Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Algorithm (3)
- Database (2)
- Agency (1)
- Agile Manifesto (1)
- AlN (1)
-
- Algorithm evaluation (1)
- Algorithmic modeling (1)
- Aluminum iodide (1)
- ArcGIS (1)
- Astronomy (1)
- Astrophysics (1)
- Atomic cluster (1)
- Axis (1)
- Bacteria (1)
- Bald eagle (1)
- Bandit problem (1)
- Body mass (1)
- Buchberger's Algorithm (1)
- Case study (1)
- Chemical (1)
- Chemometric (1)
- Chesapeake Bay (1)
- Chi-square (1)
- Chief Medical Examiner (1)
- Cluster analysis (1)
- Cluster material (1)
- Code (1)
- Composition (1)
- Computer (1)
- Covariance (1)
Articles 1 - 28 of 28
Full-Text Articles in Entire DC Network
Cowboy: An Agile Programming Methodology For A Solo Programmer, Ashby Brooks Hollar
Cowboy: An Agile Programming Methodology For A Solo Programmer, Ashby Brooks Hollar
Theses and Dissertations
Very little research in software engineering has focused on the model of a programmer working alone. These so-called cowboys are disdained for not working in teams to build software. In reality many cowboys work by themselves due to the circumstances of their work environment, not because they are unable or unwilling to work with well with others. These solo programmers could benefit from a methodology to assist them in consistently developing reliable software on time and within budget while satisfying the customer's needs. Cowboy was designed to help fill this void. This agile-based system incorporates the benefits of agile methodologies …
Isolation Of Legionella Pneumophila From Well-Maintained Emergency Showers And Eyewash Stations, Jessica Mae Myers
Isolation Of Legionella Pneumophila From Well-Maintained Emergency Showers And Eyewash Stations, Jessica Mae Myers
Theses and Dissertations
Legionella pneumophila is a gram-negative bacterium responsible for Legionnaire's disease, and is commonly transmitted via aerosolized water. Legionella colonization of emergency eyewash and shower stations may pose an exposure hazard to users of these stations. There is little information about the role of these stations as significant reservoirs for Legionella. Samples were collected from 67 stations in an industrial facility. At the time of this study, the stations within this facility were under a routine maintenance program that included at least monthly flushing. This study also included the analysis for other bacterial organisms to determine an association between the presence …
Approaching The Singularity In Gowdy Universes, Bartlett Douglas Edmonds Jr.
Approaching The Singularity In Gowdy Universes, Bartlett Douglas Edmonds Jr.
Theses and Dissertations
It has been shown that the cosmic censorship conjecture holds for polarized Gowdy spacetimes. In the more general, unpolarized case, however, the question remains open. It is known that cylindrically symmetric dust can collapse to form a naked singularity. Since Gowdy universes comprise gravitational waves that are locally cylindrically symmetric, perhaps these waves can collapse onto a symmetry axis and create a naked singularity. It is known that in the case of cylindrical symmetry, event horizons will not form under gravitational collapse, so the formation of a singularity on the symmetry axis would be a violation of the cosmic censorship …
Chemometric Analysis Of Multivariate Liquid Chromatography Data: Applications In Pharmacokinetics, Metabolomics, And Toxicology, Sarah Elizabeth Graham Porter
Chemometric Analysis Of Multivariate Liquid Chromatography Data: Applications In Pharmacokinetics, Metabolomics, And Toxicology, Sarah Elizabeth Graham Porter
Theses and Dissertations
In the first part of this work, LC-MS data were used to calculate the in-vitro intrinsic clearances (CLint) for the metabolism of p-methoxyrnethamphetamine (PMMA) and fluoxetine by the CYP2D6 enzyme using a steady-state (SS) approach and a new general enzyme (GE) screening method. For PMMA, the SS experiment resulted in a CLint of 2.7 ± 0.2 µL pmol 2D6-1min-1 and the GE experiment resulted in a CLint of 3.0 ± 0.6 µL pmol 2D6-1min-1. For fluoxetine, the SS experiment resulted in a CLint of 0.33 ± 0.17 µL pmol 2D6-1min-1 and the GE experiment resulted in a CLint of 0.188 …
Forecasting Stability Levels For The Countries Of The Former Soviet Union, Margaret Erin Keck
