Physical Sciences and Mathematics Commons^™

Gorenstein Projective Precovers In The Category Of Modules, Katelyn Coggins

Electronic Theses and Dissertations

It was recently proved that if R is a coherent ring such that R is also left n-perfect, then the class of Gorenstein projective modules, GP, is precovering. We will prove that the class of Gorenstein projective modules is special precovering over any left GF-closed ring R such that every Gorenstein projective module is Gorenstein flat and every Gorenstein flat module has finite Gorenstein projective dimension. This class of rings includes that of right coherent and left n-perfect rings.

Missing Data In Clinical Trial: A Critical Look At The Proportionality Of Mnar And Mar Assumptions For Multiple Imputation, Theophile B. Dipita

Electronic Theses and Dissertations

Randomized control trial is a gold standard of research studies. Randomization helps reduce bias and infer causality. One constraint of these studies is that it depends on participants to obtain the desired data. Whatever the researcher can do, there is a possibility to end up with incomplete data. The problem is more relevant in clinical trials when missing data can be related to the condition under study. The benefits of randomization is compromised by missing data. Multiple imputation is a valid method of treating missing data under the assumption of MAR. Unfortunately this is an unverified assumptions. Current practice advise …

Characterization Of Charge Accommodation In Biologically Important Hydrogen-Bonded Clusters, John Thomas Kelly

Electronic Theses and Dissertations

The underlying motivation of chemical physics and physical chemistry is to understand naturally occurring chemical and physical processes from the nanoscopic molecular level to the macroscopic condensed phase. Over the past half-century, experimentalists have developed a number of laser-based analytical techniques to bridge the gap between the bulk phase and the single molecule. Here, we look at bulk phase and gas phase clusters to compare the local hydrogen-bonded network. To better understand the role noncovalent interactions have on biologically relevant building blocks in a natural environment, we compare the microhydration of gas phase cluster ions to condensed phase spectra. The …

Contribution Of Shallow Geology To Hydrocarbon Seep Formation In Green Canyon Block 600, Samantha Lynn Lucker

Electronic Theses and Dissertations

The Green Canyon Federal Protraction area in the Gulf of Mexico is rich in hydrocarbons. The movement of the Sigsbee salt escarpment in green canyon has resulted in a complex bathymetric profile and extensive shallow faulting that has allomigration of hydrocarbons to the surface creating cold seep sites. Green Canyon block 600 (gc600) contains multiple naturally occurring, active hydrocarbon seeps. Multi-beam bathymetry, backscatter, and polarity preserving chirp data were collected for gc600 to study the development of these naturally occurring seeps. Using these data, the structure and sedimentation of the first fifty meters can be studied in relation to the …

Thermal Effects On Spin Currents In Non-Local Metallic Spin Valves, Alex Hojem

Electronic Theses and Dissertations

The study of non-local spin valves (NLSVs) has recently proven to be a fertile area for both applied and fundamental research in nanomagnetism due to the unique ability to separate charge currents and spin currents. NLSVs may also prove essential for a new class of high-density hard disk read heads due to their favorable scalability. Recent studies have shown thermal effects created by high current densities play a significant role in the response of NLSVs. These thermal effects also provide the opportunity to create a pure spin current from thermal gradients via a mechanism call the spin dependent Seebeck effect …

Greenc5: An Adaptive, Energy-Aware Collection For Green Software Development, Junya Michanan

Electronic Theses and Dissertations

Dynamic data structures in software applications have been shown to have a large impact on system performance. In this paper, we explore energy saving opportunities of interface-based dynamic data structures. Our results suggest that savings opportunities exist in the C5 Collection between 16.95% and 97.50%. We propose a prototype and architecture for creating adaptive green data structures by applying machine learning tools to build a model for predicting energy efficient data structures based on the dynamic workload. Our neural network model can classify energy efficient data structures based on features such as the number of elements, frequency of operations, interface …

Implementing Agile Development At Scale: An Industry Case Study, Nikita Kataria

Electronic Theses and Dissertations

Agile software development methodologies are extremely popular. Their dynamic restructuring of the development process has been seen as the silver bullet for increasing the productivity of software development. A significant number of studies have analyzed the impact of implementing agile techniques. However these are mostly evaluated only in smaller team settings. There is very little reporting done on how agile development methods can be implemented at the team level and scaled up at the program/portfolio level in large software organizations.

