Physical Sciences and Mathematics Commons^™

A Comparative Study Of Photomultiplier Tubes And Charge Coupled Devices In Glow Discharge-Optical Emission Spectrometry, Robert James Broadwater

Masters Theses

This Masters Thesis compared two glow discharge-optical emission spectrometers designed around two different types of detectors: the photomultiplier tube (PMT) and the charge-coupled device (CCD). The two instruments compared were the LECO SA2000 (PMT-based) and the LECO GDS500a (CCD-based). Detection limit, dynamic range, precision, accuracy, and drift were determined to compare the detection systems between 165 and 450nm.

The PMT-based system outperformed the CCD-based system in all five of the categories studied based on the initial protocol. However, it was shown that improvements could be made in four of the five categories studied by exploiting the CCDs ability to monitor …

Viewer-Based Directional Querying For Mobile Applications, Keith Gardiner, James Carswell

Conference papers

With the steady and fast advancements in the integration of geographic information systems and mobile location-based services, interest in exploiting this technology for Cultural Heritage (CH) data sharing has become apparent. In this area there has been an increasing need to integrate positional information with non-positional data and add a spatial dimension to the definition of a users “context”. In this paper we describe an implementation of a viewer-based directional query processor that operates on an Oracle Spatial database. The spatial position and orientation are taken from the viewer’s perspective. Using this frame of reference a view-port is defined in …

In-Field Labeling Of Western Corn Rootworm Adults (Coleoptera: Chrysomelidae) With Rubidium, Timothy M. Nowatzki, Bradley Niimi, Kelli J. Warren, Sean Putnam, Lance J. Meinke, David C. Gosselin, F. Edwin Harvey, Thomas E. Hunt, Blair Siegfried

School of Natural Resources: Faculty Publications

Field and laboratory studies were conducted in 2000 and 2001 to determine the feasibility of mass marking western corn rootworm adults, Diabrotica virgifera virgifera LeConte, with RbCl in the field. Results showed that application of rubidium (Rb) in solution to both the soil (1 g Rb/plant) and whorl (1 g Rb/plant) of corn plants was optimal for labeling western corn rootworm adults during larval development. Development of larvae on Rb-enriched corn with this technique did not significantly influence adult dry weight or survival. Rb was also highly mobile in the plant. Application of Rb to both the soil and the …

Low Temperature (2k - 20k) Heat Capacity Determination Of A Polycrystalline Zirconium Oxide (Zro) Based Material Containing Calcium (Ca) And Europium (Eu), Watasha M. Wade

Electronic Dissertations and Theses

The calorimetric properties of a CaEuZrO based sample, synthesized by a solid-state reaction process in the Electron Transport and Magnetic Properties of Materials (ETMPM) lab, are investigated by analyzing low temperature (2 -20 K) heat capacity data. The total heat capacity of a material may be expressed as C = Celec + Cph + Cnuc + Cmag + Ci. In mathematical terms, it may be expressed as C = yT + aT3 + An T-2 + Ci. In this equation, the term yT is the electronic heat capacity, aT3 is the lattice or phonon heat capacity, AnT-2 is the nuclear …

Modelling Growth And Testing Of Multilayer Cavity Structures Incorporating Birefringent Materials, Nour-Eddine El Khachia

Masters

A simple one-dimensional photonic bandgap structure, which is also known as a Fabry-Perot Microcavity (FPM) structure was studied theoretically and experimentally. In particular this project addressed introducing an optically birefringent material in the cavity. This FPM consists of two grown regular Distributed Bragg Reflector (DBR) mirrors that can be put together as a sandwich with a space between them, which will lead to the creation of the desired cavity. Each mirror, or one-dimensional dielectric stack structure, was grown using the Vacuum Evaporation Technique and consists of multiple layers of alternating high-and low-refractive index dielectric materials arranged periodically. The project covers …

Laboratory Testing Of Select Geotextiles As Biointrusion Barriers And Sediment Filters, David R. Beck

Masters Theses

It has been proposed that placing a geotextile over sediments with adsorbed contaminants can prevent bioaccumulation of the contaminants in larger animals by isolating the benthic organisms living within these sediments from fish. In conjunction with a field study carried out at Gull Creek, a laboratory study testing two geotextiles as biointrusion barriers and sediment filters was conducted.

