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2005 Quantum Control of Light and Matter - Conference July 31 - August 5, 2005 (open access)

2005 Quantum Control of Light and Matter - Conference July 31 - August 5, 2005

This report is about Quantum Control of Light and Matter Gordon Research Conference
Date: September 11, 2006
Creator: Corkum, Paul B.
System: The UNT Digital Library
2006 Multiphoton Processes Gordon Conference - June 11-16 (open access)

2006 Multiphoton Processes Gordon Conference - June 11-16

The first Gordon Research Conference on Multiphoton Processes, was held in 1982. The meeting continues to evolve as it embraces both the rapid technological and intellectual growth in the field as well as the multi-disciplinary expertise of the participants. Current areas of interest include: (1) Ionization/Dissociation of Atoms and Molecules in Intense Laser Fields; (2) Frequency Domain Multi-Photon and Multiple-Resonance Spectroscopies of Molecules; (3) Time-Resolved Photoelectron Spectroscopy; (4) Ultrafast Pump-Probe Spectroscopy; (5) Coherent Strong-Field Manipulation of Atoms and Molecules; (6) High-Harmonic Generation; (7) Attosecond Pulse Generation and Measurement; and (8) Super-Intense Laser-Matter Interactions. In developing the program, the conference organizers will strive to blur traditional disciplinary boundaries, involving chemists, physicists, and optical engineers, representing both experiment and theory, as presenters and discussion leaders. The broad range of expertise and different perspectives of attendees should provide a stimulating and unique environment for solving problems and developing new ideas in this rapidly evolving field.
Date: June 11, 2006
Creator: Jones, Robert Rivers
System: The UNT Digital Library
AGN Feedback And Evolution of Radio Sources: Discovery of An X-Ray Cluster Associated With Z=1 Quasar (open access)

AGN Feedback And Evolution of Radio Sources: Discovery of An X-Ray Cluster Associated With Z=1 Quasar

We report the first significant detection of an X-ray cluster associated with a powerful (L{sub bol} {approx} 10{sup 47} erg sec{sup -1}) radio-loud quasar at high redshift (z=1.06). Diffuse X-ray emission is detected out to {approx} 120 kpc from the CSS quasar 3C 186. A strong Fe-line emission at the z{sub rest} = 1.06 confirms its thermal nature. We find that the CSS radio source is highly overpressured with respect to the thermal cluster medium by 2-3 orders of magnitude. This provides direct observational evidence that the radio source is not thermally confined as posited in the ''frustrated'' scenario for CSS sources. Instead, the radio source may be young and at an early stage of its evolution. This source provides the first detection of the AGN in outburst in the center of a cooling flow cluster. Powerful radio sources are thought to be triggered by the cooling flows. The evidence for the AGN activity and intermittent outbursts comes from the X-ray morphology of low redshift clusters, which usually do not harbour quasars. 3C186 is a young active radio source which can supply the energy into the cluster and potentially prevent its cooling. We discuss energetics related to the quasar activity …
Date: January 11, 2006
Creator: Siemiginowska, Aneta; Cheung, C. C.; LaMassa, S.; Burke, D.; Aldcroft, T. L.; Bechtold, J. et al.
System: The UNT Digital Library
Analysis of Density Changes in Plutonium Observed from Accelerated Aging Using Pu-238 Enrichment (open access)

Analysis of Density Changes in Plutonium Observed from Accelerated Aging Using Pu-238 Enrichment

We present dimensional and density changes in an aging plutonium alloy enriched with 7.3 at.% of {sup 238}Pu and reference alloys of various ages. After 45 equivalent years of aging, the enriched alloys at 35 C have swelled in volume by 0.14 to 0.16% and now exhibit a near linear volume increase, without void swelling. Based on X-ray diffraction measurements, the lattice expansion by self-irradiation appears to be the primary cause for dimensional changes during the initial 2-3 years of aging. Following the initial transient, the density change is primarily cause by a constant helium in-growth rate as a result of {alpha}-particle decay.
Date: July 11, 2006
Creator: Chung, B. W.; Saw, C. K.; Thompson, S. R.; Quick, T. M.; Woods, C. H.; Hopkins, D. J. et al.
System: The UNT Digital Library
An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs (open access)