We present the results of an empirical study conducted at Pearson Education. The study focuses on the penetration of agile …

Topological Speedups, Drew Daehnhardt Ash

Electronic Theses and Dissertations

Given a dynamical system T:X rightarrow X one can define a speedup of (X,T) as another dynamical system conjugate to S:X rightarrow X where S(x)=T^{p(x)}(x) for some function p:X rightarrowZ^{+}. In 1985 Arnoux, Ornstein, and Weiss showed that any aperiodic measure preserving system is isomorphic to a speedup of any ergodic measure preserving system. In this thesis we study speedups in the topological category. Specifically, we consider minimal homeomorphisms on Cantor spaces. Our main theorem gives conditions on when one such system is a speedup of another. Moreover, the main theorem serves as a topological analogue of the Arnoux, Ornstein, …

A Descriptive Study Of The Effect Of Payer Source On Multiple Longitudinal Outcome Measures Within The Tbi Model Systems National Database Using Longitudinal Hlm Analyses, Melissa Carole Hofmann

Electronic Theses and Dissertations

Using longitudinal data from the TBIMS ND, this study utilized a longitudinal hierarchical linear modeling approach to describe the effect of primary payer source on individual level change in outcomes including the FIM and DRS. To facilitate the use of parametric statistics, Rasch-transformed FIM and DRS scores were utilized; thus approaching an interval level of measurement. The FIM was separated into 3 separate cognitive, mobility, and self-care subscales. In this way, rehabilitation professionals including speech, physical, and occupational therapists for this TBI sample could reference results to inform current clinical practice.

Results indicated that FIM and DRS trajectories were best …

Relaxation Of Metals And Their Impact On Nitroxides, Priyanka Aggarwal

Electronic Theses and Dissertations

Pulsed and continuous wave electron spin resonance were used to characterize the relaxation rates of selected paramagnetic metals at 5 to 15 K or 80 K, measure the impact of these rapidly relaxing metals on the relaxation rates of nitroxide radicals in glassy mixtures and in discrete complexes, and characterize novel iron-sulfur proteins.

Spin echoes were observed at 5 to 7 K in 1:1 water:glycerol for Er(diethylenetriamine pentaacetic acid)^2- (Er(DTPA)^2-), Co(DTPA)^3- and aquo Co²⁺ with relaxation times that are strongly temperature dependent. Deep proton modulation was present on spin echo decays (Ch. 3). For Gd …

Development Of Palladium Catalyzed Alkene Difunctionalization On Vinyl-Quinoline Type Substrate And Isolation Of Pd-Alkyl Intermediate, Lusha Xu

Electronic Theses and Dissertations

The synthesis of quinoline derivatives is a continuing issue facing organic chemists in both academia and industry. To address this problem, palladium-catalyzed alkene difunctionalization was developed to be a powerful and straightforward strategy of synthetic transformations for adding diversity to organic molecules. In this thesis, Pd-catalyzed olefin difunctionalization reactions of vinyl-quinoline type substrate via generating Pd-alkyl intermediates were mainly described. The reactions described herein are pursuing three significant goals: 1) to isolate and recrystallize Pd-alkyl complexes; 2) to achieve oxidation reactions on Pd-alkyl intermediate; and 3) to investigate stereochemistry of nucleopalladation step on vinyl-quinoline starting materials.

