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Articles 1531 - 1560 of 2906

Full-Text Articles in Physical Sciences and Mathematics

Characterization Of The Desorption Electrospray Ionization Mechanism Using Microscopic Imaging Of The Sample Surface, Michael Craig Wood Aug 2011

Characterization Of The Desorption Electrospray Ionization Mechanism Using Microscopic Imaging Of The Sample Surface, Michael Craig Wood

Theses and Dissertations

Desorption electrospray ionization (DESI) is an ambient ionization technique for mass spectrometry. This solvent based desorption ion source has wide applicability in surface analysis with minimal sample preparation. Interest in improving detection limits, broadening applications, and increasing the spatial resolution for chemical imaging has led to studies of the DESI mechanism. An inverted microscope has been used to image interactions between the DESI spray and test analytes on a glass surface. Microscopic images recorded with millisecond time resolution have provided important insights into the processes governing analyte transport and desorption. These insights are the basis of a rivulet-based model for …

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The Characterization Of Avian Polyomavirus, Satellite Tobacco Mosaic Virus, And Bacteriophage Cw02 By Means Of Cryogenic Electron Microscopy, Peter S. Shen Aug 2011

The Characterization Of Avian Polyomavirus, Satellite Tobacco Mosaic Virus, And Bacteriophage Cw02 By Means Of Cryogenic Electron Microscopy, Peter S. Shen

Theses and Dissertations

Viruses are the most abundant biological entity in the biosphere and are known to infect hosts from all domains of life. The aim of my work is to identify conserved and non-conserved features among the capsid structures of related and divergent icosahedral viruses via cryogenic electron microscopy, sequence analysis, molecular modeling, and other techniques. Bird polyomaviruses often cause severe disease in their hosts whereas mammalian polyomaviruses generally do not. Avian polyomavirus is a type of bird polyomavirus with an unusually broad host range compared to the restricted tropism of other polyomaviruses. Although most polyomaviruses have a conserved, rigid capsid protein …

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Fast Relabeling Of Deformable Delaunay Tetrahedral Meshes Using A Compact Uniform Grid, David C. Frogley Jul 2011

Fast Relabeling Of Deformable Delaunay Tetrahedral Meshes Using A Compact Uniform Grid, David C. Frogley

Theses and Dissertations

We address the problem of fast relabeling of deformable Delaunay tetrahedral meshes using a compact uniform grid, with CPU parallelization through OpenMP. This problem is important in visualizing the simulation of deformable objects and arises in scientific visualization, games, computer vision, and motion picture production. Many existing software tools and APIs have the ability to manipulate 3D virtual objects. Prior mesh-based representations either allow topology changes or are fast. We aim for both. Specifically, we improve the efficiency of the relabeling step in the Delaunay deformable mesh invented by Pons and Boissonnat and improved by Tychonievich and Jones. The relabeling …

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Modeling Wireless Networks For Rate Control, David C. Ripplinger Jul 2011

Modeling Wireless Networks For Rate Control, David C. Ripplinger

Theses and Dissertations

Congestion control algorithms for wireless networks are often designed based on a model of the wireless network and its corresponding network utility maximization (NUM) problem. The NUM problem is important to researchers and industry because the wireless medium is a scarce resource, and currently operating protocols such as 802.11 often result in extremely unfair allocation of data rates. The NUM approach offers a systematic framework to build rate control protocols that guarantee fair, optimal rates. However, classical models used with the NUM approach do not incorporate partial carrier sensing and interference, which can lead to significantly suboptimal performance when actually …

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Crouzeix's Conjecture And The Gmres Algorithm, Sarah Mcbride Luo Jul 2011

Crouzeix's Conjecture And The Gmres Algorithm, Sarah Mcbride Luo

Theses and Dissertations

This thesis explores the connection between Crouzeix's conjecture and the convergence of the GMRES algorithm. GMRES is a popular iterative method for solving linear systems and is one of the many Krylov methods. Despite its popularity, the convergence of GMRES is not completely understood. While the spectrum can in some cases be a good indicator of convergence, it has been shown that in general, the spectrum does not provide sufficient information to fully explain the behavior of GMRES iterations. Other sets associated with a matrix that can also help predict convergence are the pseudospectrum and the numerical range. This …

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Stability For Traveling Waves, Joshua W. Lytle Jul 2011