An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs

The harmonic generation process in a harmonic cascade (HC) FEL is subject to noise degradation which is proportional to the square of the total harmonic order. In this paper, we study the shot noise evolution in the first-stage modulator and radiator of a HC FEL that produces the dominant noise contributions. We derive the effective input noise for a modulator operating in the low-gain regime, and analyze the radiator noise for a density-modulated beam. The significance of these noise sources in different harmonic cascade designs is also discussed.
Date: December 11, 2006
Creator: Huang, Z.
System: The UNT Digital Library
BaBar: sin(2beta+gamma) (open access)

BaBar: sin(2beta+gamma)

The time-dependent CP asymmetries in fully reconstructed B{sup 0} {yields} D{sup (*){+-}}{pi}{sup {-+}}/{rho}{sup {-+}} decays (new preliminary result), and in partially reconstructed B{sup 0} {yields} D{sup (*){+-}}{pi}{sup {-+}} decays, are measured with the BABAR detector at the PEP-II asymmetric B factory at SLAC, using 232 million {Upsilon}(4S) {yields} B{bar B} decays. We combine the above results and, using other measurements and theoretical assumptions, they interpret them in terms of the angles of the unitarity triangle describing the Cabibbo-Kobayashi-Maskawa matrix. They find |sin(2{beta} + {gamma})| > 0.64(0.42) at 68%(90%) confidence level using a frequentistic approach and |2{beta}+ {gamma}| = (90 {+-} 43){sup o} using a Bayesian approach.
Date: January 11, 2006
Creator: Voena, Cecilia
System: The UNT Digital Library
Beam Interaction Measurements with a Retarding Field Analyzer in a High-Current High-Vacuum Positively-Charged Particle Accelerator (open access)

Beam Interaction Measurements with a Retarding Field Analyzer in a High-Current High-Vacuum Positively-Charged Particle Accelerator

A Retarding Field Analyzer (RFA) was inserted in a drift region of a magnetic transport section of the high-current experiment (HCX) that is at high-vacuum to measure ions and electrons resulting from beam interaction with background gas and walls. The ions are expelled during the beam by the space-charge potential and the electrons are expelled mainly at the end of the beam, when the beam potential decays. The ion energy distribution shows the beam potential of {approx} 2100 V and the beam-background gas total cross-section of 1.6x10{sup -20} m{sup 2}. The electron energy distribution reveals that the expelled electrons are mainly desorbed from the walls and gain {approx} 22 eV from the beam potential decaying with time before entering the RFA. Details of the RFA design and of the measured energy distributions are presented and discussed.
Date: July 11, 2006
Creator: Covo, M. K.; Molvik, A. W.; Friedman, A.; Barnard, J. J.; Seidl, P. A.; Logan, B. G. et al.
System: The UNT Digital Library
Blind Analysis in Nuclear and Particle Physics (open access)

Blind Analysis in Nuclear and Particle Physics

None
Date: August 11, 2006
Creator: Klein, J.R.; U., /Texas & Roodman, A.
System: The UNT Digital Library
Climatic Forecasting of Net Infiltration at Yucca Montain Using Analogue Meteororological Data (open access)

Climatic Forecasting of Net Infiltration at Yucca Montain Using Analogue Meteororological Data

At Yucca Mountain, Nevada, future changes in climatic conditions will most likely alter net infiltration, or the drainage below the bottom of the evapotranspiration zone within the soil profile or flow across the interface between soil and the densely welded part of the Tiva Canyon Tuff. The objectives of this paper are to: (a) develop a semi-empirical model and forecast average net infiltration rates, using the limited meteorological data from analogue meteorological stations, for interglacial (present day), and future monsoon, glacial transition, and glacial climates over the Yucca Mountain region, and (b) corroborate the computed net-infiltration rates by comparing them with the empirically and numerically determined groundwater recharge and percolation rates through the unsaturated zone from published data. In this paper, the author presents an approach for calculations of net infiltration, aridity, and precipitation-effectiveness indices, using a modified Budyko's water-balance model, with reference-surface potential evapotranspiration determined from the radiation-based Penman (1948) formula. Results of calculations show that net infiltration rates are expected to generally increase from the present-day climate to monsoon climate, to glacial transition climate, and then to the glacial climate. The forecasting results indicate the overlap between the ranges of net infiltration for different climates. For example, the …
Date: September 11, 2006
Creator: Faybishenko, B.
System: The UNT Digital Library
Comparative Experimental Study of X-Ray Absorption Spectroscopy and Electron Energy Loss Spectroscopy on Passivated U Surfaces (open access)

