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Analysis of Long-range Clean Energy Investment Scenarios forEritrea, East Africa (open access)

Analysis of Long-range Clean Energy Investment Scenarios forEritrea, East Africa

We discuss energy efficiency and renewable energy investments in Eritrea from the strategic long-term economic perspective of meeting Eritrea's sustainable development goals and reducing greenhouse gas emissions. Energy efficiency and renewable energy are potentially important contributors to national productive capital accumulation, enhancement of the environment, expansion of energy services, increases in household standard of living, and improvements in health. In this study we develop a spreadsheet model for calculating some of the national benefits and costs of different levels of investment in energy efficiency and renewable energy. We then present the results of the model in terms of investment demand and investment scenario curves. These curves express the contribution that efficiency and renewable energy projects can make in terms of reduced energy sector operating expenses, and reduced carbon emissions. We provide demand and supply curves that show the rate of return, the cost of carbon emissions reductions vs. supply, and the evolution of the marginal carbon emissions per dollar of GDP for different investment levels and different fuel-type subsectors.
Date: May 7, 2004
Creator: Van Buskirk, Robert D.
System: The UNT Digital Library
Assessment of Renal Ischemia By Optical Spectroscopy (open access)

Assessment of Renal Ischemia By Optical Spectroscopy

Introduction: No reliable method currently exists for quantifying the degree of warm ischemia in kidney grafts prior to transplantation. We describe a method for evaluating pretransplant warm ischemia time using optical spectroscopic methods. Methods: Lewis rat kidney vascular pedicles were clamped unilaterally in vivo for 0, 5, 10, 20, 30, 60, 90 or 120 minutes; 8 animals were studied at each time point. Injured and contra-lateral control kidneys were then flushed with Euro-Collins solution, resected and placed on ice. 335 nm excitation autofluorescence as well as cross polarized light scattering images were taken of each injured and control kidney using filters of various wavelengths. The intensity ratio of the injured to normal kidneys was compared to ischemia time. Results: Autofluorescence intensity ratios through a 450 nm filter and light scattering intensity ratios through an 800 nm filter both decreased significantly with increasing ischemia time (p < 0.0001 for each method, one-way ANOVA). All adjacent and non-adjacent time points between 0 and 90 minutes were distinguishable using one of these two modalities by Fisher's PLSD. Conclusions: Optical spectroscopic methods can accurately quantify warm ischemia time in kidneys that have been subsequently hypothermically preserved. Further studies are needed to correlate results with …
Date: January 7, 2004
Creator: Fitzgerald, J T; Demos, S; Michalopoulou, A; Pierce, J L & Troppmann, C
System: The UNT Digital Library
Bioremediation of Petroleum and Radiological Contaminated Soils at the Savannah River Site: Laboratory to Field Scale Applications (open access)

Bioremediation of Petroleum and Radiological Contaminated Soils at the Savannah River Site: Laboratory to Field Scale Applications

In the process of Savannah River Site (SRS) operations limited amounts of waste are generated containing petroleum, and radiological contaminated soils. Currently, this combination of radiological and petroleum contaminated waste does not have an immediate disposal route and is being stored in low activity vaults. SRS developed and implemented a successful plan for clean up of the petroleum portion of the soils in situ using simple, inexpensive, bioreactor technology. Treatment in a bioreactor removes the petroleum contamination from the soil without spreading radiological contamination to the environment. This bioreactor uses the bioventing process and bioaugmentation or the addition of the select hydrocarbon degrading bacteria. Oxygen is usually the initial rate-limiting factor in the biodegradation of petroleum hydrocarbons. Using the bioventing process allowed control of the supply of nutrients and moisture based on petroleum contamination concentrations and soil type. The results of this work have proven to be a safe and cost-effective means of cleaning up low level radiological and petroleum-contaminated soil. Many of the other elements of the bioreactor design were developed or enhanced during the demonstration of a ''biopile'' to treat the soils beneath a Polish oil refinery's waste disposal lagoons. Aerobic microorganisms were isolated from the aged refinery's …
Date: June 7, 2004
Creator: BRIGMON, ROBINL.
System: The UNT Digital Library
Characterization of liquid phase epitaxial GaAs forblocked-impurity-band far-infrared detectors (open access)