Stability For Traveling Waves, Joshua W. Lytle

Theses and Dissertations

In this work we present some of the general theory of shock waves and their stability properties. We examine the concepts of nonlinear stability and spectral stability, noting that for certain classes of equations the study of nonlinear stability is reduced to the analysis of the spectra of the linearized eigenvalue problem. A useful tool in the study of spectral stability is the Evans function, an analytic function whose zeros correspond to the eigenvalues of the linearized eigenvalue problem. We discuss techniques for numerical Evans function computation that ensure analyticity, allowing standard winding number arguments and rootfinding methods to be …

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3d Image Reconstruction And Level Set Methods, Spencer R. Patty Jul 2011

3d Image Reconstruction And Level Set Methods, Spencer R. Patty

Theses and Dissertations

We give a concise explication of the theory of level set methods for modeling motion of an interface as well as the numerical implementation of these methods. We then introduce the geometry of a camera and the mathematical models for 3D reconstruction with a few examples both simulated and from a real camera. We finally describe the model for 3D surface reconstruction from n-camera views using level set methods.

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Naive Bayesian Spam Filters For Log File Analysis, Russel William Havens Jul 2011

Naive Bayesian Spam Filters For Log File Analysis, Russel William Havens

Theses and Dissertations

As computer system usage grows in our world, system administrators need better visibility into the workings of computer systems, especially when those systems have problems or go down. Most system components, from hardware, through OS, to application server and application, write log files of some sort, be it system-standardized logs such syslog or application specific logs. These logs very often contain valuable clues to the nature of system problems and outages, but their verbosity can make them difficult to utilize. Statistical data mining methods could help in filtering and classifying log entries, but these tools are often out of the …

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The Constrained Isoperimetric Problem, Minh Nhat Vo Do Jul 2011

The Constrained Isoperimetric Problem, Minh Nhat Vo Do

Theses and Dissertations

Let X be a space and let S ⊂ X with a measure of set size |S| and boundary size |∂S|. Fix a set C ⊂ X called the constraining set. The constrained isoperimetric problem asks when we can find a subset S of C that maximizes the Følner ratio FR(S) = |S|/|∂S|. We consider different measures for subsets of R^2,R^3,Z^2,Z^3 and describe the properties that must be satisfied for sets S that maximize the Folner ratio. We give explicit examples.

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Photoemission By Large Electron Wave Packets Emitted Out The Side Of A Relativistic Laser Focus, Eric Flint Cunningham Jul 2011

Photoemission By Large Electron Wave Packets Emitted Out The Side Of A Relativistic Laser Focus, Eric Flint Cunningham

Theses and Dissertations

There are at least two common models for calculating the photoemission of accelerated electrons. The 'extended-charge-distribution' method uses the quantum probability current (multiplied by the electron charge) as a source current for Maxwell's equations. The 'point-like-emitter' method treats the electron like a point particle instead of like a diffuse body of charge. Our goal is to differentiate between these two viewpoints empirically. To do this, we consider a large electron wave packet in a high-intensity laser field, in which case the two viewpoints predict measurable photoemission rates that differ by orders of magnitude. Under the treatment of the 'extended-charge-distribution' model, …

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An Algebra Isomorphism For The Landau-Ginzburg Mirror Symmetry Conjecture, Jared Drew Johnson Jul 2011

An Algebra Isomorphism For The Landau-Ginzburg Mirror Symmetry Conjecture, Jared Drew Johnson

Theses and Dissertations

Landau-Ginzburg mirror symmetry takes place in the context of affine singularities in CN. Given such a singularity defined by a quasihomogeneous polynomial W and an appropriate group of symmetries G, one can construct the FJRW theory (see [3]). This construction fills the role of the A-model in a mirror symmetry proposal of Berglund and H ubsch [1]. The conjecture is that the A-model of W and G should match the B-model of a dual singularity and dual group (which we denote by WT and GT). The B-model construction is based on the Milnor ring, or local algebra, of the singularity. …

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An Introduction To Bayesian Methodology Via Winbugs And Proc Mcmc, Heidi Lula Lindsey Jul 2011

An Introduction To Bayesian Methodology Via Winbugs And Proc Mcmc, Heidi Lula Lindsey

Theses and Dissertations

Bayesian statistical methods have long been computationally out of reach because the analysis often requires integration of high-dimensional functions. Recent advancements in computational tools to apply Markov Chain Monte Carlo (MCMC) methods are making Bayesian data analysis accessible for all statisticians. Two such computer tools are Win-BUGS and SASR 9.2's PROC MCMC. Bayesian methodology will be introduced through discussion of fourteen statistical examples with code and computer output to demonstrate the power of these computational tools in a wide variety of settings.

