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Articles 61 - 90 of 194
Full-Text Articles in Physical Sciences and Mathematics
Evans Function Computation, Blake H. Barker
Evans Function Computation, Blake H. Barker
Theses and Dissertations
In this thesis, we review the stability problem for traveling waves and discuss the Evans function, an emerging tool in the stability analysis of traveling waves. We describe some recent developments in the numerical computation of the Evans function and discuss STABLAB, an interactive MATLAB based tool box that we developed. In addition, we verify the Evans function for shock layers in Burgers equation and the p-system with and without capillarity, as well as pulses in the generalized Kortweg-de Vries (gKdV) equation. We conduct a new study of parallel shock layers in isentropic magnetohydrodynamics (MHD) obtaining results consistent with stability.
Properties Of The Zero Forcing Number, Kayla Denise Owens
Properties Of The Zero Forcing Number, Kayla Denise Owens
Theses and Dissertations
The zero forcing number is a graph parameter first introduced as a tool for solving the minimum rank problem, which is: Given a simple, undirected graph G, and a field F, let S(F,G) denote the set of all symmetric matrices A=[a_{ij}] with entries in F such that a_{ij} doess not equal 0 if and only if ij is an edge in G. Find the minimum possible rank of a matrix in S(F,G). It is known that the zero forcing number Z(G) provides an upper bound for the maximum nullity of a graph. I investigate properties of the zero forcing number, …
Numerical Solutions For Stochastic Differential Equations And Some Examples, Yi Luo
Numerical Solutions For Stochastic Differential Equations And Some Examples, Yi Luo
Theses and Dissertations
In this thesis, I will study the qualitative properties of solutions of stochastic differential equations arising in applications by using the numerical methods. It contains two parts. In the first part, I will first review some of the basic theory of the stochastic calculus and the Ito-Taylor expansion for stochastic differential equations (SDEs). Then I will discuss some numerical schemes that come from the Ito-Taylor expansion including their order of convergence. In the second part, I will use some schemes to solve the stochastic Duffing equation, the stochastic Lorenz equation, the stochastic pendulum equation, and the stochastic equations which model …
Meta-Analysis Using Bayesian Hierarchical Models In Organizational Behavior, Michael David Ulrich
Meta-Analysis Using Bayesian Hierarchical Models In Organizational Behavior, Michael David Ulrich
Theses and Dissertations
Meta-analysis is a tool used to combine the results from multiple studies into one comprehensive analysis. First developed in the 1970s, meta-analysis is a major statistical method in academic, medical, business, and industrial research. There are three traditional ways in which a meta-analysis is conducted: fixed or random effects, and using an empirical Bayesian approach. Derivations for conducting meta-analysis on correlations in the industrial psychology and organizational behavior (OB) discipline were reviewed by Hunter and Schmidt (2004). In this approach, Hunter and Schmidt propose an empirical Bayesian analysis where the results from previous studies are used as a prior. This …
Modeling Temperature Reduction In Tendons Using Gaussian Processes Within A Dynamic Linear Model, Richard David Wyss
Modeling Temperature Reduction In Tendons Using Gaussian Processes Within A Dynamic Linear Model, Richard David Wyss
Theses and Dissertations
The time it takes an athlete to recover from an injury can be highly influenced by training procedures as well as the medical care and physical therapy received. When an injury occurs to the muscles or tendons of an athlete, it is desirable to cool the muscles and tendons within the body to reduce inflammation, thereby reducing the recovery time. Consequently, finding a method of treatment that is effective in reducing tendon temperatures is beneficial to increasing the speed at which the athlete is able to recover. In this project, Bayesian inference with Gaussian processes will be used to model …
Musical Query-By-Content Using Self-Organizing Maps, Kyle B. Dickerson
Musical Query-By-Content Using Self-Organizing Maps, Kyle B. Dickerson
Theses and Dissertations
