AN APPROACH TO CHARACTERIZING & EVALUATING ALTERNATIVES FOR THE DECOMMISSIONING OF SUB-GRADE STRUCTURES AT THE PLUTONIUM FINISHING PLANT (PFP) (open access)

AN APPROACH TO CHARACTERIZING & EVALUATING ALTERNATIVES FOR THE DECOMMISSIONING OF SUB-GRADE STRUCTURES AT THE PLUTONIUM FINISHING PLANT (PFP)

In 2002, the Richland Operations Office (RL) of the US Department of Energy (DOE), the US Environmental Protection Agency (EPA), and the Washington State Department of Ecology (Ecology) developed milestones for transitioning the Plutonium Finishing Plant (PFP) facility to a clean slab-on-grade configuration. These milestones required developing an engineering evaluation/cost analysis (EF/CA) for the facility's sub-grade structures and installations as part of a series of evaluations intended to provide for the transition of the facility to a clean slab-on-grade configuration. In addition to supporting decisions for interim actions, the analyses of sub-grade structures and installations performed through this EE/CA will contribute to the remedial investigation feasibility study(ies) and subsequently to the final records of decision for the relevant operable units responsible for site closure in the 200 West Area of the Hanford Site.
Date: January 25, 2007
Creator: HOPKINS, A.M. & KLOS, D.B.
Object Type: Article
System: The UNT Digital Library
ASSESSING CHEMICAL HAZARDS AT THE PLUTONIUM FINISHING PLANT (PFP) FOR PLANNING FUTURE D&D (open access)

ASSESSING CHEMICAL HAZARDS AT THE PLUTONIUM FINISHING PLANT (PFP) FOR PLANNING FUTURE D&D

This paper documents the fiscal year (FY) 2006 assessment to evaluate potential chemical and radiological hazards associated with vessels and piping in the former plutonium process areas at Hanford's Plutonium Finishing Plant (PFP). Evaluations by PFP engineers as design authorities for specific systems and other subject-matter experts were conducted to identify the chemical hazards associated with transitioning the process areas for the long-term layup of PFP before its eventual final decontamination and decommissioning (D and D). D and D activities in the main process facilities were suspended in September 2005 for a period of between 5 and 10 years. A previous assessment conducted in FY 2003 found that certain activities to mitigate chemical hazards could be deferred safely until the D and D of PFP, which had been scheduled to result in a slab-on-grade condition by 2009. As a result of necessary planning changes, however, D and D activities at PFP will be delayed until after the 2009 time frame. Given the extended project and plant life, it was determined that a review of the plant chemical hazards should be conducted. This review to determine the extended life impact of chemicals is called the ''Plutonium Finishing Plant Chemical Hazards Assessment, …
Date: January 25, 2007
Creator: Hopkins, A. M.; Klos, D. B. & Minett, M. J.
Object Type: Article
System: The UNT Digital Library
CONTAMINATED PROCESS EQUIPMENT REMOVAL FOR THE D&D OF THE 232-Z CONTAMINATED WASTE RECOVERY PROCESS FACILITY AT THE PLUTONIUM FINISHING PLANT (PFP) (open access)

CONTAMINATED PROCESS EQUIPMENT REMOVAL FOR THE D&D OF THE 232-Z CONTAMINATED WASTE RECOVERY PROCESS FACILITY AT THE PLUTONIUM FINISHING PLANT (PFP)

This paper describes the unique challenges encountered and subsequent resolutions to accomplish the deactivation and decontamination of a plutonium ash contaminated building. The 232-Z Contaminated Waste Recovery Process Facility at the Plutonium Finishing Plant was used to recover plutonium from process wastes such as rags, gloves, containers and other items by incinerating the items and dissolving the resulting ash. The incineration process resulted in a light-weight plutonium ash residue that was highly mobile in air. This light-weight ash coated the incinerator's process equipment, which included gloveboxes, blowers, filters, furnaces, ducts, and filter boxes. Significant airborne contamination (over 1 million derived air concentration hours [DAC]) was found in the scrubber cell of the facility. Over 1300 grams of plutonium held up in the process equipment and attached to the walls had to be removed, packaged and disposed. This ash had to be removed before demolition of the building could take place.
Date: January 25, 2007
Creator: Hopkins, A. M.; Minette, M. J. & Klos, D. B.
Object Type: Article
System: The UNT Digital Library
Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle (open access)

Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle

Pressure-induced electronic spin-pairing transitions of iron and associated effects on the physical properties have been reported to occur in the lower-mantle ferropericlase, silicate perosvkite, and perhaps in post silicate perovskite at high pressures and room temperature. These recent results are motivating geophysicists and geodynamicists to reevaluate the implications of spin transitions on the seismic heterogeneity, composition, as well as the stability of the thermal upwellings of the Earth's lower mantle. Here we have measured the spin states of iron in ferropericlase and its crystal structure up to 95 GPa and 2000 K using a newly constructed X-ray emission spectroscopy and diffraction with the laser-heated diamond cell. Our results show that an isosymmetric spin crossover occurs over a pressure-temperature range extending from the upper part to the lower part of the lower mantle, and low-spin ferropericlase likely exists in the lowermost mantle. Although continuous changes in physical and chemical properties are expected to occur across the spin crossover, the spin crossover results in peculiar behavior in the thermal compression and sound velocities. Therefore, knowledge of the fraction of the spin states in the lower-mantle phases is thus essential to correctly evaluate the composition, geophysics, and dynamics of the Earth's lower mantle.
Date: January 25, 2007
Creator: Lin, J. F.; Vanko, G.; Jacobsen, S. D.; Iota, V.; Struzhkin, V. V.; Prakapenka, V. B. et al.
Object Type: Article
System: The UNT Digital Library
High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction (open access)

High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 {micro}m stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 {micro}m stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to {+-} 3D of defocus and {+-} 3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large …
Date: January 25, 2007
Creator: Chen, D.; Jones, S. M.; Silva, D. A. & Olivier, S. S.
Object Type: Article
System: The UNT Digital Library
Measurement of the B+- to rho pi0 Branching Fraction and Direct CP Asymmetry (open access)

Measurement of the B+- to rho pi0 Branching Fraction and Direct CP Asymmetry

The authors present improved measurements of the branching fraction and CP asymmetry for the process B{sup {+-}} {yields} {rho}{sup {+-}}{pi}{sup 0}. The data sample corresponding to 211 fb{sup -1} comprises 232 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. The yield and CP asymmetry are measured using an extended maximum likelihood fitting method. The branching fraction and Cp asymmetry are found to be {Beta}(B{sup {+-}} {yields} {rho}{sup {+-}}{pi}{sup 0}) = [10.2 {+-} 1.4(stat) {+-} 0.9(syst)] x 10{sup -6} and {Alpha}{sub CP}(B{sup {+-}} {yields} {rho}{sup {+-}}{pi}{sup 0}) = -0.01 {+-} 0.13(stat) {+-} 0.02(syst).
Date: January 25, 2007
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
Measurements of sin2Beta and cos2Beta from b to ccbarsDecays at BaBar (open access)

Measurements of sin2Beta and cos2Beta from b to ccbarsDecays at BaBar

Recent measurements of sin2{beta} and cos2{beta} using b {yields} c{bar c}s decays are presented using data collected by the BABAR experiment at the PEP-II asymmetric-energy B-factory.
Date: January 25, 2007
Creator: George, Katherine A.
Object Type: Article
System: The UNT Digital Library
Positron Production by X Rays Emitted By Betatron Motion in a Plasma Wiggler (open access)