Characterization of liquid phase epitaxial GaAs forblocked-impurity-band far-infrared detectors

GaAs Blocked-Impurity-Band (BIB) photoconductor detectors have the potential to become the most sensitive, low noise detectors in the far-infrared below 45.5 cm{sup -1} (220 {micro}m). We have studied the characteristics of liquid phase epitaxial GaAs films relevant to BIB production, including impurity band formation and the infrared absorption of the active section of the device. Knowledge of the far-infrared absorption spectrum as a function of donor concentration combined with variable temperature Hall effect and resistivity studies leads us to conclude that the optimal concentration for the absorbing layer of a GaAs BIB detector lies between 1 x 10{sup 15} and 6.7 x 10{sup 15} cm{sup -3}. At these concentrations there is significant wavefunction overlap which in turn leads to absorption beyond the 1s ground to 2p bound excited state transition of 35.5 cm{sup -1} (282 {micro}m). There still remains a gap between the upper edge of the donor band and the bottom of the conduction band, a necessity for proper BIB detector operation.
Date: April 7, 2004
Creator: Cardozo, B. L.; Reichertz, L. A.; Beeman, J. W. & Haller, E. E.
System: The UNT Digital Library
Characterization of the Series 1000 Camera System (open access)

Characterization of the Series 1000 Camera System

The National Ignition Facility requires a compact network addressable scientific grade CCD camera for use in diagnostics ranging from streak cameras to gated x-ray imaging cameras. Due to the limited space inside the diagnostic, an analog and digital input/output option in the camera controller permits control of both the camera and the diagnostic by a single Ethernet link. The system consists of a Spectral Instruments Series 1000 camera, a PC104+ controller, and power supply. The 4k by 4k CCD camera has a dynamic range of 70 dB with less than 14 electron read noise at a 1MHz readout rate. The PC104+ controller includes 16 analog inputs, 4 analog outputs and 16 digital input/output lines for interfacing to diagnostic instrumentation. A description of the system and performance characterization is reported.
Date: April 7, 2004
Creator: Kimbrough, J. R.; Moody, J. D.; Bell, P. M. & Landen, O. L.
System: The UNT Digital Library
Classification of non-coding RNA using graph representations ofsecondary structure (open access)

Classification of non-coding RNA using graph representations ofsecondary structure

Some genes produce transcripts that function directly in regulatory, catalytic, or structural roles in the cell. These non-coding RNAs are prevalent in all living organisms, and methods that aid the understanding of their functional roles are essential. RNA secondary structure, the pattern of base-pairing, contains the critical information for determining the three dimensional structure and function of the molecule. In this work we examine whether the basic geometric and topological properties of secondary structure are sufficient to distinguish between RNA families in a learning framework. First, we develop a labeled dual graph representation of RNA secondary structure by adding biologically meaningful labels to the dual graphs proposed by Gan et al [1]. Next, we define a similarity measure directly on the labeled dual graphs using the recently developed marginalized kernels [2]. Using this similarity measure, we were able to train Support Vector Machine classifiers to distinguish RNAs of known families from random RNAs with similar statistics. For 22 of the 25 families tested, the classifier achieved better than 70% accuracy, with much higher accuracy rates for some families. Training a set of classifiers to automatically assign family labels to RNAs using a one vs. all multi-class scheme also yielded encouraging …
Date: June 7, 2004
Creator: Karklin, Yan; Meraz, Richard F. & Holbrook, Stephen R.
System: The UNT Digital Library
Computational Chemical Dynamics: From Gas- Phase to Condensed - Phase Systems (Poster Book) (open access)

Computational Chemical Dynamics: From Gas- Phase to Condensed - Phase Systems (Poster Book)

None
Date: October 7, 2004
Creator: Cramer, Christopher J.
System: The UNT Digital Library
Data acquisition and analysis for the Fermilab Collider RunII (open access)

