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- Title
- Assessment Center Structure and Construct Validity: A New Hope.
- Creator
-
Wiese, Christopher, Jentsch, Kimberly, Salas, Eduardo, Jentsch, Florian, Burke, Shawn, University of Central Florida
- Abstract / Description
-
Assessment Centers (ACs) are a fantastic method to measure behavioral indicators of job performance in multiple diverse scenarios. Based upon a thorough job analysis, ACs have traditionally demonstrated very strong content and criterion-related validity. However, researchers have been puzzled for over three decades with the lack of evidence concerning construct validity. ACs are designed to measure critical job dimensions throughout multiple situational exercises. However, research has...
Show moreAssessment Centers (ACs) are a fantastic method to measure behavioral indicators of job performance in multiple diverse scenarios. Based upon a thorough job analysis, ACs have traditionally demonstrated very strong content and criterion-related validity. However, researchers have been puzzled for over three decades with the lack of evidence concerning construct validity. ACs are designed to measure critical job dimensions throughout multiple situational exercises. However, research has consistently revealed that different behavioral ratings within these scenarios are more strongly related to one another (exercise effects) than the same dimension rating across scenarios (dimension effects). That is, results from ACs suggest that we are unsure of what these behavioral measures represent. Over the last three decades, researchers have sought to illuminate why same dimension ratings are inconsistent across scenarios. However, these investigations have been limited to changes influencing the source of the ratings (e.g., assessors, trained raters). No approach has been taken to change the structure of the AC. This study breaks with tradition and introduces a structurally different AC: A Day-In-The Life AC (DITLAC). A DITLAC structure is designed to mimic that of a normal day on the job. In the present study, the construct validity between a DITLAC and a traditionally structured AC is compared with the argument that the DITLAC will demonstrate stronger construct validity evidence. In several cases, this was found to be true.
Show less - Date Issued
- 2015
- Identifier
- CFE0005905, ucf:50878
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005905
- Title
- DESIGN AND MODELING OF RADIATION HARDENED LDMOSFET FOR SPACE CRAFT POWER SYSTEMS.
- Creator
-
Shea, Patrick, Shen, John, University of Central Florida
- Abstract / Description
-
NASA missions require innovative power electronics system and component solutions with long life capability, high radiation tolerance, low mass and volume, and high reliability in space environments. Presently vertical double-diffused MOSFETs (VDMOS) are the most widely used power switching device for space power systems. It is proposed that a new lateral double-diffused MOSFET (LDMOS) designed at UCF can offer improvements in total dose and single event radiation hardness, switching...
Show moreNASA missions require innovative power electronics system and component solutions with long life capability, high radiation tolerance, low mass and volume, and high reliability in space environments. Presently vertical double-diffused MOSFETs (VDMOS) are the most widely used power switching device for space power systems. It is proposed that a new lateral double-diffused MOSFET (LDMOS) designed at UCF can offer improvements in total dose and single event radiation hardness, switching performance, development and manufacturing costs, and total mass of power electronics systems. Availability of a hardened fast-switching power MOSFET will allow space-borne power electronics to approach the current level of terrestrial technology, thereby facilitating the use of more modern digital electronic systems in space. It is believed that the use of a p+/p-epi starting material for the LDMOS will offer better hardness against single-event burnout (SEB) and single-event gate rupture (SEGR) when compared to vertical devices fabricated on an n+/n-epi material. By placing a source contact on the bottom-side of the p+ substrate, much of the hole current generated by a heavy ion strike will flow away from the dielectric gate, thereby reducing electrical stress on the gate and decreasing the likelihood of SEGR. Similarly, the device is hardened against SEB by the redirection of hole current away from the base of the device's parasitic bipolar transistor. Total dose hardness is achieved by the use of a standard complementary metal-oxide semiconductor (CMOS) process that has shown proven hardness against total dose radiation effects.
Show less - Date Issued
- 2007
- Identifier
- CFE0001966, ucf:47468
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001966
- Title
- Nonlinear Optical Response of Simple Molecules and Two-Photon Semiconductor Lasers.
- Creator
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Reichert, Matthew, Vanstryland, Eric, Hagan, David, Likamwa, Patrick, Peale, Robert, University of Central Florida
- Abstract / Description
-
This dissertation investigates two long standing issues in nonlinear optics: complete characterization of the ultrafast dynamics of simple molecules, and the potential of a two-photon laser using a bulk semiconductor gain medium. Within the Born-Oppenheimer approximation, nonlinear refraction in molecular liquids and gases can arise from both bound-electronic and nuclear origins. Knowledge of the magnitudes, temporal dynamics, polarization and spectral dependences of each of these mechanisms...
