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An Analysis of EC-4 Pre-Service Teacher Perceptions of Knowledge and Use of Classroom Discipline Techniques

Description: The purpose of this study was to examine the perceptions of pre-service Texas Wesleyan University teachers' knowledge and use of classroom discipline techniques. The study was conducted to obtain data utilized for the evaluation of the research questions. A non-experimental, mixed research design using survey methodology was used. Part one of the Allen Classroom and Discipline Management Instrument (ACDMI) consisted of demographic information: current position, ethnicity, level of education, gender, age, teaching certification obtained, teaching certification anticipated to be obtained, type of teacher certification training, and number of clock hours received in discipline management. The demographic information was used as independent variables for comparing responses to survey items. Part two contained discipline management techniques from Skinner, Canter, Dreikurs, Gathercoal, Glasser, Faye and Funk, Curwin and Mendler, and Berne and Harris. These techniques were used to determine mean differences with the independent variables. Finally, part three was the qualitative section which consisted of four questions requesting information about helpful discipline techniques. The sample population consisted of 150 pre-service teachers from a small liberal arts university in Texas. Findings from the study indicated that EC-4 pre-service teachers' predicted use of discipline management techniques were the ones in which they were most knowledgeable. Furthermore, EC-4 pre-service teachers reported to be most knowledgeable of the following discipline management techniques: "Student Input in Developing Classroom Rules," "Social Reinforcement and Praise," and "Direct Teach and Model Appropriate Behavior." In addition, certified EC-4 pre-service teachers had more knowledge of classroom discipline techniques than non-certified EC-4 pre-service teachers. The qualitative analysis revealed a consensus among all EC-4 pre-service teachers with regard to their training in discipline management. All EC-4 pre-service teachers indicated that their overall training was inadequate in the area of classroom discipline management and that more was needed.
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Date: May 2006
Creator: Short, Selena Gutierrez

Personal Passions and Carthusian Influences Evident in Rogier Van Der Weyden's Crucified Christ between the Virgin and Saint John and Diptych of the Crucifixion

Description: This thesis examines Rogier Van Der Weyden's two unique fifteenth century Crucifixions, The Crucified Christ Between the Virgin and Saint John and The Diptych of the Crucifixion, in light of Carthusian beliefs, practices and relevant devotional texts. The specific text used to support this examination is the Vita Christi by Ludolph of Saxony, which in part deals specifically with the Hours of the Passion. Ludolph's text is given visual form in Rogier's paintings and supports the assertion that Rogier and Ludolph were connected by a shared belief and worldview. Key aspects of Rogier's life, supported by original documentation- familial ties, associates, patrons, use of finances, and his close involvement with the Carthusians-- support this assertion. Other models of connections of belief, evidenced through artist's work, are corroborated in the work of Grunewald, Sluter and Durer.
Date: May 2006
Creator: Smith, Tamytha Cameron

Effects of Cautioning and Education in the Detection of Malingered Mild Traumatic Brain Injury

Description: This study examined the effectiveness of cautioning and education on simulating a mild traumatic brain injury on several neuropsychological measures. The measures used included the Word Memory Test (WMT), Wechsler Adult Intelligence Scales® - Third Edition (WAIS®-III), Wechsler Memory Scales®-3rd Edition instrument (WMS®-III), 16-item version of the Rey Memory Test, and a self-report symptom checklist. Five experimental groups were used including clinical and non-clinical controls, as well as three simulation groups. The design and implementation of this study also attempted to correct several methodological short comings of prior research by increasing the incentives for participants, expanding the generalizability of findings and examining research compliance and participant self-perception through debriefing. Discriminant analysis was utilized to determine if specific functions existed that would correctly classify and distinguish each experimental group. Several discriminant functions had at least moderate canonical correlations and good classification accuracy. Results also include utility estimates given projected varying base rates of malingering.
Date: May 2006
Creator: Scholtz, Brendon P.

An unjust legacy: A critical study of the political campaigns of William Andrews Clark, 1888-1901.