Forecasting Stability Levels For The Countries Of The Former Soviet Union, Margaret Erin Keck
Theses and Dissertations
United States intelligence officers and policymakers need reliable forecasts of country, regional, and global stability or instability. Such forecasts require a methodology for identifying and analyzing factors that contribute to stability. The anticipation of this stability level can facilitate crisis warning and diplomatic strategies for various timelines, including five, ten, and twenty year forecasts. While the problem of forecasting can be tackled in various ways, in the interest of time and space, I will only go into a few of them. The approach I will use is multiple linear regression to generate a short-term forecast for the stability levels of …
Grobner Bases And Ideals Of Points, Eun R. Chang
Grobner Bases And Ideals Of Points, Eun R. Chang
Theses and Dissertations
The main point of this thesis is an introduction to the theory of Grobner bases. The concept of Grobner basis and construction of the Grobner basis by Buchberger's Algorithm, in which the notion of S-polynomials is introduced, and a few modified or improved versions of Grobner basis algorithm are reviewed in this paper. In Chapter 1, we have a review of ideals, the definitions and types of monomial ordering, the multivariate polynomial division algorithm and its examples. After ascertaining the monomial ordering on multivariate polynomials, we establish a leading term of a polynomial.In Chapter 2, after defining Grobner bases, we …
Silicon Oxide Nanoparticles Reveal The Origin Of Silicate Grains In Circumstellar Environments, Peneé Armaize Clayborne
Silicon Oxide Nanoparticles Reveal The Origin Of Silicate Grains In Circumstellar Environments, Peneé Armaize Clayborne
Theses and Dissertations
The processes leading to the widespread presence of crystalline silicates throughout the galaxy and the origin of silicon nanoparticles thought to be responsible for the observed extended red emission in diffuse galactic background are still far from being understood. One of the most abundant oxygen bearing species in molecular astronomical regions is SiO. It has been conjectured that silicate formation probably proceeds via the agglomeration of these molecular species; however there are no studies to reveal the microscopic mechanism. We have used a synergistic approach combining experiments in molecular beams and first principles theoretical calculation to demonstrate that the passage …
Photochemical Applications To The Study Of Complexity Phospholipid Bilayer Environments, Christopher John Wohl Jr.
Photochemical Applications To The Study Of Complexity Phospholipid Bilayer Environments, Christopher John Wohl Jr.
Theses and Dissertations
The physical and biophysical properties of a biological membrane model, phosphatidylcholine bilayers, were investigated using novel spiropyran/merocyanine molecular probes. The femtosecond to second dynamics of this system's photochemistry enabled bilayer viscosity and free volume to be studied over a broad time scale. Spiropyrans/merocyanines with different polarity were synthesized by changing the substitution of the indole moiety enabling determination of the trans-membrane properties of the bilayer. In addition, transient grating spectroscopy was used to study thermal energy transfer in phospholipid bilayers on a picosecond time scale.Femtosecond transient absorption spectroscopy was used to study the photo-induced spiropyran ring-opening and isomerization reactions that …
A Normal-Mixture Model With Random-Effects For Rr-Interval Data, Jessica Mckinney Ketchum
A Normal-Mixture Model With Random-Effects For Rr-Interval Data, Jessica Mckinney Ketchum
Theses and Dissertations
In many applications of random-effects models to longitudinal data, such as heart rate variability (HRV) data, a normal-mixture distribution seems to be more appropriate than the normal distribution assumption. While the random-effects methodology is well developed for several distributions in the exponential family, the case of the normal-mixture has not been dealt with adequately in the literature. The models and the estimation methods that have been proposed in the past assume the conditional model (fixing the random-effects) to be normal and allow a mixture distribution for the random effects (Xu and Hedeker, 2001, Xu, 1995). The methods proposed in this …
