A factor analysis of the preferred learning styles of Industrial Technology and Engineering undergraduate students at North Carolina Agriculture and Technical State University and at Iowa State University

Fazarro, Dominick E Iowa State University 2001 해외박사(DDOD)

This study examined the learning style preferences of African American and European American undergraduate students in the Industrial Technology and Engineering programs at North Carolina A&T State University and Iowa State University. In this study, the independent variables employed were ethnicity, discipline, and the named institutions. The dependent variables were the 20 learning style preferences in the Productivity Environmental Survey (PEPS). Convenience sampling was used to collect 540 students. A factor analysis was used to determine the preferred learning styles for African American and European American students at each institution. In addition, the hypotheses were tested by the Box's M test in the discriminant analysis. The hypotheses were tested at an <italic>a priori</italic> level of .05 to ascertain significant differences in the factor structures or groups. The findings of the study concluded that: (1) there were differences in the factor loading profiles of African American and European American students at each institution, regardless of discipline, and (2) there were no differences between the factor loading profiles of Industrial Technology and Engineering students at either institution. Further analyses were generated to determine additional findings on African American and European American learning styles within their respective disciplines. The analyses consisted of examining if there were differences between factor loading profiles by combining both ethnic groups from each program, regardless of institution. The findings concluded that there were no differences between the factor loading profiles of the students enrolled in the two programs.

Roles and influences of the Governor's office in state policy-making for higher education: A two-state case study (Michigan, Kentucky)

Nichols, Gregory Scott Iowa State University 2005 해외박사(DDOD)

This study focused on participant perceptions of roles and perceived influence of state Governors and their staffs in higher education policy-making. Reported increased activity by Governors and their staffs in education policy-making, coupled with increasing public demands and limited or reduced state resources for higher education lend relevance to this topic. Literature also suggests that higher education leaders and state officials may have differing views of their roles in state policy-making processes. The study was designed to capture participant perceptions as to processes, and roles and influence therein, not specific policy outcomes. Given the interpersonal and dynamic nature of the policy-making process, these perceptions were the focus of the study. Qualitative case study methodology was used in this study. Initially, a preliminary survey was administered to Governor's education policy advisors from ten states. Thereafter, a field study was conducted to examine policy-making in the states of Michigan and Kentucky. The study presents relevant background information on each state and commentary from approximately 50 in-depth personal interviews with governmental and education leaders in these states. The researcher has worked as a staff member of his state legislature, Governor's office, and as Executive Director of his state Board of Regents prior to assuming his current position as a Special Assistant to the President of Iowa State University. The commentary and emergent themes of the study are informed by those experiences as well as study data and existing literature. Study findings included a confirmation of the state-to-state variation in: public sector system design, social/economic/political culture, expectations for Executive branch involvement in higher education policy-making, and the roles and influence of the Governor and staff. While some similarities in states' approaches were noted as well, participants believed the circumstances in their state were unique from any other. The perceptions by and of some very experienced Governor's aides and state government and higher education officials in the study states may be of value in assessing similar situations. The study design, however, does not provide for quantifiable, transferable results that can necessarily be applied to differing points in time or differing locations.

The Iowa Chemistry Education Alliance, ICEA: Process and product

Burke, Kathleen Annette Iowa State University 2005 해외박사(DDOD)

The Iowa Chemistry Education Alliance, ICEA, supported by Department of Education Star Schools funding (R203F5000198), was both a Process and a Product. The Process included: (a) Design and support of high school teacher training sessions that incorporated distance learning techniques, cooperative learning and guided inquiry strategies, and a constructivist, student-centered classroom focus; (b) Design and incorporation of eight supplemental learning modules, corresponding assessment rubrics, and supporting videotapes into the existing Iowa high school chemistry curriculum; (c) Adaptation of the learning modules throughout the course of the academic year while the units were being integrated into the existing curriculum; (d) Modification and final editing of the curriculum modules and videotapes. The Product consisted of eight supplemental ICEA learning modules with corresponding assessment rubrics, and three supporting videotapes. To integrate ICEA materials into the existing curriculum, students at high schools around the state of Iowa conducted cooperative, guided-inquiry laboratory exercises. Via electronic mail and Iowa's two-way interactive audio-video system, the Iowa Communications Network (ICN), they discussed strategies for experimentation and shared results obtained. Invited guest experts also visited student groups via the ICN. Teachers conducted regular biannual on-site face-to-face planning meetings. These were augmented and supported by weekly or biweekly "staff" meetings conducted via the ICN. From the original three hundred students in four central Iowa high schools (rural, urban, and suburban), by its third and fourth year, the Project evolved to include over 1500 students in twenty-five high schools statewide.

