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Articles 2311 - 2340 of 3436

Full-Text Articles in Physical Sciences and Mathematics

Spamed: A Spam Email Detection Approach Based On Phrase Similarity, Yiu-Kai D. Ng, Maria Soledad Pera Feb 2009

Spamed: A Spam Email Detection Approach Based On Phrase Similarity, Yiu-Kai D. Ng, Maria Soledad Pera

Faculty Publications

Emails are unquestionably one of the most popular communication media these days. Not only they are fast and reliable, but also free in general. Unfortunately, a significant number of emails received by email users on a daily basis are spam. This fact is annoying, since spam emails translate into a waste of user’s time in reviewing and deleting them. In addition, spam emails consume resources, such as storage, bandwidth, and computer processing time. Many attempts have been made in the past to eradicate spam emails; however, none has been proved highly effective. In this paper, we propose a spam-email detection …

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Synthesizing Correlated Rss News Articles Based On A Fuzzy Equivalence Relation, Yiu-Kai D. Ng, Maria Soledad Pera Jan 2009

Synthesizing Correlated Rss News Articles Based On A Fuzzy Equivalence Relation, Yiu-Kai D. Ng, Maria Soledad Pera

Faculty Publications

Tens of thousands of news articles are posted on-line each day, covering topics from politics to science to current events. To better cope with this overwhelming volume of information, RSS (news) feeds are used to categorize newly posted articles. Nonetheless, most RSS users must filter through many articles within the same or different RSS feeds to locate articles pertaining to their particular interests. Due to the large number of news articles in individual RSS feeds, there is a need for further organizing articles to aid users in locating non-redundant, informative, and related articles of interest quickly. In this paper, we …

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Using A Mathematical Model Of Cadherin-Based Adhesion To Understand The Function Of The Actin Cytoskeleton, J. C. Dallon, Elijah Newren, Marc Hansen Jan 2009

Using A Mathematical Model Of Cadherin-Based Adhesion To Understand The Function Of The Actin Cytoskeleton, J. C. Dallon, Elijah Newren, Marc Hansen

Faculty Publications

The actin cytoskeleton plays a role in cell-cell adhesion but its specific function is not clear. Actin might anchor cadherins or drive membrane protrusions in order to facilitate cell-cell adhesion. Using a mathematical model of the forces involved in cadherin-based adhesion we investigate its possible functions. The immersed boundary method is used to model the cell membrane and cortex with cadherin binding forces added as linear springs. The simulations indicate that cells in suspension can develop normal cell-cell contacts without actin-based cadherin anchoring or membrane protrusions. The cadherins can be fixed in the membrane or free to move and the …

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Petromode, Eric H. Christiansen Jan 2009

Petromode, Eric H. Christiansen

Faculty Publications

PetroMode is an Excel spreadsheet that can be used to (1) calculate the modal composition of a rock given the elemental composition of the rock and (2) calculate the major element mass balance to test the derivation of a daughter liquid by removal of minerals from a parent liquid (fractional crystallization).

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Time Reversal Of Continuous-Wave, Steady-State Signals In Elastic Media, Brian E. Anderson, Robert A. Guyer, Paul A. Johnson, Timothy J. Ulrich Jan 2009

Time Reversal Of Continuous-Wave, Steady-State Signals In Elastic Media, Brian E. Anderson, Robert A. Guyer, Paul A. Johnson, Timothy J. Ulrich

Faculty Publications

Experimental observations of spatial focusing of continuous-wave, steady-state elastic waves in a reverberant elastic cavity using time reversal are reported here. Spatially localized focusing is achieved when multiple channels are employed, while a single channel does not yield such focusing. The amplitude of the energy at the focal location increases as the square of the number of channels used, while the amplitude elsewhere in the medium increases proportionally with the number of channels used. The observation is important in the context of imaging in solid laboratory samples as well as problems involving continuous-wave signals in Earth.