Show moreThis dissertation investigates two long standing issues in nonlinear optics: complete characterization of the ultrafast dynamics of simple molecules, and the potential of a two-photon laser using a bulk semiconductor gain medium. Within the Born-Oppenheimer approximation, nonlinear refraction in molecular liquids and gases can arise from both bound-electronic and nuclear origins. Knowledge of the magnitudes, temporal dynamics, polarization and spectral dependences of each of these mechanisms is important for many applications including filamentation, white-light continuum generation, all-optical switching, and nonlinear spectroscopy. In this work the nonlinear dynamics of molecules are investigated in both liquid and gas phase with the recently developed beam deflection technique which measures nonlinear refraction directly in the time domain. Thanks to the utility of the beam deflection technique we are able to completely determine the third-order response function of one of the most important molecular liquids in nonlinear optics, carbon disulfide. This allows the prediction of essentially any nonlinear refraction or two-photon absorption experiment on CS2. Measurements conducted on air (N2 and O2) and gaseous CS2 reveal coherent rotational revivals in the degree of alignment of the ensemble at a period that depends on its moment of inertia. This allows measurement of the rotational and centrifugal distortion constants of the isolated molecules. Additionally, the rotational contribution to the beam deflection measurement can be eliminated thanks to the particular polarization dependence of the mechanism. At a specific polarization, the dominant remaining contribution is due to the bound-electrons. Thus both the bound-electronic nonlinear refractive index of air, and second hyperpolarizability of isolated CS2 molecules, are measured directly. The later agrees well with liquid CS2 measurements, where local field effects are significant. The second major portion of this dissertation addresses the possibility of using bulk semiconductors as a two-photon gain medium. A two-photon laser has been a goal of nonlinear optics since shortly after the original laser's development. In this case, two-photons are emitted from a single electronic transition rather than only one. This processes is known as two-photon gain (2PG). Semiconductors have large two-photon absorption coefficients, which are enhanced by ~2 orders of magnitude when using photons of very different energies, e.g., ??_a?10??_b. This enhancement should translate into large 2PG coefficients as well, given the inverse relationship between absorption and gain. Here, we experimentally demonstrate both degenerate and nondegenerate 2PG in optically excited bulk GaAs via pump-probe experiments. This constitutes, to my knowledge, the first report of nondegenerate two-photon gain. Competition between 2PG and competing processes, namely intervalence band and nondegenerate three-photon absorption (ND-3PA), in both cases are theoretically analyzed. Experimental measurements of ND-3PA agree with this analysis and show that it is enhanced much more than ND-2PG. It is found for both degenerate and nondegenerate photon pairs that the losses dominate the two-photon gain, preventing the possibility of a two-photon semiconductor laser.
Show less - Date Issued
- 2015
- Identifier
- CFE0005874, ucf:50871
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005874
- Title
- TEACHING CHARACTERISTICS AND PRACTICES WHICH AFFECT LANGUAGE AND LITERACY DEVELOPMENT FOR STUDENTS WITH COMPLEX COMMUNICATION NEEDS.
- Creator
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King, Laura, Cross, Lee, University of Central Florida
- Abstract / Description
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This study examined teacher characteristics and practices identified as effective through current research for teaching students with complex communication needs. For this population, communication issues are more complex than those typically encountered in other settings. Specifically, the researcher asked: what are the desired characteristics and practices for this population, and are the desired characteristics and practices present in current settings? Working with six teachers in a large...
Show moreThis study examined teacher characteristics and practices identified as effective through current research for teaching students with complex communication needs. For this population, communication issues are more complex than those typically encountered in other settings. Specifically, the researcher asked: what are the desired characteristics and practices for this population, and are the desired characteristics and practices present in current settings? Working with six teachers in a large urban school district, this study utilized a multiple case study design. Criteria for participation included the teacher as the primary reading/language arts instructor for a student who used an augmentative and alternative communication system (AAC). This study builds on prior research and fills a gap in current research through a focus on the teacher. This study was conducted through three phases: a survey of teacher characteristics, observations of teacher practices, and a semi-structured interview. Four instruments were utilized to ensure validity. Results suggest that teachers for this population require knowledge on language and literacy specific to the non-verbal child. AAC training is critical in regard to programming and navigation. The use of other technology supports which offer auditory, visual, and access options are essential. Strong collaborative teams (school and district) are also important. However, one of the most significant findings documents that success may lie with the teacher's 'choice' to embrace challenges with this population. This issue of 'choice' questions the teacher's willingness (personally or professionally) to accept this commitment. This finding also questions the degree to which teachers are willing to pursue opportunities. Recommendations include the need for: training (teachers and paraprofessionals), pursuit of opportunities for supports, addressing parent issues, a district-based liaison between home and school, and to examine issues which prevent the recommended instructional time (90 minutes of reading instruction plus 45 minutes of supplemental instruction). Conclusions indicated that participants ranged from effective to ineffective. The identification of 'highly qualified' teachers through level of education and amount of experience did not correlate with participants' level of effectiveness. Given the limited research available, this study addresses a need in the field and lays the foundation for future research with this population.
Show less - Date Issued
- 2006
- Identifier
- CFE0001257, ucf:46921
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001257
- Title
- FUNDAMENTAL ASPECTS OF REGENERATIVE CERIUM OXIDE NANOPARTICLES AND THEIR APPLICATIONS IN NANOBIOTECHNOLOGY.
- Creator
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Patil, Swanand, Seal, Sudipta, University of Central Florida
- Abstract / Description
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Cerium oxide has been used extensively for various applications over the past two decades. The use of cerium oxide nanoparticles is beneficial in present applications and can open avenues for future applications. The present study utilizes the microemulsion technique to synthesize uniformly distributed cerium oxide nanoparticles. The same technique was also used to synthesize cerium oxide nanoparticles doped with trivalent elements (La and Nd). The fundamental study of cerium oxide...
