratios, and this result was interpreted in terms of the morphology and polymer-graphene interface.Besides these thin-film technologies, neat GO suspensions can be lyophilized to produce monolithic, free-standing aerogels and then reduced to produce an electrically conductive porous material with a surface area greater than 1000 m2/g. The present research focuses on functionalizing the aerogel surfaces with metal nanoparticles to increase electrical conductivity and to impart functionality. Functionalization was carried out by adding a metal salt as a precursor and a chelating agent to inhibit GO flocculation. The GO and metal salt were simultaneously reduced to form rGO aerogels homogeneously loaded with metal nanoparticles. The size and distribution of these nanoparticles was controlled by concentration and chelating agent identity and abundance. Optimum aerogel formulations were used as a functioning and reversible conductometric hydrogen gas sensor and as an anode in an asymmetric supercapacitor with excellent properties.
Show less - Date Issued
- 2015
- Identifier
- CFE0006227, ucf:51066
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006227
- Title
- Structure, stability, vibrational, thermodynamic, and catalytic properties of metal nanostructures: size, shape, support, and adsorbate effects.
- Creator
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Behafarid, Farzad, Roldan Cuenya, Beatriz, Chow, Lee, Heinrich, Helge, Kara, Abdelkader, Schoenfeld, Winston, University of Central Florida
- Abstract / Description
-
Recent advances in nanoscience and nanotechnology have provided the scientific community with exciting new opportunities to rationally design and fabricate materials at the nanometer scale with drastically different properties as compared to their bulk counterparts. In this dissertation, several challenges have been tackled in aspects related to nanoparticle (NP) synthesis and characterization, allowing us to make homogenous, size- and shape-selected NPs via the use of colloidal chemistry,...
Show moreRecent advances in nanoscience and nanotechnology have provided the scientific community with exciting new opportunities to rationally design and fabricate materials at the nanometer scale with drastically different properties as compared to their bulk counterparts. In this dissertation, several challenges have been tackled in aspects related to nanoparticle (NP) synthesis and characterization, allowing us to make homogenous, size- and shape-selected NPs via the use of colloidal chemistry, and to gain in depth understanding of their distinct physical and chemical properties via the synergistic use of a variety of ex situ, in situ, and operando experimental tools. A variety of phenomena relevant to nanosized materials were investigated, including the role of the NP size and shape in the thermodynamic and electronic properties of NPs, their thermal stability, NP-support interactions, coarsening phenomena, and the evolution of the NP structure and chemical state under different environments and reaction conditions.
Show less - Date Issued
- 2012
- Identifier
- CFE0004779, ucf:49796
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004779
- Title
- TRAFFIC SAFETY ASSESSMENT OF DIFFERENT TOLL COLLECTION SYSTEMS ON EXPRESSWAYS USING MULTIPLE ANALYTICAL TECHNIQUES.
- Creator
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Abuzwidah, Muamer, Abdel-Aty, Mohamed, Radwan, Essam, Uddin, Nizam, University of Central Florida
- Abstract / Description
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Traffic safety has been considered one of the most important issues in the transportation field. Crashes have caused extensive human and economic losses. With the objective of reducing crash occurrence and alleviating crash injury severity, major efforts have been dedicated to reveal the hazardous factors that affect crash occurrence. With these consistent efforts, both fatalities and fatality rates from road traffic crashes in many countries have been steadily declining over the last ten...
