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Articles 1771 - 1800 of 2906

Full-Text Articles in Physical Sciences and Mathematics

Impact Of Spherical Probe Scattering On Estimation Of Acoustic Vector Quantities. (A), Curtis P. Wiederhold, Kent L. Gee, Derek C. Thomas, Scott D. Sommerfeldt, Jonathan D. Blotter Apr 2009

Impact Of Spherical Probe Scattering On Estimation Of Acoustic Vector Quantities. (A), Curtis P. Wiederhold, Kent L. Gee, Derek C. Thomas, Scott D. Sommerfeldt, Jonathan D. Blotter

Faculty Publications

Multimicrophone probes are often used to measure energy-based acoustical quantities. In some cases, these probes consist of microphones mounted on the surface of a sphere, which, due to the high level of symmetry, permits scattering effects to be better characterized. Scattering of a plane wave incident on a rigid sphere has been modeled to observe how particle velocity and intensity calculations are affected by the presence of the sphere. These effects have been investigated for the traditional "finite-difference" method and a recently developed "wave vector" estimation method. In the computer model, 3-D surface plots were made showing the calculated error …

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Topics In Analytic Number Theory, Kevin James Powell Mar 2009

Topics In Analytic Number Theory, Kevin James Powell

Theses and Dissertations

The thesis is in two parts. The first part is the paper “The Distribution of k-free integers” that my advisor, Dr. Roger Baker, and I submitted in February 2009. The reader will note that I have inserted additional commentary and explanations which appear in smaller text. Dr. Baker and I improved the asymptotic formula for the number of k-free integers less than x by taking advantage of exponential sum techniques developed since the 1980's. Both of us made substantial contributions to the paper. I discovered the exponent in the error term for the cases k=3,4, and worked the case k=3 …

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Verifying Abstract Components Within Concrete Software Environments, Tonglaga Bao Mar 2009

Verifying Abstract Components Within Concrete Software Environments, Tonglaga Bao

Theses and Dissertations

In order to model check a software component which is not a standalone program, we need a model of the software which completes the program. This problem is important for software engineers who need to deploy an existing component into a new environment. The model is typically generated by abstracting the surrounding software environment in which the component will be executed. However, abstracting the surrounding software is a difficult and error-prone task, particularly when the surrounding software is a complex software artifact which can not be easily abstracted. In this dissertation, we present a new approach to the problem by …

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Functionalization, Characterization, And Applications Of Diamond Particles, Modification Of Planar Silicon, And Chemoetrics Analysis Of Ms Data, Li Yang Mar 2009

Functionalization, Characterization, And Applications Of Diamond Particles, Modification Of Planar Silicon, And Chemoetrics Analysis Of Ms Data, Li Yang

Theses and Dissertations

In spite of the stablility (lack of reactivity) of diamond powder, I have developed a method for tethering alkyl chains and polymers to deuterium/hydrogen-terminated diamond. One method is through ether linkages via thermolysis of di-tert-amyl peroxide (DTAP). This reaction with DTAP has also been applied to grow polymers on the diamond surface. The other method is atom transfer radical polymerization (ATRP), which was applied to grow polystyrene at the surface of diamond. Both polystyrene-modified diamond and sulfonated polystyrene-modified diamond can be prepared by either method, and can be used for solid phase extraction. Diamond stationary phases are stable under basic …

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Combined Visible And Infrared Video For Use In Wilderness Search And Rescue, Nathan D. Rasmussen Mar 2009

Combined Visible And Infrared Video For Use In Wilderness Search And Rescue, Nathan D. Rasmussen

Theses and Dissertations

Mini Unmanned Aerial Vehicles (mUAVs) have the potential to be a great asset to Wilderness Search and Rescue groups by providing a bird's eye view of the search area. These vehicles can carry a variety of sensors to better understand the world below. This paper proposes using both Infrared (IR) and Visible Spectrum cameras on a mUAV for Wilderness Search and Rescue. It details a method for combining the color and heat information from these two cameras into a single fused display to reduce needed screen space for remote field use. To align the video frames for fusion, a method …

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The First Attachment And Post-Functionalization Of Polybutadiene And Thio-Click Functionalized Polybutadiene On H-Terminated Si(111), Todd Devere Wickard Mar 2009

The First Attachment And Post-Functionalization Of Polybutadiene And Thio-Click Functionalized Polybutadiene On H-Terminated Si(111), Todd Devere Wickard

Theses and Dissertations

I report the attachment of polymers with pendant vinyl groups to hydrogen-terminated silicon(111) (Si(111)-H) under mild conditions. 1,2-addition polybutadiene (Mw 3200-3500) was attached to Si(111)-H at room temperature with visible light. I also report the partial functionalization, in solution, of 1,2-addition polybutadiene with various thiols using thiol-click chemistry. These compounds bind to Si(111)-H via visible light activation. The partially functionalized polybutadienes allow further functionalization at the surface through unreacted carbon-carbon double bonds. Surfaces were characterized with contact angle goniometry, spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and atomic force microscopy (AFM).