Source Apportionment Of Atmospheric Particulate Matter In Developing Countries Using Trace Elements And Stable Metal Isotope Ratios, Nitika Dewan

Electronic Theses and Dissertations

The work presented herein details the source apportionment of atmospheric particulate matter in developing countries (Kyrgyzstan in Central Asia, metropolitan cities in Northern India, and Shenzhen in China) using trace elements and stable metal isotope ratios. The first study focused on the development of a novel method for the concomitant separation of rare-earth elements in environmental samples of any geological origin. The separation procedure is based on three extraction chromatographic materials, referred to as Sr.Spec, TRU.Spec, and Ln.Spec. This triple column arrangement enables the simultaneous isolation of pure Sr and Nd fractions in less than one day and with great …

A Near-To-Far Learning Framework For Terrain Characterization Using An Aerial/Ground-Vehicle Team, Ashkan Hajjam

Electronic Theses and Dissertations

In this thesis, a novel framework for adaptive terrain characterization of untraversed far terrain in a natural outdoor setting is presented. The system learns the association between visual appearance of different terrain and the proprioceptive characteristics of that terrain in a self-supervised framework. The proprioceptive characteristics of the terrain are acquired by inertial sensors recording measurements of one second traversals that are mapped into the frequency domain and later through a clustering technique classified into discrete proprioceptive classes. Later, these labels are used as training inputs to the adaptive visual classifier. The visual classifier uses images captured by an aerial …

Enhancements To Hierarchical Pathfinding Algorithms, Xin Li

Electronic Theses and Dissertations

In this thesis we study the problem of pathfinding in static grid-based maps. We apply the approach of abstraction and refinement. We abstract the grid map into a graph representation, and use the classic A* algorithm to search for a path in the abstract space, and then refine it into low-level path.

We started with a 2013 entry program to the Grid-based Path Planning Competition, and implemented several enhancements to experiment with the tradeoff between memory usage and search speed. Our program returns the refined low-level path incrementally, therefore reduces the first-move lag in large maps. We cache the low-level …

Model Based Security Testing For Autonomous Vehicles, Seana Lisa Hagerman

Electronic Theses and Dissertations

The purpose of this dissertation is to introduce a novel approach to generate a security test suite to mitigate malicious attacks on an autonomous system. Our method uses model based testing (MBT) methods to model system behavior, attacks and mitigations as independent threads in an execution stream. The threads intersect at a rendezvous or attack point. We build a security test suite from a behavioral model, an attack type and a mitigation model using communicating extended finite state machine (CEFSM) models. We also define an applicability matrix to determine which attacks are possible with which states. Our method then builds …

Leveraging Client Processing For Location Privacy In Mobile Local Search, Wisam Mohamed Eltarjaman

Electronic Theses and Dissertations

Usage of mobile services is growing rapidly. Most Internet-based services targeted for PC based browsers now have mobile counterparts. These mobile counterparts often are enhanced when they use user's location as one of the inputs. Even some PC-based services such as point of interest Search, Mapping, Airline tickets, and software download mirrors now use user's location in order to enhance their services. Location-based services are exactly these, that take the user's location as an input and enhance the experience based on that. With increased use of these services comes the increased risk to location privacy. The location is considered an …

C-Reactive Protein Interactions With Cellular Membranes And Supported Lipid Bilayers, Aml Abd Alhamed Alnaas

Electronic Theses and Dissertations

C-reactive protein (CRP) is a serum protein that binds to damaged membranes and initiates the complement immune response. Different forms of CRP are thought to alter how the body responds to inflammation and the degradation of foreign material. Despite knowing that a modified form of CRP(mCRP) binds to downstream protein binding partners better than the native pentameric form, the role of CRP conformation on lipid binding is yet unknown. In this work, three main assays were performed to characterize how conformation affects CRP-membrane interactions. The first assay utilized supported lipid bilayers that mimic the plasma membrane of apoptotic cells. The …

The Effect Of Morphology On Carrier Dynamics In Solution Processed Solar Cells, Alexander G. Dixon

Electronic Theses and Dissertations

This dissertation looks at the charge transport properties of solution processed solar cells and how these properties are effected by the microstructure and morphology of the material. It begins with an introduction and history of the field of solution processed solar cells, focusing on organic photovoltaics and perovskites. The physics and issues of charge transport in these materials are reviewed, and the transport probing techniques of photo-Charge Extraction via Linearly Increasing Voltage (photo-CELIV), Metal Insulator Semiconductor-CELIV (MIS-CELIV), and Resistance Photovoltage (RPV) are detailed.