Comparative Experimental Study of X-Ray Absorption Spectroscopy and Electron Energy Loss Spectroscopy on Passivated U Surfaces

X-ray absorption spectroscopy and electron energy loss spectroscopy are complementary analytical techniques on energy and spatial resolution. These techniques are based on the same fundamental physical process of core excitation with either an incident photon or incident electron. In the proper experimental configuration the electron and photon inelastic scattering amplitudes are comparable and thus the x-ray and electron absorption edges look identical. We have applied these two complementary analytical techniques to investigate the electronic structure of C ion implanted U. Implantation of C{sup +} ions into U{sup 238} has been shown to produce a physically and chemically modified surface layer that passivates the surface preventing further air oxidation and corrosion. Comparison of the resultant spectra reveal that transitions between the initial state and a series of final states yield numerous strong features at the absorption edge that can provide structural information and information on the local chemical environment, including the character of the U 5f state.
Date: December 11, 2006
Creator: Nelson, A.; Moberlychan, W.; Bliss, R. A.; Siekhaus, W.; Felter, T. & Denliner, J.
System: The UNT Digital Library
Comparison of the Acceptability of Various Oil Shale Processes (open access)

Comparison of the Acceptability of Various Oil Shale Processes

While oil shale has the potential to provide a substantial fraction of our nation's liquid fuels for many decades, cost and environmental acceptability are significant issues to be addressed. Lawrence Livermore National Laboratory (LLNL) examined a variety of oil shale processes between the mid 1960s and the mid 1990s, starting with retorting of rubble chimneys created from nuclear explosions [1] and ending with in-situ retorting of deep, large volumes of oil shale [2]. In between, it examined modified-in-situ combustion retorting of rubble blocks created by conventional mining and blasting [3,4], in-situ retorting by radio-frequency energy [5], aboveground combustion retorting [6], and aboveground processing by hot-solids recycle (HRS) [7,8]. This paper reviews various types of processes in both generic and specific forms and outlines some of the tradeoffs for large-scale development activities. Particular attention is given to hot-recycled-solids processes that maximize yield and minimize oil shale residence time during processing and true in-situ processes that generate oil over several years that is more similar to natural petroleum.
Date: March 11, 2006
Creator: Burnham, A K & McConaghy, J R
System: The UNT Digital Library
CP Violation Measurements in B to Charm Decays at BaBar (open access)

CP Violation Measurements in B to Charm Decays at BaBar

This article summarizes measurements of time-dependent CP asymmetries in decays of neutral B mesons to charm final states using data collected by the BABAR detector at the PEP-II asymmetric-energy B factory. All results are preliminary unless otherwise stated.
Date: October 11, 2006
Creator: George, Katherine A.
System: The UNT Digital Library
Dark Energy in the Dark Ages (open access)

Dark Energy in the Dark Ages

Non-negligible dark energy density at high redshifts would indicate dark energy physics distinct from a cosmological constant or"reasonable'" canonical scalar fields. Such dark energy can be constrained tightly through investigation of the growth of structure, with limits of<~;;2percent of total energy density at z>> 1 for many models. Intermediate dark energy can have effects distinct from its energy density; the dark ages acceleration can be constrained to last less than 5percent of a Hubble e-fold time, exacerbating the coincidence problem. Both the total linear growth, or equivalently sigma 8, and the shape and evolution of the nonlinear mass power spectrum for z<2 (using the Linder-White nonlinear mapping prescription) provide important windows. Probes of growth, such as weak gravitational lensing, can interact with supernovae and CMB distance measurements to scan dark energy behavior over the entire range z=0-1100.
Date: April 11, 2006
Creator: Linder, Eric V.
System: The UNT Digital Library
The Dark Matter Halos of Massive, Relaxed Galaxy Clusters Observed With Chandra (open access)