Show moreCerium oxide has been used extensively for various applications over the past two decades. The use of cerium oxide nanoparticles is beneficial in present applications and can open avenues for future applications. The present study utilizes the microemulsion technique to synthesize uniformly distributed cerium oxide nanoparticles. The same technique was also used to synthesize cerium oxide nanoparticles doped with trivalent elements (La and Nd). The fundamental study of cerium oxide nanoparticles identified variations in properties as a function of particle size and also due to doping with trivalent elements (La and Nd). It was found that the lattice parameter of cerium oxide nanoparticles increases with decrease in particle size. Also Raman allowed mode shift to lower energies and the peak at 464 cm-1 becomes broader and asymmetric. The size dependent changes in cerium oxide were correlated to increase in oxygen vacancy concentration in the cerium oxide lattice. The doping of cerium oxide nanoparticles with trivalent elements introduces more oxygen vacancies and expands the cerium oxide lattice further (in addition to the lattice expansion due to the size effect). The lattice expansion is greater for La-doped cerium oxide nanoparticles compared to Nd-doping due to the larger ionic radius of La compared to Nd, the lattice expansion is directly proportional to the dopant concentration. The synthesized cerium oxide nanoparticles were used to develop an electrochemical biosensor of hydrogen peroxide (H2O2). The sensor was useful to detect H2O2 concentrations as low as 1µM in water. Also the preliminary testing of the sensor on tomato stem and leaf extracts indicated that the sensor can be used in practical applications such as plant physiological studies etc. The nanomolar concentrations of cerium oxide nanoparticles were also found to be useful in decreasing ROS (reactive oxygen species) mediated cellular damages in various in vitro cell cultures. Cerium oxide nanoparticles reduced the cellular damages to the normal breast epithelial cell line (CRL 8798) induced by X-rays and to the Keratinocyte cell line induced by UV irradiation. Cerium oxide nanoparticles were also found to be neuroprotective to adult rat spinal cord and retinal neurons. We propose that cerium oxide nanoparticles act as free radical scavenger (via redox reactions on its surface) to decrease the ROS induced cellular damages. Additionally, UV-visible spectroscopic studies indicated that cerium oxide nanoparticles possess auto-regenerative property by switching its oxidation state between Ce3+ and Ce4+. The auto-regenerative antioxidant property of these nanoparticles appears to be a key component in all the biological applications discussed in the present study.
Show less - Date Issued
- 2006
- Identifier
- CFE0001271, ucf:46932
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001271
- Title
- OPTIMIZING THE PERFORMANCE OF AS-MANUFACTURED GRAZING INCIDENCE X-RAY TELESCOPES USING MOSAIC DETECTOR ARRAYS.
- Creator
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Atanassova, Martina, Harvey, James, University of Central Florida
- Abstract / Description
-
The field of X-ray astronomy is only forty (43) years old, and grazing incidence X-ray telescopes have only been conceived and designed for a little over fifty (50) years. The Wolter Type I design is particularly well suited for stellar astronomical telescopes (very small field-of-view). The first orbiting X-ray observatory, HEAO-1 was launched in 1977, a mere twenty-eight (28) years ago. Since that time large nested Wolter Type I X-ray telescopes have been designed, build, and launched by...
Show moreThe field of X-ray astronomy is only forty (43) years old, and grazing incidence X-ray telescopes have only been conceived and designed for a little over fifty (50) years. The Wolter Type I design is particularly well suited for stellar astronomical telescopes (very small field-of-view). The first orbiting X-ray observatory, HEAO-1 was launched in 1977, a mere twenty-eight (28) years ago. Since that time large nested Wolter Type I X-ray telescopes have been designed, build, and launched by the European Space Agency (ROSAT) and NASA (the Chandra Observatory). Several smaller grazing incidence telescopes have been launched for making solar observations (SOHO, HESP, SXI). These grazing incidence designs tend to suffer from severe aberrations and at these very short wavelengths scattering effects from residual optical fabrication errors are another major source of image degradation. The fabrication of precision optical surfaces for grazing incidence X-ray telescopes thus poses a great technological challenge. Both the residual "figure" errors and the residual microroughness or "finish" of the manufactured mirrors must be precisely measured, and the image degradation due to these fabrication errors must be accurately modeled in order to predict the final optical performance of the as manufactured telescope. The fabrication process thus consists of a series of polishing and testing cycles with the predictions from the metrology data of each cycle indicating the strategy for the next polishing cycle. Most commercially available optical design and analysis software analyzes the image degradation effects of diffraction and aberrations, but does not adequately model the image degradation effects of surface scatter or the effects of state-of-the-art mosaic detectors. The work presented in this dissertation is in support of the Solar X-ray Imager (SXI) program. We have developed a rigorous procedure by which to analyze detector effects in systems which exhibit severe field-dependent aberrations (conventional transfer function analysis is not applicable). Furthermore, we developed a technique to balance detector effects with geometrical aberrations, during the design process, for wide-field applications. We then included these detector effects in a complete systems engineering analysis (including the effects of diffraction, geometrical aberrations, surface scatter effects, the mirror manufacturer error budget tree, and detector effects) of image quality for the five SXI telescopes being fabricated for NOAA's next generation GOES weather satellites. In addition we have re-optimized the remaining optical design parameters after the grazing incidence SXI mirrors have been imperfectly fabricated. This ability depends critically upon the adoption of an image quality criterion, or merit function, appropriate for the specific application. In particular, we discuss in detail how the focal plane position can be adjusted to optimize the optical performance of the telescope to best compensate for optical figure and/or finish errors resulting from the optical fabrication process. Our systems engineering analysis was then used to predict the increase in performance achieved by the re-optimization procedure. The image quality predictions are also compared with real X-ray test data from the SXI program to experimentally validate our system engineering analysis capability.
Show less - Date Issued
- 2005
- Identifier
- CFE0000428, ucf:46387
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000428
- Title
- EFFECT OF ANNEALING ON COPPER THIN FILMS:THE CLASSICAL SIZE EFFECT AND AGGLOMERATION.
- Creator
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Gadkari, Parag, Sundaram, Kalpathy, University of Central Florida
- Abstract / Description
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With continued shrinking of CMOS technology to reduce the gate delay times, an increase in the resistivity of the metal corresponding to the wire dimension is a concern. This phenomenon of increase in resistivity with decreasing dimension of the thin metallic film or interconnect is known as the "classical size effect". Various theories have been postulated to explain the phenomenon of classical size effect; these theories can be broadly classified as resistivity due to scattering arising...