Show moreTraffic safety has been considered one of the most important issues in the transportation field. Crashes have caused extensive human and economic losses. With the objective of reducing crash occurrence and alleviating crash injury severity, major efforts have been dedicated to reveal the hazardous factors that affect crash occurrence. With these consistent efforts, both fatalities and fatality rates from road traffic crashes in many countries have been steadily declining over the last ten years. Nevertheless, according to the World Health Organization, the world still lost 1.24 million lives from road traffic crashes in the year of 2013. And without action, traffic crashes on the roads network are predicted to result in deaths of around 1.9 million people, and up to 50 million more people suffer non-fatal injuries annually, with many incurring a disability as a result of their injury by the year 2020. To meet the transportation needs, the use of expressways (toll roads) has risen dramatically in many countries in the past decade. In fact, freeways and expressways are considered an important part of any successful transportation system. These facilities carry the majority of daily trips on the transportation network. Although expressways offer high level of service, and are considered the safest among other types of roads, traditional toll collection systems may have both safety and operational challenges. The traditional toll plazas still experience many crashes, many of which are severe. Therefore, it becomes more important to evaluate the traffic safety impacts of using different tolling systems. The main focus of the research in this dissertation is to provide an up-to-date safety impact of using different toll collection systems, as well as providing safety guidelines for these facilities to promote safety and enhance mobility on expressways. In this study, an extensive data collection was conducted that included one hundred mainline toll plazas located on approximately 750 miles of expressways in Florida. Multiple sources of data available online maintained by Florida Department of Transportation were utilized to identify traffic, geometric and geographic characteristics of the locations as well as investigating and determination of the most complete and accurate data. Different methods of observational before-after and Cross-Sectional techniques were used to evaluate the safety effectiveness of applying different treatments on expressways. The Before-After method includes Na(&)#239;ve Before-After, Before-After with Comparison Group, and Before-After with Empirical Bayesian. A set of Safety Performance Functions (SPFs) which predict crash frequency as a function of explanatory variables were developed at the aggregate level using crash data and the corresponding exposure and risk factors. Results of the aggregate traffic safety analysis can be used to identify the hazardous locations (hot spots) such as traditional toll plazas, and also to predict crash frequency for untreated sites in the after period in the Before-After with EB method or derive Crash Modification Factors (CMF) for the treatment using the Cross-Sectional method. This type of analysis is usually used to improve geometric characteristics and mainly focus on discovering the risk factors that are related to the total crash frequency, specific crash type, and/or different crash severity levels. Both simple SPFs (with traffic volume only as an explanatory variable) and full SPFs (with traffic volume and additional explanatory variable(s)) were used to estimate the CMFs and only CMFs with lower standard error were recommended.The results of this study proved that safety effectiveness was significantly improved across all locations that were upgraded from Traditional Mainline Toll Plazas (TMTP) to the Hybrid Mainline Toll Plazas (HMTP) system. This treatment significantly reduced total, Fatal-and-Injury (F+I), and Rear-End crashes by 47, 46 and 65 percent, respectively. Moreover, this study examined the traffic safety impact of using different designs, and diverge-and-merge areas of the HMTP. This design combines either express Open Road Tolling (ORT) lanes on the mainline and separate traditional toll collection to the side (design-1), or traditional toll collection on the mainline and separate ORT lanes to the side (design-2). It was also proven that there is a significant difference between these designs, and there is an indication that design-1 is safer and the majority of crashes occurred at diverge-and-merge areas before and after these facilities. However, design-2 could be a good temporary design at locations that have low prepaid transponder (Electronic Toll Collection (ETC)) users. In other words, it is dependent upon the percentage of the ETC users. As this percentage increases, more traffic will need to diverge and merge; thus, this design becomes riskier. In addition, the results indicated significant relationships between the crash frequency and toll plaza types, annual average daily traffic, and drivers' age. The analysis showed that the conversion from TMTP to the All-Electronic Toll Collection (AETC) system resulted in an average reduction of 77, 76, and 67 percent for total, F+I, and Property Damage Only (PDO) crashes, respectively; for rear end and Lane Change Related (LCR) crashes the average reductions were 81 and 75 percent, respectively. The conversion from HMTP to AETC system enhanced traffic safety by reducing crashes by an average of 23, 29 and 19 percent for total, F+I, and PDO crashes; also, for rear end and LCR crashes, the average reductions were 15 and 21 percent, respectively. Based on these results, the use of AETC system changed toll plazas from the highest risk sections on Expressways to be similar to regular segments. Therefore, it can be concluded that the use of AETC system was proven to be an excellent solution to several traffic operations as well as environmental and economic problems. For those agencies that cannot adopt the HMTP and the AETC systems, improving traffic safety at traditional toll plazas should take a priority.This study also evaluates the safety effectiveness of the implementation of High-Occupancy Toll lanes (HOT Lanes) as well as adding roadway lighting to expressways. The results showed that there were no significant impact of the implementation of HOT lanes on the roadway segment as a whole (HOT and Regular Lanes combined). But there was a significant difference between the regular lanes and the HOT lanes at the same roadway segment; the crash count increased at the regular lanes and decreased at the HOT lanes. It was found that the total and F+I crashes were reduced at the HOT lanes by an average of 25 and 45 percent, respectively. This may be attributable to the fact that the HOT lanes became a highway within a highway. Moreover adding roadway lighting has significantly improved traffic safety on the expressways by reducing the night crashes by approximately 35 percent.Overall, the proposed analyses of the safety effectiveness of using different toll collection systems are useful in providing expressway authorities with detailed information on where countermeasures must be implemented. This study provided for the first time an up-to-date safety impact of using different toll collection systems, also developed safety guidelines for these systems which would be useful for practitioners and roadway users.
Show less - Date Issued
- 2014
- Identifier
- CFE0005751, ucf:50100
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005751
- Title
- Chlamydia trachomatis Transformants Show a Significant Reduction in Rates of Invasion upon Removal of Key Tarp Domains.
- Creator
-
Parrett, Christopher, Jewett, Travis, Roy, Herve, Moore, Sean, University of Central Florida
- Abstract / Description
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Chlamydia trachomatis is an obligate, intracellular bacterium which is known to cause multiple human infections including nongonococcal urethritis (serovars D-K), lymphogranuloma venereum (serovars L1, L2, L3) and trachoma (serovars A-C). The infectious form of the bacterium, called the elementary body (EB), harbors a type III secreted effector known as Tarp (translocated actin recruiting phosphoprotein) which is a candidate virulence factor and is hypothesized to play a role in C....
Show moreChlamydia trachomatis is an obligate, intracellular bacterium which is known to cause multiple human infections including nongonococcal urethritis (serovars D-K), lymphogranuloma venereum (serovars L1, L2, L3) and trachoma (serovars A-C). The infectious form of the bacterium, called the elementary body (EB), harbors a type III secreted effector known as Tarp (translocated actin recruiting phosphoprotein) which is a candidate virulence factor and is hypothesized to play a role in C. trachomatis' ability to invade and grow within epithelial cells in a human host. C. trachomatis L2 Tarp harbors five unique protein domains which include the Phosphorylation Domain, the Proline Rich Domain, the Actin Binding Domain, and two F-Actin Binding Domains. Tarp has been biochemically characterized in vitro, but it has yet to be characterized in vivo due to a lack of genetic tools in C. trachomatis. Through the recent generation of a chlamydial transformation system, we have created transformants which express epitope tagged wild type or mutant Tarp effectors. In this thesis, C. trachomatis transformants expressing Tarp lacking one of the five biochemically defined protein domains were used to examine both bacterial invasion and bacterial development within mammalian host cells. Our results demonstrate that those EBs which harbor mutant Tarp missing either its Phosphorylation Domain or its Actin Binding Domain were less capable of host cell invasion. However, these transformants, once internalized, were capable of normal development when compared to wild type C. trachomatis or C. trachomatis harboring an epitope tagged wild type Tarp effector. These results suggest that transformant expressed Tarp lacking the Phosphorylation Domain or Actin Binding Domain may be acting as a dominant-negative effector protein. Ultimately, these results support the hypothesis that Tarp is a virulence factor for Chlamydia trachomatis. Furthermore, this data indicates that through the manipulation of the Tarp effector, C. trachomatis pathogenesis may be attenuated.
Show less - Date Issued
- 2016
- Identifier
- CFE0006159, ucf:51142
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006159