The Dark Matter Halos of Massive, Relaxed Galaxy Clusters Observed With Chandra

We use the Chandra X-ray Observatory to study the dark matter halos of 34 massive, dynamically relaxed galaxy clusters, spanning the redshift range 0.06 < z < 0.7. The observed dark matter and total mass (dark-plus-luminous matter) profiles can be approximated by the Navarro Frenk & White (hereafter NFW) model for cold dark matter (CDM) halos; for {approx} 80 percent of the clusters, the NFW model provides a statistically acceptable fit. In contrast, the singular isothermal sphere model can, in almost every case, be completely ruled out. We observe a well-defined mass-concentration relation for the clusters with a normalization and intrinsic scatter in good agreement with the predictions from simulations. The slope of the mass-concentration relation, c {infinity} M{sub vir}{sup a}/(1 + z){sup b} with a = -0.41 {+-} 0.11 at 95 percent confidence, is steeper than the value a {approx} -0.1 predicted by CDM simulations for lower mass halos. With the slope a included as a free fit parameter, the redshift evolution of the concentration parameter, b = 0.54 {+-} 0.47 at 95 percent confidence, is also slower than, but marginally consistent with, the same simulations (b {approx} 1). Fixing a {approx} -0.1 leads to an apparent evolution that …
Date: October 11, 2006
Creator: Schmidt, Robert W.; /Heidelberg, Astron. Rechen Inst.; Allen, S.W. & /KIPAC, Menlo Park
System: The UNT Digital Library
Diagnosis of the summertime warm and dry bias over the U. S. Southern Great Plains in the GFDL climate model using a weather forecasting approach (open access)

Diagnosis of the summertime warm and dry bias over the U. S. Southern Great Plains in the GFDL climate model using a weather forecasting approach

Weather forecasts started from realistic initial conditions are used to diagnose the large warm and dry bias over the United States Southern Great Plains simulated by the GFDL climate model. The forecasts exhibit biases in surface air temperature and precipitation within 3 days which appear to be similar to the climate bias. With the model simulating realistic evaporation but underestimated precipitation, a deficit in soil moisture results which amplifies the initial temperature bias through feedbacks with the land surface. The underestimate of precipitation is associated with an inability of the model to simulate the eastward propagation of convection from the front-range of the Rocky Mountains and is insensitive to an increase of horizontal resolution from 2{sup o} to 0.5{sup o} latitude.
Date: July 11, 2006
Creator: Klein, S. A.; Jiang, X.; Boyle, J.; Malyshev, S. & Xie, S.
System: The UNT Digital Library
Discrete Symmetries on the Light Front and a General Relation connecting Nucleon Electric Dipole and Anomalous Magnetic Moments (open access)

Discrete Symmetries on the Light Front and a General Relation connecting Nucleon Electric Dipole and Anomalous Magnetic Moments

We consider the electric dipole form factor, F{sub 3}(q{sup 2}), as well as the Dirac and Pauli form factors, F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}), of the nucleon in the light-front formalism. We derive an exact formula for F{sub 3}(q{sup 2}) to complement those known for F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F{sub 2}(q{sup 2}) and F{sub 3}(q{sup 2}), Fock-state by Fock-state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo the isospin structure of the anomalous magnetic moments, {kappa}{sup n} {approx} -{kappa}{sup p}.
Date: January 11, 2006
Creator: Brodsky, Stanley J.; Gardner, Susan & Hwang, Dae Sung
System: The UNT Digital Library
DOs and DON'Ts in Developing In-House Industrial Hygiene Software (open access)

DOs and DON'Ts in Developing In-House Industrial Hygiene Software

None
Date: May 11, 2006
Creator: Chen, C & Lowe, T
System: The UNT Digital Library
Evidence of gating in hundred nanometer diameter pores: an experimental and theoretical study (open access)

Evidence of gating in hundred nanometer diameter pores: an experimental and theoretical study