Show moreWith continued shrinking of CMOS technology to reduce the gate delay times, an increase in the resistivity of the metal corresponding to the wire dimension is a concern. This phenomenon of increase in resistivity with decreasing dimension of the thin metallic film or interconnect is known as the "classical size effect". Various theories have been postulated to explain the phenomenon of classical size effect; these theories can be broadly classified as resistivity due to scattering arising from surface and grain boundaries. The total resistivity of metals depends on the electron scattering due to impurities, phonons, surfaces, grain boundaries, and other crystal defects. Managing the size effect in a practical and manufacturing way is of major concern to the microelectronics industry. Since each of the processes (phonon, surface and grain boundary scattering) adds to the resistivity and are interrelated, it further complicates managing the size effect. However, these effects have been separately studied. In this work, the effect of annealing on the classical size effect in Cu thin films deposited on SiO2 substrate is investigated. Polycrystalline Cu thin films having thicknesses in the range of 10nm to 200nm were ultra high vacuum sputter deposited on thermally grown SiO2 surfaces. The films were annealed at temperatures in the range of 150°C to 800°C in argon and argon+3% hydrogen gases. The un-annealed Cu thin films exhibit higher resistivity than the annealed films. The resistivities of un-annealed films were in good agreement with Mayadas and Shatzkes model. When annealed the films undergoes grain growth resulting in lowering the resistivities by about 20%-30% thereby confirming the role of grain size on resistivity of the film. However, there is a limit to annealing, i.e. agglomeration phenomenon. Agglomeration is a thermally activated process resulting in a reduction of the free energy of the filmsubstrate system and can occur well below the melting point of the material by surface and interfacial diffusion. The reduction of film-substrate interfacial energy, film-surface interfacial energy and stresses within the film are possible driving forces for agglomeration. This work also includes the study of agglomeration phenomenon. The agglomeration behavior of Cu is investigated and compared with that of Ru, Au and Pt thin films with thicknesses in the range of 10 nm to 100 nm UHV deposited on thermally grown SiO2 substrate. The films were annealed at temperatures in the range of 150°C to 800°C in argon and argon+3% hydrogen gases. Scanning electron microscopy was used to investigate the agglomeration behavior, and transmission electron microscopy was used to characterize the microstructure of the as-deposited and annealed films. The agglomeration sequence in all the films is found to follow a two step process of void nucleation and void growth. However, void growth in Au and Pt thin films is different from Cu and Ru thin films. Residual stress and adhesion were observed to play important part in deciding the mode of void growth in Au and Pt thin films. Lastly, it is also observed that the tendency for agglomeration can be reduced by encapsulating the metal film with an oxide overlayer, which in turn improves the resistivity of the thin film due to prolonged grain growth without film breakup.
Show less - Date Issued
- 2005
- Identifier
- CFE0000496, ucf:46363
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000496
- Title
- EVALUATING TEACHER PERFORMANCE IN HIGHER EDUCATION:THE VALUE OF STUDENT RATINGS.
- Creator
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Campbell, Judith, Bozeman, William, University of Central Florida
- Abstract / Description
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The purposes of this research were to: (a) assess community college students' perceptions of the student evaluation practice; (b) assess community college faculty members' responses to student evaluations of teachers and the extent to which instructional modifications resulted from student ratings; and (c) assess community college administrators' responses to student evaluations of teachers, the extent student ratings influenced administrators' evaluations of faculty, and how the results from...
Show moreThe purposes of this research were to: (a) assess community college students' perceptions of the student evaluation practice; (b) assess community college faculty members' responses to student evaluations of teachers and the extent to which instructional modifications resulted from student ratings; and (c) assess community college administrators' responses to student evaluations of teachers, the extent student ratings influenced administrators' evaluations of faculty, and how the results from student ratings were used to promote instructional effectiveness. A total of 358 students, faculty, and administrators from 5 Florida community colleges contributed their opinions on the value of the practice of student evaluation of teaching. Data were collected using mixed methodology. The survey and interview sessions were conducted on location at the respective community colleges. Descriptive statistics, correlation and regression procedures, one-way analysis of variance, t-test, and phenomenological analysis were used to analyze the data. Quantitative results indicated that these 320 community college students believed that student ratings had value, and, thus their role as instructor evaluator was important. Furthermore, the students believed student evaluations were important to faculty and administrators. However, most students were either unaware or did not believe that student evaluations had any effect. Phenomenological analysis of the extensive descriptions provided by 21 faculty participants suggested that the numeric data provided by student evaluations was generally an ineffective method to impact instruction. Faculty described their frustration with inadequately designed instruments, ineffective methods of receiving ratings results, and limited or non-existent feedback from supervisors. Phenomenological analysis of the 17 administrators' transcriptions suggested that although the student ratings practice was vital to institutional integrity the results from student evaluations were marginally valuable in their impact on enhancing instruction and of limited value in faculty evaluation. Implications for student evaluation practices drawn from this study included the need for institutions to: (a) assess the value of their student evaluation practice and its impact on teaching effectiveness; (b) define and clearly articulate a statement of purpose for conducting student evaluations; (c) refine procedures for administering the student evaluation practice; (d) examine their student evaluation practices and instrument on a regular review cycle; (e) adopt alternative methods for collecting and disseminating student feedback; (f) implement student evaluation measures that reflect the varied teaching approaches and diverse learning environments.
Show less - Date Issued
- 2005
- Identifier
- CFE0000593, ucf:46481
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000593
- Title
- THE EFFECT OF TECHNOLOGY ACCEPTANCE ON POST SECONDARY AFRICAN- AMERICAN STUDENTS' ACHIEVEMENT IN MATHEMATICS:A PATH ANALYTIC INQUIRY.