The ever-increasing density of computer storage devices has allowed the average user to store enormous quantities of multimedia content, and a large amount of this content is usually music. Current search techniques for musical content rely on meta-data tags which describe artist, album, year, genre, etc. Query-by-content systems, however, allow users to search based upon the actual acoustical content of the songs. Recent systems have mainly depended upon textual representations of the queries and targets in order to apply common string-matching algorithms and are often confined to a single query style (e.g., humming). These methods also lose much of the …
Finding Alternatives To The Hard Disk Drive For Virtual Memory, Bruce Albert Embry
Finding Alternatives To The Hard Disk Drive For Virtual Memory, Bruce Albert Embry
Theses and Dissertations
Current computer systems fill the demand of operating systems and applications for ever greater amounts of random access memory by paging the least recently used data to the hard disk drive. This paging process is called "virtual memory," to indicate that the hard disk drive is used to create the illusion that the computer has more random access memory than it actually has. Unfortunately, the fastest hard disk drives are over five orders of magnitude slower than the DRAM they are emulating. When the demand for memory increases to the point that processes are being continually saved to disk and …
Radio Determination On Mini-Uav Platforms: Tracking And Locating Radio Transmitters, Braden Russell Huber
Radio Determination On Mini-Uav Platforms: Tracking And Locating Radio Transmitters, Braden Russell Huber
Theses and Dissertations
Aircraft in the US are equipped with Emergency Locator Transmitters (ELTs). In emergency situations these beacons are activated, providing a radio signal that can be used to locate the aircraft. Recent developments in UAV technologies have enabled mini-UAVs (5-foot wingspan) to possess a high level of autonomy. Due to the small size of these aircraft they are human-packable and can be easily transported and deployed in the field. Using a custom-built Radio Direction Finder, we gathered readings from a known transmitter and used them to compare various Bayesian reasoning-based filtering algorithms. Using a custom-developed simulator, we were able to test …
Novel Cinchona Alkoloid Derived Ammonium Salts As Phase-Transfer Catalysts For The Asymmetric Synthesis Of Beta-Hydroxy Alpha-Amino Acids Via Aldol Reactions And Total Synthesis Of Celogentin C., Bing Ma
Theses and Dissertations
Project I. Cinchona alkaloid-derived quaternary ammonium salts have been successfully used as phase-transfer catalysts, particularly in asymmetric alkylations. Our group applied this type of catalyst in the synthesis of β-hydroxy α-amino acids via aldol reactions and discovered that the Park-Jew catalyst afforded good yields and good enantiomeric excess of the syn diasteromers, but negligible diastereoselectivity. This project was therefore focused on the synthesis of novel cinchonidine-derived catalysts with the Park-Jew catalyst as the lead structure. The C3 position of cinchonidine nucleus was modified to achieve dimers and catalysts possessing electron-deficient alkyne and alkene moieties. Synthesized catalysts were tested in the …
A Functional Framework For Content Management, Robert Emer Broadbent
A Functional Framework For Content Management, Robert Emer Broadbent
Theses and Dissertations
This thesis proposes a functional framework for content management. This framework provides concepts and vocabulary for analysis and description of content management systems. The framework is derived from an analysis of eight content management systems. It describes forty-five conceptual functions organized into five functional groups. The functionality derived from the analysis of the content management systems is described using the vocabulary provided by the functional framework. Coverage of the concepts in the existing systems is verified. The utility of the framework is validated through the creation of a prototype that implements sufficient functionality to support a set of specific use …
Fusion Of The Parastrophic Matrix And Weak Cayley Table, Nathan C. Perry
Fusion Of The Parastrophic Matrix And Weak Cayley Table, Nathan C. Perry
Theses and Dissertations
The parastrophic matrix and Weak Cayley Tables are matrices that have close ties to the character table. Work by Ken Johnson has shown that fusion of groups induces a relationship between the character tables of the groups. In this paper we will demonstrate a similar induced relationship between the parastrophic matrices and Weak Cayley Tables of the fused groups.