Description: In a time of laissez-faire government, monopolistic businesses and political debauchery, William Andrews Clark played a significant role in the developing West, achieving financial success rivaling Jay Gould, George Hearst, Andrew Carnegie, and J. P. Morgan. Clark built railroads, ranches, factories, utilities, and developed timber and water resources, and was internationally known as a capitalist, philanthropist and art collector. Nonetheless, Clark is unjustly remembered for his bitter twelve-year political battle with copper baron Marcus Daly that culminated in a scandalous senatorial election in January 1899. The subsequent investigation was a judicial travesty based on personal hatred and illicit tactics. Clark's political career had national implications and lasting consequences. His enemies shaped his legacy, and for one hundred years historians have unquestioningly accepted it.
Date: May 2006
Creator: Pitts, Stanley Thomas

Functional Ontology Construction: A Pragmatic Approach to Addressing Problems Concerning the Individual and the Informing Environment

Description: Functional ontology construction (FOC) is an approach for modeling the relationships between a user and the informing environment by means of analysis of the user's behavior and the elements of the environment that have behavioral function. The FOC approach is an application of behavior analytic techniques and concepts to problems within information science. The FOC approach is both an alternative and a compliment to the cognitive viewpoint commonly found in models of behavior in information science. The basis for the synthesis of behavior analysis and information science is a shared tradition of pragmatism between the fields. The application of behavior analytic concepts brings with it the notion of selection by consequence. Selection is examined on the biological, behavioral, and cultural levels. Two perspicuous examples of the application of the FOC modeling approach are included. The first example looks at the document functioning as a reinforcer in a human operant experimental setting. The second example is an examination of the verbal behavior of expert film analyst, Raymond Bellour, the structure of a film he analyzed, and the elements of the film's structure that had behavioral function for Bellour. The FOC approach is examined within the ontological space of information science.
Date: May 2006
Creator: Anderson, Richard L.

Leaf elemental analysis and growth characteristics of mycorrhizal treated post oak seedlings via particle induced X-ray emission spectroscopy.

Description: Growth and element assimilation was investigated in post oak seedlings exposed to four different treatment combinations of fertilization and ectomycorrhizal inoculation. Element concentration in excised leaves was analyzed via particle induced X-ray emission spectrometry with a 1.8 MeV proton macrobeam. Mean growth was significantly different across the treatment groups as well as mean concentration of Mg, Al, S, K, Ca, Fe, Cu, and Zn. The data suggest that fertilization rather than mycorrhizal inoculation had a stronger influence on plant growth and nutrient uptake. A follow up study was conducted with a 3 MeV microbeam. A 850 μm2 scanned area of a post oak leaf produced topographical maps of 11 elements.
Date: May 2006
Creator: Boling, Blake C.

The Flora and Fauna in Eighteenth-Century Colonial Mexican Casta Paintings

Description: The primary objective of this thesis is to identify patterns of appearance among the flora and fauna of selected eighteenth-century New Spanish casta paintings. The objectives of the thesis are to determine what types of flora and fauna are present within selected casta paintings, whether the flora and fauna's provenance is Spanish or Mexican and whether there are any potential associations of particular flora and fauna with the races being depicted in the same composition. I focus my flora and fauna research on three sets of casta paintings produced between 1750 and 1800: Miguel Cabrera's 1763 series, José Joaquín Magón's 1770 casta paintings, and Andrés de Islas' 1774 sequence. Although the paintings fall into the same genre and within a period of a little over a decade, they nevertheless offer different visions of New Spain's natural bounty and include objects designed to satisfy Europe's interest in the exotic.
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Date: May 2006
Creator: Torres, Anita Jacinta

Cross-Cultural Validation of the Will, Skill, Tool Model of Technology Integration

