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Articles 1711 - 1740 of 2906

Full-Text Articles in Physical Sciences and Mathematics

Development And Comparison Of Methods For Measuring Directional Sound Arrivals In Rooms, Brian Trevor Thornock Oct 2009

Development And Comparison Of Methods For Measuring Directional Sound Arrivals In Rooms, Brian Trevor Thornock

Theses and Dissertations

In room acoustics, the directional information of sound arrivals at a listening location can be used to diagnose the origins of problematic reflections so offending surfaces or other features can be properly treated. It can also be used for other purposes, including the study of psychoacoustic indicators. Many methods have been developed in the past to derive directional information, but despite their benefits, each has had significant drawbacks that have necessitated further research into their properties and development of an improved method. This thesis presents a review of past methods, their benefits and shortcomings. It discusses many theoretical and practical …

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Uav Intelligent Path Planning For Wilderness Search And Rescue, Michael A. Goodrich, Lanny Lin Oct 2009

Uav Intelligent Path Planning For Wilderness Search And Rescue, Michael A. Goodrich, Lanny Lin

Faculty Publications

In the priority search phase of Wilderness Search and Rescue, a probability distribution map is created. Areas with higher probabilities are searched first in order to find the missing person in the shortest expected time. When using a UAV to support search, the onboard video camera should cover as much of the important areas as possible within a set time. We explore several algorithms (with and without set destination) and describe some novel techniques in solving this problem and compare their performances against typical WiSAR scenarios. This problem is NP-hard, but our algorithms yield high quality solutions that approximate the …

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Livecut: Learning-Based Interactive Video Segmentation By Evaluation Of Multiple Propagated Cues, Bryan S. Morse, Brian L. Price, Scott Cohen Oct 2009

Livecut: Learning-Based Interactive Video Segmentation By Evaluation Of Multiple Propagated Cues, Bryan S. Morse, Brian L. Price, Scott Cohen

Faculty Publications

Video sequences contain many cues that may be used to segment objects in them, such as color, gradient, color adjacency, shape, temporal coherence, camera and object motion, and easily-trackable points. This paper introduces LIVEcut, a novel method for interactively selecting objects in video sequences by extracting and leveraging as much of this information as possible. Using a graph-cut optimization framework, LIVEcut propagates the selection forward frame by frame, allowing the user to correct any mistakes along the way if needed. Enhanced methods of extracting many of the features are provided. In order to use the most accurate information from the …

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Versatile Reactive Navigation, Robert P. Burton, Luther A. Tychonievich, Louis P. Tychonievich Oct 2009

Versatile Reactive Navigation, Robert P. Burton, Luther A. Tychonievich, Louis P. Tychonievich

Faculty Publications

Most autonomous mobile agents operate in a highly constrained environment. Despite significant research, existing solutions are limited in their ability to handle heterogeneous constraints within highly dynamic or uncertain environments. This paper presents a novel maneuver selection technique suited for both 2D and 3D environments with highly dynamic maneuvering constraints and multiple mobile obstacles. Agents may have any arbitrary set of nonholonomic control variables; maneuvers can be constrained by a broad class of function inequalities, including time-dependent constraints involving nonlinear relationships between controlled and agent-state variables. The resulting algorithm has been implemented to run in real time using only a …

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Pore Size Characterization Of Monolithic Capillary Columns Using Capillary Flow Porometry, Yan Fang Sep 2009

Pore Size Characterization Of Monolithic Capillary Columns Using Capillary Flow Porometry, Yan Fang

Theses and Dissertations

A simple capillary flow porometer (CFP) was assembled for pore structure characterization of monolithic capillary liquid chromatography columns based on ASTM standard F316-86. Determination of differential pressures and flow rates through dry and wet samples provided the necessary information to determine the through-pore throat diameter, bubble point pore diameter, mean flow pore diameter, and pore distribution. Unlike measurements in bulk using traditional techniques to provide indirect information about the pore properties of monolithic columns, monoliths can be characterized in their original chromatographic forms with this system. The performance of the new CFP was first evaluated by characterizing the pore size …