Comparing Bootstrap And Jackknife Variance Estimation Methods For Area Under The Roc Curve Using One-Stage Cluster Survey Data, Allison Dunning
Comparing Bootstrap And Jackknife Variance Estimation Methods For Area Under The Roc Curve Using One-Stage Cluster Survey Data, Allison Dunning
Theses and Dissertations
The purpose of this research is to examine the bootstrap and jackknife as methods for estimating the variance of the AUC from a study using a complex sampling design and to determine which characteristics of the sampling design effects this estimation. Data from a one-stage cluster sampling design of 10 clusters was examined. Factors included three true AUCs (.60, .75, and .90), three prevalence levels (50/50, 70/30, 90/10) (non-disease/disease), and finally three number of clusters sampled (2, 5, or 7). A simulated sample was constructed for each of the 27 combinations of AUC, prevalence and number of clusters. Estimates of …
Effect Of Advanced Synthetically Enhanced Detector Resolution Algorithm On Specificity And Sensitivity Of Portable High Purity Germanium Gamma Detector Spectra, Latosha M. Bell
Theses and Dissertations
The ability to identify special nuclear material is one of the necessary prevention mechanisms for preventing proliferation of special nuclear materials. Additionally, if a nuclear event were to occur, information about the nuclear material used may be extracted from gamma spectra, provided it is obtained quickly and accurately. This can be made possible with the use of the exceptional resolution of the HPGe detector. This experiment applied the Advanced Synthetically Enhanced Detector Resolution Algorithm (ASEDRA) to a portable HPGe detector's spectra, to investigate whether improvements in specificity and sensitivity can be obtained. This method has been used to improve performance …
An Efficient And Effective Implementation Of The Trust System For Power Grid Compartmentalization, Juan M. Carlos Gonzalez
An Efficient And Effective Implementation Of The Trust System For Power Grid Compartmentalization, Juan M. Carlos Gonzalez
Theses and Dissertations
As utility companies develop and incorporate new technologies, such as moving to utility Internet technology based architecture and standard; it is crucial that we do so with history in mind. We know that traditional utility protection and control systems were not designed with security in their top priorities. This presents a danger in an environment where near real-time responses are required to ensure safe operations. As a consequence, system security becomes a burden to the system rather than necessary protection. Unfortunately, technology implementation is not the only concern. The number of utility privately-owned companies has multiplied as the market has …
Coalition Robustness Of Multiagent Systems, Nghia Cong Tran
Coalition Robustness Of Multiagent Systems, Nghia Cong Tran
Theses and Dissertations
Many multiagent systems are environments where distinct decision-makers compete, explicitly or implicitly, for scarce resources. In these competitive environments, itcan be advantageous for agents to cooperate and form teams, or coalitions; this cooperation gives agents strategic advantage to compete for scarce resources. Multiagent systems thus can be characterized in terms of competition and cooperation. To evaluate the effectiveness of cooperation for particular coalitions, we derive measures based on comparing these different coalitions at their respective equilibria. However, relying on equilibrium results leads to the interesting question of stability. Control theory and cooperative game theory have limitations that make it hard …
Genetic Analysis Of Ribosome Stalling And Rescue, Douglas Ray Tanner
Genetic Analysis Of Ribosome Stalling And Rescue, Douglas Ray Tanner
Theses and Dissertations
In eubacteria, ribosome stalling on broken messenger RNA transcripts can lead to cell death. The trans-translation quality control mechanism rescues many of these stalled ribosomes. In this process, tmRNA enters stalled ribosomes by mimicking a transfer RNA, accepting the stalled nascent peptide. The ribosome then releases the broken mRNA and resumes translation on a coding region within tmRNA itself. Translation of tmRNA marks the nascent peptide for destruction by the addition of a short proteolysis tag and the ribosome is released at a stop codon within the tmRNA open reading frame. An intriguing aspect of trans-translation is that …
Video Scene Detection Using Closed Caption Text, Gregory Smith
Video Scene Detection Using Closed Caption Text, Gregory Smith
Theses and Dissertations
Issues in Automatic Video Biography Editing are similar to those in Video Scene Detection and Topic Detection and Tracking (TDT). The techniques of Video Scene Detection and TDT can be applied to interviews to reduce the time necessary to edit a video biography. The system has attacked the problems of extraction of video text, story segmentation, and correlation. This thesis project was divided into three parts: extraction, scene detection, and correlation. The project successfully detected scene breaks in series television episodes and displayed scenes that had similar content.
Easemail: Easy Accessible Secure Email, Ryan B. Segeberg
Easemail: Easy Accessible Secure Email, Ryan B. Segeberg
Theses and Dissertations
Traditional email encryption methods are difficult to set up, as they require senders to obtain a message recipient's public key before a secure communication can be sent. Easy Accessible Secure Email (EASEmail) addresses the key establishment and exchange issues of encrypted email by using a lightweight symmetric key server. Users can send a secure email without establishing or exchanging keys with the recipient in advance. With usability as its primary goal, EASEmail strives to bring usable secure email communication to the masses.