Description: The teacher professional development component of the will, skill, tool model of technology integration was tested for predictive validity in the cross-cultural context of data from Texas, USA, and data from Mexico City, Mexico. Structural equation modeling (SEM) analysis, path analysis, and multiple regression analysis, were statistical procedures employed. The analyses yielded positive results for the model's validity and reliability. The resulting model was found to be a reliable tool to evaluate technology integration among elementary and middle school teachers in Texas and in Mexico City. For the purposes of this study, the teacher professional development component of the will, skill, tool model of technology integration is referred to as the will, skill, tool model of technology integration (WiSTTI). This was one of the seven alternative models tested for goodness of fit across a total of 7 data samples. The structural equation modeling approach proved to be a good technique to find the best fit model in a cross-cultural environment. Latent variables and a set of parameters to judge the validity and reliability of each model were set for testing and retesting in an iterative process. Eventually a "new" modified version of the WiSSTI model was found to fit the data for all samples studied from both countries. From a theoretical perspective, the variation of the WiSTTI model found to be the best fit to the data indicates that increased teacher willingness to integrate technology brings about increased skill, and increased skill leads to more advanced technology integration, if access to technology is available for instruction. Results derived from the model with respect to the evaluation of technology integration for teachers from Texas and Mexico City suggest a differential effect by country, with the Texas teachers (representing USA) currently more advanced in technology integration than their colleagues from Mexico. No ...
Date: May 2006
Creator: Morales Velázquez, Cesáreo

An investigation of prior learning assessment processes in Texas public universities offering nontraditional baccalaureate degrees.

Description: Undergraduate enrollment in colleges and universities has grown and changed drastically over the past 2 decades, with a significant portion of this growth coming from the increased number of nontraditional students who have made the decision to make their way onto college and university campuses to pursue a college degree. Due to these changes, many institutions of higher education have had to rethink the way they have historically operated. In an attempt to better meet the needs and demands of adult nontraditional students, colleges and universities have reviewed their existing programs and instituted programs that allow for the awarding of academic credit for prior learning. For those institutions of higher education involved in the prior learning assessment (PLA) process and interested in providing a quality program, an increased emphasis and focus should be on the importance of determining what a learning activity is, and more importantly, what constitutes college-level learning. This study focused on the identification and profiling of prior learning assessment (PLA) processes in Texas public universities offering nontraditional baccalaureate degree programs, the identification of commonalties among such programs, and the determination of program quality based on established standards. The instrument utilized in this study was designed on Urban Whitaker's 10 Standards of Good Practice. The population consisted of those public institutions of higher education in Texas that offer the Texas CIP code 30.9999.40 - Applied Arts and Sciences - baccalaureate degree. A within-stage mixed-model methodology was used. Open-ended questions were used to strengthen the data obtained from the quantitative portion. This research study suggests that, although there are similarities with regards to the types of PLA processes used in the awarding of PLA credit, many of the organizations could benefit from an evaluation of their current policies, procedures, and/or common practices related to the process of awarding credit ...
Date: May 2006
Creator: Freed, Rusty

Synthesis and Characterization of 2,3-Dichloropyrrolo[1,2-a]benzimidazol-1-one and Its Methylthiol Derivatives

Description: Condensation of 2,3-dichloromaleic anhydride and o-phenylenediamine in refluxing toluene affords the three compounds 2,3-dichloro-N-o-C6H4(NH2)maleimide (1), N,N¢-o-C6H4-bis(2,3-dichloromaleimide) (2), and 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one (3), with compound 1 as the major product. Repeating the same reaction in the presence of added PTSA furnishes compound 3 as the major product. Treatment of 3 with methylthiol in the presence of pyridine affords monosulfide compounds 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one (4) and and the disulfide derivatives 2,3-di(methylthio)pyrrolo[1,2-a]benzimidazol-1-one (5). The substitution of the first chlorine group in compound 3 occurs regioselectively at C-3 to produce compound 4, followed by replacement of the remaining chlorine group to furnish the disulfide compounds 5. The new compounds 1-5 have been isolated by column chromatography and characterized by IR, NMR, XRD, CV and etc.
Date: May 2006
Creator: Wu, Guanmin

Improving Recall of Browsing Sets in Image Retrieval from a Semiotics Perspective