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Comment On "Generation Of Cold Low Divergent Atomic Beam Of Indium By Laser Ablation", A. Denning, A. Booth, S. Lee, M. Amonson, Scott D. Bergeson Jan 2009

Comment On "Generation Of Cold Low Divergent Atomic Beam Of Indium By Laser Ablation", A. Denning, A. Booth, S. Lee, M. Amonson, Scott D. Bergeson

Faculty Publications

We present measurements of the velocity distribution of calcium atoms in an atomic beam generated using a dual-stage laser back-ablation apparatus. Distributions are measured using a velocity selective Doppler time-of-flight technique. They are Boltzmann-like with rms velocities corresponding to temperatures above the melting point for calcium. Contrary to a recent report in the literature, this method does not generate a subthermal atomic beam.

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Measurement And Simulation Of Laser-Induced Fluorescence From Nonequilibrium Ultracold Neutral Plasmas, A. Denning, Scott D. Bergeson, F. Robicheaux Jan 2009

Measurement And Simulation Of Laser-Induced Fluorescence From Nonequilibrium Ultracold Neutral Plasmas, A. Denning, Scott D. Bergeson, F. Robicheaux

Faculty Publications

We report measurements and simulations of laser-induced fluorescence in ultracold neutral plasmas. We focus on the earliest times, when the plasma equilibrium is evolving and before the plasma expands. In the simulation, the ions interact via the Yukawa potential in a small cell with wrapped boundary conditions. We solve the optical Bloch equation for each ion in the simulation as a function of time. Both the simulation and experiment show the initial increase in ion fluorescence, disorder-induced heating, and coherent oscillation of the rms ion velocity. Detailed modeling of the fluorescence signal makes it possible to use fluorescence spectroscopy to …

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Author Entropy Vs. File Size In The Gnome Suite Of Applications, Jason R. Casebolt, Daniel P. Delorey, Charles D. Knutson, Jonathan Krein, Alexander C. Maclean Jan 2009

Author Entropy Vs. File Size In The Gnome Suite Of Applications, Jason R. Casebolt, Daniel P. Delorey, Charles D. Knutson, Jonathan Krein, Alexander C. Maclean

Faculty Publications

We present the results of a study in which author entropy was used to characterize author contributions per file. Our analysis reveals three patterns: banding in the data, uneven distribution of data across bands, and file size dependent distributions within bands. Our re- sults suggest that when two authors contribute to a file, large files are more likely to have a dominant author than smaller files.

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Psoda: Open Source Phylogenetic Search And Dna Analysis, Mark J. Clement, Quinn O. Snell, Kenneth Sundberg Jan 2009

Psoda: Open Source Phylogenetic Search And Dna Analysis, Mark J. Clement, Quinn O. Snell, Kenneth Sundberg

Faculty Publications

PSODA is an open source (GPL v2) sequence analysis package that implements sequence alignment using biochemical properties, phylogeny search with parsimony or maximum likelihood criteria and selection detection using biochemical properties (TreeSAAP ). PSODA is compatible with PAUP and the search algorithms are competitive with those in PAUP. PSODA also adds a basic scripting language to the PAUP block, making it possible to easily create advanced meta-searches. Because PSODA is open-source, we have also been able to easily add in advanced search techniques and characterize the benefits of various optimizations. PSODA is available for Macintosh OS X, Windows, and Linux.

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Hardware Accelerated Sequence Alignment With Traceback, Scott Lloyd, Quinn O. Snell Jan 2009

Hardware Accelerated Sequence Alignment With Traceback, Scott Lloyd, Quinn O. Snell

Faculty Publications

Biological sequence alignment is an essential tool used in molecular biology and biomedical applications. The growing volume of genetic data and the complexity of sequence alignment present a challenge in obtaining alignment results in a timely manner. Known methods to accelerate alignment on reconfigurable hardware only address sequence comparison, limit the sequence length, or exhibit memory and I/O bottlenecks. A space-efficient, global sequence alignment algorithm and architecture is presented that accelerates the forward scan and traceback in hardware without memory and I/O limitations. With 256 processing elements in FPGA technology, a performance gain over 300 times that of a desktop …

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Effective Medium Theory, Rough Surfaces, And Moth’S Eyes, David D. Allred, Zephne Larsen, Joseph Muhlestein, R. Steven Turley, Anthony Willey Jan 2009

