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Regression Analysis of Injuries on NFL Quarterbacks
Get PDFRisk assessment is an important aspect of many careers such as first responders and the military. This is no different for people who play sports, especially people who are in contact sports such as football. These players’ lives can be changed forever with one bad hit. The goal of this research is to analyze the probability of an injury for the National Football League’s (NFL) quarterbacks. It is hard to predict when, what, and where an injury will occur, because of this very little work has been done on the subject matter in a general form. The goal of this paper is to determine what variables play a role in factoring into a player being injured. The data was collected using NFL combine data as well as historical injury reports. We performed a binary logistic regression analysis with the variables and whether or not a player was injured in a season. This general model can be used for quarterbacks within the NFL to determine if they should keep playing based on their data during that time or end their careers
School Leadership Initiatives: To Promote Equitable and Inclusive Family Engagement Practices for English Language Learners
Get PDFThis qualitative case study aimed to understand and document changes that coincided with a planned district-wide initiative, especially from the perspectives of the school system leadership team and families of English language learners (ELL). The following research questions were addressed in this study: How did school leaders experience the initiative to increase equitable family and inclusive family engagement practices for English Language Learners? How did the parents of ELL students experience change through the initiative? The findings of this study revealed that to work effectively with parents of ELL students, school systems must understand the experiences and needs of these families. Working with families of diverse backgrounds must be important to school system leaders to affect important change initiatives on their behalf. Increasing equitable and inclusive family engagement practices for ELLs requires that school systems understand the group’s social, cultural, and linguistic needs and values, which requires training and open mindsets
Research on Rubik\u27s Snake and Quasi-Surfaces
Get PDFIn this dissertation, we have two topics in applied math. For the first one, we studied the Rubik’s snake by mathematical methods.
The Rubik’s snake is a toy invented by Professor Erno Rubik in 1981. It consists of right isosceles triangular prisms. Since the shape of a snake depends only on how we twist it, we can get a unique sequence from every snake. Those sequences record the way we twist snakes. In this dissertation, we will study the relations between some structures of the snake and the sequences.
For a snake with a specific structure, we will find out what type of sequence may be possible from such a structure. Also, we can predict the properties of a snake if we know its sequences.
The second chapter of the dissertation delves into Wagner’s theorem, first introduced in 1936, and extend the same questions to a new type of topological space, referred to as a quasi-surface. The diagonal flip is an operation on the edges of a graph. Wagner proved that two triangulations of the sphere could be transformed into each other by a sequence of the diagonal flips. The resulting graph after each transformation is still a triangulation. Many mathematicians have proved that this theorem works not only for the triangulations of the sphere but also for other surfaces, such as the torus.
In the second part of this dissertation, we will study multitriangulations of Tk, a quasi-surface first introduced by Turner. Similar to Wagner’s theorem, we aim to show that every two multitriangulations of Tk can be transformed into each other by a sequence of graph operations. In order to achieve the goal, we determine two more operations which appear to help solve those problems; and we introduce a number of results which put us within close reach of a Wagner-type theorem for Tk
Development of a Rubric to Measure Radiography Programmatic Assessment Plan Quality
Get PDFThis dissertation attempts to fill an existing gap in the literature concerning radiography programmatic assessment and provide a method of self-assessment for programs to create and evaluate their programmatic assessment plan. There is limited radiography-specific literature concerning programmatic assessment plans, and what does exist concerns general assessment best practices and some other allied health or health science related empirical research. Assessment plans are a necessary part of accreditation by the Joint Review Committee on Education in Radiologic Technology (JRCERT), which is required by many programs. However, education for many radiography program assessment plan contributors is limited in this area, and JRCERT citations concerning assessment plan standards are numerous. In order to mitigate this problem, this dissertation study created a rubric to evaluate the quality of radiography programmatic assessment plans. The methodology for this study was the Delphi technique to both develop and validate the rubric. The Delphi panel was made up of radiography programmatic assessment plan experts and consisted of multiple rounds to gain consensus for each of the rubric’s criteria and indicators. A finalized rubric is presented in Appendix D
Modeling and Analysis of the Selective Lightning Strike Phenomenon at Locations in a Chemical Manufacturing Plant