Description: The purpose of dissertation is to utilize connotative messages for enhancing image retrieval and browsing. By adopting semiotics as a theoretical tool, this study explores problems of image retrieval and proposes an image retrieval model. The semiotics approach conceptually demonstrates that: 1) a fundamental reason for the dissonance between retrieved images and user needs is representation of connotative messages, and 2) the image retrieval model which makes use of denotative index terms is able to facilitate users to browse connotatively related images effectively even when the users' needs are potentially expressed in the form of denotative query. Two experiments are performed for verifying the semiotic-based image retrieval model and evaluating the effectiveness of the model. As data sources, 5,199 records are collected from Artefacts Canada: Humanities by Canadian Heritage Information Network, and the candidate terms of connotation and denotation are extracted from Art & Architecture Thesaurus. The first experiment, by applying term association measures, verifies that the connotative messages of an image can be derived from denotative messages of the image. The second experiment reveals that the association thesaurus which is constructed based on the associations between connotation and denotation facilitates assigning connotative terms to image documents. In addition, the result of relevant judgments presents that the association thesaurus improves the relative recall of retrieved image documents as well as the relative recall of browsing sets. This study concludes that the association thesaurus indicating associations between connotation and denotation is able to improve the accessibility of the connotative messages. The results of the study are hoped to contribute to the conceptual knowledge of image retrieval by providing understandings of connotative messages within an image and to the practical design of image retrieval system by proposing an association thesaurus which can supplement the limitations of the current content-based image retrieval systems ...
Date: May 2006
Creator: Yoon, JungWon

Beyond Rocking the Vote: An Analysis of Rhetoric Designed to Motivate Young Voters

Description: Attempts to solve the continued problem of low youth voter turnout in the U.S. have included get out the vote drives, voter registration campaigns, and public service announcements targeting 18- to 25-year-old voters. Pay Attention and Vote added to this effort to motivate young voters in its 2006 campaign. This thesis analyzes the rhetorical strategies employed by the Pay Attention and Vote campaign advertisements, measures their effectiveness, and adds to the limited body of knowledge describing the attitudes and behaviors of young nonvoters. This thesis applies a mixed method approach, utilizing both rhetorical criticism and quantitative method. The results of both analyses are integrated into a discussion which critiques current strategies of addressing the youth voter turnout problem and offers suggestions for future research on the topic.
Date: August 2007
Creator: Brewer, Angela

Reported Impact of a Correctional Facility's Presence on Community Solidarity: Huntsville, Texas

Description: The problem examined is community solidarity in a well-established prison town. The primary question addressed in this study is "what is the reported impact of a correctional facility's presence on community solidarity?" This study is concerned with the community's perception about the problems, as well as the benefits involved in the housing of a prison and in particular the solidarity of the community. The relevant literature dates from 1929 to 2004 and examines a wide range of concepts associated with community studies and prison studies. Based on themes found in the review of prison literature; work issues, safety, concern about children, stress, community image, benefits, community identity, and community cohesion, seven research questions were constructed. A semi-structured interview was conducted of 81 residents of Walker County in Huntsville, Texas. Huntsville houses 9 prisons. The prison system is the primary employer in the county. A qualitative data analysis using Altius/tr as a tool for content analysis was used. Throughout the data, community residents consistently indicated solidarity. Emerging from the data were seven themes associated with community solidarity:(a) unqualified community pride, (b) normalization, (c) defensiveness against the media, (d) qualified community pride, (e) denial, (f) community and myths, (g) economics.
Date: May 2006
Creator: Nation, Patricia Ann Campo

The Effects of an Electronic Feedback Sign on Speeding

Description: Although a handful of experiments have utilized indirect feedback in attempts to reduce speeding on roadways, fewer experiments have utilized direct feedback as a means to reduce incidences of speeding. The current study evaluated the effects of direct and individualized feedback provided by a large electronic feedback sign that displayed the speed of oncoming vehicles as they approached the sign along the roadways of a college campus. The effects of the sign were evaluated using a non-simultaneous multiple baseline experimental design employing two control conditions and intervention phase. Each condition was implemented at three sites on the college campus. The results showed that intervention produced significant decreases in both measures of vehicle speeds at each site, relative to measures collected during both control conditions.
Date: May 2006
Creator: Flores, Jaime

Teacher certification content area tests: Predictors of teacher knowledge for post-baccalaureate secondary candidates.