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Gas Phase Chiral Recognition, Characterization Of Porous Polymer Monolith Nanospray Ionization, And The Negative Mode Crafti Method Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Nannan Fang Sep 2009

Gas Phase Chiral Recognition, Characterization Of Porous Polymer Monolith Nanospray Ionization, And The Negative Mode Crafti Method Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Nannan Fang

Theses and Dissertations

Our group has been studying chiral recognition in gas phase using mass spectrometry for more than 10 years. We are interested in gas phase studies of fundamental interactions because the gas phase avoids complications and masking effects that may arise upon solvation. Therefore, the results of gas phase experiments can be directly compared with those of high-level computational studies. In chapter 2, I studied the roles of hydrogen bonding and pi stacking in gas phase chiral recognition between aromatic crown molecules and aromatic amines. High affinity between host and guest doesn't necessarily result in better recognition. If the affinity is …

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Guided Testing For Automatic Error Discovery In Concurrent Software, Neha Shyam Rungta Sep 2009

Guided Testing For Automatic Error Discovery In Concurrent Software, Neha Shyam Rungta

Theses and Dissertations

The quality and reliability of software systems, in terms of their functional correctness, critically relies on the effectiveness of the testing tools and techniques to detect errors in the system before deployment. A lack of testing tools for concurrent programs that systematically control thread scheduling choices has not allowed concurrent software development to keep abreast with hardware trends of multi-core and multi-processor technologies. This motivates a need for the development of systematic testing techniques that detect errors in concurrent programs. The work in this dissertation presents a potentially scalable technique that can be used to detect concurrency errors in production …

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Total Synthesis Of (-)-Acutumine, Fang Li Aug 2009

Total Synthesis Of (-)-Acutumine, Fang Li

Theses and Dissertations

Acutumine is a tetracyclic alkaloid isolated from the Asian vine Menispermum dauricum with selective T-cell cytotoxicity and antiamnestic properties. We have developed a total synthetic route to this congested alkaloid, during which we also found a novel, stereoselective radical-crossover reaction that combines an intramolecular radical conjugate addition with a subsequent enolate hydroxylation. Key features of this synthesis also include a reagent-controlled diastereoselective ketone allylation, an anionic oxy-Cope rearrangement to form a congested quaternary sterocenter, a pyridine-mediated selective ozonolysis, and a Lewis acid promoted Michael-type cyclization.

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Kiwivault: Encryption Software For Portable Storage Devices, Trevor Bradshaw Florence Aug 2009

Kiwivault: Encryption Software For Portable Storage Devices, Trevor Bradshaw Florence

Theses and Dissertations

While many people use USB flash drives, most do not protect their stored documents. Solutions for protecting flash drives exist but inherently limit functionality found in unprotected drives such as portability, usability, and the ability to share documents between multiple people. In addition, other drawbacks are introduced such as the possibility of losing access to protected documents if a password is lost. Assuming protecting portable documents is important, in order for people to be willing to protect their documents they should be required to make as few sacrifices in functionality as possible. We introduce KiwiVault, a USB flash drive encryption …

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Scan-Based Near-Field Acoustical Holography On Partially Correlated Sources, Michael D. Gardner Aug 2009

Scan-Based Near-Field Acoustical Holography On Partially Correlated Sources, Michael D. Gardner

Theses and Dissertations

Scan-based near-field acoustical holography (NAH) is applied to partially correlated sources. Partial field decomposition via the virtual coherence method is used to implement the scan-based NAH. The background and theory of these methods are developed. Multiple stationary reference microphones are required for the partial field decomposition. Guidelines for reference microphone placement in the literature thus far have been limited. Improved guidelines for reference microphones are given after the results of two sets of experiments. The first set involves discrete, partially correlated sources, both physical and numerical. The second set of experiments is strictly numerical and involves continuous sources. Fewer microphones …

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Development Of Biocompatible Polymer Monoliths For The Analysis Of Proteins And Peptides, Yun Li Aug 2009