We report on the observation of an unexpected gating mechanism at the 100 nm scale on track-etched polycarbonate membranes. Transport measurements of methyl viologen performed by absorption spectroscopy under various pH conditions demonstrated that perfect gating was achieved for 100 nm diameter pores at pH 2, while the positively charged molecular ions moved through the membrane according to diffusion laws at pH 5. An oppositely charged molecular ion, naphthalene disulfonate, in the same membrane, showed the opposite trend: diffusion of the negative ion at pH 2 and perfect gating at pH 5. The influence of parameters such as ionic strength and membrane surface coating were also investigated. A theoretical study of the system shows that at this larger length scale the magnitude of the electric field in the vicinity of the pores is too small to account for the experimental observations, rather, it is the surface trapping of the mobile ion (Cl{sup -} or Na{sup +}) which gives rise to the gating phenomena. This surprising effect might have potential applications for high-throughput separation of large molecules and bio-organisms.
Date: January 11, 2006
Creator: Letant, S. E.; Schaldach, C. M.; Johnson, M. R.; Sawvel, A.; Bourcier, W. L. & Wilson, W. D.
System: The UNT Digital Library
Factors Influencing the Quality of Carbon Coatings onLiFePO4 (open access)

Factors Influencing the Quality of Carbon Coatings onLiFePO4

Several LiFePO4/C composites were prepared and characterizedelectrochemically in lithium half-cells. Pressed pellet conductivitiescorrelated well with the electrochemical performance in lithiumhalf-cells. It was found that carbon structural factors such as sp2/sp3,D/G, and H/C ratios, as determined by Raman spectroscopy and elementalanalysis, influenced the conductivity and rate behavior strongly. Thestructure of the residual carbon could be manipulated through the use ofadditives during LiFePO4 synthesis. Increasing the pyromellitic acid (PA)content in the precursor mix prior to calcination resulted in asignificant lowering of the D/G ratio and a concomitant rise in thesp2/sp3 ratio of the carbon. Addition of both iron nitrate and PAresulted in higher sp2/sp3 ratios without further lowering the D/Gratios, or increasing carbon contents. The best electrochemical resultswere obtained for LiFePO4 processed with both ferrocene and PA. Theimprovement is attributed to better decomposition of the carbon sources,as evidenced by lower H/C ratios, a slight increase of the carbon content(still below 2 wt. percent), and more homogeneous coverage. A discussionof the influence of carbon content vs. structural factors on thecomposite conductivities and, by inference, the electrochemicalperformance, is included.
Date: October 11, 2006
Creator: Wilcox, James D.; Doeff, Marca M.; Marcinek, Marek & Kostecki,Robert
System: The UNT Digital Library
From Question Answering to Visual Exploration (open access)

From Question Answering to Visual Exploration

Research in Question Answering has focused on the quality of information retrieval or extraction using the metrics of precision and recall to judge success; these metrics drive toward finding the specific best answer(s) and are best supportive of a lookup type of search. These do not address the opportunity that users? natural language questions present for exploratory interactions. In this paper, we present an integrated Question Answering environment that combines a visual analytics tool for unstructured text and a state-of-the-art query expansion tool designed to compliment the cognitive processes associated with an information analysts work flow. Analysts are seldom looking for factoid answers to simple questions; their information needs are much more complex in that they may be interested in patterns of answers over time, conflicting information, and even related non-answer data may be critical to learning about a problem or reaching prudent conclusions. In our visual analytics tool, questions result in a comprehensive answer space that allows users to explore the variety within the answers and spot related information in the rest of the data. The exploratory nature of the dialog between the user and this system requires tailored evaluation methods that better address the evolving user goals and …
Date: August 11, 2006
Creator: McColgin, Dave W.; Gregory, Michelle L.; Hetzler, Elizabeth G. & Turner, Alan E.
System: The UNT Digital Library
Gravitational Gauge Mediation (open access)

Gravitational Gauge Mediation

It is often the case that naive introduction of the messenger sector to supersymmetry breaking models causes the supersymmetry restoration. We discuss a possibility of stabilizing the supersymmetry broken vacuum by the gravitational interaction.
Date: August 11, 2006
Creator: Kitano, Ryuichiro
System: The UNT Digital Library
Hadronic Tau Decay at BaBar (open access)