Synthesis And Evaluation Of Stimulatory Properties Of Glycolipids For Natural Killer T Cells, Xiangtian Long
Synthesis And Evaluation Of Stimulatory Properties Of Glycolipids For Natural Killer T Cells, Xiangtian Long
Theses and Dissertations
Natural killer T cells (NKT cells) are a subset of T cells. They regulate a wide range of diseases including infection, tumor growth, and autoimmune diseases, through recognizing glycolipid antigens in the context of CD1d. An understanding of the scope of glycolipid antigens would facilitate use of this cell type in controlling immune responses. Till today, a lysosomal glycolipid, isoglobotrihexosylceramide (iGb3), is the only natural glycolipid that has been found to be recognized by both human and mouse NKT cells. To elucidate the molecular basis of this specific recognition, iGb3 variants were designed and prepared: i) replacement of the C26 …
Development And Investigation Of Intensity-Modulated Radiation Therapy Treatment Planning For Four-Dimensional Anatomy, Yelin Suh
Theses and Dissertations
Lung cancer is the leading cause of cancer-related deaths worldwide. Radiotherapy is one of the main treatment modalities of lung cancer. However, the achievable accuracy of radiotherapy treatment is limited for lung-based tumors due to respiratory motion. Four-dimensional radiotherapy explicitly accounts for anatomic motion by characterizing the motion, creating a treatment plan that accounts for this motion, and delivering this plan to the moving anatomy. This thesis focuses on the current problems and solutions throughout the course of four-dimensional radiotherapy. For characterization of respiratory-induced motion, patient tumor motion data were analyzed. It is shown that tumor motion can be significant …
Cancellation Properties Of Direct Products Of Digraphs, Katherine Toman
Cancellation Properties Of Direct Products Of Digraphs, Katherine Toman
Theses and Dissertations
This paper discusses the direct product cancellation of digraphs. We define the exact conditions on G such that GxK=HxK implies G=H. We focus first on simple equations such as GxK_2=HxK_2 where K_2 denotes a single arc and then extend this to the more general situation, GxK = HxK. Our results are achieved by using a “factorial” operation on graphs, which is in some sense analogous to the factorial of an integer.
Shrinking The Janzen-Connell Doughnut: Consequences Of An Invasive Multiplier (Microstegium Vimineum) On The Mid-Canopy In A Mixed Pine-Oak Forest, Rebekha Shaw
Theses and Dissertations
Introduction of invasive species can alter seed fate predictions made by the Janzen-Connell Escape Hypothesis (JCEH). The JCEH states that there is a suitable region around a plant that is ideal for seed germination, growth, and recruitment. Seeds dispersed too close to the maternal plant are subject to competition from the maternal individual and perhaps density-dependent predation, whereas seeds dispersed further away may end up in suboptimal habitats. Invasive species may change the amount of these suitable habitats for native plants by creating unsuitable light environments and as a result, may influence the size of the ideal recruitment zone surrounding …
Density Functional Investigations Of Pure And Ligated Clusters, Kristen Casalenuovo
Density Functional Investigations Of Pure And Ligated Clusters, Kristen Casalenuovo
Theses and Dissertations
Atomic clusters are attractive candidates for building motifs for new nano-assembled materials with desirable properties. At this nano-regime of matter, the size, shape, and composition of clusters changes their electronic structure and hence their properties. Computational modeling must work hand in hand with experiment to provide robust descriptions of the geometries and energetics of atomic clusters and how they might behave in a nano-assembled material. To this end, we have investigated three distinct species as model systems: antimony oxides SbxOy (x = 1, 2; y = 0 - 3), metal ion-solvent complexes Mm(NH3)n (M = Bi, Pb; m = 1 …
Haar Measures For Groupoids, Benjamin Grannan
Haar Measures For Groupoids, Benjamin Grannan
Theses and Dissertations
The definition of a groupoid is presented as well as examples of common structures from which a groupoid can be formed. Haar measure existence and uniqueness theorems for topological groups are used for the construction of Haar systems on groupoids. Some Haar systems are presented in addition to an example of a groupoid which admits no Haar system.