Data acquisition and analysis for the Fermilab Collider RunII

Operating and improving the understanding of the Fermilab Accelerator Complex for the colliding beam experiments requires advanced software methods and tools. The Shot Data Acquisition and Analysis (SDA) has been developed to fulfill this need. The SDA takes a standard set of critical data at relevant stages during the complex series of beam manipulations leading to {radical}(s) {approx} 2 TeV collisions. Data is stored in a relational database, and is served to programs and users via Web based tools. Summary tables are systematically generated during and after a store. Written entirely in Java, SDA supports both interactive tools and application interfaces used for in-depth analysis. In this talk, we present the architecture and described some of our analysis tools. We also present some results on the recent Tevatron performance as illustrations of the capabilities of SDA.
Date: July 7, 2004
Creator: al., Paul L. G. Lebrun et
System: The UNT Digital Library
Development and Characterization of a High Performance Thin-Film Planar Solid-Oxide Fuel Cell Stack (open access)

Development and Characterization of a High Performance Thin-Film Planar Solid-Oxide Fuel Cell Stack

A planar solid oxide fuel cell (SOFC) was fabricated using a tape-cast Ni/yttria-stabilized zirconia (YSZ) anode support, a YSZ thin film electrolyte, and a composite cathode of YSZ and (La{sub 0.85}Sr{sup 0.14}){sub 0.98}MnO{sub 3} (LSM). Using pure hydrogen as the fuel gas, a three cell stack with a cross-flow design and external manifolds produced peak power densities of 0.85 W/cm{sup 2} and 0.41 W/cm{sup 2} at 800 C and 700 C, respectively. Using wet methane as the fuel gas, the stack produced a peak power density of 0.22 W/cm{sup 2} at 700 C. Individual cells in the stack showed identical current-voltage (I -V) characteristics. Stack lifetime was limited because of degradation of the cells from oxidation products coming from the metallic interconnect used.
Date: April 7, 2004
Creator: Chung, Brandon W.; Chervin, Christopher N; Haslam, Jeffrey J.; Pham, Ai-Quoc & Glass, Robert S.
System: The UNT Digital Library
An Eclectic Journey Through Experimental Nuclear Physics, or How I Learned to Stop Worrying and Love Nuclear Data (open access)

An Eclectic Journey Through Experimental Nuclear Physics, or How I Learned to Stop Worrying and Love Nuclear Data

In this paper, I illustrate how the ability to rapidly access the broad range of nuclear data has facilitated my research in fields from searches for double beta decay, to measurements of astrophysical reaction rates, to issues in homeland security. In doing this, I hope to persuade even the skeptics that for the benefit of the broad scientific community, it is imperative that the outstanding work of the nuclear data community continue.
Date: December 7, 2004
Creator: Norman, E B
System: The UNT Digital Library
Effect of Initial Conditions on Compressible Rayleigh-Taylor Instability and Transition to Turbulence (open access)

Effect of Initial Conditions on Compressible Rayleigh-Taylor Instability and Transition to Turbulence

Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, we present the first results from a computational study of such a system under drive conditions to be attainable on the National Ignition Facility. Using the multiphysics, AMR, higher order Godunov Eulerian hydrocode, Raptor, we consider the late nonlinear instability evolution for multiple amplitude and phase realizations of a variety of multimode spectral types. We show that compressibility effects preclude the emergence of a regime of self-similar instability growth independent of the initial conditions by allowing for memory of the initial conditions to be retained in the mix-width at all times. The loss of transverse spectral information is demonstrated, however, along with the existence of a quasi-self-similar regime over short time intervals. The initial conditions are shown to have a strong affect on the time to transition to the quasi-self-similar regime.
Date: January 7, 2004
Creator: Miles, A R; Edwards, M & Greenough, J A
System: The UNT Digital Library
Experimental Evidence of the Role of Intericosahedral Chains in the Hardness of Boron Carbide Films Deposited by Sputtering (open access)

Experimental Evidence of the Role of Intericosahedral Chains in the Hardness of Boron Carbide Films Deposited by Sputtering

The relationship between structure and mechanical properties of sputter-deposited boron carbide films was investigated. Changes in the structure induced by annealing were characterized in terms of chemical composition, chemical bonding and concentrations of defects and of trapped impurities. The creation of new intericosahedral chains for higher annealing temperatures was revealed by infrared and Raman measurements, and the intensity of the infrared band at 1500 cm{sup -1} was found to be related with the hardness. The content of trapped Ar atoms and of open-volume defects are insensitive to relatively high annealing temperatures and do not influence the recovery of the hardness. Our results suggest annealing as a pathway to enhance the mechanical properties of boron carbide films.
Date: January 7, 2004
Creator: Nastasi, M.; Asoka-Kumar, P.; Jenei, Z.; Jacobsohn, L. G.; Averitt, R. D.; Wetteland, C. J. et al.
System: The UNT Digital Library
An Experimental Study of Drag Reduction Devices for a Trailer Underbody and Base (open access)