Bayesian Analysis, Endogenous Data,And Convergence Of Beliefs, Andrew T. Foerster
Bayesian Analysis, Endogenous Data,And Convergence Of Beliefs, Andrew T. Foerster
Theses and Dissertations
Problems in statistical analysis, economics, and many other disciplines often involve a trade-off between rewards and additional information that could yield higher future rewards. This thesis investigates such a trade-off, using a class of problems known as bandit problems. In these problems, a reward-seeking agent makes decisions based upon his beliefs about a parameter that controls rewards. While some choices may generate higher short-term rewards, other choices may provide information that allows the agent to learn about the parameter, thereby potentially increasing future rewards. Learning occurs if the agent's subjective beliefs about the parameter converge over time to the parameter's …
Quantitative Model For The Prediction Of Hydrodynamic Size Of Nonionic Reverse Micelles, Melissa A. Michaels
Quantitative Model For The Prediction Of Hydrodynamic Size Of Nonionic Reverse Micelles, Melissa A. Michaels
Theses and Dissertations
The sizes of nonionic reverse micelles were investigated as a function of the molecular structure of the surfactant, the type of oil, the total concentration of surfactant [NP], the ratio of NP4 to total surfactant (r), the water to surfactant molar ratio (ω), temperature, salt concentration, and polar phase. The basis of our investigation was nonylphenol polyethoxylates - NP4 and NP7. Micelle sizes were determined using dynamic light scattering (DLS). A central composite experimental design was used to quantitatively model reverse micelle size as a function of ω, [NP], and r. The model has demonstrated the capability of predicting the …
Determination Of The Band Gap Bowing Parameter Of A1xga1-Xn With Contactless Electroreflectance, Laura C. Mcglinchey
Determination Of The Band Gap Bowing Parameter Of A1xga1-Xn With Contactless Electroreflectance, Laura C. Mcglinchey
Theses and Dissertations
Contactless electroreflectance (CER), a modulation spectroscopy (MS) technique, has been used to study the A and C exciton transitions in A1xGa1-xN layers for a composition range of 0 ≤ x ≤ 0.48 at room temperature. Taking the entire composition range (0 ≤ x ≤ 1) into account by incorporating a previously reported band gap energy for AlN, the dependence of the A-exciton transition on composition showed a downward bowing from linearity. A bowing parameter of b = 1.7 eV was found. Analysis of the lower composition range 0 ≤ x ≤ 0.48 resulted in a linear fit, as did the …
Meta-Analysis Of Open Vs Closed Surgery Of Mandibular Condyle Fractures, Marcy Lauren Nussbaum
Meta-Analysis Of Open Vs Closed Surgery Of Mandibular Condyle Fractures, Marcy Lauren Nussbaum
Theses and Dissertations
A review of the literature reveals a difference of opinion regarding whether open or closed reduction of condylar fractures produces the best results. It would be beneficial to critically analyze past studies that have directly compared the two methods in an attempt to answer this question. A Medline search for articles using the key words 'mandibular condyle fractures' and 'mandibular condyle fractures surgery' was performed. The articles chosen for the meta-analysis contained data on at least one of the following: postoperative maximum mouth opening, lateral excursion, protrusion, deviation on opening, asymmetry, and joint pain or muscle pain. Several common statistical …
A Comparison Of Methods To Construct An Optimal Membership Function In A Fuzzy Database System, Joanne Marie Cunningham
A Comparison Of Methods To Construct An Optimal Membership Function In A Fuzzy Database System, Joanne Marie Cunningham
Theses and Dissertations
A fuzzy set is one in which membership in a category is not Boolean, rather items have a degree of membership. Fuzzy databases expand on this idea by storing fuzzy data and allowing data to be retrieved based on its degree of membership. Determining the degree of membership that satisfies the largest number of users is difficult. Five different methods of determining the membership function: the Direct Rating Method, the Random Method with step sizes of .02 and .03, the Steplock Method, and the Weighted Average Method, were compared on the basis of convergence and user satisfaction. The results support …