Development Of Biocompatible Polymer Monoliths For The Analysis Of Proteins And Peptides, Yun Li

Theses and Dissertations

Biocompatibility is an important issue for the development of chromatographic stationary phases for the analysis of biomolecules (including proteins and peptides). A biocompatible stationary phase material is a material that resists nonspecific adsorption of biomolecules and does not interact with them in a way that would alter or destroy their structures or biochemical functions. The monolithic column format is a good alternative to typical spherical particle packed columns for capillary liquid chromatography of biomacromolecules. Several novel anion-exchange polymer monoliths for the analysis of proteins were synthesized for improved biocompatibility. Two novel polymeric monoliths were prepared in a single step by …

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Real-Time Virus Analysis Via Image Charge Detection Surface Induced Dissociation Tandem Mass Spectrometry, Seth T. Call Aug 2009

Real-Time Virus Analysis Via Image Charge Detection Surface Induced Dissociation Tandem Mass Spectrometry, Seth T. Call

Theses and Dissertations

This thesis reports on the development of a novel mass spectrometer combining image charge detection with surface induced dissociation for real-time analysis of intact viruses. Protonated viruses produced using electrospray are accelerated and subsequently impact on a solid surface. Capsid peptides released during the impact are analyzed using time-of-flight mass spectrometry. Image charge detection is used to measure the mass and charge states of structurally intact, electrosprayed viruses prior to impact. Since virus capsids are composed of loosely-bound proteins, collision of viruses with surfaces at moderate impact energies could release intact proteins. The masses and numbers of different protein types …

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Supporting Remote Manipulation: An Ecological Approach, John A. Atherton Aug 2009

Supporting Remote Manipulation: An Ecological Approach, John A. Atherton

Theses and Dissertations

User interfaces for remote robotic manipulation widely lack sufficient support for situation awareness and, consequently, can induce high mental workload. With poor situation awareness, operators may fail to notice task-relevant features in the environment often leading the robot to collide with the environment. With high workload, operators may not perform well over long periods of time and may feel stressed. We present an ecological visualization that improves operator situation awareness. Our user study shows that operators using the ecological interface collided with the environment on average half as many times compared with a typical interface, even with a poorly calibrated …

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Design And Characterization Of A Human Exposure Chamber And Inversion Episodes In Salt Lake City, Utah In January/February Of 2009, Roman Yuri Kuprov Aug 2009

Design And Characterization Of A Human Exposure Chamber And Inversion Episodes In Salt Lake City, Utah In January/February Of 2009, Roman Yuri Kuprov

Theses and Dissertations

Research on health effects of particulate matter (PM) has been a very active area in the last two decades. One plausible mechanism by which exposure to PM affects human health includes modification of autonomic endothelium function. Decreased endothelium activity causes heightened risks of cardiovascular disease. A human exposure chamber designed to conduct experiments to quantify diminished function of endothelium from short term exposure to PM is described. The chamber consists of two stages for containment and pre-treatment of PM and exposure of human subjects. Concentrations of CO, CO2, NO, NO2, O3, and PM2.5, are monitored and controlled in the exposure …

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Reducing Source Load In Bittorrent, Brian Sanderson, Daniel Zappala Aug 2009

Reducing Source Load In Bittorrent, Brian Sanderson, Daniel Zappala

Faculty Publications

One of the main goals of BitTorrent is to reduce load on web servers by encouraging clients to share content between themselves. However, BitTorrent’s current design relies heavily on the original source to serve a disproportionate amount of the file. We modify standard BitTorrent software so that a source determines the current popularity of each of the blocks of a file and tries to serve only those blocks that are rare. Using extensive PlanetLab experiments, we show that this modification can save a significant amount of the source’s upload bandwidth, with the tradeoff of some increased peer download time. In …

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Generating Derivative Structures From Multilattices: Algorithm And Application To Hcp Alloys, Gus L. W. Hart, Rodney W. Forcade Jul 2009

Generating Derivative Structures From Multilattices: Algorithm And Application To Hcp Alloys, Gus L. W. Hart, Rodney W. Forcade