Ordinal Indexing Of The Class Of Strictly Singular Operators, Craig Stevenson
Ordinal Indexing Of The Class Of Strictly Singular Operators, Craig Stevenson
Theses and Dissertations
The Schreier families are a collection of finite subsets of N and have been used to provide refinements of the following Banach space notions: unconditional basic sequences, convergent sequences, spreading model and strictly singular operators to name a few. We use the Schreier families to study subclasses of strictly singular operators on Banach spaces. We also provide a sufficient condition on the strictly singular operators implying every operator falls into one of these subclasses.
Construction Site Sedimentary Pollution In A Watershed, Imo Okwu
Construction Site Sedimentary Pollution In A Watershed, Imo Okwu
Theses and Dissertations
In the study of sediment pollution on and near a construction site, it is necessary to remember that sediment movement and deposition are part of the natural environment before the intervention of construction. As with many hydrologic problems, most sedimentation problems have visual impacts for relatively short periods, because they are rainstorm-related. Perhaps the most serious sedimentation problem is general deterioration of the total environment, a condition usually not recognized by the public. This research presents an analytical evaluation of five construction sites. The analytical framework categorized the life cycle of construction sites into three stages in order to facilitate …
Spectroscopic Characterizations Of The Compound Ii Intermediate Of Soybean Peroxidase From Soybean Seed Coatings, Andoh-Baidoo Rosemarie Agyepong
Spectroscopic Characterizations Of The Compound Ii Intermediate Of Soybean Peroxidase From Soybean Seed Coatings, Andoh-Baidoo Rosemarie Agyepong
Theses and Dissertations
Spectroscopic characterization of ferric soybean peroxidase with peroxides were studied to determine the ligand coordination and to characterize the structure of the heme active site and its intermediates (ferryl species). The lifetime, chemical reactivity and distinctive colors of the ferryl species (FeIV) formed during the oxidation of peroxidase (FeIII) by peroxides enabled structure, dynamics and reaction mechanisms to be studied. Resonance Raman spectroscopy was used as a means of characterizing the structure of the soybean peroxidase and its intermediates. Excitation in the Soret absorption band at 406.7nm with 2-5mW laser power was used for this study. Resonance Raman spectra in …
An Agent Based Gene Flow Model, Erich Foster
An Agent Based Gene Flow Model, Erich Foster
Theses and Dissertations
The understanding of gene movement in plant species is critical to the management of both plant and animal species reliant on that plant. Pollen is the mechanism by which plants pass their genetic material from one generation to the next. Pollen dispersal studies have focused primarily on purely random diffusion processes, while this may be a good assumption for species pollinated mainly by abiotic means, such as wind, it is most likely an over simplification for species that are pollinated by biotic means, such as insects [3]. Correlated random walk (CRW) models are a model of animal movement [10] and …
Probability Elicitation Methods For Avoiding Biases: An Exposition, Bethany Mihajlovits
Probability Elicitation Methods For Avoiding Biases: An Exposition, Bethany Mihajlovits
Theses and Dissertations
A large portion of decision analysis lies in a decision maker’s uncertainty about an outcome and what they perceive is the chance (probability) of that outcome occurring (in other words, an individual’s “degree of belief” that an outcome will occur). However, thinking probabilistically can be difficult and we rely on “rather primitive cognitive techniques to make” such assessments (these techniques are termed heuristics) (Clemen & Reilly, 2001 p.311). Heuristics are simple and intuitive but tend to result in probabilities that are biased. This thesis will connect the literature available from both the psychology behind the biases and the mathematical problems …
Habitat Suitability Criteria For Fishes Of The South Fork Of The Shenandoah River And An Investigation Into Observer Effects Associated With Two Techniques Of Direct Underwater Observation, Robert Clayton Ramey
Habitat Suitability Criteria For Fishes Of The South Fork Of The Shenandoah River And An Investigation Into Observer Effects Associated With Two Techniques Of Direct Underwater Observation, Robert Clayton Ramey
Theses and Dissertations
This study constructed habitat suitability criteria for fishes of the South Fork of the Shenandoah River, in Virginia. The criteria will be used in an IFIM study to produce estimates of the discharge required by fishes in the South Fork. Chi-square tests were used to evaluate whether criteria described habitat use to a statistically significant degree. Secondly, chi-square tests were used to test transferability. The criteria described the habitat use of seven taxa commonly found in the South Fork to a statistically significant degree. Habitat criteria for two taxa did not describe their habitat use to a statistically significant degree. …