- Creator
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Sen, Sulakshana, Sivo, Stephen, University of Central Florida
- Abstract / Description
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The purpose of this research was to investigate the effect of technology acceptance on post secondary African American students' achievement in Mathematics. The study was conducted in a historically Black four-year college in Daytona Beach, Florida on students using the computer to enhance their mathematics performance in an introductory algebra mathematics course. By using Technology Acceptance Model (TAM) developed by F. Davis (1989), this study focused on variables such as perceived...
Show moreThe purpose of this research was to investigate the effect of technology acceptance on post secondary African American students' achievement in Mathematics. The study was conducted in a historically Black four-year college in Daytona Beach, Florida on students using the computer to enhance their mathematics performance in an introductory algebra mathematics course. By using Technology Acceptance Model (TAM) developed by F. Davis (1989), this study focused on variables such as perceived usefulness, perceived ease of use, computer self-efficacy, subjective norms, attitude and actual use of the computer to account the effect towards the achievement in the final exam which is an outcome variable. The data were collected over four different time periods during the fall semester of 2004 to find how these results changed over time. The study was conducted by using six instruments to measure perceived usefulness, perceived ease of use, computer self-efficacy, subjective norms, actual use of computer (frequency and duration), attitude and an additional demographic instrument. The data were analyzed by path analysis using multiple regressions (SPSS for windows) to find the contribution of each independent variable to the dependent variable that ultimately predicted the final outcome. Computer self-efficacy and subjective norms were determinants of perceived usefulness and perceived ease of use which in turn determined the attitude of students using computer for enhancing their math score in the final. The findings of path analysis indicated that the research did not support TAM. The results suggested that perceived usefulness is the most significant predictor of perceived ease of use. The duration of actual use of the computer in a single session contributed significantly towards their final score for achievement in mathematics. The students preferred a face-to-face instruction in mathematics by the instructor than interaction with a computer. Additional research endeavors should be devoted to the measurement of system use in different set up with different ethnic background to further analyze students' acceptance or rejection of technology towards their achievement in mathematics.
Show less - Date Issued
- 2005
- Identifier
- CFE0000572, ucf:46435
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000572
- Title
- STUDY FOR DEVELOPMENT OF A BLAST LAYER FOR THE VIRTUAL RANGE PROJECT.
- Creator
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Rosales, Sergio, Sepulveda, Jose, University of Central Florida
- Abstract / Description
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In this work we develop a Blast-Propellant-Facility integrated analysis study, which evaluates, by using two different approaches, the blast-related impact of an explosive accident of the Space Shuttle during the first ten seconds after launch at Kennedy Space Center. The blast-related risk associated with an explosion at this stage is high because of the quantity of energy involved in both multiple and complex processes. To do this, one of our approaches employed BlastFX®, a software...
Show moreIn this work we develop a Blast-Propellant-Facility integrated analysis study, which evaluates, by using two different approaches, the blast-related impact of an explosive accident of the Space Shuttle during the first ten seconds after launch at Kennedy Space Center. The blast-related risk associated with an explosion at this stage is high because of the quantity of energy involved in both multiple and complex processes. To do this, one of our approaches employed BlastFX®, a software system that facilitates the estimation of the level of damage to people and buildings, starting from an explosive device and rendering results through a complete report that illustrates and facilitates the evaluation of consequences. Our other approaches employed the Hopkinson-Cranz Scaled Law for estimating similar features at a more distant distance and by evaluating bigger amounts of TNT equivalent. Specifically, we considered more than 500 m and 45,400 kg, respectively, which are the range and TNT content limits that our version of BlastFX® can cover. Much research has been done to study the explosion phenomena with respect to both solid and liquid propellants and the laws that underlie the blast waves of an explosion. Therefore our methodology is based on the foundation provided by a large set of literature review and the actual capacities of an application like BlastFX®. By using and integrating the lessons from the literature and the capabilities of the software, we have obtained very useful information for evaluating different scenarios that rely on the assumption, which is largely studied, that the blast waves' behavior is affected by the distance. All of this has been focused on the Space Shuttle system, in which propellant mass represents the source of our analysis and the core of this work. Estimating the risks involved in it and providing results based on different scenarios augments the collective knowledge of risks associated with space exploration.
Show less - Date Issued
- 2004
- Identifier
- CFE0000190, ucf:46171
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000190
- Title
- EVALUATING THE EFFECTIVENESS OF TRAINING SYSTEM APPROACHES FOR HIGHLY COMPLEX FLIGHT TRAINING.
- Creator
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Bauer, Maria, Proctor, Michael, University of Central Florida
- Abstract / Description
-
This research investigates the Training Effectiveness of a low-cost, PC-based training system when compared with two modes (motion and no motion) of a cab training system with large screen for various aviation flying tasks. While much research on this topic has been done in the past, advances in technology have significantly altered what is considered a "low-cost" "simulator." The technology advances have in effect increased the ability of a "low-cost" "simulator" to deliver desired...