Description: In response to a growing teacher shortage, increasing numbers of secondary teachers are prepared through streamlined certification programs. For this reason, assessing candidates' content area knowledge gained from institutions of higher education across the United States is an important program admission factor as candidates must demonstrate content area knowledge by passing a Texas content area certification test (TExES). This study examines content knowledge for candidates enrolled in an online post­-baccalaureate program from September 1, 2002 through April 30, 2005. Academic transcript analysis and grades 8-­12 subject tests of the TExES were used as a proxy for subject matter knowledge for a sample of individuals seeking initial teacher certification in a post­-baccalaureate teacher certification at the University of North Texas. Descriptive data,linear regression, and logistic regression analyses were used to draw conclusions about the content area knowledge of the individuals in the sample. Scores on the TExES were used to determine the relationships between the content area knowledge of initial certification students and the number of content area courses completed, the grade point averages, and time elapsed between the completion of the last content area course and the student's initial attempt on the TExES. Results differed by the content area of the candidates. Analysis of variance results indicate significant differences between the five test groups with regard to number of courses taken F(4,139) = 9.334, p < .001 grade point average F(4,139) = 5.733, p < .001 and time between the last course taken F(4,139) = 6.135, p < .001. The three­-predictor model was statistically significant F(3,32) = 3.753, p = .02 for the History test group. The variable, upper-­level grade point average accounted for approximately 12% variance among scores within the History test group, and the variable months of time elapsed between last content area course work and the initial ...
Date: May 2006
Creator: Jackson, Jennifer K.

Democratic Pantheism in the Political Theory of Alexis de Tocqueville

Description: According to Alexis de Tocqueville, humanity is entering a new age of political and social equality, a new epoch in which the human race has no historical example or experience. As a result, he holds humanity's future will be largely determined by the political and moral choices made in this transitional time. For Tocqueville, the new egalitarian era is a forgone conclusion, but for him, the pressing question is whether humanity will choose a future in which it enchains itself to new forms of tyranny, or, whether the human race can establish the political and moral institutions designed to assure human freedom and dignity. In Tocqueville's view, liberty or slavery are the two choices modern men and women have in front of them, and it is the intent of this dissertation to explore Tocqueville's warning in regard to the latter choice. Tocqueville warns us that modern democratic peoples must beware of the moral and political effects of a new type of political philosophy, a political theory he terms democratic pantheism. Democratic pantheism is a philosophic doctrine that treats egalitarianism as a "religion" in which all social and political striving is directed toward realizing a providentially ordained strict equality of conditions. To attain this end, modern humanity gives up its right to self-government to an all-powerful "representative" state that will unconsciously (and as a result, unjustly) force equality on unequal human beings. Because this philosophy informs the core "soul" of a pantheistic social state, the vast majority of individuals are blissfully unaware that their humanity is diminished and their freedom is lost. The effect is a political and intellectual torpor wherein democratic citizens fall prey to a deterministic and insipid existence; and any thoughts of true independence and freedom of action are eventually extinguished--all due to the unknowing acceptance of a ...
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Date: May 2006
Creator: Bearry, Brian Anthony

A Dual Dielectric Approach for Performance Aware Reduction of Gate Leakage in Combinational Circuits

Description: Design of systems in the low-end nanometer domain has introduced new dimensions in power consumption and dissipation in CMOS devices. With continued and aggressive scaling, using low thickness SiO2 for the transistor gates, gate leakage due to gate oxide direct tunneling current has emerged as the major component of leakage in the CMOS circuits. Therefore, providing a solution to the issue of gate oxide leakage has become one of the key concerns in achieving low power and high performance CMOS VLSI circuits. In this thesis, a new approach is proposed involving dual dielectric of dual thicknesses (DKDT) for the reducing both ON and OFF state gate leakage. It is claimed that the simultaneous utilization of SiON and SiO2 each with multiple thicknesses is a better approach for gate leakage reduction than the conventional usage of a single gate dielectric (SiO2), possibly with multiple thicknesses. An algorithm is developed for DKDT assignment that minimizes the overall leakage for a circuit without compromising with the performance. Extensive experiments were carried out on ISCAS'85 benchmarks using 45nm technology which showed that the proposed approach can reduce the leakage, as much as 98% (in an average 89.5%), without degrading the performance.
Date: May 2006
Creator: Mukherjee, Valmiki

Ion-Induced Damage In Si: A Fundamental Study of Basic Mechanisms over a Wide Range of Implantation Conditions