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The Molecular Mechanism Of Migraine, Kristin Dawn Watson Jul 2011

The Molecular Mechanism Of Migraine, Kristin Dawn Watson

Theses and Dissertations

Migraine is a common, episodic neurological disorder that includes headache, nausea and hypersensitivity to sensory stimuli. During the headache phase of migraine, migraine patients can be especially hypersensitive to thermal stimuli. The unpredictable and episodic nature of migraine makes it difficult to treat and much of the mechanism of migraine has yet to be elucidated. A T44A substitution in casein kinase 1δ is inherited with migraine with aura. A transgenic mouse model suggests that animals with this mutation exhibit increased sensitivity to thermal stimuli after injection with nitroglycerin (NTG). We performed behavior assays that measure animal responses to thermal stimuli, …

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Structures Of Poliovirus And Antibody Complexes Reveal Movements Of The Capsid Protein Vp1 During Cell Entry, Jun Lin Jul 2011

Structures Of Poliovirus And Antibody Complexes Reveal Movements Of The Capsid Protein Vp1 During Cell Entry, Jun Lin

Theses and Dissertations

In the infection process, native poliovirus (160S) first converts to a cell-entry intermediate (135S) particle, which causes the externalization of capsid proteins VP4 and the N-terminus of VP1 (residues 1-53). The externalization of these entities is followed by release of the RNA genome, leaving an empty (80S) particle. Three antibodies were utilized to track the location of VP1 residues in different states of poliovirus by cryogenic electron microscopy (cryo-EM). "P1" antibody binds to N-terminal residues 24-40 of VP1. Three-dimensional reconstruction of 135S-P1 showed that P1 binds to a prominent capsid peak known as the "propeller tip". In contrast, our initial …

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Assessing The Effect Of Wal-Mart In Rural Utah Areas, Angela Nelson Jul 2011

Assessing The Effect Of Wal-Mart In Rural Utah Areas, Angela Nelson

Theses and Dissertations

Walmart and other “big box” stores seek to expand in rural markets, possibly due to cheap land and lack of zoning laws. In August 2000, Walmart opened a store in Ephraim, a small rural town in central Utah. It is of interest to understand how Walmart's entrance into the local market changes the sales tax revenue base for Ephraim and for the surrounding municipalities. It is thought that small “Mom and Pop” stores go out of business because they cannot compete with Walmart's prices, leading to a decrease in variety, selection, convenience, and most importantly, sales tax revenue base in …

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Maximal Unramified Extensions Of Cyclic Cubic Fields, Ka Lun Wong Jul 2011

Maximal Unramified Extensions Of Cyclic Cubic Fields, Ka Lun Wong

Theses and Dissertations

Maximal unramified extensions of quadratic number fields have been well studied. This thesis focuses on maximal unramified extensions of cyclic cubic fields. We use the unconditional discriminant bounds of Moreno to determine cyclic cubic fields having no non-solvable unramified extensions. We also use a theorem of Roquette, developed from the method of Golod-Shafarevich, and some results by Cohen to construct cyclic cubic fields in which the unramified extension is of infinite degree.

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Novel Ion Trap Made Using Lithographically Patterned Plates, Ying Peng Jul 2011

Novel Ion Trap Made Using Lithographically Patterned Plates, Ying Peng

Theses and Dissertations

A new approach of making ion trap mass analyzers was developed in which trapping fields are created in the space between two ceramic plates. Based on microfabrication technology, a series of independently-adjustable electrode rings is lithographically patterned on the facing surfaces of each ceramic plate. The trapping field can be modified or fine-tuned simply by changing the RF amplitude applied to each electrode ring. By adjusting the potential function applied to the plates, arbitrary trapping fields can be created using the same set of ceramic plates. Unlike conventional ion traps, the electrodes of planar ion traps have a non-equipotential surface, …

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Photoemission From A Laser-Driven Electron Wave Packet, John Purvis Corson Jun 2011

Photoemission From A Laser-Driven Electron Wave Packet, John Purvis Corson

Theses and Dissertations

We use quantum electrodynamics (QED) to investigate the possibility of radiative interference from a single laser-driven electron wave packet. Intuition gleaned from classical electrodynamics suggests that radiation from a large electron wave packet might interfere destructively when different regions of the packet oscillate out of phase with each other. We show that when the incident light is represented with a multi-mode coherent state, the relative phases of the electron's constituent momenta have no influence of the amount of scattered light. Hence, the radiation does not depend on the amount of free-particle spreading experienced by the electron before the interaction. This …