No full textThis research was motivated by the overly simplified claims, from a previous study, that attempted to explain the cause of the reportedly repeated lightning strikes at certain locations in the chemical manufacturing plant. The findings, without any model, claimed that the electronic monitoring and control devices’ fire damage occurred, due to the raised electrical ground potential during lightning strikes. It proceeded that the raised electrical ground potential caused a power flow reversal, which exceeded the ratings of the affected electronic control modules, damaging them. This claim is inconsistent with published research work in the failure mechanisms of industrial control systems, caused by lightning strike induced effects such as electric and magnetic fields. The critical questions to be answered that may confirm or refute this claim are: Given the well-researched and understood lightning related ground potential rise, as well as electronic process control modules failure mechanisms, would a rise in electric ground potential cause damages to a power module or the device input/output module? If all the failed electronic modules are certified to be identically rated, why do only a few, not all, fail when reverse biased? Why do these electronic failures not occur during every lightning strike, given the high lightning strike frequency of the chemical manufacturing plant’s location on the keraunic map. The overall objective of this research project was to use a detailed physics-based model, and carry out numerical modeling of lightning strikes at the chemical plant, by incorporating the actual geometrical structures and conditions. Firstly, the stepped leader, which is propagated at a slower speed of about 1 to 2 x 105 m/s, relative to the speed of light (3 x 108 m/s), was formulated using the Poisson equation to describe the local electric and magnetic fields. Secondly, the Maxwell’s time dependent equations were used to describe the fast propagated (1 x 108 m/s), ground originated, cloud-oriented return stroke. The third part of the study analyzed the model response to the inputs that include the geometry of the plant’s structures, as well as the existing lightning protection system. Model simulation results were correlated with the electronic controllers’ failure mechanisms that better explained the observed failures during lightning strikes in certain locations of the chemical manufacturing plant. The Finite Difference Time Domain (FDTD) model simulation to study the possible effects of the return stroke on the chemical plant’s ground potential, indicated that, the damages due to the raised electrical ground potential during lightning strikes’ attachment to the ground or grounded structure in the area is less or comparable to the damage that is caused by induced currents. Because of the long vertical and horizontal runs of the instrument loops that connect the instrument sensors with the I/O cards of the electronic controllers, the circuits are more vulnerable to high voltages resulting from the coupling of lightning induced electromagnetic fields than they are to the raised ground potential. The surge protectors on the input sensor circuits of the electronic control modules were verified to be absent, confirming that the simulated induced voltages, due to lightning strike induced electromagnetic field interferences, in the sensor circuits, will far exceed the typical rating of 5 V, resulting in a probable I/O module failure. The I/O module happened to be the commonly failed module in the affected electronic process controllers
New Porous Nanomaterials For Battery and Supercapacitor
Get PDFLithium-Sulfur batteries have a high energy storage capacity while their sulfur cathode suffers large volume change, polysulfides dissolution and shuttle effect, and capacity fading during long-term cycling. To help lock sulfur and mitigate these problems, we introduced halloysite, a natural clay material with a nanotube format, to disperse and confine sulfur nanoparticles as well as to suppress the dissolution and migration of polysulfides. Halloysite was made conductive by covering it with a glucose-derived carbon skin. Sulfur nanoparticles were then trapped in both the lumen and outside surface of individual nanotubes with a loading dosage up to 80 %. In this new halloysite/sulfur composites cathode, the hollow nanostructure of halloysite provides space to allow dimension changes of encapsulated sulfur nanoparticles during repeated lithiation while limiting their size up to the diameter of nanotube lumen (i.e., 25 nm or less). The stacked halloysite clusters further create many nanoscale voids to divide the sulfur-electrolyte interface into isolated domains and increase the migration tortuosity in electrolytes to suppress the dissolution and shuttle effect of polysulfides. These features together contribute to improved cycling stability, retaining nearly ~84% of the starting capacity over 250 cycles, though the diffusion of lithium ions going in and out of nanotubes show some differences.
In project 2, we worked on the anode development for LIBs. Silicon-rich (e.g., \u3e30 wt.%) anodes are desired to leverage the current capacity of lithium-ion batteries (LIBs) towards commercial cell performance requirements in critical markets, such as the transportation sector. A new type of nanofiber-in-microfiber silicon/carbon composite electrode was prepared and tested as a potential silicon-rich anode candidate. A co-axial electrospinning setup was used to produce a unique hybrid composite fiber configuration, in which silicon nanoparticles were suspended in a polymer solution to serve as the middle stream while the sheath stream was comprised of another polymer solution. Polyvinyl alcohol (PVA) was chosen as the silicon dispersion fluid because of its limited viscosity increase even at a very high solid allowance, which after carbonization held those nanoparticles together as short, branched nanofibers. Polyacrylonitrile (PAN) sheath fluid helped wrap the formed short, silicon-rich nanofiber bundles to form a nonwoven, ductile microfiber mat. After being carbonized into composite anodes, the silicon-rich nanofibers were used to host the majority of lithium ions while their thin carbon skin, originating from carbonized PVA, promotes conductivity and charge transfer. The nanofibrous morphology and the mesoscale space in between help accommodate the notorious volume expansion issues in silicon anodes during lithiation/delithiation processes. The outside PAN-derived microfibers provide structural support for the encapsulated silicon-rich nanofibers and simultaneously serve as the three-dimensional current collector. The new composite anodes were confirmed on their unique fibrous configuration and improved electrochemical performance. With 40 wt% Si, such silicon-rich, nanofiber-in-microfiber anodes achieve ~900 mAhg-1 reversible capacity and ~90% capacity retention over 250 cycles by effectively balancing challenges on silicon-rich fibrous anode and electrode pulverization.