The photo-CEILV technique is used to probe P3HT devices of varying molecular weights. This material is known …

A Comparison Of Latent Class Analysis And The Mixture Rasch Model: A Cross-Cultural Comparison Of 8th Grade Mathematics Achievement In The Fourth International Mathematics And Science Study (Timss-2011), Turker Toker

Electronic Theses and Dissertations

This study provides a comparison of the results of latent class analysis (LCA) and mixture Rasch model (MRM) analysis using data from the Trends in International Mathematics and Science Study - 2011 (TIMSS-2011) with a focus on the 8th-grade mathematics section. The research study focuses on the comparison of LCA with Mplus version 7.31 and MRM with WinMira 2011 to determine if results obtained differ when the assumed psychometric model differs. Also, a log-linear analysis was conducted to understand the interactions between latent classes identified by LCA and MRM. The data set used in the study was from four diverse …

Stereographic Visualization Of Bose-Einstein Condensate Clouds To Measure The Gravitational Constant, Ed Wesley Wells

Electronic Theses and Dissertations

This thesis describes a set of tools that can be used for the rapid design of atom interferometer schemes suitable for measuring Newton's Universal Gravitation constant also known as "Big G". This tool set is especially applicable to Bose--Einstein--condensed systems present in NASA's Cold Atom Laboratory experiment to be deployed to the International Space Station in 2017. These tools include a method of approximating the solutions of the nonlinear Schrödinger or Gross--Pitaevskii equation (GPE) using the Lagrangian Variational Method. They also include a set of software tools for translating the approximate solutions of the GPE into images of the optical …

Investigating Coastal Erosion Variability And Framework Geology Influence Along The Grand Strand, South Carolina, Aundrea Marie Dolan

Electronic Theses and Dissertations

Increasing erosional pressures along coastal systems require a better understanding of the mechanisms of natural and human-induced alterations. This is especially important in sediment-starved coastal systems where the effects from geologic framework may exert a disproportionate influence on shoreline behavior. Existing studies into geologic framework and shoreline variability are comprehensive and well documented; yet analysis into the spatial relationships between shoreline variability, lower shoreface morphodynamics, and framework in South Carolina is limited. The Grand Strand region of South Carolina has an extensive set of geophysical data, such as CHIRP seismic, sidescan sonar, borehole logs, and inner shelf cores. In addition, …

Gorenstein Projective (Pre)Covers, Michael J. Fox

Electronic Theses and Dissertations

The existence of the Gorenstein projective precovers is one of the main open problems in Gorenstein Homological algebra. We give sufficient conditions in order for the class of Gorenstein projective complexes to be special precovering in the category of complexes of R-modules Ch(R). More precisely, we prove that if every complex in Ch(R) has a special Gorenstein flat cover, every Gorenstein projective complex is Gorenstein flat, and every Gorenstein flat complex has finite Goenstein projective dimension, then the class of Gorenstein projective complexes, GP(C), is special precovering in Ch(R).

Optimizing Vehicle Usage Using Csp, Sat And Max-Sat, Raheem T. Al Rammahi

Electronic Theses and Dissertations

Most of the companies in Iraq spend significant amounts of time and money when transferring employees between home and work. In this thesis, we model the problem of the Dhi Qar Oil company (DQOC) transportations using three modeling languages from AI: Constraint Programing (CP), Boolean Satisfiability (SAT), and Maximum Satisfiability (MAX-SAT). We then use solvers to find optimal solutions to this problem.

We show which of these solvers is more efficient when finding optimal solutions. For this purpose, we create a test suite of 360 problems to test these solvers. All solvers are applied to these problems and the final …

Implementation Of An Air Supply Unit Control Scheme For The Uc2av (Unmanned Circulation Control Aerial Vehicle), Cameron Rosen

Electronic Theses and Dissertations

The expanded prevalence of Unmanned Aerial Vehicles (UAVs) in recent years has created many opportunities to research novel applications for their use, enabled by the reduced cost, mission flexibility, and reduced risk that small-scale unmanned platforms provide in comparison to larger aircraft. Despite the versatility of unmanned aviation, limitations on payload size and weight, fuel and power capacity, and takeoff and landing infrastructure can restrict UAV applications, and have created a need for lift augmenting technologies that can reduce the impact of these limitations. Circulation Control (CC) is an active flow technique that has been proven as a method for …