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Resonant Microwave Cavity For 8.5-12 Ghz Optically Detected Electron Spin Resonance With Simultaneous Nuclear Magnetic Resonance, John S. Colton, L. R. Wienkes Mar 2009

Resonant Microwave Cavity For 8.5-12 Ghz Optically Detected Electron Spin Resonance With Simultaneous Nuclear Magnetic Resonance, John S. Colton, L. R. Wienkes

Faculty Publications

We present a newly developed microwave resonant cavity for use in optically detected magnetic resonance (ODMR) experiments. The cylindrical quasi-TE 011 mode cavity is designed to fit in a 1 in. magnet bore to allow the sample to be optically accessed and to have an adjustable resonant frequency between 8.5 and 12 GHz. The cavity uses cylinders of high dielectric material, so-called "dielectric resonators," in a double-stacked configuration to determine the resonant frequency. Wires in a pseudo-Helmholtz configuration are incorporated into the cavity to provide frequencies for simultaneous nuclear magnetic resonance (NMR). The system was tested by measuring cavity absorption …

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Alternating Links And Subdivision Rules, Brian Craig Rushton Mar 2009

Alternating Links And Subdivision Rules, Brian Craig Rushton

Theses and Dissertations

The study of geometric group theory has suggested several theorems related to subdivision tilings that have a natural hyperbolic structure. However, few examples exist. We construct subdivision tilings for the complement of every nonsingular, prime alternating link and all torus links, and explore some of their properties and applications. Several examples are exhibited with color coding of tiles.

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The 20-Minute Genealogist: A Context-Preservation Metaphor For Assisted Family History Research, Charles D. Knutson, Jonathan Krein Mar 2009

The 20-Minute Genealogist: A Context-Preservation Metaphor For Assisted Family History Research, Charles D. Knutson, Jonathan Krein

Faculty Publications

What can you possibly do to be productive as a family history researcher in 20 minutes per week? Our studies suggest that currently the answer is, “Nothing.” In 20 minutes a would-be researcher can’t even remember what happened last week, let alone what they were planning to do next. The 20-Minute Genealogist is a powerful metaphor within which software solutions must consider context preservation as the fundamental domain of the system, thus freeing the researcher to do research while the software manages the tasks that computers do best. Two survey-based studies were conducted that indicate a significant disconnect between the …

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Measuring Skill Importance In Women's Soccer And Volleyball, Michelle L. Allan Mar 2009

Measuring Skill Importance In Women's Soccer And Volleyball, Michelle L. Allan

Theses and Dissertations

The purpose of this study is to demonstrate how to measure skill importance for two sports: soccer and volleyball. A division I women's soccer team filmed each home game during a competitive season. Every defensive, dribbling, first touch, and passing skill was rated and recorded for each team. It was noted whether each sequence of plays led to a successful shot. A hierarchical Bayesian logistic regression model is implemented to determine how the performance of the skill affects the probability of a successful shot. A division I women's volleyball team rated each skill (serve, pass, set, etc.) and recorded rally …

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Super-Resolution Via Image Recapture And Bayesian Effect Modeling, Neil B. Toronto Mar 2009

Super-Resolution Via Image Recapture And Bayesian Effect Modeling, Neil B. Toronto

Theses and Dissertations

The goal of super-resolution is to increase not only the size of an image, but also its apparent resolution, making the result more plausible to human viewers. Many super-resolution methods do well at modest magnification factors, but even the best suffer from boundary and gradient artifacts at high magnification factors. This thesis presents Bayesian edge inference (BEI), a novel method grounded in Bayesian inference that does not suffer from these artifacts and remains competitive in published objective quality measures. BEI works by modeling the image capture process explicitly, including any downsampling, and modeling a fictional recapture process, which together allow …

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Variable Uplift From Quaternary Folding Along The Northern Coast Of East Timor, Based On U-Series Age Determinations Of Coral Terraces, Nicole L. Cox Mar 2009

Variable Uplift From Quaternary Folding Along The Northern Coast Of East Timor, Based On U-Series Age Determinations Of Coral Terraces, Nicole L. Cox

Theses and Dissertations

Surveys of emergent terraces and U-series ages for ten sites along the coast of East Timor provide estimates of late Quaternary differential vertical strain in the most mature region of the Banda Arc-continent collision complex. Over a distance of ~180 km vertical displacement rates vary between 0.0 and 1.6 meters per 1000 years for the last 150,000 years. Two models of terrace formation (constructional and erosional) are applied to interpret terrace ages from coral ages and to estimate uplift rates. The highest uplift rates are from three sites over a distance of 15 km along the coast. Uplift rates were …