Hadronic Tau Decay at BaBar

Recent results on hadronic decays of tau from BaBar are reviewed. The branching fraction of {tau}{sup -} {yields} 3h{sup -} 2h{sup +}{nu}{sub {tau}} is measured to be (8.56 {+-} 0.05{sub stat} {+-} 0.42{sub sys}) x 10{sup -4}. The underlaying substructure of this decay exposes strong contribution from {rho} resonance. The decay {tau}{sup -} {yields} f{sub 1}(1285){pi}{sup -} {nu}{sub {tau}} with f{sub 1}(1285) {yields} 2{pi}{sup -}2{pi}{sup +} is observed and the corresponding branching fraction is measured to be (3.9 {+-} 0.7{sub stat} {+-} 0.5{sub sys}) x 10{sup -4}. The search for {tau}{sup -} {yields} 4{pi}{sup -}3{pi}{sup +}({pi}{sup 0}){nu}{sub {tau}} decay was performed and without evidence of the signal the upper limit of B({tau}{sup -} {yields} 4{pi}{sup -}3{pi}{sup +}({pi}{sup 0}){nu}{sub {tau}}) is estimated to be 3.0 x 10{sup -7} at 90% confidence limit. The upper limits on branching fractions for the exclusive decays {tau}{sup -} {yields} 4{pi}{sup -}3{pi}{sup +}{nu}{sub {tau}} and {tau}{sup -} {yields} 4{pi}{sup -}3{pi}{sup +}{pi}{sup 0}{nu}{sub {tau}} are found to be 4.3 x 10{sup -7} and 2.5 x 10{sup -7} at 90% confidence limit, respectively.
Date: April 11, 2006
Creator: Igonkina, O. & U., /Oregon
System: The UNT Digital Library
Half-life of 14O (open access)

Half-life of 14O

We have measured the half-life of 14O, a superallowed (0+\rightarrow 0+) \beta decay isotope. The 14O was produced by the12C(3He,n)14O reaction using a carbon aerogel target. A low-energy ionbeam of 14O was mass separated and implanted in a thin beryllium foil.The beta particles were counted with plastic scintillator detectors. Wefind \tau 1/2 = 70.696 +- 0.037\sigma. This result is 2.0\sigma higherthan an average value from six earlier experiments, but agrees moreclosely with the most recent previous measurment.
Date: January 11, 2006
Creator: Burke, Jason T.; Vetter, Paul A.; Freedman, Stuart J.; Fujikawa,Brian K. & Winter, Wesley T.
System: The UNT Digital Library
High-Performance Corrosion-Resistant Iron-Based Amorphous Metals: The Effects of Composition, Structure and Environment on Corrosion Resistance (open access)

High-Performance Corrosion-Resistant Iron-Based Amorphous Metals: The Effects of Composition, Structure and Environment on Corrosion Resistance

New corrosion-resistant, iron-based amorphous metals have been identified from published data or developed through combinatorial synthesis, and tested to determine their relative thermal phase stability, microstructure, mechanical properties, damage tolerance, and corrosion resistance. Some alloy additions are known to promote glass formation and to lower the critical cooling rate [F. Guo, S. J. Poon, Applied Physics Letters, 83 (13) 2575-2577, 2003]. Other elements are known to enhance the corrosion resistance of conventional stainless steels and nickel-based alloys [A. I. Asphahani, Materials Performance, Vol. 19, No. 12, pp. 33-43, 1980] and have been found to provide similar benefits to iron-based amorphous metals. Many of these materials can be cast as relatively thick ingots, or applied as coatings with advanced thermal spray technology. A wide variety of thermal spray processes have been developed by industry, and can be used to apply these new materials as coatings. Any of these can be used for the deposition of the formulations discussed here, with varying degrees of residual porosity and crystalline structure. Thick protective coatings have now been made that are fully dense and completely amorphous in the as-sprayed condition. An overview of the High-Performance Corrosion Resistant Materials (HPCRM) Project will be given, with particular …
Date: April 11, 2006
Creator: Farmer, J; Choi, J S; Haslam, J; Lian, T; Day, S; Yang, N et al.
System: The UNT Digital Library