Description: A new understanding of the damage formation mechanisms in Si is developed and investigated over an extended range of ion energy, dose, and irradiation temperature. A simple model for dealing with ion-induced damage is proposed, which is shown to be applicable over the range of implantation conditions. In particular the concept of defect "excesses" will be discussed. An excess exists in the lattice when there is a local surplus of one particular type of defect, such as an interstitial, over its complimentary defect (i.e., a vacancy). Mechanisms for producing such excesses by implantation will be discussed. The basis of this model specifies that accumulation of stable lattice damage during implantation depends upon the excess defects and not the total number of defects. The excess defect model is validated by fundamental damage studies involving ion implantation over a range of conditions. Confirmation of the model is provided by comparing damage profiles after implantation with computer simulation results. It will be shown that transport of ions in matter (TRIM) can be used effectively to model the ion-induced damage profile, i.e. excess defect distributions, by a simple subtraction process in which the spatially correlated defects are removed, thereby simulating recombination. Classic defect studies illuminate defect interactions from concomitant implantation of high- and medium-energy Si+-self ions. Also, the predictive quality of the excess defect model was tested by applying the model to develop several experiments to engineer excess defect concentrations to substantially change the nature and distribution of the defects. Not only are the excess defects shown to play a dominant role in defect-related processing issues, but their manipulation is demonstrated to be a powerful tool in tailoring the implantation process to achieve design goals. Pre-amorphization and dual implantation of different energetic ions are two primary investigative tools used in this work. Various analyses, ...
Date: May 2006
Creator: Roth, Elaine Grannan

Sexual harassment: Do gender and organizational status of harasser really matter?

Description: The research investigated the impact of sexual harassment on withdrawal behaviors and attitudes toward harassment by examining the gender composition of the harassment dyad and the organizational status of the perpetrator in relation to the victim. Archival data from the Inter-University Consortium for Political and Social Research at the University of Michigan was used to obtain surveys in which participants rated their attitudes and experiences related to sexual harassment. Only individuals who reported experiencing sexual harassment within the 24 months prior to data collection are included in the current research. A MANOVA was conducted to determine if withdrawal behaviors and attitudes of victims varied by the gender dyad and/or the organizational status of the perpetrator. Results indicated that individuals harassed by people with higher organizational status displayed more withdrawal behaviors in the form of decreased productivity and increased use of sick, annual, and unpaid leave. Individuals harassed by a member of the same gender also used more unpaid leave. Interestingly, individuals harassed by members of the opposite gender, tended to disagree more strongly with the attitude index measuring cautious awareness of sexual harassment.
Date: December 2007
Creator: Barnett, Michelle L.

Teacher Turnover among Teachers of Students with Emotional and Behavior Disorders

Description: The purpose of this study was to investigate factors that compel teachers of students with emotional and behavioral disorders (E/BD) to quit or stay in their job. Invitations to participate in the study were sent to a sample of educators from each the four census regions of the United States who currently work or have worked in the past worked with students with E/BD and have participated in one or more of the Council for Children with Behavioral Disorders (CCBD) professional development events. A total of 156 educators responded to the online survey and 9 participated in the focus groups. Quantitative information generated from the survey was analyzed using frequency distributions and ANOVA, whereas, qualitative information were analyzed by summarizing and sorting information into different categories. The results were presented in narrative and tabular form and organized in response to each of the research questions. The projected high teacher turnover as depicted in the findings, were mainly attributed to workplace variables and classroom conditions. Both variables are likely to be associated with high levels of dissatisfaction and lack of commitment eventually leading to decisions by teachers of students with E/BD to leave their job. Most respondents perceived themselves as being adequately prepared for responsibilities associated with teaching students with E/BD. The low variances associated with the grouping variable, career decisions did not explain a significant amount of variance in perceived levels of preparedness with regards to implementation of various program components and instructional activities. Hence, teacher qualifications and perceptions did not play a significant role in career decisions made by teachers of students with E/BD. In addition, findings reveal the need for all future teachers regardless of their certification to take specialized courses in special education to ensure that all teachers understand the unique characteristics and needs of students with ...
Date: December 2007
Creator: Adera, Beatrice Atieno

Propagation analysis of a 900 MHz spread spectrum centralized traffic signal control system.

