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Articles 5671 - 5700 of 8341

Full-Text Articles in Physical Sciences and Mathematics

Thermodynamics Of Modified Theories Of Gravity, Aric Hackebill May 2010

Thermodynamics Of Modified Theories Of Gravity, Aric Hackebill

Theses and Dissertations

Einstein’s equations are derived by following Jacobson’s thermodynamic method. It is seen that a family of possible field equations exist which satisfy the thermodynamic argument. Modified theories of gravity are addressed as possible candidates for replacing dark matter as an explanation for anomalous cosmological phenomena. Many of the proposed modified theories are not powerful enough to explain the currently observed phenomena and are rejected as viable theories of gravity. A surviving candidate, TeVeS, is further analyzed under the aforementioned thermodynamic argument to check for its consistency with thermodynamics.

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Analysis Of Medical Images By Colonies Of Prehending Entities, Rebecca Smith May 2010

Analysis Of Medical Images By Colonies Of Prehending Entities, Rebecca Smith

Theses and Dissertations

The concept of emergent behavior is difficult to define, but can be considered as higher-level activity created by the individual actions of a population of simple agents. A potential means to model such behavior has been previously developed using Alfred North Whitehead's concept of Actual Entities. In computational form, actual entities are agents which evolve over time in response to interactions with their environment via the process of prehension. This occurs within the context of a Colony of Prehending Entities, a framework for implementation of AE concepts. This thesis explores the practical application of this framework in analysis of medical …

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Theoretical Investigation Of The Structures And Stability Of Gas Phase Neutral And Cationic Tixoy Clusters., Baljeet Kaur May 2010

Theoretical Investigation Of The Structures And Stability Of Gas Phase Neutral And Cationic Tixoy Clusters., Baljeet Kaur

Theses and Dissertations

Theoretical investigation of the structure and stability of neutral and cationic TixOy cluster series (where y =2x-1, 2x, 2x+1) have been performed. The lowest lying structures for the neutral clusters are usually found in the singlet state. Generally, in bulk and in the case of the neutral TixOy clusters, the 2x cluster series is relatively more abundant than the 2x-1 and the 2x+1 cluster series. But in the case of cationic TixOy clusters, the 2x-1 series is more abundant. To understand the origin of the stability of the TixO2x-1+ clusters, we use density functional theory within the NRLMOL set of …

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Domination In Benzenoids, Nisreen Bukhary May 2010

Domination In Benzenoids, Nisreen Bukhary

Theses and Dissertations

A benzenoid is a molecule that can be represented as a graph. This graph is a fragment of the hexagon lattice. A dominating set $D$ in a graph $G$ is a set of vertices such that each vertex of the graph is either in $D$ or adjacent to a vertex in $D$. The domination number $\gamma=\gamma(G)$ of a graph $G$ is the size of a minimum dominating set. We will find formulas and bounds for the domination number of various special benzenoids, namely, linear chains $L(h)$, triangulenes $T_k$, and parallelogram benzenoids $B_{p,q}$. The domination ratio of a graph $G$ is …

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The Axiom Of Choice, Cristian Allen May 2010

The Axiom Of Choice, Cristian Allen

Theses and Dissertations

We will discuss the 9th axiom of Zermelo-Fraenkel set theory with choice, which is often abbreviated ZFC, since it includes the axiom of choice (AC). AC is a controversial axiom that is mathematically equivalent to many well known theorems and has an interesting history in set theory. This thesis is a combination of discussion of the history of the axiom and the reasoning behind why the axiom is controversial. This entails several proofs of theorems that establish the fact that AC is equivalent to such theorems and notions as Tychonoff's Theorem, Zorn's Lemma, the Well-Ordering Theorem, and many more.

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Single-Step Factor Screening And Response Surface Optimization Using Optimal Designs With Minimal Aliasing, David Hien Truong May 2010

Single-Step Factor Screening And Response Surface Optimization Using Optimal Designs With Minimal Aliasing, David Hien Truong

Theses and Dissertations

Cheng and Wu (2001) introduced a method for response surface exploration using only one design by using a 3-level design to first screen a large number of factors and then project onto the significant factors to perform response surface exploration. Previous work generally involved selecting designs based on projection properties first and aliasing structure second. However, having good projection properties is of little concern if the correct factors cannot be identified. We apply Jones and Nachtsheim’s (2009) method for finding optimal designs with minimal aliasing to find 18, 27, and 30-run designs to use for single-step screening and optimization. Our …