Beside battery research, we also worked on supercapacitors with high power density in project 3. Despite the great benefits plastics have brought to our modern lives, a large volume of plastic wastes increasingly threatens our environment and human health. Through a hydrothermal carbonization and crystallization process involving nitric acid and ethanol, drinking bottles made of polyethylene terephthalate were successfully converted into carbon quantum dots (CQDs) and thin carbon sheets simultaneously, with the former well dispersed and intercalated in the latter as a ball-sheet carbon structure (BSCs). The formed unique, connected, and conductive carbon network allows rapid transport of ions and electrons besides their large surface area and numerous ion hosting sites. The electrodes made of such a plastic ball-sheet carbon structure (PBSCs) therefore exhibit pseudocapacitance behavior with the specific capacity reaching 237 F/g at the charge rate of 1 A/g. Superior cycling stability on the energy storage was also found. Our method offers a new avenue to upcycle some plastic wastes as valuable energy storage systems, to help boost the recycling of plastic waste, and move forwards to the sustainable deployment of various clean energy resources
The Perceived Impact of the Use of African American Vernacular English in a Sales Situation
Get PDFAccording to William Raspberry “Good English, well-spoken and written, will open more doors than a college degree. Bad English will slam doors you didn’t even know existed.” This dissertation examines the use of Standard American English (SAE) vis-à-vis African American Vernacular English (AAVE) in a sales situation. This dissertation is grounded in the Stereotype Content Model (SCM) and its two dimensions, warmth and competence. This research reveals the perceived influence that a particular dialect has on stereotype activation, through warmth and competence in a personal selling situation. This study extends marketing and sales literature by specifically focusing on AAVE vis-à-vis SAE in a sales situation to better understand how language activates the perceived warmth and competence of consumers and managers and in turn impacts cognitive, affective, and behavioral outcomes. This dissertation analyzes SCM and its effect on cognitive, affective, and behavioral outcomes through two studies representing the consumer perspective and managerial perspective.
Communication plays a significant role in the exchange process that occurs in a sales context and in a hiring situation involving a sales context. Language can provide cues about the speaker’s ethnicity, geographic location, and educational background. Based on the salesperson’s presentation, the consumer and manager can determine whether he/she would like to initiate a business relationship. Unfamiliarity with the use of AAVE vis-à-vis SAE as well as difficulty with processing the information being conveyed can prompt consumers and managers to base their perceptions on biases and stereotypes.
The consumer perspective examined the impact of AAVE vis-à-vis SAE on the activation of warmth and competence. The activation of warmth and competence was examined in regard to its influence on the consumer’s attitude toward the brand, evaluations of the salesperson, and purchase intention. The manager perspective examines how the use of AAVE vis-à-vis SAE activates the dimensions of warmth and competence. The activation of warmth and competence was examined for its effect on the manager’s attitude toward the salesperson, evaluations of the salesperson, and hiring recommendation. The results of the experiment indicate the need for a salesperson who wants to increase the likelihood of career success to speak SAE in order to obtain a more favorable rating from both customers and managers.