Effective Medium Theory, Rough Surfaces, And Moth’S Eyes, David D. Allred, Zephne Larsen, Joseph Muhlestein, R. Steven Turley, Anthony Willey

Faculty Publications

Optics in the extreme ultraviolet (XUV) have important applications in microelectronics, microscopy, space physics, and in imaging plasmas. Because of the short wavelengths involved in these applications, it is critical to account for interfacial roughness to accurately predict the reflection and absorption of XUV optics. This paper examines two possible effects of roughness on optical absorption, non-specular reflection and enhanced transmission and compares these to measured experimental data on a rough Y2O3 thin film.

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Spin Dynamics For Wave Packets In Rashba Systems, Bailey C. Hsu, Jean F. Van Huele Jan 2009

Spin Dynamics For Wave Packets In Rashba Systems, Bailey C. Hsu, Jean F. Van Huele

Faculty Publications

We explore spin dynamics for localized wave packets in Rashba systems using spin quantum propagators. We derive exact (one-dimensional) and approximate (two-dimensional) analytic expressions for the propagators and apply them to Gaussian wave packets to obtain localized solutions of systems manifesting Rashba interactions. We observe and describe the evolution of the wave packets. We identify characteristic structures in the wave-packet evolution and look for features with specific spintronics applications such as spin separation and spin accumulation. We discuss the relative importance of those features as a function of the Rashba coupling strength α and the width of the wave packet …

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Towards The Total Synthesis Of Thioviridamide: Thiyl Radical Approach To The Beta-Thioenamide Linkage Formation, Jung-Hoon Kang Dec 2008

Towards The Total Synthesis Of Thioviridamide: Thiyl Radical Approach To The Beta-Thioenamide Linkage Formation, Jung-Hoon Kang

Theses and Dissertations

We developed an approach to the β-thioenamide linkage contained in the S-(2-aminovinyl)cysteine (avCys) residue of thioviridamide.1,2 Kinetic and thermodynamic control of radical additions of thiols to ynamides were studied for the formation of β-thioenamide linkage. Thiyl radicals are electrophilic and ynamides are electron-rich alkynes. This complementary polarity of the radical and acceptor increases the likelihood of a successful radical addition reaction. Because little is known about these types of compounds (β-thioenamides), we were unsure what kinds of yields and stereoselectivities (cis vs. trans) to expect. The adduct stability is another issue to consider. Fortunately, under typical radical addition conditions, the …

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Improving Library Searches Using Word-Correlation Factors And Folksonomies, Maria Soledad Pera Dec 2008

Improving Library Searches Using Word-Correlation Factors And Folksonomies, Maria Soledad Pera

Theses and Dissertations

Libraries, private and public, offer valuable resources to library patrons; however, formulating library queries to retrieve relevant results can be difficult. This occurs because when using a library catalog for library searches, patrons often do not know the exact keywords to be included in a query that match the rigid subject terms (chosen by the Library of Congress) or terms in other fields of a desired library catalog record. These improperly formulated queries often translate into a high percentage of failed searches that retrieve irrelevant results or no results at all. This explains why frustrated library patrons nowadays rely on …

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Ontology Generation, Information Harvesting And Semantic Annotation For Machine-Generated Web Pages, Cui Tao Dec 2008

Ontology Generation, Information Harvesting And Semantic Annotation For Machine-Generated Web Pages, Cui Tao

Theses and Dissertations

The current World Wide Web is a web of pages. Users have to guess possible keywords that might lead through search engines to the pages that contain information of interest and browse hundreds or even thousands of the returned pages in order to obtain what they want. This frustrating problem motivates an approach to turn the web of pages into a web of knowledge, so that web users can query the information of interest directly. This dissertation provides a step in this direction and a way to partially overcome the challenges. Specifically, this dissertation shows how to turn machine-generated web …

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Learning-Based Fusion For Data Deduplication, Sabra Dinerstein, Parris K. Egbert, Stephen W. Clyde, Jared Dinerstein Dec 2008