Show moreThis research investigates the Training Effectiveness of a low-cost, PC-based training system when compared with two modes (motion and no motion) of a cab training system with large screen for various aviation flying tasks. While much research on this topic has been done in the past, advances in technology have significantly altered what is considered a "low-cost" "simulator." The technology advances have in effect increased the ability of a "low-cost" "simulator" to deliver desired experiences to the user. These "simulators" often are nothing more than PC training system, with only notional representations of the actual aircraft. This research considers the use of such training systems in training for a highly complex and dynamic task situation, that task being a search and rescue mission. A search and rescue mission is far more complex task than those studied for possible "low-cost" simulation substitution in the past. To address that aspect, one mode of the cab involves motion in two degrees of freedom. The results of this research advances the body of literature on the capability of "low-cost" simulation to deliver the experiences necessary to learn highly complex tasks associated with search and rescue as well as further clarify the extent to which a motion platform aides in flight training. This research utilizes available platforms provided by the US Army Research, Development and Engineering Command Simulation and Training Technology Center. Additionally, all the participants in the research are in training to be helicopter pilots. Participants were randomly assigned to one of three training configurations: a) Cab with motion turned ON, b) Cab with motion turned OFF and c) PC-based simulator. Training effectiveness is evaluated using measures for learning, task performance, and human factors. Statistically significant results are shown for the Cab with Motion and the Cab with No Motion configurations.
Show less - Date Issued
- 2005
- Identifier
- CFE0000754, ucf:46569
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000754
- Title
- EFFECTS OF THE INFLUENZA VACCINE ON THE ORAL CAVITY.
- Creator
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Sawires, Laura, Webster, Danielle, Wells, Brittny, University of Central Florida
- Abstract / Description
-
According to existing literature, there is a suggested correlation between certain vaccinations and oral cavity symptoms. Studies have shown that the Diphtheria, Tetanus, Acellular Pertusis, as well as Polio Vaccinations have an association with presented symptoms of bleeding gums, sores, ulcers, white spots in the mouth or on lips, and unpleasant breath odor. Although these symptoms may not occur simultaneously or directly after administration of the immunization, there has been supported...
Show moreAccording to existing literature, there is a suggested correlation between certain vaccinations and oral cavity symptoms. Studies have shown that the Diphtheria, Tetanus, Acellular Pertusis, as well as Polio Vaccinations have an association with presented symptoms of bleeding gums, sores, ulcers, white spots in the mouth or on lips, and unpleasant breath odor. Although these symptoms may not occur simultaneously or directly after administration of the immunization, there has been supported evidence of correlation. Given the relevance of an association between vaccinations and orally manifested side effects, an investigation on the presence of such association with the widely administered flu vaccine was conducted. Data for this work was collected from a population including undergraduate students studying at the University of Central Florida. A brief voluntary online survey requesting demographic information regarding administration of the vaccine as well as any experienced side effects was used. The study was cohort in nature as it tracked subjects with known exposure to the flu shot in the past six months to understand the outcome of interest. Results from the survey were used to determine that there is no correlation between orally manifested side effects and administration of the flu vaccine.
Show less - Date Issued
- 2018
- Identifier
- CFH2000306, ucf:45755
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000306
- Title
- INVESTIGATING A POTENTIAL RELATIONSHIP BETWEEN SIBLING GENDER COMPOSITION AND HEALTH BEHAVIOR INDICATORS IN YOUNG ADULT AND ADOLESCENT MALES.
- Creator
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Goss, Taylor N, Rovito, Michael J., Jasinski, Jana, University of Central Florida
- Abstract / Description
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The presence of siblings during childhood and adolescence has a significant impact on the behaviors and perceptions of adults later in life. Effects of mixed-gendered sibling dyads on delinquent behavior, gender typing, and romantic and sexual relationships are of interest. These behaviors can lead to notable health disparities, making it imperative to gain insight into factors associated with such behaviors in young adult and adolescent males. This project explored possible correlations...
Show moreThe presence of siblings during childhood and adolescence has a significant impact on the behaviors and perceptions of adults later in life. Effects of mixed-gendered sibling dyads on delinquent behavior, gender typing, and romantic and sexual relationships are of interest. These behaviors can lead to notable health disparities, making it imperative to gain insight into factors associated with such behaviors in young adult and adolescent males. This project explored possible correlations between gender composition of siblings and health behavior indicators for violence, competition and risk, and sexual and romantic relationships. Analysis of these variables was performed using data from the Young Adult and Adolescent Male Health Behavior Indicator Scale [YAAMHBIS]. Descriptive analyses showed YAAM understanding of abuse and successful marriage and relationship qualities, as well as a conditional acceptance of violence, competition, and risk. Means testing between those with and without sisters indicated that those with sisters acknowledged abuse, marriage qualities, and the consequences of infidelity. Additionally, those with sisters had, on average, an earlier age of sexual debut than those without supporting previous research regarding the effects of female communication in childhood on adult interactions. The correlations found between sibling gender and YAAM perceptions later in life could lay the groundwork for future studies further investigating sibling gender or split households and an association with health behaviors.
Show less - Date Issued
- 2018
- Identifier
- CFH2000317, ucf:45807
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000317
- Title
- AN EXAMINATION OF RELATIVE AGE EFFECTS AMONG JUNIOR ELITE WRESTLERS.
- Creator
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Kelly, Jayla, Fukuda, David, University of Central Florida
- Abstract / Description
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The purpose of this examination was to evaluate relative age effects among junior elite wrestlers across gender, weight class, and competitive rule sets. Using biographical data, this thesis explores trends representing an oversampling of athletes born earlier in the year, accompanied by potential effects for success in sport and an impact on retention rates. Currently, the use of chronological age is the most common form of classifying sports participants, though this type of classification...
Show moreThe purpose of this examination was to evaluate relative age effects among junior elite wrestlers across gender, weight class, and competitive rule sets. Using biographical data, this thesis explores trends representing an oversampling of athletes born earlier in the year, accompanied by potential effects for success in sport and an impact on retention rates. Currently, the use of chronological age is the most common form of classifying sports participants, though this type of classification may have potentially negative long- and short-term implications. Thus, the results may provide an evaluation of weight categorization as a less discriminatory competitive format in junior elite wrestlers.