Optimal Clustering: Genetic Constrained K-Means And Linear Programming Algorithms, Jianmin Zhao
Optimal Clustering: Genetic Constrained K-Means And Linear Programming Algorithms, Jianmin Zhao
Theses and Dissertations
Methods for determining clusters of data under- specified constraints have recently gained popularity. Although general constraints may be used, we focus on clustering methods with the constraint of a minimal cluster size. In this dissertation, we propose two constrained k-means algorithms: Linear Programming Algorithm (LPA) and Genetic Constrained K-means Algorithm (GCKA). Linear Programming Algorithm modifies the k-means algorithm into a linear programming problem with constraints requiring that each cluster have m or more subjects. In order to achieve an acceptable clustering solution, we run the algorithm with a large number of random sets of initial seeds, and choose the solution …
Synthesis Of Novel Antimycobacterials And A Fluorescent Sensor For Simple Carbohydrates, Brian Thomas Walker
Synthesis Of Novel Antimycobacterials And A Fluorescent Sensor For Simple Carbohydrates, Brian Thomas Walker
Theses and Dissertations
Cell surface carbohydrates play an important role in a wide variety of biological processes such as inflammation, tumor metastasis, and viral and bacterial infection. The goal of our research has been two-fold. The first objective was the synthesis of antimycobacterial compounds. A mannose containing tetrasaccharide from the mannan core of lipoarabinomannan (LAM) of Mycobacterium tuberculosis has been synthesized using α-D-methylmannopyranoside as starting material and Koeings-Knorr reactions to couple saccharides. The synthesis was completed in nine steps and in 14% total yield. This compound should be useful in competitive inhibition studies with macrophages or as an immunological marker. We have successfully …
Stature And Criminal Behavior, Rebecca J. Fish
Stature And Criminal Behavior, Rebecca J. Fish
Theses and Dissertations
Minorities are significantly overrepresented in America's prison population, and many studies have been conducted to determine possible causes for such a disparity. Few of these studies, however, have examined small stature as a potential contributor to criminal behavior. This study examines the relationship between criminal behavior and stature among American males. The heights, weights, stature scores (a function of the product of height and weight) and the body mass indices of criminals are examined as a whole, as well as by subgroup based on race, locality, and nature of the crime committed. The average weight of the male criminal population …
K X N Trust-Based Agent Reputation, Christopher Alonzo Parker
K X N Trust-Based Agent Reputation, Christopher Alonzo Parker
Theses and Dissertations
In this research, a multi-agent system called KMAS is presented that models an environment of intelligent, autonomous, rational, and adaptive agents that reason about trust, and adapt trust based on experience. Agents reason and adapt using a modification of the k-Nearest Neighbor algorithm called (k X n) Nearest Neighbor where k neighbors recommend reputation values for trust during each of n interactions. Reputation allows a single agent to receive recommendations about the trustworthiness of others. One goal is to present a recommendation model of trust that outperforms MAS architectures relying solely on direct agent interaction. A second goal is to …
A Prelude To A Third Dimension Of The Periodic Table: Superatoms Of Aluminum Iodide Clusters, Naiche Owen Jones
A Prelude To A Third Dimension Of The Periodic Table: Superatoms Of Aluminum Iodide Clusters, Naiche Owen Jones
Theses and Dissertations
Calculations have been carried out to investigate the stability and electronic structure of aluminum iodide clusters using first principles gradient-corrected density functional theory. Analysis of A113Ix-, A114Ix-, and A17I- clusters reveals that their stability is governed by the geometrically unperturbed A113-, A1142+, and A17+ units, respectively, that are demonstrated to constitute the compact cores of the clusters upon significant iodine content. The compact, icosahedral A113, icosahedral-like A1 14, and capped square bi-pyramid A17 superatom structures of the stable aluminum cores have an analogous electronic configuration to that of halogen, alkaline-earth, and alkaline atoms, respectively. Novel chemistry is demonstrated in superatoms, …