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Multivariate Steepest Ascent Using Bayesian Reliability, Jeffrey Fuerte May 2010

Multivariate Steepest Ascent Using Bayesian Reliability, Jeffrey Fuerte

Theses and Dissertations

The path of steepest ascent can used to optimize a response in an experiment, but problems can occur with multiple responses. Past approaches to this issue such as Del Castillo’s overlap of confidence cones and Mee and Xiao’s Pareto Optimality, have not considered the correlations of the responses or parameter uncertainty. We propose a new method using the Bayesian reliability to calculate this direction. We utilize this method with four examples: a 2 factor, 2-response experiment where the paths of steepest ascent are similar, ensuring our results match Del Castillo’s and Mee and Xiao’s; a 2 factor, 2-response experiment with …

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The Axiom Of Determinacy, Samantha Stanton May 2010

The Axiom Of Determinacy, Samantha Stanton

Theses and Dissertations

Working within the Zermelo-Frankel Axioms of set theory, we will introduce two important contradictory axioms: Axiom of Choice and Axiom of Determinacy. We will explore perfect polish spaces and games on these spaces to see that the Axiom of Determinacy is inconsistent with the Axiom of Choice. We will see some of the major consequences of accepting the Axiom of Determinacy and how some of these results change when accepting the Axiom of Choice. We will consider 2-player games of perfect information wherein we will see some powerful results having to do with properties of the real numbers. We will …

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Implementing The Intelligent Mail Barcode In The N-Tiered Service Library Of A Print Mail Enterprise, Christopher E. Bunch May 2010

Implementing The Intelligent Mail Barcode In The N-Tiered Service Library Of A Print Mail Enterprise, Christopher E. Bunch

Theses and Dissertations

Starting in autumn, 2009, the Intelligent Mail Barcode fully replaced the PostNet barcode for the United States Postal Service. This barcode enables a sender of a mailpiece to track the mailpiece through the entire mail stream, as well as track any remit mail returned to the sender. This thesis explains how the Intelligent Mail Barcode was implemented in the n- tiered Windows Communication Foundation service architecture of the Emdeon, Inc. print-mail engine. To help provide a full understanding of the environment, this document, also, explains the operation of the print mail engine at Emdeon.

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A Study Of Three Artificial Neural Networks Models' Ability To Identify Emotions From Facial Images, Timothy Scott Hyde May 2010

A Study Of Three Artificial Neural Networks Models' Ability To Identify Emotions From Facial Images, Timothy Scott Hyde

Theses and Dissertations

Facial expressions conveying emotions are vital for human communication. They are also important in the studies of human interaction and behavioral studies. Recognition of emotions, using facial images, may provide a fast and practical approach that is noninvasive. Most previous studies of emotion recognition through facial images were based on the Facial Action Coding System (FACS). The FACS, which was developed by Ekman and Freisen in 1978, was created to identify different facial muscular actions. Previous artificial neural network-based approaches for classification of facial expressions focused on improving one particular neural network model for better accuracy. The purpose of this …

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Automated Selected Of Mixed Integer Program Solver Parameters, Charles Stewart Apr 2010

Automated Selected Of Mixed Integer Program Solver Parameters, Charles Stewart

Theses and Dissertations

This paper presents a method that uses designed experiments and statistical models to extract information about how solver parameter settings perform for classes of mixed integer programs. The use of experimental design facilitates fitting a model that describes the response surface across all combinations of parameter settings, even those not explicitly tested, allowing identification of both desirable and poor settings. Identifying parameter settings that give the best expected performance for a specific class of instances and a specific solver can be used to more efficiently solve a large set of similar instances, or to ensure solvers are being compared at …

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Patterns In Fish Community Structure In A Regulated River, Richard Davis Apr 2010

Patterns In Fish Community Structure In A Regulated River, Richard Davis

Theses and Dissertations

I examined the abundance, composition, and distribution of fish communities in the lower Roanoke River, a hydropeaking system in North Carolina. Fishes were sampled at before and after peaking events over three years; 2007 to 2009. I evaluated trends in species richness, diversity, and assemblage composition. There were no significant differences in either richness or diversity suggesting consistent trends in richness and diversity throughout the study. I used non-metric multidimensional scaling (NMDS) to create a community composition model. Fish composition was noticeably greater post-peaking and changed minimally across time and event. There were no statistically significant differences in species composition …

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Local Charging Behavior On Gan Surfaces, Josephus Ferguson Apr 2010