Show less - Date Issued
- 2015
- Identifier
- CFH0004804, ucf:45487
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004804
- Title
- ASSESSING THE RELATIONSHIP BETWEEN TERRORIST ATTACKS AND THE LIMITING OF MUSLIM IMMIGRATION DUE TO ANTI-ISLAMIC SENTIMENTS.
- Creator
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Okhai, Ratna, Mirilovic, Nikola, University of Central Florida
- Abstract / Description
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In the last 12 years, since the devastating attack on the United States Twin Towers on September 11, 2001, the global community has become increasingly wary. The continuing terrorism on July 7, 2005 on the United Kingdom subway system increased tensions between citizens and immigrants in these countries. I use these two countries to examine the consequences effects that these terrorist attacks have had on, in particular, the Muslim immigrant population. In addition to that, I use Germany as a...
Show moreIn the last 12 years, since the devastating attack on the United States Twin Towers on September 11, 2001, the global community has become increasingly wary. The continuing terrorism on July 7, 2005 on the United Kingdom subway system increased tensions between citizens and immigrants in these countries. I use these two countries to examine the consequences effects that these terrorist attacks have had on, in particular, the Muslim immigrant population. In addition to that, I use Germany as a control, since it has not faced a major terrorist attack, yet has a substantial Muslim immigrant population. In the United States and United Kingdom, I use public opinion data polls and immigration policies before and after the attacks. In Germany's case, I utilize the same data and to assess any correlation to the other two countries data. Using the literature already written, public opinion data polls and policy initiatives enacted before and after these attacks, I examine the overall effect, if any, on the Muslim immigrant population in these countries. The intent of this thesis is to explore if the significant changes in immigration policies after the attacks have occurred due to economic or cultural factors. Because public opinion is central to policy changes, I also consider the implications of public's views on immigration after the attacks, along with the effect all this has on the number of Muslim immigrants entering these countries.
Show less - Date Issued
- 2013
- Identifier
- CFH0004474, ucf:45093
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004474
- Title
- FABRICATION AND TRANSPORT STUDIES OF N-TYPE ORGANIC FIELD EFFECT TRANSISTORS USING ALIGNED ARRAY CARBON NANOTUBES ELECTRODES.
- Creator
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Jimenez, Edwards, Khondaker, Saiful, University of Central Florida
- Abstract / Description
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We present fabrication of n-type organic field effect transistors (OFETs) using densely aligned array carbon nanotube (CNT) electrodes. The CNTs were aligned with a high linear density via dielectrophoresis (DEP) from an aqueous solution. In order to fabricate the CNT electrodes, aligned CNTs were cut by using electron beam lithography (EBL) and precise oxygen plasma etching. The n-type OFETs were fabricated in a bottom-contact configuration by depositing a thin film of C60 molecules between...
Show moreWe present fabrication of n-type organic field effect transistors (OFETs) using densely aligned array carbon nanotube (CNT) electrodes. The CNTs were aligned with a high linear density via dielectrophoresis (DEP) from an aqueous solution. In order to fabricate the CNT electrodes, aligned CNTs were cut by using electron beam lithography (EBL) and precise oxygen plasma etching. The n-type OFETs were fabricated in a bottom-contact configuration by depositing a thin film of C60 molecules between the CNT source and drain electrodes, and compared against a controlled C60 OFET with gold electrodes. The electron transport measurements of the OFETs using CNT electrodes show better transistor characteristics compared to OFETs using gold electrodes due to improved charge injection from densely aligned and open-ended nanotube tips.
Show less - Date Issued
- 2012
- Identifier
- CFH0004217, ucf:44941
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004217
- Title
- NURSING INTERVENTIONS IN THE CARE OF PATIENTS UNDERGOING INDUCED HYPOTHERMIA.
- Creator
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Zimmerman, Angela, Amidei, Christina, University of Central Florida
- Abstract / Description
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Use of induced hypothermia for the purpose of lowering intracranial pressure and preserving neuronal function has increased as research data reveals a trend of positive outcomes in patients treated with this therapy. Recently induced hypothermia following cardiac arrest due to ventricular fibrillation has been deemed successful. Current research has expanded to evaluate the effectiveness of induced hypothermia as a treatment modality for severe stroke and head trauma. In spite of its efficacy...
Show moreUse of induced hypothermia for the purpose of lowering intracranial pressure and preserving neuronal function has increased as research data reveals a trend of positive outcomes in patients treated with this therapy. Recently induced hypothermia following cardiac arrest due to ventricular fibrillation has been deemed successful. Current research has expanded to evaluate the effectiveness of induced hypothermia as a treatment modality for severe stroke and head trauma. In spite of its efficacy, complications exist with this treatment modality. The purpose of this literature review is to examine potential complications secondary to induced hypothermia and highlight the nurse's role in managing patient care. At the present, patient protocols for induced hypothermia are lacking. The success of treatment is largely dependent on the skill of the healthcare team to prevent further harm and enhance therapeutic outcomes by providing astute assessment and management of complications in patients undergoing induced hypothermia. The desired outcome of this review is to promote integration of research in the development of evidence-based protocols for induced hypothermia.
Show less - Date Issued
- 2011
- Identifier
- CFH0003836, ucf:44718
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0003836
- Title
- EFFECTIVE METHODS OF PARENT-TEACHER COMMUNICATION FOR TEACHERS OF ENGLISH LANGUAGE LEARNERS.
- Creator
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Alfonzo-Reyes, Luzeana, Hoffman, Elizabeth, University of Central Florida
- Abstract / Description
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Families from all over the world come to the United States for a new beginning. More often than not, these families speak little or no English. A challenge that teachers face every day is trying to communicate with children and their families who speak little or no English. Following a review of the various forms of communication and types of parental involvement, a survey was created. This survey was completed by elementary teachers in a local lower socioeconomic area elementary school with...