An Experimental Study of Drag Reduction Devices for a Trailer Underbody and Base

Low speed wind tunnel measurements are made on a 1/16th scale generic tractor-trailer model at a width-based Reynolds number of 325,000. The model is fixed to a turntable, allowing the yaw angle to be varied between {+-}14 degrees in 2 degree increments. Various add-on drag reduction devices are mounted to the model underbody and base. The wind-averaged drag coefficient at 65 mph is computed for each configuration, allowing the effectiveness of the add-on devices to be assessed. The most effective add-on drag reduction device for the trailer underbody is a wedge-shaped skirt, which reduces the wind-averaged drag coefficient by 2.0%. For the trailer base, the most effective add-on drag reduction device is a set of curved base flaps having a radius of curvature of 0.91 times the trailer width. These curved base flaps reduce the wind-averaged drag coefficient by 18.8%, providing the greatest drag reduction of any of the devices tested. When the wedge-shaped skirt and curved base flaps are used in conjunction with one another, the wind-averaged drag coefficient is reduced by 20%.
Date: May 7, 2004
Creator: Ortega, J M & Salari, K
System: The UNT Digital Library
Fabrication of wide-IF 200–300GHz superconductor–insulator–superconductor mixers with suspended metal beam leads formed on silicon-on-insulator (open access)

Fabrication of wide-IF 200–300GHz superconductor–insulator–superconductor mixers with suspended metal beam leads formed on silicon-on-insulator

This article reports on a fabrication process that uses silicon-oninsulator (SOI) substrates and micromachining techniques to form wide-IF superconductor–insulator–superconductor (SIS) mixer devices that have suspended metal beam leads for rf grounding. Aside from a description of the fabrication process, electrical measurements of these Nb/Al–AlNₓ /Nb trilayer devices will also be presented.
Date: October 7, 2004
Creator: Kaul, Anupama; Bumble, Bruce; Lee, Karen A.; LeDuc, Henry G.; Rice, Frank & Zmuidzinas, Jonas
System: The UNT Digital Library
FEMTOSECOND X-RAY PULSES FROM A FREQUENCY CHIRPED SASE FEL. (open access)

FEMTOSECOND X-RAY PULSES FROM A FREQUENCY CHIRPED SASE FEL.

We discuss the temporal and spectral properties of self-amplified spontaneous emission (SASE) utilizing an energy-chirped electron beam. A short temporal pulse is generated by using a monochromator to select a narrow radiation bandwidth from the frequency chirped SASE. For the filtered radiation, the minimum pulse length is limited by the intrinsic SASE bandwidth, while the number of modes and the energy fluctuation can be controlled through the monochromator bandwidth. Two cases are considered: (1) placing the monochromator at the end of a single long undulator; (2) placing the monochromator after an initial undulator and amplifying the short-duration output in a second undulator. We analyze these cases and show that tens of femtosecond x-ray pulses may be generated for the linac coherent light source.
Date: January 7, 2004
Creator: KRINSKY,S. HUANG,Z.
System: The UNT Digital Library
Fermion Monte Carlo calculations on liquid-3He (open access)

Fermion Monte Carlo calculations on liquid-3He

None
Date: June 7, 2004
Creator: Kalos, M. H.; Colletti, L. & Pederiva, F.
System: The UNT Digital Library
Fick's Insights on Liquid Diffusion (open access)