Constant-head permeameters were run for seven days using cores from the field study area with a geotextile placed over the cores. For biointrusion barrier tests, medium sand was placed over the geotextile and spiked with nutrients. Following each trial, benthic organisms in …

Reviewed Work(S): Electronic Tagging And Tracking In Marine Fisheries., David W. Kerstetter

Marine & Environmental Sciences Faculty Articles

No abstract provided.

Towards A Connection Between Linear Embedding And The Poincaré Functional Equation., Tara Marie Michels

Electronic Theses and Dissertations

Several linear embeddings of the logistic equation, x_n+1=ax_n(1-x_n) are considered, the goal being to establish a connection between linear embedding and the Poincaré Functional Equation. In particular, we consider linear embedding schemes in a classical Hardy space.

Optimization And Feedback Control Of Constrained Parabolic Systems Under Uncertain Perturbations, Boris S. Mordukhovich, Ilya Shvartsman

Mathematics Research Reports

This paper concerns a minimax control design problem for a class of parabolic systems with nonregular boundary conditions and uncertain distributed perturbations under pointwise control and state constraints. We deal with boundary controllers acting through Dirichlet boundary conditions that are the most challenging for the parabolic dynamics.

Ica Using Spacings Estimates Of Entropy, Erik Learned-Miller, John Fisher

Erik G Learned-Miller

This paper presents a new algorithm for the independent components analysis (ICA) problem based on an efficient entropy estimator. Like many previous methods, this algorithm directly minimizes the measure of departure from independence according to the estimated Kullback-Leibler divergence between the joint distribution and the product of the marginal distributions. We pair this approach with efficient entropy estimators from the statistics literature. In particular, the entropy estimator we use is consistent and exhibits rapid convergence. The algorithm based on this estimator is simple, computationally efficient, intuitively appealing, and outperforms other well known algorithms. In addition, the estimator’s relative insensitivity to …

The Relation Of Dietary Patterns To Future Survival, Health, And Cardiovascular Events In Older Adults, Paula Diehr

Paula Diehr

BACKGROUND: There have been few long-term follow-up studies of older adults who follow different dietary patterns. METHODS: We cluster-analyzed data on dietary fat, fiber, protein, carbohydrate, and calorie consumption from the U.S. Cardiovascular Health Study (mean age=73), and examined the relationship of the dietary clusters to outcomes 10 years later. RESULTS: The five clusters were named "Healthy diet" (relatively high in fiber and carbohydrate and low in fat), "Unhealthy diet" (relatively high in protein and fat, relatively low in carbohydrates and fiber); "High Calorie," "Low Calorie," and "Low 4," which was distinguished by higher alcohol consumption. The clusters were strongly …

Optimization Of Breast Cancer Screening Modalities, Yu Shen, Giovanni Parmigiani

Johns Hopkins University, Dept. of Biostatistics Working Papers

Mathematical models and decision analyses based on microsimulations have been shown to be useful in evaluating relative merits of various screening strategies in terms of cost and mortality reduction. Most investigations regarding the balance between mortality reduction and costs have focused on a single modality, mammography. A systematic evaluation of the relative expenses and projected benefit of combining clinical breast examination and mammography is not at present available. The purpose of this report is to provide methodologic details including assumptions and data used in the process of modeling for complex decision analyses, when searching for optimal breast cancer screening strategies …

Modeling The Incubation Period Of Anthrax, Ron Brookmeyer, Elizabeth Johnson, Sarah Barry

Johns Hopkins University, Dept. of Biostatistics Working Papers

Models of the incubation period of anthrax are important to public health planners because they can be used to predict the delay before outbreaks are detected, the size of an outbreak and the duration of time that persons should remain on antibiotics to prevent disease. The difficulty is that there is little direct data about the incubation period in humans. The objective of this paper is to develop and apply models for the incubation period of anthrax. Mechanistic models that account for the biology of spore clearance and germination are developed based on a competing risks formulation. The models predict …