Positron Production by X Rays Emitted By Betatron Motion in a Plasma Wiggler

Positrons in the energy range of 3-30 MeV, produced by x rays emitted by betatron motion in a plasma wiggler of 28.5 GeV electrons from the SLAC accelerator, have been measured. The extremely high-strength plasma wiggler is an ion column induced by the electron beam as it propagates through and ionizes dense lithium vapor. X rays in the range of 1-50 MeV in a forward cone angle of 0.1 mrad collide with a 1.7 mm thick tungsten target to produce electron-positron pairs. The positron spectra are found to be strongly influenced by the plasma density and length as well as the electron bunch length. By characterizing the beam propagation in the ion column these influences are quantified and result in excellent agreement between the measured and calculated positron spectra.
Date: January 25, 2007
Creator: Johnson, D. K.; Auerbach, D.; Blumenfeld, I.; Barnes, C. D.; Clayton, C. E.; Decker, F. J. et al.
Object Type: Article
System: The UNT Digital Library
The role of EBIT in X-ray laser research (open access)

The role of EBIT in X-ray laser research

Back in the early 1980's the X-ray laser program required a new level of understanding and measurements of the atomic physics of highly charged ions. The electron-beam ion trap (EBIT) was developed and built at Lawrence Livermore National Laboratory (LLNL) as part of the effort to understand and measure the cross sections and wavelengths of highly charged ions. In this paper we will discuss some of the early history of EBIT and how it was used to help in the development of X-ray lasers. EBIT's capability was unique and we will show some of the experimental results obtained over the years that were done related to X-ray lasers. As X-ray lasers have now become a table-top tool we will show some new areas of research that involve understanding the index of refraction in partially ionized plasmas and suggest new areas where EBIT may be able to contribute.
Date: January 25, 2007
Creator: Nilsen, J
Object Type: Article
System: The UNT Digital Library
Scrutinizing Exotic Cosmological Models Using ESSENCE Supernova Data Combined With Other Cosmological Probes (open access)

Scrutinizing Exotic Cosmological Models Using ESSENCE Supernova Data Combined With Other Cosmological Probes

The first cosmological results from the ESSENCE supernova survey (Wood-Vasey et al. 2007) are extended to a wider range of cosmological models including dynamical dark energy and non-standard cosmological models. We fold in a greater number of external data sets such as the recent Higher-z release of high-redshift supernovae (Riess et al. 2007) as well as several complementary cosmological probes. Model comparison statistics such as the Bayesian and Akaike information criteria are applied to gauge the worth of models. These statistics favor models that give a good fit with fewer parameters. Based on this analysis, the preferred cosmological model is the flat cosmological constant model, where the expansion history of the universe can be adequately described with only one free parameter describing the energy content of the universe. Amongst the more exotic models that provide good fits to the data, we note a preference for models whose best-fit parameters reduce them to the cosmological constant model.
Date: January 25, 2007
Creator: Davis, Tamara M.; Mortsell, E.; Sollerman, J.; Becker, A. C.; Blondin, S.; Challis, P. et al.
Object Type: Article
System: The UNT Digital Library
Searches for D0 - Anti-D0 Mixing, Rare Charm And Tau Decays (open access)

Searches for D0 - Anti-D0 Mixing, Rare Charm And Tau Decays

I discuss the results on D{sup 0}-{bar D}{sup 0} mixing through hadronic as well as semi-leptonic charm decays, rare flavor-changing neutral currents in the charm sector and the lepton flavor violating {tau} decaying to charged lighter leptons. The results from both BABAR and Belle are presented in this review.
Date: January 25, 2007
Creator: Swain, Sanjay K.
Object Type: Report
System: The UNT Digital Library
Start-to-end Beam Optics Development and Multi-particle Tracking for the ILC Positron Source (open access)

Start-to-end Beam Optics Development and Multi-particle Tracking for the ILC Positron Source