Fick's Insights on Liquid Diffusion

In 1855, Adolph Fick published ''On Liquid Diffusion'', mathematically treating salt movements in liquids as a diffusion process, analogous to heat diffusion. Less recognized is the fact that Fick also provided a detailed account of the implications of salt diffusion to transport through membranes. A careful look at Fick (1855) shows that his conceptualization of molecular diffusion was more comprehensive than could be captured with the mathematical methods available to him, and therefore his expression, referred to as Fick's Law, dealt only with salt flux. He viewed salt diffusion in liquids as a binary process, with salt moving in one way and water moving in the other. Fick's analysis of the consequences of such a binary process operating in a hydrophilic pore in a membrane offers insights that are relevant to earth systems. This paper draws attention to Fick's rationale, and its implications to hydrogeological systems. Fick (1829-1901; Figure 1), a gifted scientist, published the first book on medical physics (Fick, 1858), discussing the application of optics, solid mechanics, gas diffusion, and heat budget to biological systems. Fick's paper is divisible into two parts. The first describes his experimental verification of the applicability of Fourier's equation to liquid diffusion. The …
Date: October 7, 2004
Creator: Narasimhan, T. N.
System: The UNT Digital Library
The Full Aperture Backscatter Station Measurement System on the National Ignition Facility (open access)

The Full Aperture Backscatter Station Measurement System on the National Ignition Facility

A Full Aperture Backscatter Station (FABS) target diagnostic has been activated on the first four beams of the National Ignition Facility (NIF). Backscattered light from the target propagates back down the beam path into the FABS diagnostic system. FABS measures both stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) with a suite of measurement instruments. Digital cameras and spectrometers record spectrally resolved energy for both P and S polarized light. Streaked spectrometers measure the spectral and temporal behavior of the backscattered light. Calorimeters and fast photodetectors measure the integrated energy and temporal behavior of the light, respectively. This paper provides an overview of the FABS measurements system and detailed descriptions of the diagnostic instruments and the optical path.
Date: April 7, 2004
Creator: Bower, D.; McCarville, T.; Alvarez, S.; Ault, L.; Brown, M.; Chrisp, M. et al.
System: The UNT Digital Library
Geophysical Model Research and Results (open access)

Geophysical Model Research and Results

Geophysical models constitute an important component of calibration for nuclear explosion monitoring. We will focus on four major topics: (1) a priori geophysical models, (2) surface wave models, (3) receiver function derived profiles, and (4) stochastic geophysical models. The first, a priori models, can be used to predict a host of geophysical measurements, such as body wave travel times, and can be derived from direct regional studies or even by geophysical analogy. Use of these models is particularly important in aseismic regions or regions without seismic stations, where data of direct measurements might not exist. Lawrence Livermore National Laboratory (LLNL) has developed the Western Eurasia and North Africa (WENA) model which has been evaluated using a number of data sets, including travel times, surface waves, receiver functions, and waveform analysis (Pasyanos et al., 2004). We have joined this model with our Yellow Sea - Korean Peninsula (YSKP) model and the Los Alamos National Laboratory (LANL) East Asia model to construct a model for all of Eurasia and North Africa. Secondly, we continue to improve upon our surface wave model by adding more paths. This has allowed us to expand the region to all of Eurasia and into Africa, increase the …
Date: July 7, 2004
Creator: Pasyanos, M; Walter, W; Tkalcic, H; Franz, G & Flanagan, M
System: The UNT Digital Library
High Explosive Deonation Threshold Sensitivity Due to Multiple Fragment Impacts (open access)

High Explosive Deonation Threshold Sensitivity Due to Multiple Fragment Impacts

Fragments, bullets or projectiles can initiate a detonation in a high explosive (HE). For this to happen certain critical conditions need to be exceeded. For a given explosive, these critical conditions are the projectile velocity, the projectile size and shape, and the projectile material properties. A lot of work has been done in the area of metal shaped charge jets and individual fragments impacting the HE. One major gap in understanding initiation phenomena is the effect of multiple fragment impact. This study shows that multiple fragments can lower the fragment size and the kinetic energy thresholds.
Date: January 7, 2004
Creator: Georgevich, V; Pincosy, P & Chase, J
System: The UNT Digital Library
An investigation of 154Eu as a high-precision multi-gamma-ray intensity calibration standard for detector arrays (open access)

An investigation of 154Eu as a high-precision multi-gamma-ray intensity calibration standard for detector arrays

