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Articles 5851 - 5880 of 8341
Full-Text Articles in Physical Sciences and Mathematics
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 …
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 …
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 …
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.
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 …
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 …
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 …
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 …
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 …
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. …
A Mathematical Model For Anti-Malarial Drug Resistance, Amanda Matthews
A Mathematical Model For Anti-Malarial Drug Resistance, Amanda Matthews
Theses and Dissertations
Despite the array of medical advances of our modern day society, infectious diseases still plague millions of people worldwide. Malaria, in particular, causes substantial suffering and death throughout both developed and developing countries. Aside from the socioeconomic challenges presented by the disease's prevalence in impoverished nations, one of the major difficulties scientists have encountered while attempting to eradicate the disease is the parasite's ability to become resistant to new drugs and methods of treatment. In an effort to better understand the dynamics of malaria, we analyze a mathematical model that accounts for both the treatment aspect as well as the …
An Environmental And Economic Assessment Of Future Municipal Solid Waste Disposal: A Case Study Of Select High Growth Regions Of Virginia., Joseph Krouse
Theses and Dissertations
This research analyzed environmental and economic factors associated with municipal solid waste (MSW) management of select high growth Planning District Commissions (PDCs) of Virginia. Current MSW management scenarios were compared to future hypothetical scenarios utilizing a regional landfill or waste-to-energy (WTE) combustion facility. Life-cycle inventory and full cost accounting methods of the Municipal Solid Waste Decision Support Tool, developed by the Environmental Protection Agency (EPA), were utilized to estimate annualized environmental emissions and economic costs. Model results and analysis indicate that a regional landfill would be the least cost intensive MSW management strategy in comparison to current management methods; however …
Hyperspectral Reflectance For Rapid Viability Assessment Of Bacillus Endospores, Jarrod Edwards
Hyperspectral Reflectance For Rapid Viability Assessment Of Bacillus Endospores, Jarrod Edwards
Theses and Dissertations
A study was conducted to optically determine the viability of the Gram +, endospore-forming bacterial genera Bacillus using a hyperspectral reflectance spectrometer. Endospores are a dormant, differentiated cellular capsule form taken by select bacteria to ensure survival when environmental conditions become unfavorable. Two species of Bacillus were used for this study, Bacillus megaterium and Bacillus subtilis. These endospores were killed using a chemical treatment of sodium hypochlorite or a physical treatment of heat and pressure in an autoclave. The treated samples along with viable samples were lyophilized to form a powder. A reflectance spectrometer measuring 350 nm to 2500 nm …
Uav Intelligent Path Planning For Wilderness Search And Rescue, Rongbin Lin
Uav Intelligent Path Planning For Wilderness Search And Rescue, Rongbin Lin
Theses and Dissertations
In Wilderness Search and Rescue (WiSAR), the incident commander (IC) creates a probability distribution map of the likely location of the missing person. This map is important because it guides the IC in allocating search resources and coordinating efforts, but it often depends almost exclusively on prior experience and subjective judgment. We propose a Bayesian model that utilizes publicly available terrain features data to help model lost-person behaviors. This approach enables domain experts to encode uncertainty in their prior estimations and also make it possible to incorporate human-behavior data collected in the form of posterior distributions, which are used to …
Elemental Composition And Nutrient Effect On The Uptake And Metabolism Of Dissolved Organic Carbon By Bacteria From A Temperate Region River, Anne Stuart
Theses and Dissertations
Rivers are arteries that connect land and sea, and provide a conduit and reactor for allochthonous and autochthonous organic carbon sources (OC) delivered to the coastal ocean. In comparison to marine waters, inland waters quantitatively represent only a fraction of the marine system; however, their importance to global C cycling maybe disproportional to its actual size. Inland systems are subject to multiple sources of OC (autochthonous and allochthonous) that vary individually in space and time with respect to their concentration and potential bacterial bioavailability. This study investigates the impact of high and ambient inorganic nutrient concentrations on the bacterial bioavailability …
Band Bending In Gan, Michael Foussekis
Band Bending In Gan, Michael Foussekis
Theses and Dissertations
Steady-state and transient surface photovoltages in undoped GaN are studied in various environments (air, nitrogen, oxygen, vacuum) at room temperature and 400 K with a Kelvin probe attached to an optical cryostat. The results are explained within a phenomenological model accounting for the accumulation of photo-generated holes at the surface, capture of free electrons from the bulk over the near-surface potential barrier, and emission of electrons from surface states into the bulk. Mechanisms of surface photovoltage are discussed in detail. Photoadsorption and photodesorption of negatively charged species will either increase or decrease the surface potential and thus band bending. Oxygen …
The Responses Of Blue Crabs (Callinectes Sapidus) To Hypoxia/Hypercapnia In Freshwater, James Martin
The Responses Of Blue Crabs (Callinectes Sapidus) To Hypoxia/Hypercapnia In Freshwater, James Martin
Theses and Dissertations
The present research examined respiratory responses of blue crabs to long term (4, 13, and 21 days) hypercapnic hypoxia in freshwater at 23 C. Hypoxic conditions (50-60 & 75-85 mmHg O2) were induced by allowing the crabs to consume their oxygen supply, resulting in a hypercapnic induced decrease in pH that remained through the exposure. Postbranchial hemolymph responses to hypoxia/hypercapnia in freshwater demonstrate decreases in PO2, increases in PCO2, and decreases in pH. Lactate levels decreased over time, but hemocyanin concentration was highly variable with no trends. PH, lactate, and hemocyanin observations also demonstrated high variability and a variety of …
Development Of An Adaptive Equalization Algorithm Using Acoustic Energy Density, Panu Tapani Puikkonen
Development Of An Adaptive Equalization Algorithm Using Acoustic Energy Density, Panu Tapani Puikkonen
Theses and Dissertations
Sound pressure equalization of audio signals using digital signal processors has been a subject of ongoing study for many years. The traditional approach is to equalize sound at a point in a listening environment, but because of its specific dependence on the room frequency response between a source and receiver position, this equalization generally causes the spectral response to worsen significantly at other locations in the room. This work presents both a time-invariant and a time-varying implementation of an adaptive acoustic energy density equalization filter for a one-dimensional sound field. Energy density equalization addresses the aforementioned challenge and others that …