Low Latitude Ionospheric Disturbance Electric Field Effects Duringthe Recovery Phase Of The October 19-21, 1998 Magnetic Storm, Bela G. Fejer, J. T. Emmert

Bela G. Fejer

[1] Low-latitude ionospheric electric fields and currents are often strongly disturbed during periods of enhanced geomagnetic activity. These perturbations can last for several hours after geomagnetic quieting. We use incoherent scatter radar measurements from Jicamarca and Arecibo during 19–21 October 1998 to study, for the first time, the low-latitude disturbance electric fields during the recovery phase of a large magnetic storm. On 19 October the Jicamarca data showed initially large and short-lived (time scale of about 10–20 min) upward and westward drift perturbations in the early afternoon sector, due to the penetration of strong magnetospheric electric fields probably driven by …

The Second Hull Of A Knotted Curve, Jason Cantarella, Greg Kuperberg, Robert B. Kusner, John M. Sullivan

Robert Kusner

The convex hull of a set K in space consists of points which are, in a certain sense, "surrounded" by K. When K is a closed curve, we define its higher hulls, consisting of points which are "multiply surrounded" by the curve. Our main theorem shows that if a curve is knotted then it has a nonempty second hull. This provides a new proof of the Fary/Milnor theorem that every knotted curve has total curvature at least 4pi.

The Recent Evolution Of The Dwarf Starburst Galaxy Ngc 625 From Hubble Space Telescope Imaging, John M. Cannon, R C. Dohm-Palmer, E D. Skillman, D J. Bomans, S Cote, B W. Miller

John Cannon

No abstract provided.

Physica: The Newsletter Of Utep's Department Of Physics, Utep Department Of Physics

The Department of Physics

Electronic newsletter of UTEP's Department of Physics, December 2003.

Immobilization Of Fission Iodine By Reaction With A Fullerene Containing Carbon Compound And Insoluble Natural Organic Matrix: Quaterly Report September-December 2003, Spencer M. Steinberg

Separations Campaign (TRP)

The recovery of iodine released during the processing of used nuclear fuel poses a significant challenge to the transmutation of radioactive iodine. This proposal will develop and examine the use of Fullerene Containing Carbon (FCC) compounds as potential sorbents for iodine release from the reprocessing of nuclear fuel. This work will also include the development of bench-scale testing capabilities at UNLV to allow the testing of the FCC material in a simulated process off-gas environment. This experimental capability will also be used to test other potential sorption materials and processes, such as natural organic matter (NOM) and other promising alternatives. …

Development Of Dose Conversion Coefficients For Radionuclides Produced In Spallation Neutron Sources: Quarterly Progress Report 8/20/03 – 12/01/03, Phillip W. Patton, Mark Rudin

Transmutation Sciences Physics (TRP)

A research consortium comprised of representatives from several universities and national laboratories has been established as part of this project to generate internal and external dose conversion coefficients for radionuclides produced in spallation neutron sources. Information obtained from this multi-year study will be used to support the siting and licensing of future accelerator-driven nuclear initiatives within the U.S. Department of Energy complex, including the Spallation Neutron Source (SNS) and Accelerator Production of Tritium (APT) Projects. Determination of these coefficients will also fill data gaps for several hundred radionuclides that exist in Federal Guide Report No. 11 and in Publications 68 …

Afci Quarterly Input – Unlv October Through December, 2003, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects and objectives of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support.

Inside Unlv, Gian Galassi, Katrina Hudak, Carol C. Harter, Eric Sandgren, Tom Hagge

Inside UNLV

No abstract provided.