Faculty Publications

We present an algorithm for generating all derivative superstructures of a nonprimitive parent lattice. The algorithm has immediate application in important materials design problems such as modeling hexagonal-close-packed (hcp) alloys. Extending the work of Hart and Forcade [Phys. Rev. B 77, 224115 (2008)] (which applies only to Bravais lattices), this approach applies to arbitrary multilattices. The algorithm enumerates superlattices and atomic configurations using permutation groups rather than direct geometric comparisons. The key concept is to use the quotient group associated with each superlattice to determine all unique atomic configurations. The algorithm is very efficient; the run time scales linearly with …

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A Hop-By-Hop Architecture For Multicast Transport In Ad Hoc Wireless Networks, Manoj Kumar Pandey Jul 2009

A Hop-By-Hop Architecture For Multicast Transport In Ad Hoc Wireless Networks, Manoj Kumar Pandey

Theses and Dissertations

Ad hoc wireless networks are increasingly being used to provide connectivity where a wired networking infrastructure is either unavailable or inaccessible. Many deployments utilize group communication, where several senders communicate with several receivers; multicasting has long been seen as an efficient way to provide this service. While there has been a great deal of research on multicast routing in ad hoc networks, relatively little attention has been paid to the design of multicast transport protocols, which provide reliability and congestion control. In this dissertation we design and implement a complete multicast transport architecture that includes both routing and transport protocols. …

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A Top-Down Proteomic Approach For The Discovery Of Novel Serum Biomarkers Of Pregnancy-Related Disease, Karen Merrell Jul 2009

A Top-Down Proteomic Approach For The Discovery Of Novel Serum Biomarkers Of Pregnancy-Related Disease, Karen Merrell

Theses and Dissertations

The serum fraction of blood is an ideal material in which to search for novel biomarkers for disease. It is easily obtained through relatively non-invasive means, routinely collected, and a rich treasure-trove of information about the health of an individual. Cells react to signal molecules, take up nutrients, and release waste products, fragments that are the result of proteolysis, and other molecules out into the bloodstream. If these components are unique to the cells in question, that part of the complex mixture that is the blood stream can potentially characterize the health of the tissue or organ those cells are …

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Massively Parallel Indirect Dielectrophoresis Controlled Placement Of Carbon Nanotubes, Hiram Jacob Conley Jul 2009

Massively Parallel Indirect Dielectrophoresis Controlled Placement Of Carbon Nanotubes, Hiram Jacob Conley

Theses and Dissertations

Placement of single walled carbon nanotubes is demonstrated through massively parallel indirect dielectrophoresis (MPID). MPID is shown to be able to control the placement of carbon tubes as well as the number of tubes placed. Lumped element analysis for AC circuits is used to model MPID. This model allows for predictions of the number of tubes that will be captured in a trap. This model has been consistent with experimental data of numbers of nanotube placed in a junction. Carbon nanotubes placed with MPID are shown to be electrically active.

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Extreme Ultraviolet Polarimetry With Laser-Generated High-Order Harmonics: Characterization Of Uranium, Nicole Brimhall Jul 2009

Extreme Ultraviolet Polarimetry With Laser-Generated High-Order Harmonics: Characterization Of Uranium, Nicole Brimhall

Theses and Dissertations

We developed an extreme ultraviolet (EUV) polarimeter, which employs laser-generated high-order harmonics as the light source. This relatively high-flux, directional EUV source has available wavelengths between 10 nm and 47 nm with easily rotatable linear polarization. The polarimeter has allowed us to characterize the optical constants of materials that may be useful for EUV optics. The instrument has a versatile positioning system and a spectral resolution of about 180, and we have demonstrated that reflectance as low as 0.1% can be measured repeatably at EUV wavelengths. We investigate the high harmonic source used for polarimetry measurements by documenting the spatial …

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Four-Body Problem With Collision Singularity, Duokui Yan Jul 2009