Photochemistry and internal eliminations of organosulfur and organoselenium compounds

McCulla, Ryan David Iowa State University 2005 해외박사(DDOD)

This dissertation focuses on two specific aspects of the chemistry of organosulfur and organoselnium compounds. The first is the internal elimination of the sulfinate esters, sulfonic esters, and the effects of silyl-substitution on the internal elimination of sulfoxides. The internal elimination of sulfinate esters proceeds through a 5-membered transition state whereas sulfonate esters proceed through a 6-membered transition state. Using computations, it was determined in the 6-membered transition state that substantial charge separation occurs, but less charge separation is observed in the 5-membered transition state. The ability of the sulfonate leaving group to incorporate charge favors the 6-member transition state. In the 5-centered elimination, a nucleophilic-electrophilic mismatch in the transition state is made worse when the sulfur atom is more positively charged, as in the sulfonate. Silyl groups attached at either the Calpha or Cbeta position of an alkyl sulfoxide lower the activation enthalpy of the sulfoxide syn elimination reaction by a few kcal mol-1. A Silyl substituent at Cbeta can stabilize the transition state by either stabilizing the developing positive charge at Calpha or negative charge at Cbeta. Silyl substitution at Calpha is not positioned to interact favorably with either developing charge in the transition state, and the lower activation barrier is more likely a response to the overall less endothermic reaction than any silyl interaction in the transition state. The second topic is the photochemistry of organosulfur and organoselenium ylides. The photodeoxygenation of dibenzoselenophene oxide (DBSeO) was found to have a greater quantum efficiency in producing O(3P) than dibenzothiophene oxide (DBTO). However, the photo sensitization and direct irradiation of DBTO (or DBSeO) were found to undergo photodeoxygenation by, in most cases, different mechanisms. Both of these conclusions were supported by monitoring the relative oxidized product ratios. Using calculations, the bond strengths of a variety of sulfur and selenium ylides were determined. This information is used in the elucidation of the photodeoxygenation mechanism of diaryl sulfoxides and selenoxides.

The identification and characterization of electronic defect bands in organic photovoltaic devices

Carr, John Anthony Iowa State University 2014 해외박사(DDOD)

In any microelectronic device, fundamental physical parameters must be well understood if electronic properties are to be successfully optimized. One such prominent parameter is energetic trap states, which are well-known to plague amorphous or otherwise impure semiconducting materials. Organic semiconductors are no strangers to such states and their electronic properties are evidently tied to these defects. This dissertation aims to elucidate these states in organic photovoltaic (OPV) devices. The literature to date is first reviewed and the author's contributions are subsequently detailed. Within the community, several techniques have been leveraged to study these mid-gap states. Atop the list are optical, capacitance and current based measurements and each has provided important pieces to the overall defect profile. Piecing together the works to date, organic photovoltaic materials are depicted as disordered semiconductors with a seemingly continuous distribution of both energetically shallow and deep trap bands. Upon blending the pure materials to create the modern day bulk heterojunction -- the currently preferred photovoltaic architecture -- energetic disorder increases and new trap bands appear. These states have been shown to stem from both intrinsic (e.g. structural disorder) and extrinsic (e.g. oxygen and synthesis contaminates) sources and it is quite clear that such states can have profound effects on, if not completely control, the electronic properties and long term stability of OPV devices. Most prominently, these states are known to enhance trap-assisted recombination, induce Fermi-level pinning and generate space-charge effects. Though these mid-gap traps have a large negative impact, they also can give an advantageous inherent doping, improving conductivity and interfacial electric fields. Evidently, continued progress in understanding the nature, sources, affects and possible mitigation of these defects in both current and future materials will be crucial to the optimization of this promising technology. The primary work of this study is to build upon these reports and to further the current body of knowledge on the identification and characterization of defect states in OPV devices. Capacitance techniques are heavily employed herein. As such, the accurate capacitance characterization of OPV devices was first visited. It was found that, owing to thinner films and larger series resistance, the series based parasitics could not be neglected in the typical frequency range of interest or significant errors and misinterpretations were introduced. Armed with this more accurate model, deeper, previously unknown trap states were then identified using low frequency capacitance measurements coupled with a point by point differential of high frequency capacitance-voltage measurements. The discovered defects remain important as it is those states closer to the midgap which more efficiently contribute to recombination and can be detrimental to device performance. More generally, the presented technique gives a generic overview of the capacitance response of OPV devices -- resolving anomalies and enabling others to better study the defect profile in their devices. Lastly, the pre-exponential factor of trap emission, also known as the attempt-to-escape frequency, was characterized. This parameter is essential if trap occupancy kinetics are to be accurately described -- important for any measurement or model dependent on the detrapping dynamics. It was found that the polymer based devices studied herein have a prefactor within a similar range, yielding similar trap capture cross sections. Not only does this give guidance as to the proper value to be used in the detrapping measurements/models, but also indicates that the trapping mechanisms in these devices are likely similar.