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Experimental Performance Evaluation Of Atp (Ad-Hoc Transport Protocol) In A Wireless Mesh Network, Xingang Zhang Jun 2011

Experimental Performance Evaluation Of Atp (Ad-Hoc Transport Protocol) In A Wireless Mesh Network, Xingang Zhang

Theses and Dissertations

It is well known that TCP performs poorly in wireless mesh networks. There has been intensive research in this area, but most work uses simulation as the only evaluation method; however, it is not clear whether the performance gains seen with simulation will translate into benefits on real networks. To explore this issue, we have implemented ATP (Ad-hoc Transport Protocol), a transport protocol designed specifically for wireless ad hoc networks. We have chosen ATP because it uses a radically different design from TCP and because reported results claim significant improvement over TCP. We show how ATP must be modified in …

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Hierarchical Probit Models For Ordinal Ratings Data, Allison M. Butler Jun 2011

Hierarchical Probit Models For Ordinal Ratings Data, Allison M. Butler

Theses and Dissertations

University students often complete evaluations of their courses and instructors. The evaluation tool typically contains questions about the course and the instructor on an ordinal Likert scale. We assess instructor effectiveness while adjusting for known confounders. We present a probit regression model with a latent variable to measure the instructor effectiveness accounting for student specific covariates, such as student grade in the course, high school and university GPA, and ACT score.

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Rendering Realistic Cloud Effects For Computer Generated Films, Cory A. Reimschussel Jun 2011

Rendering Realistic Cloud Effects For Computer Generated Films, Cory A. Reimschussel

Theses and Dissertations

This work addresses the problem of rendering clouds. The task of rendering clouds is important to film and video game directors who want to use clouds to further the story or create a specific atmosphere for the audience. While there has been significant progress in this area, other solutions to this problem are inadequate because they focus on speed instead of accuracy, or focus only on a few specific properties of rendered clouds while ignoring others. Another common shortcoming with other methods is that they are not integrated into existing rendering pipelines. We propose a solution to this problem based …

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A Multi-Frequency Inverse Source Problem For The Helmholtz Equation, Sebastian Ignacio Acosta Jun 2011

A Multi-Frequency Inverse Source Problem For The Helmholtz Equation, Sebastian Ignacio Acosta

Theses and Dissertations

The inverse source problem for the Helmholtz equation is studied. An unknown source is to be identified from the knowledge of its radiated wave. The focus is placed on the effect that multi-frequency data has on establishing uniqueness. In particular, we prove that data obtained from finitely many frequencies is not sufficient. On the other hand, if the frequency varies within an open interval of the positive real line, then the source is determined uniquely. An algorithm is based on an incomplete Fourier transform of the measured data and we establish an error estimate under certain regularity assumptions on the …

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A Study Analyzing Five Instructional Methods For Teaching Software To Junior High Students, Scott Ronald Bartholomew Jun 2011

A Study Analyzing Five Instructional Methods For Teaching Software To Junior High Students, Scott Ronald Bartholomew

Theses and Dissertations

If you ask 5 different teachers what the best way to teach a new technology to a student is you will get 5 different answers. (Bork, 2001; Cheong, 2008; Egal, 2009; Howell, 2001) What is the best way to teach a new computer software application to a student? In the technological world we live in today the effective transfer of technological knowledge is paramount. With varying opinions even among the leaders of national technology teacher associations (Haynie, 2005) there is a large level of ambiguity in relation to best practices in technology teaching. This study evaluates five commonly used methods …

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Three-Dimensional Galois Representations And A Conjecture Of Ash, Doud, And Pollack, Vinh Xuan Dang Jun 2011

Three-Dimensional Galois Representations And A Conjecture Of Ash, Doud, And Pollack, Vinh Xuan Dang

Theses and Dissertations

In the 1970s and 1980s, Jean-Pierre Serre formulated a conjecture connecting two-dimensional Galois representations and modular forms. The conjecture came to be known as Serre's modularity conjecture. It was recently proved by Khare and Wintenberger in 2008. Serre's conjecture has various important consequences in number theory. Most notably, it played a key role in the proof of Fermat's last theorem. A natural question is, what is the analogue of Serre's conjecture for higher dimensional Galois representations? In 2002, Ash, Doud and Pollack formulated a precise statement for a higher dimensional analogue of Serre's conjecture. They also provided numerous computational examples …