Learning-Based Fusion For Data Deduplication, Sabra Dinerstein, Parris K. Egbert, Stephen W. Clyde, Jared Dinerstein

Faculty Publications

Rule-based deduplication utilizes expert domain knowledge to identify and remove duplicate data records. Achieving high accuracy in a rule-based system requires the creation of rules containing a good combination of discriminatory clues. Unfortunately, accurate rule-based deduplication often requires significant manual tuning of both the rules and the corresponding thresholds. This need for manual tuning reduces the efficacy of rule-based deduplication and its applicability to real-world data sets. No adequate solution exists for this problem. We propose a novel technique for rule-based deduplication. We apply individual deduplication rules, and combine the resultant match scores via learning-based information fusion. We show empirically …

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Decision Tree Ensemble: Small Heterogeneous Is Better Than Large Homogeneous, Mike Gashler, Christophe G. Giraud-Carrier, Tony R. Martinez Dec 2008

Decision Tree Ensemble: Small Heterogeneous Is Better Than Large Homogeneous, Mike Gashler, Christophe G. Giraud-Carrier, Tony R. Martinez

Faculty Publications

Using decision trees that split on randomly selected attributes is one way to increase the diversity within an ensemble of decision trees. Another approach increases diversity by combining multiple tree algorithms. The random forest approach has become popular because it is simple and yields good results with common datasets. We present a technique that combines heterogeneous tree algorithms and contrast it with homogeneous forest algorithms. Our results indicate that random forests do poorly when faced with irrelevant attributes, while our heterogeneous technique handles them robustly. Further, we show that large ensembles of random trees are more susceptible to diminishing returns …

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Dynamic Load Balancing Of Virtual Machines Hosted On Xen, Terry Clyde Wilcox Dec 2008

Dynamic Load Balancing Of Virtual Machines Hosted On Xen, Terry Clyde Wilcox

Theses and Dissertations

Currently systems of virtual machines are load balanced statically which can create load imbalances for systems where the load changes dynamically over time. For throughput and response time of a system to be maximized it is necessary for load to be evenly distributed among each part of the system. We implement a prototype policy engine for the Xen virtual machine monitor which can dynamically load balance virtual machines. We compare the throughput and response time of our system using the cpu2000 and the WEB2005 benchmarks from SPEC. Under the loads we tested, dynamic load balancing had 5%-8% higher throughput than …

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Nowhere To Hide: Finding Plagiarized Documents Based On Sentence Similarity, Nathaniel Gustafson, Yiu-Kai D. Ng, Maria Soledad Pera Dec 2008

Nowhere To Hide: Finding Plagiarized Documents Based On Sentence Similarity, Nathaniel Gustafson, Yiu-Kai D. Ng, Maria Soledad Pera

Faculty Publications

Plagiarism is a serious problem that infringes copyrighted documents/materials, which is an unethical practice and decreases the economic incentive received by authors (owners) of the original copies. Unfortunately, plagiarism is getting worse due to the increasing number of online publications on the Web, which facilitates locating and paraphrasing information. In solving this problem, we propose a novel plagiarism-detection method, called SimPaD, which (i) establishes the degree of resemblance between any two documents D1 and D2 based on their sentence-to-sentence similarity computed by using pre-defined word-correlation factors, and (ii) generates a graphical view of sentences that are similar (or the same) …

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Using Geoscience Education Graduate Students To Help Faculty Transform Teaching Practice, Teagan L. Tomlin Dec 2008

Using Geoscience Education Graduate Students To Help Faculty Transform Teaching Practice, Teagan L. Tomlin

Theses and Dissertations

Universities make claims about student learning that graduates don't often achieve and are under pressure to show improvement in teaching and learning in their undergraduate programs. This has been the constant focus of university-level professional development programs, but most teachers are still not using the most effective teaching methods. Individual departments need to find ways to help their instructors overcome three main challenges associated with adopting more effective student-centered teaching methods. No matter what strategy is adopted, instructors need considerable support to 1) change their beliefs about what constitutes effective teaching and learning, 2) learn to effectively implement new strategies, …