The decay of {sup 154}Eu has been studied using {gamma}-ray singles and {gamma}-{gamma} coincidence spectroscopy with an array of Compton-suppressed Ge detectors. Particular attention to coincidence summing in the analysis, with consideration of detailed decay cascades and angular correlation effects, suggests that previous studies have overlooked necessary corrections. It is concluded that {sup 154}Eu provides 26 {gamma}-rays that can be used for relative efficiency calibrations from 120 to 1600 keV at the 0.7% precision level and that this precision could be improved in the future.
Date: October 7, 2004
Creator: Kulp, W D; Wood, J L; Krane, K S; Loats, J; Schmelzenbach, P D; Stapels, C J et al.
System: The UNT Digital Library
Isotopic evidence of magmatism and a sedimentary carbon source at the Endeavour hydrothermal system (open access)

Isotopic evidence of magmatism and a sedimentary carbon source at the Endeavour hydrothermal system

Stable and radiocarbon isotope measurements made on CO{sub 2} from high temperature hydrothermal vents on the Endeavour Segment of the Juan de Fuca Ridge indicate both magmatic and sedimentary sources of carbon to the hydrothermal system. The Endeavour segment is devoid of overlying sediments and has shown no observable signs of surficial magmatic activity during the {approx}20 years of ongoing studies. The appearance of isotopically heavy, radiocarbon dead CO{sub 2} after a 1999 earthquake swarm requires that this earthquake event was magmatic in origin. Evidence for a sedimentary organic carbon source suggests the presence of buried sediments at the ridge axis. These findings, which represent the first temporally coherent set of radiocarbon measurements from hydrothermal vent fluids, demonstrate the utility of radiocarbon analysis in hydrothermal studies. The existence of a sediment source at Endeavour and the occurrence of magmatic episodes illustrate the extremely complex and evolving nature of the Endeavour hydrothermal system.
Date: January 7, 2004
Creator: Brown, T A; Proskurowski, G & Lilley, M D
System: The UNT Digital Library
A Kinematically Beamed, Low Energy Pulsed Neutron Source for Active Interrogation (open access)

A Kinematically Beamed, Low Energy Pulsed Neutron Source for Active Interrogation

We are developing a new active interrogation system based on a kinematically focused low energy neutron beam. The key idea is that one of the defining characteristics of SNM (Special Nuclear Materials) is the ability for low energy or thermal neutrons to induce fission. Thus by using low energy neutrons for the interrogation source we can accomplish three goals, (1) Energy discrimination allows us to measure the prompt fast fission neutrons produced while the interrogation beam is on; (2) Neutrons with an energy of approximately 60 to 100 keV do not fission 238U and Thorium, but penetrate bulk material nearly as far as high energy neutrons do and (3) below about 100keV neutrons lose their energy by kinematical collisions rather than via the nuclear (n,2n) or (n,n') processes thus further simplifying the prompt neutron induced background. 60 keV neutrons create a low radiation dose and readily thermal capture in normal materials, thus providing a clean spectroscopic signature of the intervening materials. The kinematically beamed source also eliminates the need for heavy backward and sideway neutron shielding. We have designed and built a very compact pulsed neutron source, based on an RFQ proton accelerator and a lithium target. We are developing …
Date: October 7, 2004
Creator: Dietrich, D; Hagmann, C; Kerr, P; Nakae, L; Rowland, M; Snyderman, N et al.
System: The UNT Digital Library
Laser Performance Operations Model (LPOM) (open access)

Laser Performance Operations Model (LPOM)

The Laser Performance Operations Model (LPOM) has been developed to provide real time predictive capabilities for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. LPOM uses diagnostic feedback from previous NIF shots to maintain accurate energetics models for each of the 192 NIF beamlines (utilizing one CPU per laser beamline). This model is used to determine the system setpoints (initial power, waveplate attenuations, laser diagnostic settings) required for all requested NIF shots. In addition, LPOM employs optical damage models to minimize the probability that a proposed shot may damage the system. LPOM provides post-shot diagnostic reporting to support the NIF community. LPOM was deployed prior to the first main laser shots in NIF, and has since been used to set up every shot in NIF's first quad (four beamlines). Real-time adjustments of the codes energetics parameters allows the LPOM to predict total energies within 5%, and provide energy balance within the four beamlines to within 2% for shots varying from 0.5 to 26 kJ (1.053 {micro}m) per beamline. The LPOM has been a crucial tool in the commissioning of the first quad of NIF.
Date: January 7, 2004
Creator: Shaw, M; Williams, W; House, R & Haynam, C
System: The UNT Digital Library