Undulator-based positron source is adopted as the ILC baseline design. Complete optics to transport the positron beam having large angular divergence and large energy spread from an immersed thin Ti target to the entrance of the 5 GeV damping ring injection line is developed. Start-to-end multi-particle tracking through the beamline is performed including the optical matching device, capture system, transport system, superconducting booster linac, spin rotators, and energy compressor. It shows that 49.8% of the positrons from the target are captured within the damping ring 6-D acceptance--A{sub x} + A{sub y} {le} 0.09 m and {Delta}E x {Delta}z ({+-} 25 MeV) x ({+-} 3.46cm)--at the entrance of the damping ring injection line. The field and alignment errors and orbit correction are analyzed.
Date: January 25, 2007
Creator: Zhou, F.; Batygin, Y.; Nosochkov, Y.; Sheppard, J. C. & Woodley, M. D.
Object Type: Report
System: The UNT Digital Library
Start-Up of FEL Oscillator from Shot Noise (open access)

Start-Up of FEL Oscillator from Shot Noise

In free-electron laser (FEL) oscillators, as inself-amplified spontaneous emission (SASE) FELs, the buildup of cavitypower starts from shot noise resulting from the discreteness ofelectronic charge. It is important to do the start-up analysis for thebuild-up of cavity power in order to fix the macropulse width from theelectron accelerator such that the system reaches saturation. In thispaper, we use the time-dependent simulation code GINGER [1]toperformthis analysis. We present results of this analysis for theparameters of the Compact Ultrafast TErahertz FEL (CUTE-FEL) [2]beingbuilt atRRCAT.
Date: January 25, 2007
Creator: Kumar, V.; Krishnagopal, S. & Fawley, W. M.
Object Type: Article
System: The UNT Digital Library

EUV inspection of reticle defect repair sites

None
Date: February 25, 2007
Creator: Goldberg, Kenneth; Barty, Anton; Seidel, Phillip; Kearney, Patrick & Fettig, Rainer
Object Type: Presentation
System: The UNT Digital Library
Euv Inspection of Reticle Defect Repair Sites (open access)

Euv Inspection of Reticle Defect Repair Sites

None
Date: February 25, 2007
Creator: Goldberg, Ken & Barty, Anton
Object Type: Article
System: The UNT Digital Library

EUV MET Printing and Actinic Imaging Analysis of The Effects of Phase Defects on Wafer CDs

None
Date: February 25, 2007
Creator: Han, Hakseung & Barty, Anton
Object Type: Presentation
System: The UNT Digital Library
Final Report: Performance Modeling Activities in PERC2 (open access)

Final Report: Performance Modeling Activities in PERC2

Progress in Performance Modeling for PERC2 resulted in: • Automated modeling tools that are robust, able to characterize large applications running at scale while simultaneously simulating the memory hierarchies of mul-tiple machines in parallel. • Porting of the requisite tracer tools to multiple platforms. • Improved performance models by using higher resolution memory models that ever before. • Adding control-flow and data dependency analysis to the tracers used in perform-ance tools. • Exploring and developing several new modeling methodologies. • Using modeling tools to develop performance models for strategic codes. • Application of modeling methodology to make a large number of “blind” per-formance predictions on certain mission partner applications, targeting most cur-rently available system architectures. • Error analysis to correct some systematic biases encountered as part of the large-scale blind prediction exercises. • Addition of instrumentation capabilities for communication libraries other than MPI. • Dissemination the tools and modeling methods to several mission partners, in-cluding DoD HPCMO and two DARPA HPCS vendors (Cray and IBM), as well as to the wider HPC community via a series of tutorials.
Date: February 25, 2007
Creator: Snavely, Allan
Object Type: Report
System: The UNT Digital Library
Fundamentals of Energy Transport in Nanofluids (open access)

Fundamentals of Energy Transport in Nanofluids

We performed computational simulations and theoretical analysis to investigate the underlying origins of large thermal conductivity enhancements observed in nanofluids (colloidal suspensions of solid nanoparticles and/or nanofibers in thermal fluids) and to identify strategies towards tailoring nanofluids for better thermal performance.
Date: February 25, 2007
Creator: Keblinski, Pawel
Object Type: Report
System: The UNT Digital Library
Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska (open access)

Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska

A 5.6-m-long lake sediment core from Bear Lake, Alaska, located 22 km southeast of Redoubt Volcano, contains 67 tephra layers deposited over the last 8750 cal yr, comprising 15% of the total thickness of recovered sediment. Using 12 AMS {sup 14}C ages, along with the {sup 137}Cs and {sup 210}Pb activities of recent sediment, we evaluated different models to determine the age-depth relation of sediment, and to determine the age of each tephra deposit. The age model is based on a cubic smooth spline function that was passed through the adjusted tephra-free depth of each dated layer. The estimated age uncertainty of the 67 tephras averages {+-} 105 yr (1{sigma}). Tephra-fall frequency at Bear Lake was among the highest during the past 500 yr, with eight tephras deposited compared to an average of 3.7 per 500 yr over the last 8500 yr. Other periods of increased tephra fall occurred 2500-3500, 4500-5000, and 7000-7500 cal yr. Our record suggests that Bear Lake experienced extended periods (1000-2000 yr) of increased tephra fall separated by shorter periods (500-1000 yr) of apparent quiescence. The Bear Lake sediment core affords the most comprehensive tephrochronology from the base of the Redoubt Volcano to date, with an …
Date: February 25, 2007
Creator: Schiff, Caleb J.; Kaufman, Darrell S.; Wallace, Kristi L.; Werner, Al; Ku, Teh-Lung & Brown, Thomas A.
Object Type: Article
System: The UNT Digital Library
Development of Radar Navigation and Radio Data Transmission for Microhole Coiled Tubing Bottom Hole Assemblies (open access)

Development of Radar Navigation and Radio Data Transmission for Microhole Coiled Tubing Bottom Hole Assemblies

This Final Technical Report summarizes the research and development (R&D) work performed by Stolar Research Corporation (Stolar) under U.S. Department of Energy (DOE) Contract Number DE-FC26-04NT15477. This work involved the development of radar navigation and radio data transmission systems for integration with microhole coiled tubing bottom hole assemblies. Under this contract, Stolar designed, fabricated, and laboratory and field tested two advanced technologies of importance to the future growth of the U.S. oil and gas industry: (1) real-time measurement-while-drilling (MWD) for guidance and navigation of coiled tubing drilling in hydrocarbon reservoirs and (2) two-way inductive radio data transmission on coiled tubing for real-time, subsurface-to-surface data transmission. The operating specifications for these technologies are compatible with 3.5-inch boreholes drilled to a true vertical depth (TVD) of 5,000 feet, which is typical of coiled tubing drilling applications. These two technologies (i.e., the Stolar Data Transmission System and Drill String Radar) were developed into pre-commercial prototypes and tested successfully in simulated coiled tubing drilling conditions. Integration of these two technologies provides a real-time geosteering capability with extremely quick response times. Stolar is conducting additional work required to transition the Drill String Radar into a true commercial product. The results of this advanced development work …
Date: March 25, 2007
Creator: Stolarczyk, Larry G.; Stolarczyk, Gerald L.; Icerman, Larry; Howard, John & Tehrani, Hooman
Object Type: Report
System: The UNT Digital Library
Waste Isolation Pilot Plant Geotechnical Analysis Report for July 2005 - June 2006, Volume 2, Supporting Data (open access)

Waste Isolation Pilot Plant Geotechnical Analysis Report for July 2005 - June 2006, Volume 2, Supporting Data

This report is a compilation of geotechnical data presented as plots for each active instrument installed in the underground at the Waste Isolation Pilot Plant (WIPP) through June 30, 2006. A summary of the geotechnical analyses that were performed using the enclosed data is provided in Volume 1 of the Geotechnical Analysis Report (GAR).
Date: March 25, 2007
Creator: Westinghouse TRU Solutions LLC
Object Type: Report
System: The UNT Digital Library
Advanced Simulation and Computing FY08-09 Implementation Plan Volume 2 Revision 0 (open access)

Advanced Simulation and Computing FY08-09 Implementation Plan Volume 2 Revision 0