Multi-Phase Homework Assignments In Cs I And Cs Ii, James Huggins

Computer Science Presentations And Conference Materials

ll of the panelists have used small sets of related programming assignments in introductory CS courses. These assignments are essentially larger programs which are developed during several separate phases. This approach has several advantages: • Students are able to develop more realistic and interesting programs. • Students are motivated to write better code as well as documentation. Those who don't are quickly confronted by the implications. • Student interest in completing the projects is better sustained, since there is continuity from one project to the next. • It models desirable techniques such as iterative development and encapsulation. • It demonstrates …

Drill 3.1, Vadim Ponomarenko

Mathematics Faculty Research

Distance learning can offer a solution to a long-standing challenge of undergraduate education: how to assign an appropriate amount of work to each student, and how to assess this work efficiently. In this paper I describe the Depository of Repetitive Internet-based probLems and Lessons (DRILL), an online system for providing education and assessment for precalculus, which can substitute for routine problems given in homework and as exam questions. Its special features include:

• adaptive testing,
• on-the-fly question generation,
• instant assessment,
• context-sensitive help,
• question balancing, and
• two-dimensional test design.

Deconstructing Bases: Fair, Fitting, And Fast Bases, Thomas Q. Sibley

Mathematics Faculty Publications

No abstract provided.

Parallaxes And Distance Estimates For 14 Cataclysmic Variable Stars, John R. Thorstensen

Dartmouth Scholarship

I used the 2.4 m Hiltner Telescope at MDM Observatory in an attempt to measure trigonometric parallaxes for 14 cataclysmic variable stars. Techniques are described in detail. In the best cases the parallax uncertainties are below 1 mas, and significant parallaxes are found for most of the program stars. A Bayesian method that combines the parallaxes together with proper motions and absolute magnitude constraints is developed and used to derive distance estimates and confidence intervals. The most precise distance derive here is for WZ Sge, for which I find 43: 3.1:6 1:5 pc. Six Luyten Half-Second stars with previous precise …

Objectivity, Information, And Maxwell's Demon, Steven Weinstein

Dartmouth Scholarship

This paper examines some common measures of complexity, structure, and information, with an eye toward understanding the extent to which complexity or information‐content may be regarded as objective properties of individual objects. A form of contextual objectivity is proposed which renders the measures objective, and which largely resolves the puzzle of Maxwell's Demon.

A Solution To Einstein’S Field Equations For A Tachyonic Gas: Possible Astrophysical Applications, Kris H. Green, W. John Cocke

Mathematical and Computing Sciences Faculty/Staff Publications

In this paper we show that a change in the signs of some of the metric components of the solution of the field equations for the classical cosmic string results in a solution which we interpret as a time-dependent wall composed of tachyons. We show that the walls have the property of focusing the paths of particles which pass through them. As an illustration of this focusing, we demonstrate the results of a simple simulation of the interaction between one such tachyon wall and a rotating disk of point masses. This interaction leads to the temporary formation of spiral structures. …

Global Solutions To The Lake Equations With Isolated Vortex Regions, Chaocheng Huang

Mathematics and Statistics Faculty Publications

The vorticity formulation for the lake equations in R² is studied.

Galaxies At Z = 3 Around Damped Ly-Α Clouds, N. Bouché, James D. Lowenthal

Astronomy: Faculty Publications

We are exploring the connection between Damped Ly-α Absorption systems and Lyman Break Galaxies using deep m (5σ)=26 m - broad band imaging (UBVI) of four wide fields (0.25deg each) obtained at the Kitt Peak 4-m telescope with MOSAIC. Each field contains a DLA at z ∼ 3. We want to address the nature of DLA at high-redshifts: (1) Are the DLAs embedded in much larger systems of galaxies? (2) How does the spatial distribution of emitters in 3D (space and redshift) correlate with the absorber? Contrary to most previous DLA studies, we are not looking for the absorber, and …

Internal Phosphorus Loading In Spring Lake: Year 1, Dr. Alan Steinman, Dr. Rick Rediske

Scientific Technical Reports

The rate of phosphorus release from sediments, and the degree to which alum reduces phosphorus release from sediments, was investigated in Spring Lake during the summer of 2003. Triplicate cores were sampled from 4 sites in the lake, and exposed to one of four treatments in the laboratory: 1) oxygen/alum; 2) oxygen/ no alum; 3) nitrogen/alum; or 4) nitrogen/no alum. Both soluble reactive phosphorus (SRP) and total phosphorus (TP) release rates were virtually undetectable in the alum treatments (both with and without oxygen). Low, but detectable, release rates were measured in the oxygen/no alum treatment. The highest release rates were …