Local Charging Behavior On Gan Surfaces, Josephus Ferguson

Theses and Dissertations

Gallium nitride is an important III-V semiconductor which is used in many optoelectronic and high-frequency devices. The nature of the GaN surface and its electrical characteristics can impact the performance of such devices. In this study, several GaN surfaces are locally charged using an atomic force microscope, and then subsequently studied by measuring the surface potential with scanning Kelvin probe microscopy (SKPM). The charging and discharging behavior of the surface appears to be strongly influenced by surface preparation and the presence of a surface oxide layer. If a substantial oxide layer exists, then both positive and negative charging is possible …

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Image Segmentation And Analysis For Automated Classification Of Traumatic Pelvic Injuries, Simina Vasilache Apr 2010

Image Segmentation And Analysis For Automated Classification Of Traumatic Pelvic Injuries, Simina Vasilache

Theses and Dissertations

In the past decades, technical advances have allowed for the collection and storage of more types and larger quantities of medical data. The increase in the volume of existing medical data has increased the need for processing and analyzing such data. Medical data holds information that is invaluable for diagnostic as well as treatment planning purposes. Presently, a large portion of the data is not optimally used towards medical decisions because information contained in the data is inaccessible through simple human inspection, or traditional computational methods. In the field of trauma medicine, where caregivers are frequently confronted with situations where …

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A Numerical Method For Estimating The Variance Of Age At Maximum Growth Rate In Growth Models, Semhar Ogbagaber Apr 2010

A Numerical Method For Estimating The Variance Of Age At Maximum Growth Rate In Growth Models, Semhar Ogbagaber

Theses and Dissertations

Most studies on maturation and body composition using the Fels Longitudinal data mention peak height velocity (PHV) as an important outcome measure. The PHV is often derived from growth models such as the triple logistic model fitted to the stature (height) data. The age at PHV is sometimes ordinalized to designate an individual as an early, average or late maturer. In theory, age at PHV is the age at which the rate of growth reaches the maximum. Theoretically, for a well behaved growth function, this could be obtained by setting the second derivative of the growth function to zero and …

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Fundamental Work Toward An Image Processing-Empowered Dental Intelligent Educational System, Grace Olsen Apr 2010

Fundamental Work Toward An Image Processing-Empowered Dental Intelligent Educational System, Grace Olsen

Theses and Dissertations

Computer-aided education in dental schools is greatly needed in order to reduce the need for human instructors to provide guidance and feedback as students practice dental procedures. A portable computer-aided educational system with advanced digital image processing capabilities would be less expensive than current computer-aided dental educational systems and would also address some of their limitations. This dissertation outlines the development of novel components that would be part of such a system. This research includes the design of a novel image processing technique, the Directed Active Shape Model algorithm, which is used to locate the tooth and drilled preparation from …

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Scalar Waves In An Almost Cylindrical Spacetime, Joseph Gordon Apr 2010

Scalar Waves In An Almost Cylindrical Spacetime, Joseph Gordon

Theses and Dissertations

The scalar wave equation is investigated for a scalar field propagating in a spacetime background ds²=e^{2a}(-dt²+dr²)+R(e^{-2ψ}dφ²+e^{2ψ}dz²). The metric is compactified in the radial direction. The spacetime slices of constant φ and z are foliated into outgoing null hypersurfaces by the null coordinate transformation u=t-r. The scalar field imitates the amplitude behavior of a light ray, or a gravitational wave, traveling along a null hypersurface when the area function R is a constant or is a function of u. These choices for R restrict the gravitational wave factor ψ to being an arbitrary function of u.

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The Inner Power Of A Graph, Neal Livesay Apr 2010

The Inner Power Of A Graph, Neal Livesay

Theses and Dissertations

We define a new graph operation called the inner power of a graph. The construction is similar to the direct power of graphs, except that factors are intertwined in such a way that certain structural properties of graphs are more clearly reflected in their inner powers. We investigate various properties of inner powers, such as connectivity, bipartiteness, and their interaction with the direct product. We explore possible connections between inner powers and the problem of cancellation over the direct product of graphs.