Field evaluation of winterkill in annual bluegrass (Poa annua L.) and creeping bentgrass (Agrostis stolonifera L.)

Valverde, Federico J Iowa State University 2007 해외박사(DDOD)

Winterkill, in putting greens and fairways of annual bluegrass ( Poa annua L.) and creeping bentgrass (Agrostis stolonifera L.), is a common phenomenon in North-Central Region of United States and in other temperate areas. Extensive research in controlled environments has evaluated injury mechanisms in creeping bentgrass and annual bluegrass. A large number of studies have evaluated winter injury in other turfgrass species and in cereal grasses. Most agree that damages can be explained by factors such as intracellular and extracellular ice formation, cellular dehydration and hydration, plant desiccation, macro scale tissue and organ rupture, diseases, anoxia, cellular acidosis, oxidative stress and retarded growth. Despite the vast amount of information generated during several decades of research, winterkill in creeping bentgrass and annual bluegrass is a problem that still leaves golf course superintendent with many unanswered questions. It is proposed that, to minimize winterkill, it is necessary to understand the high complexity of the system at field level and not only in controlled environments. The purpose of this research was to quantify the relative injury on putting greens as it relates to snow cover, ice formation, desiccation, crown hydration, and freeze/thaw cycles. Our approach was to evaluate the relative amount of injury that is associated with various scenarios of winter, instead of focusing solely on the mechanisms that cause the injury. Also, it is of interest to determine not only what condition causes the most winter injury, but when during the season does damage occur and if it is worth the expense or effort to try and minimize the injury by taking action. This study was conducted at the Iowa State University (ISU) Horticulture Research Center and at ISU Veenker Memorial golf course, both in Ames Iowa. The species evaluated were creeping bentgrass (Agrostis stolonifera L) and annual bluegrass (Poa annua L). Ten possible winter scenarios; dry/open, wet, ice continuous, snow continuous, impermeable artificial cover and ice continuous, ice removal, ice/melt freeze, snow removal/melt freeze, an artificial permeable turf cover, and artificial permeable turf cover with snow, were created on two Iowa putting greens in January, February and March of 2003, 2004, and 2005. Dry weight yield produced by samples collected in the field and grown on controlled chambers was used to indicate the amount of winter injury. Hourly temperatures were registered through the length of the study. Growing degree days (GDD) and stress degree days (SDD) were calculated with temperature data. Creeping bentgrass was not killed under any treatment. Continuous ice cover of 66 days caused creeping bentgrass bleaching but never resulted in any turf kill or decline in creeping bentgrass cover. Annual bluegrass was susceptible to winter injury when exposed to ice encasement. Damages by ice formation occurred during the first 15 days after encasement. The formation and type of ice is more important than the duration of ice cover in predicting annual bluegrass winter injury when ice is present. In both species, the treatments that offered a better visual quality at the end of the winter period were those that had a better protection such as impermeable-ice, permeable-snow, and snow treatments. However, the visual results did not necessarily mirror on those results of biomass production. In regard to temperatures and insulation characteristics of winter practices, greens without any protective layer suffer almost twice the amount of stress degrees that snow covered plots. As accumulative units, SDD 0°C had larger mean separation than any of the temperature variables; as such it was a better descriptor of intensity or risk of damage than temperatures alone. In the north central region of the United States, the use of artificial covers combined with snow blankets provided the best insulation and therefore the best condition for turf survival and early spring turf quality. Keywords. winterkill, annual bluegrass, creeping bentgrass, ice, temperature, stress degree days.