The Stockpile Stewardship Program (SSP) is a single, highly integrated technical program for maintaining the safety and reliability of the U.S. nuclear stockpile. The SSP uses past nuclear test data along with current and future nonnuclear test data, computational modeling and simulation, and experimental facilities to advance understanding of nuclear weapons. It includes stockpile surveillance, experimental research, development and engineering programs, and an appropriately scaled production capability to support stockpile requirements. This integrated national program requires the continued use of current facilities and programs along with new experimental facilities and computational enhancements to support these programs. The Advanced Simulation and Computing Program (ASC) is a cornerstone of the SSP, providing simulation capabilities and computational resources to support the annual stockpile assessment and certification, to study advanced nuclear-weapons design and manufacturing processes, to analyze accident scenarios and weapons aging, and to provide the tools to enable Stockpile Life Extension Programs (SLEPs) and the resolution of Significant Finding Investigations (SFIs). This requires a balanced resource, including technical staff, hardware, simulation software, and computer science solutions. In its first decade, the ASC strategy focused on demonstrating simulation capabilities of unprecedented scale in three spatial dimensions. In its second decade, ASC is focused on …
Date: April 25, 2007
Creator: McCoy, M; Kusnezov, D; Bikkel, T & Hopson, J
Object Type: Report
System: The UNT Digital Library
ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER (open access)

ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER

A workshop was held on January 23-24, 2007 to discuss the status of processes to leach constituents from High Level Waste (HLW) sludges at the Hanford and Savannah River Sites. The objective of the workshop was to examine the needs and requirements for the HLW flowsheet for each site, discuss the status of knowledge of the leaching processes, communicate the research plans, and identify opportunities for synergy to address knowledge gaps. The purpose of leaching of non-radioactive constituents from the sludge waste is to reduce the burden of material that must be vitrified in the HLW melter systems, resulting in reduced HLW glass waste volume, reduced disposal costs, shorter process schedules, and higher facility throughput rates. The leaching process is estimated to reduce the operating life cycle of SRS by seven years and decrease the number of HLW canisters to be disposed in the Repository by 1000 [Gillam et al., 2006]. Comparably at Hanford, the aluminum and chromium leaching processes are estimated to reduce the operating life cycle of the Waste Treatment Plant by 20 years and decrease the number of canisters to the Repository by 15,000-30,000 [Gilbert, 2007]. These leaching processes will save the Department of Energy (DOE) billions …
Date: April 25, 2007
Creator: McCabe, D; Jeff Pike, J & Bill Wilmarth, B
Object Type: Report
System: The UNT Digital Library
Chemical Bonding and Structural Information of Black Carbon Reference Materials and Individual Carbonaceous Atmospheric Aerosols (open access)

Chemical Bonding and Structural Information of Black Carbon Reference Materials and Individual Carbonaceous Atmospheric Aerosols

The carbon-to-oxygen ratios and graphitic nature of a rangeof black carbon standard reference materials (BC SRMs), high molecularmass humic-like substances (HULIS) and atmospheric particles are examinedusing scanning transmission X-ray microscopy (STXM) coupled with nearedge X-ray absorption fine structure (NEXAFS) spectroscopy. UsingSTXM/NEXAFS, individual particles with diameter>100 nm are studied,thus the diversity of atmospheric particles collected during a variety offield missions is assessed. Applying a semi-quantitative peak fittingmethod to the NEXAFS spectra enables a comparison of BC SRMs and HULIS toparticles originating from anthropogenic combustion and biomass burns,thus allowing determination of the suitability of these materials forrepresenting atmospheric particles. Anthropogenic combustion and biomassburn particles can be distinguished from one another using both chemicalbonding and structural ordering information. While anthropogeniccombustion particles are characterized by a high proportion ofaromatic-C, the presence of benzoquinone and are highly structurallyordered, biomass burn particles exhibit lower structural ordering, asmaller proportion of aromatic-C and contain a much higher proportion ofoxygenated functional groups.
Date: April 25, 2007
Creator: Hopkins, Rebecca J.; Tivanski, Alexei V.; Marten, Bryan D. & Gilles, Mary K.
Object Type: Article
System: The UNT Digital Library