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Parameter Estimation In Linear-Linear Segmented Regression, Erika Lyn Hernandez Apr 2010

Parameter Estimation In Linear-Linear Segmented Regression, Erika Lyn Hernandez

Theses and Dissertations

Segmented regression is a type of nonlinear regression that allows differing functional forms to be fit over different ranges of the explanatory variable. This paper considers the simple segmented regression case of two linear segments that are constrained to meet, often called the linear-linear model. Parameter estimation in the case where the joinpoint between the regimes is unknown can be tricky. Using a simulation study, four estimators for the parameters of the linear-linear model are evaluated. The bias and mean squared error of the estimators are considered under differing parameter combinations and sample sizes. Parameters estimated in the model are …

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Cluster And Classification Analysis Of Fossil Invertebrates Within The Bird Spring Formation, Arrow Canyon, Nevada: Implications For Relative Rise And Fall Of Sea-Level, Scott L. Morris Apr 2010

Cluster And Classification Analysis Of Fossil Invertebrates Within The Bird Spring Formation, Arrow Canyon, Nevada: Implications For Relative Rise And Fall Of Sea-Level, Scott L. Morris

Theses and Dissertations

Carbonate strata preserve indicators of local marine environments through time. Such indicators often include microfossils that have relatively unique conditions under which they can survive, including light, nutrients, salinity, and especially water temperature. As such, microfossils are environmental proxies. When these microfossils are preserved in the rock record, they constitute key components of depositional facies. Spence et al. (2004, 2007) has proposed several approaches for determining the facies of a given stratigraphic succession based upon these proxies. Cluster analysis can be used to determine microfossil groups that represent specific environmental conditions. Identifying which microfossil groups exist through time can indicate …

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Automatic Transition To Peer-To-Peer Download, Roger D. Pack Apr 2010

Automatic Transition To Peer-To-Peer Download, Roger D. Pack

Theses and Dissertations

For traditional web servers, available bandwidth decreases as the number of clients increases. This can cause servers to serve files slowly or to become completely overwhelmed when load grows too high. BitTorrent is a peer-to-peer solution to this problem, but it requires manual configuration for each file to be delivered this way. We develop a new system that integrates peer-to-peer file delivery with traditional client-server downloads. Clients initially attempt to download a file from a web server; if this is too slow, they transition to peer-to-peer delivery. Experiments with a prototype system show that it serves up to 30x faster …

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Zero Divisors Among Digraphs, Heather Christina Smith Apr 2010

Zero Divisors Among Digraphs, Heather Christina Smith

Theses and Dissertations

This thesis generalizes to digraphs certain recent results about graphs. There are special digraphs C such that AxC is isomorphic to BxC for some pair of distinct digraphs A and B. Lovasz named these digraphs C zero-divisors and completely characterized their structure. Knowing that all directed cycles are zero-divisors, we focus on the following problem: Given any directed cycle D and any digraph A, enumerate all digraphs B such that AxD is isomorphic to BxD. From our result for cycles, we generalize to an arbitrary zero-divisor C, developing upper and lower bounds for the collection of digraphs B satisfying AxC …

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Ribosomal Rna Mutations That Inhibit The Activity Of Transfer-Messenger Rna Of Stalled Ribosomes, Jacob N. Crandall Apr 2010

Ribosomal Rna Mutations That Inhibit The Activity Of Transfer-Messenger Rna Of Stalled Ribosomes, Jacob N. Crandall

Theses and Dissertations

In eubacteria, stalled ribosomes are rescued by a conserved quality-control mechanism involving transfer-messenger RNA (tmRNA) and its protein partner SmpB. Mimicking a tRNA, tmRNA enters stalled ribosomes, adds Ala to the nascent polypeptide, and serves as a template to encode a short peptide that tags the nascent protein for destruction. To further characterize the tagging process, we developed two genetic selections that link tmRNA activity to cell death. These negative selections can be used to identify inhibitors of tagging or to identify mutations in key residues essential for ribosome rescue. Little is known about which ribosomal elements are specifically required …

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Segmentation And Fracture Detection In X-Ray Images For Traumatic Pelvic Injury, Rebecca Smith Apr 2010

Segmentation And Fracture Detection In X-Ray Images For Traumatic Pelvic Injury, Rebecca Smith

Theses and Dissertations

Due to the risk of complications such as hemorrhage, severe pelvic trauma is associated with a high mortality rate. Prompt medical treatment is therefore vital. However, the complexity of the injuries can make successful diagnosis and treatment challenging. By generating predictions and recommendations based on patient data, computer-aided decision support systems have the potential to assist physicians in improving outcomes. However, no current system considers features automatically extracted from medical images. This dissertation describes a system to extract diagnostic features from pelvic X-ray images that can be used as input to the prediction process; specifically, the presence of fracture and …

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Electrodeposited Silica Thin Films, Debbie Campbell-Rance Mar 2010