The Integration of Virtual Reality Technology into Agricultural Education

Wells, Kevin Trenton Iowa State University ProQuest Dissertations & The 2019 해외박사(DDOD)

The purpose of this dissertation was to examine virtual reality (VR) technology in the context of agricultural education. This study used both quantitative and qualitative approaches to address three objectives: (1) describe the opinions that school-based agricultural education (SBAE) teachers have about VR technology in the context of SBAE settings, (2) describe the perspectives that students have regarding the use of VR technology in the context of a university-level agricultural mechanics course, and (3) determine the impacts of the use of VR technology on university students' achievement in the context of welding skill performance.To address objective one, a census study was conducted during the 2017-2018 academic year with 90 SBAE teachers across Iowa. A questionnaire was distributed to the teachers via Qualtrics. Descriptive statistics were used to analyze the data. The results indicated that the teachers generally held favorable opinions about VR technology intertwined with a considerable degree of uncertainty about the technology and its uses.To address objective two, a qualitative study was conducted with nine students in a university-level agricultural mechanics course who provided their perspectives on using a VR technology application to develop welding-related psychomotor skills. Two focus groups were convened during the Spring 2018 semester. Qualitative data analysis procedures were used. Three major themes emerged: (1) VR welding and live welding have some degree of alignment, (2) VR technology can have some form of utility as a tool for teaching and learning, and (3) the value of using VR technology often depends on the individual. Student feedback indicated that while using a VR technology application can be useful, it should not take the place of using actual welding equipment as part of the teaching and learning processes.To address objective three, an experimental study was conducted with 101 undergraduate- and graduate-level students at Iowa State University (ISU). All participants were randomly assigned to undergo one of four training protocols: (1) 100% live welding, (2) 100% VR welding, (3) 50% live welding / 50% VR welding, or (4) 50% VR welding / 50% live welding. Each training protocol was an hour long. A one-way analysis of variance (ANOVA) indicated that there were no statistically significant differences (p > .05) in total weld scores between participants in the four training protocol groups.The mixed results from this dissertation indicated that while VR technology may have potential for inclusion in agricultural education settings, further examination of the suitability of this technology is needed. Future research should include a focus on the efficacy of VR technology for teaching and learning purposes. Research should also examine the effectiveness of other educational technologies, such as augmented reality (AR) and mixed reality (MR), to determine their potential for impacting the teaching and learning processes. Regarding implications for practice, agricultural education practitioners (e.g., SBAE teachers and university faculty) should consider a myriad of factors before making educational technology adoption decisions, including cost, ease of use, and alignment with course and program objectives.

Bayesian analysis of factors affecting crash frequency and severity during winter seasons in Iowa

Shaheed, Mohammad Saad B Iowa State University 2014 해외박사(DDOD)

Traffic safety during winter seasons has been a serious concern in Iowa as hundreds of people are injured on Iowa's highways each winter. As the goal of the state transportation agency is to ensure the mobility of road users without compromising the safety during winter periods, it is important to understand the factors affecting winter-weather crash frequency and occupant injury risk through quantitative prediction models. It is of utmost importance to identify locations prone to winter-weather crashes to utilize the limited resources efficiently for improving safety during winter conditions. This research intended to develop a systematic prioritization technique to identify winter-weather crash hotspots by using Empirical Bayes technique that addresses the serious limitations of the traditional methods to screen road networks for identifying high crash locations. This research also addresses the issue of hierarchical structure in the crash data by developing quantitative models to predict occupant injury risk for crashes occurring during winter seasons to obtain unbiased and accurate estimation of the parameters for better management of road safety during winter seasons. Along with developing site prioritization techniques for identifying roadway segments with potential for safety improvement through traditional statistical methods using raw crash data, Empirical Bayes technique is used to screen roadway segment through developing safety performance functions for winter-weather crashes. A novel approach is adopted to extract weather data from information reported by winter maintenance crew members to incorporate weather related factors in developing safety performance functions at network level for three roadway types in Iowa. Weather factors such as visibility, wind velocity, air temperature are found to have statistically significant effects on winter-weather crash frequency. The ranking of roadway segments based on Potential for Safety Improvement (PSI) by employing Empirical Bayes technique differs from the ranking produced by simple crash frequency. Safety Performance Functions developed in this research can be used to produce ranking based on PSI by using crash observations made over a specific number of years for winter-weather crashes. Models predicting occupant injury risk with binomial logit formulation are developed considering the hierarchical structure of the crash data in a Bayesian framework in this research for weather-related crashes, non-weather related crashes, and all crashes occurring during the four winter seasons (2008/09 to 2011/12) in Iowa. These models are developed using disaggregate crash data with occupants nested within crashes. High values of between-crash variance for the three models underscore the justification of considering the hierarchical nature of the crash data due to the natural crash data collection process. Factors related to occupants (gender, seating position, trap status, ejection status, airbag deployment, safety equipment used) had statistically significant effects on occupant injury risk for all the models. Weather-related variables such as visibility and air temperature were found significant predictors of all crashes and weather-related crashes during the winter seasons. The variable representing road surface condition is also found to be a significant factor in all three models developed to predict occupant injury risk during the winter seasons.