Show moreFamilies from all over the world come to the United States for a new beginning. More often than not, these families speak little or no English. A challenge that teachers face every day is trying to communicate with children and their families who speak little or no English. Following a review of the various forms of communication and types of parental involvement, a survey was created. This survey was completed by elementary teachers in a local lower socioeconomic area elementary school with a high mobility rates and high levels of English Language Learner (ELL) students. The results of this study will offer the most effective ways teachers can openly communicate with families who speak little or no English. The results suggest that although vital, communication between the parents of ELL students and the teacher varies from teacher to teacher. Additionally, having resources available to teachers at the school and using the resources available allows parents and teachers to communicate effectively.
Show less - Date Issued
- 2012
- Identifier
- CFH0004190, ucf:44833
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004190
- Title
- CLASSICAL SIZE EFFECT IN CU THIN FILMS: IMPACT OF SURFACE AND GRAIN BOUNDARY SCATTERING ON RESISTIVITY.
- Creator
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Sun, Tik, Coffey, Kevin, University of Central Florida
- Abstract / Description
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Surface and grain boundary electron scattering contribute significantly to resistivity as the dimensions of polycrystalline metallic conductors are reduced to, and below, the electron mean free path. A quantitative measurement of the relative contributions of surface and grain boundary scattering to resistivity is very challenging, requiring not only the preparation of suitably small conductors having independent variation of the two relevant length scales, namely, the sample critical...
Show moreSurface and grain boundary electron scattering contribute significantly to resistivity as the dimensions of polycrystalline metallic conductors are reduced to, and below, the electron mean free path. A quantitative measurement of the relative contributions of surface and grain boundary scattering to resistivity is very challenging, requiring not only the preparation of suitably small conductors having independent variation of the two relevant length scales, namely, the sample critical dimension and the grain size, but also independent experimental quantification of these two length scales. In most work to date the sample grain size has been either assumed equal to conductor dimension or measured for only a small number of grains. Thus, the quantification of the classical size effect still suffers from an uncertainty in the relative contributions of surface and grain boundary scattering. In this work, a quantitative analysis of both surface and grain boundary scattering in Cu thin films with independent variation of film thickness (27 nm to 158 nm) and grain size (35 nm to 425 nm) in samples prepared by sub-ambient temperature film deposition followed by annealing is reported. Film resistivities of carefully characterized samples were measured at both room temperature and at 4.2 K and were compared with several scattering models that include the effects of surface and grain boundary scattering. Grain boundary scattering is found to provide the strongest contribution to the resistivity increase. However, a weaker, but significant, role is also observed for surface scattering. Several of the published models for grain boundary and surface scattering are explored and the Matthiessen's rule combination of the Mayadas and Shatzkes' model of grain boundary scattering and Fuchs and Sondheimer's model of surface scattering resistivity contributions is found to be most appropriate. It is found that the experimental data are best described by a grain boundary reflection coefficient of 0.43 and a surface specularity coefficient of 0.52. This analysis finds a significantly lower contribution from surface scattering than has been reported in previous works, which is in part due to the careful quantitative microstructural characterization of samples performed. The data does suggest that there is a roughness dependence to the surface scattering, but this was not conclusively demonstrated. Voids and impurities were found to have negligible impact on the measured resistivities of the carefully prepared films.
Show less - Date Issued
- 2009
- Identifier
- CFE0002959, ucf:47949
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002959
- Title
- PRESSURE DROP AND ENDWALL HEAT TRANSFER EFFECTS OF POROUS TURBULATORS IN A RECTANGULAR CHANNEL.
- Creator
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Pent, Jared, Kapat, Jay, University of Central Florida
- Abstract / Description
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This study examines the local and averaged endwall heat transfer effects of a staggered array of porous pin fins within a rectangular channel. The porous pin fins were made from aluminum and had a pore density of 10 pores per inch (PPI). The pressure drop through the channel was also determined for several flow rates and presented in terms of the friction factor. Local heat transfer coefficients on the endwall were measured using Thermochromic Liquid Crystal (TLC) sheets recorded with a...
Show moreThis study examines the local and averaged endwall heat transfer effects of a staggered array of porous pin fins within a rectangular channel. The porous pin fins were made from aluminum and had a pore density of 10 pores per inch (PPI). The pressure drop through the channel was also determined for several flow rates and presented in terms of the friction factor. Local heat transfer coefficients on the endwall were measured using Thermochromic Liquid Crystal (TLC) sheets recorded with a charge-coupled device (CCD) camera. Static and total pressure measurements were taken at the entrance and exit of the test section to determine the overall pressure drop through the channel and explain the heat transfer trends through the channel. Results are presented for Reynolds numbers between 25000 and 130000 and a blockage ratio (blocked channel area divided by open channel area) of 50%. All results were compared to the corresponding results obtained using solid pins. All experiments were carried out in a 150 mm by 500 mm channel with an X/D of 1.72, a Y/D of 2.0, and a Z/D of 1.72 for the porous pins. It was found that for the range of Reynold's numbers tested in this study, the porous pin array consistently resulted in a larger friction factor, and therefore greater losses than a geometrically similar array of solid pins. The friction factors for the solid pin array were between 9.5 and 10.5, similar to the results found in the literature. For the porous pins, however, the friction factors were significantly increased as the Reynold's number increased, reaching as high as 15.3 at the highest Reynold's number tested. The heat transfer enhancement for the porous pins was found to be between 150 and 170% while the solid pins resulted in a heat transfer enhancement between 190 and 230%.
Show less - Date Issued
- 2009
- Identifier
- CFE0002819, ucf:48085
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002819