Description: The objective of this research is to investigate different propagation models to determine if specified models accurately predict received signal levels for short path 900 MHz spread spectrum radio systems. The City of Denton, Texas provided data and physical facilities used in the course of this study. The literature review indicates that propagation models have not been studied specifically for short path spread spectrum radio systems. This work should provide guidelines and be a useful example for planning and implementing such radio systems. The propagation model involves the following considerations: analysis of intervening terrain, path length, and fixed system gains and losses.
Date: May 2006
Creator: Urban, Brian L.

MBE Growth and Instrumentation

Description: This thesis mainly aims at application of principles of engineering technology in the field of molecular beam epitaxy (MBE). MBE is a versatile technique for growing epitaxial thin films of semiconductors and metals by impinging molecular beams of atoms onto a heated substrate under ultra-high vacuum (UHV) conditions. Here, a LabVIEW® (laboratory virtual instrument engineering workbench) software (National Instruments Corp., http://www.ni.com/legal/termsofuse/unitedstates/usH) program is developed that would form the basis of a real-time control system that would transform MBE into a true-production technology. Growth conditions can be monitored in real-time with the help of reflection high energy electron diffraction (RHEED) technique. The period of one RHEED oscillation corresponds exactly to the growth of one monolayer of atoms of the semiconductor material. The PCI-1409 frame grabber card supplied by National Instruments is used in conjunction with the LabVIEW software to capture the RHEED images and capture the intensity of RHEED oscillations. The intensity values are written to a text file and plotted in the form of a graph. A fast Fourier transform of these oscillations gives the growth rate of the epi-wafer being grown. All the data being captured by the LabVIEW program can be saved to file forming a growth pedigree for future use. Unattended automation can be achieved by designing a control system that monitors the growth in real-time and compares it with the data recorded from the LabVIEW program from the previous growth and adjusts the growth parameters automatically thereby growing accurate device structures.
Date: May 2006
Creator: Tarigopula, Sriteja

Investigation of Selected Optically-Active Nanosystems Fashioned using Ion Implantation

Description: Opto-electronic semiconductor technology continues to grow at an accelerated pace, as the industry seeks to perfect devices such as light emitting diodes for purposes of optical processing and communication. A strive for greater efficiency with shrinking device dimensions, continually pushes the technology from both a design and materials aspect. Nanosystems such a quantum dots, also face new material engineering challenges as they enter the realm of quantum mechanics, with each system and material having markedly different electronic properties. Traditionally, the semiconductor industry has focused on materials such Group II-VI and III-V compounds as the basis material for future opto-electronic needs. Unfortunately, these material systems can be expensive and have difficulties integrating into current Si-based technology. The industry is reluctant to leave silicon due in part to silicon's high quality oxide, and the enormous amount of research invested into silicon based circuit fabrication. Although recently materials such as GaN are starting to dominate the electro-optical industry since a Si-based substitute has not been found. The purpose of the dissertation was to examine several promising systems that could be easily integrated into current Si-based technology and also be produced using simple inexpensive fabrication techniques such ion implantation. The development of optically active nano-sized precipitates in silica to form the active layer of an opto-electronic device was achieved with ion implantation and thermal annealing. Three material systems were investigated. These systems consisted of carbon, silicon and metal silicide based nanocrystals. The physical morphology and electronic properties were monitored using a variety of material characterization techniques. Rutherford backscattering/channeling were used to monitor elemental concentrations, photoluminescence was used to monitor the opto-electronic properties and transmission electron microscopy was used to study the intricate morphology of individual precipitates. The electronic properties and the morphology were studied as a function of implant dose, anneal times and anneal ...
Date: May 2006
Creator: Mitchell, Lee

FACET Simulation in the Imataca Forest Reserve, Venezuela: Permanent Plot Data and Spatial Analysis

Description: Tree diameter data from 29 years of observations in six permanent plots was used to calculate the growth rate parameter of the FACET gap model for 39 species in the Imataca forests in Venezuela. The compound topographic index was used as a measure of differential soil water conditions and was calculated using geographic information systems. Growth rate values and topographic conditions typical of hill and valley were input to FACET to simulate dynamics at the species level and by ecological and functional groups. Species shade-tolerance led to expected successional patterns. Drought-tolerant/saturation-intolerant species grew in the hills whereas drought-intolerant/saturation-tolerant species occurred in the valleys. The results help to understand forest composition in the future and provide guidance to forest management practices.
Date: May 2006
Creator: Figuera, Dilcia