Molecular Mechanisms Of Protein Thermal Stability, Lucas Sawle

Electronic Theses and Dissertations

Organisms that thrive under extreme conditions, such as high salt concentration, low pH, or high temperature, provide an opportunity to investigate the molecular and cellular strategies these organisms have adapted to survive in their harsh environments. Thermophilic proteins, those extracted from organisms that live at high temperature, maintain their structure and function at much higher temperatures compared to their mesophilic counterparts, found in organisms that live near room temperature. Thermophilic and mesophilic homolog protein pairs have identical functionality, and show a high degree of structural and sequential similarity, but differ significantly in their response to high temperature. Addressing the principles …

Peccit: An Omniscient Debugger For Web Development, Zachary Ryan Azar

Electronic Theses and Dissertations

Debugging can be an extremely expensive and time-consuming task for a software developer. To find a bug, the developer typically needs to navigate backwards through infected states and symptoms of the bug to find the initial defect. Modern debugging tools are not designed for navigating back-in-time and typically require the user to jump through hoops by setting breakpoints, re-executing, and guessing where errors occur. Omniscient debuggers offer back-in-time debugging capabilities to make this task easier. These debuggers trace the program allowing the user to navigate forwards and backwards through the execution, examine variable histories, and visualize program data and control …

Remobilization Of Cobalt, Copper, Nickel, Lead, And Zinc In A Riparian Wetland Model, Richard Glenn Dolly

Electronic Theses and Dissertations

The mobility of chemically persistent metals in riparian wetland systems that could have a detrimental impact on the environment is an area of active research. This study utilized a physical model consisting of open water and wetland cells designed to simulate a natural riparian wetland to examine the mobility of five metals. The objective of the study was to determine if riparian wetlands have the potential to serve as permanent sinks for metals, or if they only serve as temporary sinks and with time metals could be remobilized and released. Specifically, this study examined the long-term behavior of Co, Cu, …

Biophysical Characterization Of A Proline Mutant Of Neural Cadherin, Keshia S. Dykes

Electronic Theses and Dissertations

Cadherins are calcium dependent glycoproteins whose homophilic interactions mediate cell-cell adhesion in solid tissues. They are comprised of an extracellular region, a transmembrane region and a cytoplasmic region. The extracellular region plays a critical role in cadherin-mediated cell adhesion, and has five tandemly repeated ectodomains (ec1-ec5), with three calcium binding sites situated in each interface between the domains. Dimerization of cadherin occurs through formation of adhesive interactions between extracellular domains of cadherins from neighboring cells. Adhesive interaction occurs at the interfaces of ec1 domains of two molecules originating from different cell surfaces. Dimerization is critically dependent on the binding of …

Up-Converted Emissions Of Er3+ Doped Gd2(Wo4)3 Phosphors, Grayson L. Wiggins

Electronic Theses and Dissertations

In this work, the up-conversion (UC) emissions of Er3+ in a gadolinium tungstate host was investigated to analyze the possible processes of up-conversion by 1500 nm and 980 nm excitation. Studies were conducted to see how the 4S3/2 -> 4I15/2 transition changed with varying current through the excitation source, varying excitation wavelength, and doping concentration. Power dependent studies revealed that under 1500 nm excitation the 4S3/2 -> 4I15/2 transition needed 3 photons, while 980 nm excitation could do the same transition with 2 photons. It was found that 1500 nm could produce more efficient red emission due to the 4I9/2 …

Garch(1,1) With Sifted Gamma-Distributed Errors, Alan C. Budd

Electronic Theses and Dissertations

Typical General Autoregressive Conditional Heteroskedastic (GARCH) processes involve normally-distributed errors, and they model strictly-positive error processes poorly. This thesis will present a method for estimating the parameters of a GARCH(1,1) process with shifted Gamma-distributed errors, conduct a simulation study to test the method, and apply the method to real time series data.