Four-Body Problem With Collision Singularity, Duokui Yan

Theses and Dissertations

In this dissertation, regularization of simultaneous binary collision, existence of a Schubart-like periodic orbit, existence of a planar symmetric periodic orbit with multiple simultaneous binary collisions, and their linear stabilities are studied. The detailed background of those problems is introduced in chapter 1. The singularities of simultaneous binary collision in the collinear four-body problem is regularized in chapter 2. We use canonical transformations to collectively analytically continue the singularities of the simultaneous binary collision solutions in both the decoupled case and the coupled case. All the solutions are found and more importantly, we find a crucial first integral which describes …

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Energy Current Imaging Method For Time Reversal In Elastic Media, Brian E. Anderson, Michele Griffa, Robert A. Guyer, Paul A. Johnson, Carene Larmat, Pierre-Yves Le Bas, Timothy J. Ulrich Jul 2009

Energy Current Imaging Method For Time Reversal In Elastic Media, Brian E. Anderson, Michele Griffa, Robert A. Guyer, Paul A. Johnson, Carene Larmat, Pierre-Yves Le Bas, Timothy J. Ulrich

Faculty Publications

An energy current imaging method is presented for use in locating sources of wave energy during the back propagation stage of the time reversal process. During the back propagation phase of an ideal time reversal experiment, wave energy coalesces from all angles of incidence to recreate the source event; after the recreation, wave energy diverges in every direction. An energy current imaging method based on this convergence/divergence behavior has been developed. The energy current imaging method yields a smaller spatial distribution for source reconstruction than is possible with traditional energy imaging methods.

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Verifying Predictions Of The L13 Crystal Structure In Cd-Pt And Pd-Pt By Exhaustive Enumeration, Gus L. W. Hart Jul 2009

Verifying Predictions Of The L13 Crystal Structure In Cd-Pt And Pd-Pt By Exhaustive Enumeration, Gus L. W. Hart

Faculty Publications

In 2001, S. Müller and A. Zunger [Phys. Rev. Lett. 87, 165502 (2001)] predicted a never-before-observed crystal structure in Ag-Pd. Recently, Curtarolo predicted the same structure to be stable in Pt-Cd and Pt-Pd [S. Curtarolo et. Al., CALPHAD: Comput. Coupling Phase Diagrams Thermochem. 29, 163 (2005)]. The predicted structure is unique in several ways. though never seen in any other face-centered-cubic-based intermetallic binary compound or ordered alloy, it is relatively simple—it contains only four atoms per unit cell. Furthermore, the structure is the only one of this small size, except the L12 structure, that cannot be characterized as a simple …

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The Expectation Of Transition Events On Finite-State Markov Chains, Jeremy Michael West Jul 2009

The Expectation Of Transition Events On Finite-State Markov Chains, Jeremy Michael West

Theses and Dissertations

Markov chains are a fundamental subject of study in mathematical probability and have found wide application in nearly every branch of science. Of particular interest are finite-state Markov chains; the representation of finite-state Markov chains by a transition matrix facilitates detailed analysis by linear algebraic methods. Previous methods of analyzing finite-state Markov chains have emphasized state events. In this thesis we develop the concept of a transition event and define two types of transition events: cumulative events and time-average events. Transition events generalize state events and provide a more flexible framework for analysis. We derive computable, closed-form expressions for the …

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The Orbifold Landau-Ginzburg Conjecture For Unimodal And Bimodal Singularities, Natalie Wilde Bergin Jul 2009

The Orbifold Landau-Ginzburg Conjecture For Unimodal And Bimodal Singularities, Natalie Wilde Bergin

Theses and Dissertations

The Orbifold Landau-Ginzburg Mirror Symmetry Conjecture states that for a quasihomogeneous singularity W and a group G of symmetries of W, there is a dual singularity WT and dual group GT such that the orbifold A-model of W/G is isomorphic to the orbifold B-model of WT/GT. The Landau-Ginzburg A-model is the Frobenius algebra HW,G constructed by Fan, Jarvis, and Ruan, and the B-model is the Orbifold Milnor ring of WT . The unorbifolded conjecture has been verified for Arnol'd's list of simple, unimodal and bimodal quasi-homogeneous singularities with G the maximal diagonal symmetry group by Priddis, Krawitz, Bergin, Acosta, et …