Overall, this study advances the marketing literature by revealing practical and theoretical implications surrounding salespersons’ linguistic ability and their overall success in the sales arena. The results of this study demonstrate that SAE speakers are perceived as being both warmer and more competent than speakers of AAVE. The findings of this dissertation extend the knowledge regarding how language, specifically AAVE vis-à-vis SAE, can influence consumer and manager perceptions of salespersons in a sales situation
First-Principles Calculations on Optoelectronic Properties of Halide Perovskites for Solar and Sensing Devices
Get PDFPerovskites are a class of semiconductors which has been rapidly growing in popularity due to their potential as absorbing layers for solar cells and applications in other devices such as sensors. There are several types based on the constituent species making up their ABX3 structure, and the flexible formulation results in tunable electronic properties. The research contained within this work aims to contribute to the knowledge of some of the most promising sub-types of halide-containing perovskites by way of first-principles density functional theory calculations, with the aim of improving the commercialization potential of derivative devices. The formulations of (MA)BX3 (A = methylammonium (MA); B = Sn, Pb; X = F, Cl, Br, I) perovskites were systematically studied in the orthorhmobic phase, which are less studied relative to the higher-temperature cubic counterpart. In addition, A = formamadinium (FA) and A = Cs cases are also selected for defect physics studies. For A = MA, structural differences were examined, including lattice geometry and bulk modulus. Thermodynamic stability was calculated, revealing potential stability of the F-containing formulations, previously unreported. It was revealed that the p-orbitals of the halogens determine the valence band levels while those of the B-site metal determine that of the conduction band. Optoelectronic calculations reveal Sn-containing perovskites, more environmentally friendly than the alternative Pb, have smaller band-gaps which results in greater absorbance in the practically-critical visible light range. Motivated by experimental results suggesting FAPbCl3’s potential as an NH3 sensor, defect formation energetics for all possible vacancy, interstitial and antisite defects were calculated. An established GGA exchange-correlation functional was compared with the meta-GGA SCAN functional, finding similar carrier-type (n vs p) predictions and Fermi-pinning defects but with significantly different pinning depth in the band gap. Additionally, ordering of the rotations of the FA ions was found to be critical to defect energetics. All-inorganic CsPbI3’s defect-dependent electronic structure was characterized with and without small gas molecules. It was found that NH3 strongly interacts with deep trap defects, potentially paving the way for a new sensor that has potential applications in processes such as Haber-Bosch, meriting further study. This work serves as a compendium of case studies for the importance of the defect physics in perovskite applications and contributes several hitherto unreported insights on perovskite optoelectronic properties. Finally, appendix A contains a hydrogen storage project completed in which a database of metal hydrides was built and used for machine learning for prediction of formation energy; a web-tool was constructed, with intention for use for high-throughput screening of potential new metal hydride formulations by composition
Pollinator Diversity on a Shortleaf Pine-Oak-Hickory Restoration Site
Get PDFLand use and cover are increasingly changing due to climate change and anthropogenic activities with many of these changes negatively impacting biodiversity. However, ecosystem restoration may help reverse these patterns. Northern Louisiana was historically dominated by shortleaf pine-oak-hickory forests but has been converted largely to loblolly pine forests with little-to-no herbaceous ground cover. The objective of this study is to determine how different practices on a shortleaf pine-oak-hickory forest restoration site affect pollinator diversity. I sampled pollinators from locations within areas under three different management regimes: 1) prescribed burning with active herbicide treatments for non-desirable plant species, 2) burning only, and 3) no active management. I predicted prescribed burning would increase pollinator species diversity and abundance and increases will be highest when combined with herbicide treatments. For data collection I set out pan traps containing ~200 ml of water with soap. Pan traps were placed 5m apart in an “X” shape and left out for 24 hrs. Three plots in each of the three management regimes (n=9) were sampled once a month for 6 months. I found greater diversity, evenness, and richness where burning occurred compared to no management. Specifically, Burn+Herbicide sites had ~1.5 times higher diversity than no management sites, and Burn+Herbicide sites were similar to burn only sites. These results are useful for future restoration efforts and management practices of shortleaf pine-hardwood forests because they show prescribed fire alone has positive impacts on pollinator diversity
Lunar Applications of Direct Contact Membrane Distillation For Regolith And Hydroponic Water Processing
Get PDFWater management has always been a critical issue facing lunar missions, since its uses are as numerous as they are vital. Using ionic liquids has been proposed for the purpose of processing the metal oxides in lunar regolith into oxygen and metals. The process used dilutes the ionic liquid. Recycling the ionic liquid solution after regolith processing is essential to reduce materials required in resupply missions and to supply oxygen. Water will also be needed for lunar farms to both grow food and assist in maintaining a habitable atmosphere. The use of direct contact membrane distillation (DCMD) technology is a method of water purification that was tested for viability in both concentrating ionic liquid streams and in hydroponic salt based nutrient streams. It was found that the ability of PTFE and PVDF based polymer membranes to separate solutes from water held potential in concentrating aqueous solutions and in recovering water from aqueous solutions. This was tested using a bench scale DCMD system to perform the operation at the temperatures of 50 ℃, 65 ℃, and 80 ℃. The results were tested using UV-Visible spectroscopy to determine concentrations. Through this method, the benefits and limitations of PTFE and PVDF membranes were found when operating at various temperatures with either aqueous ionic liquid solution or simulated hydroponic nutrient solutions