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Investigating A Model Reversed-Phase Liquid Chromatography Stationary Phase With Vibrationally Resonant Sum Frequency Generation Spectroscopy, Arthur D. Quast Jun 2011

Investigating A Model Reversed-Phase Liquid Chromatography Stationary Phase With Vibrationally Resonant Sum Frequency Generation Spectroscopy, Arthur D. Quast

Theses and Dissertations

Reversed-phase liquid chromatography (RPLC) is a widely used technique for analytical separations but routinely requires empirical optimization. Gaining a better understanding of the molecular reasons for retention may mean more efficient separations with fewer trial and error runs to obtain optimized separations. Vibrationally resonant sum frequency generation (VR-SFG) is a surface specific technique that has allowed for in situ examination of model RPLC stationary phases under various solvent and pressure conditions. In order to improve on past work with model RPLC stationary phases two challenges had to be overcome. First, improved vibrational mode assignments of the C18 stationary phase were …

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Progress Toward Theonellamide F, Jennifer Dawn Bettale Jun 2011

Progress Toward Theonellamide F, Jennifer Dawn Bettale

Theses and Dissertations

Theonellamide is a bicyclic peptide isolated from a marine sponge, which shows interesting biological activity. It contains several unnatural amino acids, among which are (2S,3R)-3-hydroxyasparagine (L-erythro-β-hydroxyasparagine) (β-OHAsn) and τ-L-histindino-D-alanine (τ-HAL). Although there were previous synthetic efforts toward each of these unnatural amino acids, the efforts were not ideal due to expensive starting material, time-consuming steps, and poor regioselectivity. The presented work demonstrates an inexpensive, enantioselective synthesis of β-OHAsn, which can be completed in a matter of weeks, as well as several attempts at a novel regiospecific approach toward τ-HAL, including work on a model study.

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A Bayesian Approach To Missile Reliability, Taylor Hardison Redd Jun 2011

A Bayesian Approach To Missile Reliability, Taylor Hardison Redd

Theses and Dissertations

Each year, billions of dollars are spent on missiles and munitions by the United States government. It is therefore vital to have a dependable method to estimate the reliability of these missiles. It is important to take into account the age of the missile, the reliability of different components of the missile, and the impact of different launch phases on missile reliability. Additionally, it is of importance to estimate the missile performance under a variety of test conditions, or modalities. Bayesian logistic regression is utilized to accurately make these estimates. This project presents both previously proposed methods and ways to …

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The Weak Cayley Table And The Relative Weak Cayley Table, Melissa Anne Mitchell May 2011

The Weak Cayley Table And The Relative Weak Cayley Table, Melissa Anne Mitchell

Theses and Dissertations

In 1896, Frobenius began the study of character theory while factoring the group determinant. Later in 1963, Brauer pointed out that the relationship between characters and their groups was still not fully understood. He published a series of questions that he felt would be important to resolve. In response to these questions, Johnson, Mattarei, and Sehgal developed the idea of a weak Cayley table map between groups. The set of all weak Cayley table maps from one group to itself also has a group structure, which we will call the weak Cayley table group. We will examine the weak Cayley …

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Proofs Of Correctness For Three Decentralized Authentication Protocols Using Strand Spaces, Pavan Kumar Vankamamidi May 2011

Proofs Of Correctness For Three Decentralized Authentication Protocols Using Strand Spaces, Pavan Kumar Vankamamidi

Theses and Dissertations

Security is a major concern is today's online world. As online activities become increasingly sensitive, service providers rely on security protocols to ensure confidentiality, integrity and authentication of their users and data. Greater assurance is provided when these protocols are verified to be correct. Strand Spaces is a method to formally analyze security protocols. The arguments are based on the messages being transmitted and received while assuming that the underlying cryptographic primitives are secure. This thesis demonstrates that the protocols Luau, pwdArmor and Kiwi are secure using Strand Spaces methodology.

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Flexible Storylines, Ivan Dmitrievich Romashka May 2011

Flexible Storylines, Ivan Dmitrievich Romashka

Theses and Dissertations

A long-standing goal of computer-based entertainment is the creation of a story where a user is in control of portions of the storyline. These non-linear stories give a user an opportunity to adapt the story to his or her interests, schedule and needs. The Internet has made non-linear video a reality. Different approaches have been taken to create and play non-linear video stories. They suffer from lack of simplicity, smoothness, and television-like experience in story creation and presentation. Flexible Storylines provide a way to easily create and present non-linear video stories. The creation of these stories is done using a …

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