Integration of technology into the instructional practice of new teachers: Case studies of beginning teachers' use of technology

Clausen, Jon Michael Iowa State University 2005 해외박사(DDOD)

The purpose of this study is to investigate how two first-year teachers use technology with their students. Each teacher was encouraged to use technology with students at different times in their development as teachers. One teacher participated in Iowa State University's PT3 grant project as a member of the TechCo cohort and began her career at a traditional elementary school. The second teacher was not a member of the PT3 cohort, but began her career at a school that had been a partner with Iowa State University's PT3 grant project. A case study analysis of these teachers investigated how each teacher used technology with their students and how their teacher education experience and the institutional and classroom context affected each teacher's instructional decisions and technology use with students during their initial year in the classroom. Results from this study demonstrate that these two teachers' personal conceptions about technology use with their students had an affect on how each first-year teacher used technology with her students. Each teacher used technology in meaningful ways with their students, but upon closer examination of this use, it became clear that the personal conceptions about technology use developed during teacher education was an important indicator of how they used technology with students in their own classroom. How each teacher responded to challenges of being a first-year teacher and the support they received within the institutional context could also be analyzed through their personal conceptions about how technology should be used. The study of these two first-year teachers suggests that modeling effective technology use, providing access to technology, and support for technology continue to be important factors in helping new teachers use technology. Results from this study also suggested that the beliefs formed during teacher preparation on the use of technology played a powerful role in how these first year teachers used technology with their students. These results suggest the importance of providing opportunities for preservice teachers to reflect and make conceptual connections between their preparation and practice as they develop and understand their visions of technology use in K-12 classrooms.

Understanding conformational transitions in ras proteins using all-atom and coarse-grained molecular dynamics

Kapoor, Abhijeet Iowa State University 2014 해외박사(DDOD)

RAS subfamily proteins regulates cell growth and differentiation by cycling between active (GTP-bound) and inactive (GDP-bound) states. Mutations intervening normal Ras functioning are associated with several human cancers and developmental disorders. The three RAS isoforms in human HRAS, KRAS, and NRAS are the most common oncogene found in human cancers. Despite considerable experimental and computational efforts, it has remained difficult to achieve a therapeutic grip on RAS proteins mainly due to the incomplete understanding of the intermediate structures in RAS GDP-GTP transitions. Identifying the distinct features of intermediate states in RAS signaling processes is thus highly desirable for the design of small molecule inhibitors. The primary focus of this work was to develop a generic coarse-grained model of proteins, use it to study conformational transitions in RAS proteins with the goal to identify the critical structural features controlling the intrinsic conformational transitions, and complement the results using all-atom simulations. Knowledge of such critical features is bound to provide invaluable understanding of the ways in which these processes would be catalyzed by regulatory proteins. Thus, the present work also lays the foundation for future works involving coarse-grained modeling of RAS conformational switch mechanisms in the presence of regulatory proteins. In the first part of the thesis, we developed a coarse-grained model that successfully folded nineteen different proteins into their native states (containing beta-sheet, &agr;-helix, and mixed &agr;/beta) starting from completely random configurations. The model is sensitive to small changes in protein sequence, and more importantly, the results obtained from the coarse-grained model were shown to complement very well with results from all-atom molecular dynamics. Using coarse-grained simulations in combination with all-atom simulations (total of 3.02micros) of HRAS, we identified the structural features that regulate the intrinsic nucleotide (GDP) exchange reaction. Our results suggests that dissociation of GDP/Mg from the nucleotide binding pocket is initiated by a loss of interaction between GDP and the base binding region of RAS. Further, we provide the first simulation study showing displacement of GDP/Mg away from the nucleotide pocket in both mutant and wild-type RAS. Both SwitchI and SwitchII, the known critical elements in RAS signaling, delay the escape of displaced GDP/Mg in the absence of guanine nucleotide exchange factors (GEFs). A model for the mechanism of GEF in accelerating the exchange process is presented. We also provided a comprehensive comparison of the dynamics of all the three RAS isoforms using extensive molecular dynamics simulations in both the GDP- (total of 3.06micros) and GTP-bound (total of 2.4micros) states. We identified a new pocket on RAS structure, which opens transiently during MD simulations, and can be targeted to regulate the nucleotide exchange reaction or possibly interfere with membrane localization. Furthermore, we have identified a new cluster of wild-type GTP-bound structures that potentially represents an intermediate conformation in the GTP hydrolysis process.