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Characterizing The Statistical Properties And Global Distribution Of Dansgaard-Oeschger Events, Andrea Michelle Thomas Mar 2009

Characterizing The Statistical Properties And Global Distribution Of Dansgaard-Oeschger Events, Andrea Michelle Thomas

Theses and Dissertations

Ice core records from Greenland have shown times of rapid warming during the most recent glacial period, called Dansgaard-Oeschger (D-O) events. D-O events are important to our understanding of both past climate systems and modern climate volatility. In this paper, we present new approaches for statistically evaluating the existence of cyclicity in D-O events and the possible lagged correlation between the Greenland and Antarctica temperature records. Specifically, we consider permutation testing and bootstrapping methodologies for assessing the cyclicity of D-O events and the correlation between the Greenland and Antarctica records. We find that there is not enough evidence to conclude …

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A Dynamic Attribute-Based Data Filtering And Recovery Scheme For Web Information Processing, Amit Ahuja, Yiu-Kai D. Ng Mar 2009

A Dynamic Attribute-Based Data Filtering And Recovery Scheme For Web Information Processing, Amit Ahuja, Yiu-Kai D. Ng

Faculty Publications

Web data being transmitted over a network channel on the Internet with excessive amount of data causes data processing problems, which include selectively choosing useful information to be retained for various data applications. In this paper, we present an approach for filtering less-informative attribute data from a source Website. A scheme for filtering attributes, instead of tuples (records), from a Website becomes imperative, since filtering a complete tuple would lead to filtering some informative, as well as less-informative, attribute data in the tuple. Since filtered data at the source Website may be of interest to the user at the destination …

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Polymer Microfluidic Devices For Bioanalysis, Xuefei Sun Feb 2009

Polymer Microfluidic Devices For Bioanalysis, Xuefei Sun

Theses and Dissertations

Polymeric microchips have received increasing attention in chemical analysis because polymers have attractive properties, such as low cost, ease of fabrication, biocompatibility and high flexibility. However, commercial polymers usually exhibit analyte adsorption on their surfaces, which can interfere with microfluidic transport in, for example, chemical separations such as chromatography or electrophoresis. Usually, surface modification is required to eliminate this problem. To perform stable and durable surface modification, a new polymer, poly(methyl methacrylate-co-glycidyl methacrylate) (PGMAMMA) was prepared for microchip fabrication, which provides epoxy groups on the surface. Whole surface atom transfer radical polymerization (ATRP) and in-channel ATRP approaches were employed to …

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A Unified Approach To Gpu-Accelerated Aerial Video Enhancement Techniques, Stephen Thayn Cluff Feb 2009

A Unified Approach To Gpu-Accelerated Aerial Video Enhancement Techniques, Stephen Thayn Cluff

Theses and Dissertations

Video from aerial surveillance can provide a rich source of data for analysts. From the time-critical perspective of wilderness search and rescue operations, information extracted from aerial videos can mean the difference between a successful search and an unsuccessful search. When using low-cost, payload-limited mini-UAVs, as opposed to more expensive platforms, several challenges arise, including jittery video, narrow fields of view, low resolution, and limited time on screen for key features. These challenges make it difficult for analysts to extract key information in a timely manner. Traditional approaches may address some of these issues, but no existing system effectively addresses …

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Survival Analysis With High-Dimensional Covariates: An Application In Microarray Studies, David Engler, Yi Li Feb 2009

Survival Analysis With High-Dimensional Covariates: An Application In Microarray Studies, David Engler, Yi Li

Faculty Publications

Use of microarray technology often leads to high-dimensional and low-sample size (HDLSS) data settings. A variety of approaches have been proposed for variable selection in this context. However, only a small number of these have been adapted for time-to-event data where censoring is present. Among standard variable selection methods shown both to have good predictive accuracy and to be computationally efficient is the elastic net penalization approach. In this paper, adaptations of the elastic net approach are presented for variable selection both under the Cox proportional hazards model and under an accelerated failure time (AFT) model. Assessment of the two …

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Quasi-Anosov Diffeomorphisms Of 3-Manifolds, Todd L. Fisher, Hertz M. Rodriguez Feb 2009

Quasi-Anosov Diffeomorphisms Of 3-Manifolds, Todd L. Fisher, Hertz M. Rodriguez

Faculty Publications

In 1969, Hirsch posed the following problem: given a diffeomorphism f:N → N and a compact invariant hyperbolic set Λ of f, describe the topology of Λ and the dynamics of f restricted to Λ. We solve the problem where Λ=M^3 is a closed 3-manifold: if M^3 is orientable, then it is a connected sum of tori and handles; otherwise it is a connected sum of tori and handles quotiented by involutions.

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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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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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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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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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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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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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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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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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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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