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Simulation And Analysis Of Cadmium Sulfide Nanoparticles, Chad Everett Junkermeier Dec 2008

Simulation And Analysis Of Cadmium Sulfide Nanoparticles, Chad Everett Junkermeier

Theses and Dissertations

I used ab initio molecular dynamics calculations to model cadmium sulfide nanoparticles. The nanoparticles were originaly spherical, bulk-like zinc-blende structures. Constant temperature molecular dynamics calculations reveals that CdS nanoparticles that are about 2 nm in diameter and have unpassivated surfaces are in an amorphous structure with short range order. The nearest neighbor distance on the surface of the nanoparticles being near the wurtzite nearest neighbor distance. I wrote the program xyzSTATS and used its results in justifying the amorphous nanoparticles claim. I also estimated the band gap of the CdS nanoparticles with unpassivated dangling bonds.

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Sequence Alignment With Traceback On Reconfigurable Hardware, Scott Lloyd, Quinn O. Snell Dec 2008

Sequence Alignment With Traceback On Reconfigurable Hardware, Scott Lloyd, Quinn O. Snell

Faculty Publications

Biological sequence alignment is an essential tool used in molecular biology and biomedical applications. The growing volume of genetic data and the complexity of sequence alignment present a challenge in obtaining alignment results in a timely manner. Known methods to accelerate alignment on reconfigurable hardware only address sequence comparison, limit the sequence length, or exhibit memory and I/O bottlenecks. A space-efficient, global sequence alignment algorithm and architecture is presented that accelerates the forward scan and traceback in hardware without memory and I/O limitations. With 256 processing elements in FPGA technology, a performance gain over 300 times that of a desktop …

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Real-Time Automatic Price Prediction For Ebay Online Trading, Ilya Igorevitch Raykhel Nov 2008

Real-Time Automatic Price Prediction For Ebay Online Trading, Ilya Igorevitch Raykhel

Theses and Dissertations

While Machine Learning is one of the most popular research areas in Computer Science, there are still only a few deployed applications intended for use by the general public. We have developed an exemplary application that can be directly applied to eBay trading. Our system predicts how much an item would sell for on eBay based on that item's attributes. We ran our experiments on the eBay laptop category, with prior trades used as training data. The system implements a feature-weighted k-Nearest Neighbor algorithm, using genetic algorithms to determine feature weights. Our results demonstrate an average prediction error of 16%; …

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An Analysis Of Document Retrieval And Clustering Using An Effective Semantic Distance Measure, Nathan Scott Davis Nov 2008

An Analysis Of Document Retrieval And Clustering Using An Effective Semantic Distance Measure, Nathan Scott Davis

Theses and Dissertations

As large amounts of digital information become more and more accessible, the ability to effectively find relevant information is increasingly important. Search engines have historically performed well at finding relevant information by relying primarily on lexical and word based measures. Similarly, standard approaches to organizing and categorizing large amounts of textual information have previously relied on lexical and word based measures to perform grouping or classification tasks. Quite often, however, these processes take place without respect to semantics, or word meanings. This is perhaps due to the fact that the idea of meaningful similarity is naturally qualitative, and thus difficult …

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Parameter Estimation For The Beta Distribution, Claire Elayne Bangerter Owen Nov 2008

Parameter Estimation For The Beta Distribution, Claire Elayne Bangerter Owen

Theses and Dissertations

The beta distribution is useful in modeling continuous random variables that lie between 0 and 1, such as proportions and percentages. The beta distribution takes on many different shapes and may be described by two shape parameters, alpha and beta, that can be difficult to estimate. Maximum likelihood and method of moments estimation are possible, though method of moments is much more straightforward. We examine both of these methods here, and compare them to three more proposed methods of parameter estimation: 1) a method used in the Program Evaluation and Review Technique (PERT), 2) a modification of the two-sided power …

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A See-Ability Metric To Improve Mini Unmanned Aerial Vehicle Operator Awareness Using Video Georegistered To Terrain Models, Cameron Howard Engh Nov 2008