Assessing, Modifying, And Combining Data Fields From The Virginia Office Of The Chief Medical Examiner (Ocme) Dataset And The Virginia Department Of Forensic Science (Dfs) Datasets In Order To Compare Concentrations Of Selected Drugs, Amy Elizabeth Herrin
Theses and Dissertations
The Medical Examiner of Virginia (ME) dataset and the Virginia Department of Forensic Science Driving Under the Influence of Drugs (DUI) datasets were used to determine whether people have the potential to develop tolerances to diphenhydramine, cocaine, oxycodone, hydrocodone, methadone, and morphine. These datasets included the years 2000-2004 and were used to compare the concentrations of these six drugs between people who died from a drug-related cause of death (of the drug of interest) and people who were pulled over for driving under the influence. Three drug pattern groups were created to divide each of the six drug-specific datasets in …
Design And Analysis Methods For Cluster Randomized Trials With Pair-Matching On Baseline Outcome: Reduction Of Treatment Effect Variance, Misook Park
Theses and Dissertations
Cluster randomized trials (CRT) are comparative studies designed to evaluate interventions where the unit of analysis and randomization is the cluster but the unit of observation is individuals within clusters. Typically such designs involve a limited number of clusters and thus the variation between clusters is left uncontrolled. Experimental designs and analysis strategies that minimize this variance are required. In this work we focus on the CRT with pre-post intervention measures. By incorporating the baseline measure into the analysis, we can effectively reduce the variance of the treatment effect. Well known methods such as adjustment for baseline as a covariate …
Enhancing The Third-Order Nonlinear Optical Properties Of Porphyrins And Molecular Wires, Jonathan L. Humphrey
Enhancing The Third-Order Nonlinear Optical Properties Of Porphyrins And Molecular Wires, Jonathan L. Humphrey
Theses and Dissertations
The third-order nonlinear optical (NLO) properties of indium tin oxide (ITO) thin films, Fe3+, Mn3+, Co2+ 5,10,15,20-tetrakis-4hydroxytetraphenyl)porphyrin (TPP) films, and a series of ethynyl-linked azobenzene oligomers were investigated using degenerate four wave mixing (DFWM) with 100 fs laser pulses. To measure the NLO of ITO thin films, A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100 nm thick and applied to ITO films ~25 nm thick. It was found that the third-order nonlinear susceptibility of ITO, χ(3)ITO, is purely electronic at 900 - 1300 nm (11000 - 7700 cm-1) …
A Model To Predict 24-Hour Urinary Creatinine Level Using Repeated Measurements, Donna S. Kroos
A Model To Predict 24-Hour Urinary Creatinine Level Using Repeated Measurements, Donna S. Kroos
Theses and Dissertations
Creatinine is a metabolic waste product, removed from the blood by the kidneys, and excreted in the urine. The measurement of creatinine is used in the assessment and monitoring of many medical conditions as well as in the determination or adjustment of absorbed dosage of pesticides. Earlier models to predict 24-hour urinary creatinine used ordinary least squares regression and assumed that the subjects' observations were uncorrelated. However, many of these studies had repeated creatinine measurements for each of their subjects. Repeated measures on the same subject frequently are correlated. Using data from the NIOSH-CDC "Pesticide Dose Monitoring in Turf Applicators" …
A Gis And Remote Sensing Based Analysis Of Impervious Surface Influences On Bald Eagle (Haliaeetus Leucocephalus) Nest Presence In The Virginia Portion Of The Chesapeake Bay, Jennifer M. Ciminelli
A Gis And Remote Sensing Based Analysis Of Impervious Surface Influences On Bald Eagle (Haliaeetus Leucocephalus) Nest Presence In The Virginia Portion Of The Chesapeake Bay, Jennifer M. Ciminelli
Theses and Dissertations