Electrodeposited Silica Thin Films, Debbie Campbell-Rance

Theses and Dissertations

Sol-gel derived silica thin film synthesis has gained prominence because of the mild processing conditions and widespread understanding of the chemistry of the process. Traditionally, silicate films are prepared by spin- and dip-coating but these materials lack the desired porosity for sensing, separations and catalysis applications. Electrochemical deposition was proposed to improve the porosity of silicate films. The main aims of this work were threefold. First we wanted to elucidate what parameters influenced film formation during electrodeposition. Then we wanted to understand how these parameters affected the morphology of the materials prepared. These films were characterized by profilometry, AFM, and …

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Topological Properties Of A Network Of Spiking Neurons In Face Image Recognition, Joo-Heon Shin Mar 2010

Topological Properties Of A Network Of Spiking Neurons In Face Image Recognition, Joo-Heon Shin

Theses and Dissertations

We introduce a novel system for recognition of partially occluded and rotated images. The system is based on a hierarchical network of integrate-and-fire spiking neurons with random synaptic connections and a novel organization process. The network generates integrated output sequences that are used for image classification. The network performed satisfactorily given appropriate topology, i.e. the number of neurons and synaptic connections, which corresponded to the size of input images. Comparison of Synaptic Plasticity Activity Rule (SAPR) and Spike Timing Dependant Plasticity (STDP) rules, used to update connections between the neurons, indicated that the SAPR gave better results and thus was …

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Extensions Of Nearest Shrunken Centroid Method For Classification, Tomohiko Funai Mar 2010

Extensions Of Nearest Shrunken Centroid Method For Classification, Tomohiko Funai

Theses and Dissertations

Stylometry assumes that the essence of the individual style of an author can be captured using a number of quantitative criteria, such as the relative frequencies of noncontextual words (e.g., or, the, and, etc.). Several statistical methodologies have been developed for authorship analysis. Jockers et al. (2009) utilize Nearest Shrunken Centroid (NSC) classification, a promising classification methodology in DNA microarray analysis for authorship analysis of the Book of Mormon. Schaalje et al. (2010) develop an extended NSC classification to remedy the problem of a missing author. Dabney (2005) and Koppel et al. (2009) suggest other modifications of NSC. This paper …

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Applications Of Descriptive Set Theory In Homotopy Theory, Samuel M. Corson Mar 2010

Applications Of Descriptive Set Theory In Homotopy Theory, Samuel M. Corson

Theses and Dissertations

This thesis presents new theorems in homotopy theory, in particular it generalizes a theorem of Saharon Shelah. We employ a technique used by Janusz Pawlikowski to show that certain Peano continua have a least nontrivial homotopy group that is finitely presented or of cardinality continuum. We also use this technique to give some relative consistency results.

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Electrospray Ionization Mass Spectrometry For The Characterization Of Covalent And Noncovalent Polynuclear Platinum Compounds Interacting With Bio-Molecules, John Mangrum Mar 2010

Electrospray Ionization Mass Spectrometry For The Characterization Of Covalent And Noncovalent Polynuclear Platinum Compounds Interacting With Bio-Molecules, John Mangrum

Theses and Dissertations

Polynuclear platinum compounds represent a new class of potential platinum anticancer therapeutics. Derived from the most widely used platinum anticancer drug, cisplatin, these novel compounds are distinct in their interactions with bio-molecules. The effectiveness of platinum anticancer agents is influenced by three pharmacological factors: (i) their resistance to deactivating sulfur nucleophiles, (ii) the ability to gain cellular entry and efficient cellular uptake, and (iii) the ability to form stable and specific complexes with DNA. BBR 3464, the first multinuclear platinum compound to reach phase II clinical trials, has created a new approach to cancer drug design. Large, highly charged platinum …

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The Role Of Algorithmic Decision Processes In Decision Automation: Three Case Studies, Blake Edward Durtschi Mar 2010

The Role Of Algorithmic Decision Processes In Decision Automation: Three Case Studies, Blake Edward Durtschi

Theses and Dissertations

This thesis develops a new abstraction for solving problems in decision automation. Decision automation is the process of creating algorithms which use data to make decisions without the need for human intervention. In this abstraction, four key ideas/problems are highlighted which must be considered when solving any decision problem. These four problems are the decision problem, the learning problem, the model reduction problem, and the verification problem. One of the benefits of this abstraction is that a wide range of decision problems from many different areas can be broken down into these four “key” sub-problems. By focusing on these key …

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