A See-Ability Metric To Improve Mini Unmanned Aerial Vehicle Operator Awareness Using Video Georegistered To Terrain Models, Cameron Howard Engh

Theses and Dissertations

Search and rescue operations conducted in wilderness environments can be greatly aided by the use of video filmed from mini-UAVs. While lightweight, inexpensive and easily transportable, these small aircraft suffer from wind buffeting and may produce video that is difficult to search. To aid in the video search process, we have created a system to project video frames into a 3D representation of the search region. This projection allows us to tie each frame of video to a real-world location, enabling a myriad of novel views, mosaics and metrics that can be used to guide the search including a new …

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The Hybrid Game Architecture: Distributing Bandwidth For Mmogs While Maintaining Central Control, Jared L. Jardine Nov 2008

The Hybrid Game Architecture: Distributing Bandwidth For Mmogs While Maintaining Central Control, Jared L. Jardine

Theses and Dissertations

Current Massively Multi-player Online Games (MMOGs) have enormous server-side bandwidth requirements. The costs of providing this bandwidth is in turn passed on to the consumer in the form of high monthly subscription fees. Prior work has primarily focused on distributing this bandwidth using peer-to-peer architectures, but these architectures have difficulty preventing cheating, overwhelming low resource peers, and maintaining consistent game state. We have developed a hybrid game architecture that combines client-server and peer-to-peer technologies to prevent cheating, maintain centralized and consistent game state, significantly reduce central server bandwidth, and prevent lower capacity players from being overwhelmed. By dramatically reducing the …

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Antiphase Ordering And Surface Phases In Lithium Aluminate, Richard R. Vanfleet, J. A. Simmons, D. W. Hill, M. M. C. Chou, B. H. Chai Nov 2008

Antiphase Ordering And Surface Phases In Lithium Aluminate, Richard R. Vanfleet, J. A. Simmons, D. W. Hill, M. M. C. Chou, B. H. Chai

Faculty Publications

Antiphase domains are seen in single crystal gamma lithium aluminate (gamma-LiAlO2) with 16.7 nm periodicity in the <110> direction. Alternate domains have a (1/2) [001] shift. Beta phase lithium aluminate (beta-LiAlO2) is seen to form on the surface of the as-received wafers with an epitaxial strain limited relationship with the bulk gamma phase. The orthorhombic beta phase aligns with the a and b axes (0.528 and 0.630 nm) matching with the tetragonal gamma phase's a and c axes (0.5168 and 0.6268 nm). The gamma and beta phases are seen to have different etch rates. The beta phase converts back to the …

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Investigating The Margins Of Pleistocene Lake Deposits With High-Resolution Seismic Reflection In Pilot Valley, Utah, John V. South Nov 2008

Investigating The Margins Of Pleistocene Lake Deposits With High-Resolution Seismic Reflection In Pilot Valley, Utah, John V. South

Theses and Dissertations

A vast area of the northeastern Great Basin of the western USA was inundated by a succession of Plio-Pleistocene lakes, including Lake Bonneville (28 ka to 12 ka). The Pilot Valley playa, located just east of the Utah-Nevada border near Wendover, Utah, within the eastern Basin and Range Province, represents an 8 to 16 km wide and ~50 km long remnant of these lakes. The playa corresponds to the upper surface of a closed basin that is delimited by two mountain ranges, which are mantled by recent alluvial fans over which the playa sediments have prograded. In order to investigate …

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Photocycloaddition Of Allenes, Crystal Ward Nov 2008

Photocycloaddition Of Allenes, Crystal Ward

Theses and Dissertations

For the past ten years the Fleming research group has been involved in the research of allene compounds. We have explored the synthesis of allenes as well as several reactions involving allenes, such as oxidation and nitrene addition. Recently, we have explored the synthesis and photochemistry of allenic alcohols tethered to silicon. There are literature examples using allenes in synthesis, but very few examples exist using allenes in photochemical cycloaddition reactions. We have found that a diisopropylallenyloxy(cinnamyloxy)silane derivative undergoes [2+2] photochemical cycloaddition to produce a cyclobutylsilane product when irradiated for 60-75 minutes.

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