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Relaxation Of Vibrationally Excited Trifluorobenzene And Tetrafluorobenzene By Collisions With Carbon Dioxide, Alan M. Johnson Jul 2009

Relaxation Of Vibrationally Excited Trifluorobenzene And Tetrafluorobenzene By Collisions With Carbon Dioxide, Alan M. Johnson

Theses and Dissertations

An investigation into the relaxation of highly vibrationally excited trifluorobenzene and tetrafluorobenzene following collisions with carbon dioxide was performed using diode laser transient absorption spectroscopy. A 248 nm excimer laser prepared the vibrationally hot (E'~41,000 cm-1) fluorobenzene molecules. Large amounts of translational and rotational energy are transferred through collisions between the hot donor molecule and CO2. Rate constants and collisional probabilities were calculated by probing the high J states (J=58~80) of CO2 in the vibrational ground state, 0000, with measurements taken 1 µsec, ¼ the mean gas collision time, following each excimer laser pulse. The energy transfer probability distribution function, …

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Estimating The Effect Of Disability On Medicare Expenditures, David Morris Burk Jul 2009

Estimating The Effect Of Disability On Medicare Expenditures, David Morris Burk

Theses and Dissertations

We consider the effect of disability status on Medicare expenditures. Disabled elderly historically have accounted for a significant portion of Medicare expenditures. Recent demographic trends exhibit a decline in the size of this population, causing some observers to predict declines in Medicare expenditures. There are, however, reasons to be suspicious of this rosy forecast. To better understand the effect of disability on Medicare expenditures, we develop and estimate a model using the generalized method of moments technique. We find that newly disabled elderly generally spend more than those who have been disabled for longer periods of time. Also, we find …

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Ion Transport Behaviors Upstream And Downstream From The Sampling Cone Of An Inductively Coupled Plasma Mass Spectrometer, Haibin Ma Jul 2009

Ion Transport Behaviors Upstream And Downstream From The Sampling Cone Of An Inductively Coupled Plasma Mass Spectrometer, Haibin Ma

Theses and Dissertations

Inductively coupled plasma - mass spectrometry (ICP-MS) is the technique of choice worldwide for trace elemental determinations because of its excellent ionization ability, low detection limits and fast analysis speeds. However, the ICP-MS still suffers from some disadvantages, such as spectral overlap and severe matrix effects. Matrix effects or interferences, partly arise from changes in the analyte transmission through the interfacial region between the ICP and mass spectrometer with changes in sample matrix. Better understanding of the transmission behaviors of analyte through the sampling and skimmer cones will provide the insights needed to alleviate matrix interferences and to improve the …

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The Role Of Smpb In The Early Stages Of Trans-Translation, Deanna June Cazier Jul 2009

The Role Of Smpb In The Early Stages Of Trans-Translation, Deanna June Cazier

Theses and Dissertations

Ribosomes stall on defective messenger RNA transcripts in eubacteria. Without a mechanism to release stalled ribosomes, these cells would die. Transfer-messenger RNA (tmRNA) and small protein B (SmpB) reactivate stalled ribosomes in a process known as trans-translation. Together, tmRNA and SmpB mimic alanyl-tRNA, entering the A site of stalled ribosomes and accepting transfer of the stalled polypeptide. A portion of tmRNA is then positioned as a template for the ribosome to resume translating. The tmRNA open reading frame encodes a proteolysis tag to mark the aberrant polypeptide for degradation and a stop codon to release the ribosome. How are tmRNA …

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Some Congruence Properties Of Pell's Equation, Nathan C. Priddis Jul 2009

Some Congruence Properties Of Pell's Equation, Nathan C. Priddis

Theses and Dissertations

In this thesis I will outline the impact of Pell's equation on various branches of number theory, as well as some of the history. I will also discuss some recently discovered properties of the solutions of Pell's equation.

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