GIS (Geographic Information Systems) and remote sensing techniques were used to predict relationships between bald eagle nest presences and land type, distance to land type and impervious surface cover area. Data plots revealed bald eagle nest presence decreases in response to an increase in area of bareland; increases with an increase in area of forested land; decreases with an increase in distance (m) to shoreline, and decreases in response to an increase in area of impervious surfaces. Logistic regression models identified impervious surfaces as an indicator for bald eagle nest presence (P 24% as unsuitable. Unsuitable area covered 17.82% of …
Membership Functions For A Fuzzy Relational Database: A Comparison Of The Direct Rating And New Random Proportional Methods, Shweta Sanghi
Membership Functions For A Fuzzy Relational Database: A Comparison Of The Direct Rating And New Random Proportional Methods, Shweta Sanghi
Theses and Dissertations
Fuzzy relational databases deal with imprecise data or fuzzy information in a relational database. The purpose of this fuzzy database implementation is to retrieve images by using fuzzy queries whose common-language descriptions are defined by the consensus of a particular user community. The fuzzy set, which is presentation of fuzzy attribute values of the images, is determined through membership function. This paper compares two methods of constructing membership functions, the Direct Rating and New Random Proportional, to determine which method gives maximum users satisfaction with minimum feedback from the community. The statistical analysis of results suggests the use of Direct …
A Comparison For Longitudinal Data Missing Due To Truncation, Rong Liu
A Comparison For Longitudinal Data Missing Due To Truncation, Rong Liu
Theses and Dissertations
Many longitudinal clinical studies suffer from patient dropout. Often the dropout is nonignorable and the missing mechanism needs to be incorporated in the analysis. The methods handling missing data make various assumptions about the missing mechanism, and their utility in practice depends on whether these assumptions apply in a specific application. Ramakrishnan and Wang (2005) proposed a method (MDT) to handle nonignorable missing data, where missing is due to the observations exceeding an unobserved threshold. Assuming that the observations arise from a truncated normal distribution, they suggested an EM algorithm to simplify the estimation.In this dissertation the EM algorithm is …
Statistical Methods And Experimental Design For Inference Regarding Dose And/Or Interaction Thresholds Along A Fixed-Ratio Ray, Sharon Dziuba Yeatts
Statistical Methods And Experimental Design For Inference Regarding Dose And/Or Interaction Thresholds Along A Fixed-Ratio Ray, Sharon Dziuba Yeatts
Theses and Dissertations
An alternative to the full factorial design, the ray design is appropriate for investigating a mixture of c chemicals, which are present according to a fixed mixing ratio, called the mixture ray. Using single chemical and mixture ray data, we can investigate interaction among the chemicals in a particular mixture. Statistical models have been used to describe the dose-response relationship of the single agents and the mixture; additivity is tested through the significance of model parameters associated with the coincidence of the additivity and mixture models.It is often assumed that a chemical or mixture must be administered above an unknown …
Quantifying The Effects Of Correlated Covariates On Variable Importance Estimates From Random Forests, Ryan Vincent Kimes
Quantifying The Effects Of Correlated Covariates On Variable Importance Estimates From Random Forests, Ryan Vincent Kimes
Theses and Dissertations
Recent advances in computing technology have lead to the development of algorithmic modeling techniques. These methods can be used to analyze data which are difficult to analyze using traditional statistical models. This study examined the effectiveness of variable importance estimates from the random forest algorithm in identifying the true predictor among a large number of candidate predictors. A simulation study was conducted using twenty different levels of association among the independent variables and seven different levels of association between the true predictor and the response. We conclude that the random forest method is an effective classification tool when the goals …