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Onset of Ferrielectricity and the Hidden Nature of Nanoscale Polarization in Ferroelectric Thin Films (open access)

Onset of Ferrielectricity and the Hidden Nature of Nanoscale Polarization in Ferroelectric Thin Films

Article on the onset of ferrielectricity and the hidden nature of nanoscale polarization in ferroelectric thin films.
Date: September 5, 2008
Creator: Nuñez, Matías & Buongiorno Nardelli, Marco
System: The UNT Digital Library
Equivalence of dipole correction and Coulomb cutoff techniques in supercell calculations (open access)

Equivalence of dipole correction and Coulomb cutoff techniques in supercell calculations

Article on the equivalence of dipole correction and Coulomb cutoff techniques in supercell calculations. In this work, the authors compare the dipole correction and Coulomb cutoff methods under the same conditions in the framework of plane-wave based density-functional theory.
Date: June 3, 2008
Creator: Yu, Liping; Ranjan, Vivek; Lu, W.; Bernholc, Jerry & Buongiorno Nardelli, Marco
System: The UNT Digital Library
Zebrafish May Help Solve Ringing in Vets' Ears (open access)

Zebrafish May Help Solve Ringing in Vets' Ears

Article discussing research by Dr. Ernest J. Moore, professor of molecular pharmacology and audiology. This article discusses his research on tinnitus in zebrafish.
Date: May 6, 2008
Creator: Paul, Marla & Moore, Ernest J.
System: The UNT Digital Library
Fighting Fat: How Do Fat Stereotypes Influence Beliefs About Physical Education (open access)

Fighting Fat: How Do Fat Stereotypes Influence Beliefs About Physical Education

Article discussing a study on how fat stereotypes influence beliefs about physical education.
Date: November 2008
Creator: Greenleaf, Christy; Martin, Scott B. & Rhea, Deborah J.
System: The UNT Digital Library
Prevalence of Eating Disorders and Disordered Eating Behaviors Among Male Collegiate Athletes (open access)

Prevalence of Eating Disorders and Disordered Eating Behaviors Among Male Collegiate Athletes

This article discusses the prevalence of eating disorders and disordered eating behaviors among male collegiate athletes.
Date: 2008
Creator: Petrie, Trent A.; Greenleaf, Christy; Reel, Justine J. & Carter, Jennifer
System: The UNT Digital Library
Sun-Climate Complexity Linking (open access)

Sun-Climate Complexity Linking

Article discussing sun-climate complexity linking and how this property is a consequence of the phenomenon of information transfer.
Date: February 29, 2008
Creator: West, Bruce J. & Grigolini, Paolo
System: The UNT Digital Library
Using SPARK as a Solver for Modelica (open access)

Using SPARK as a Solver for Modelica

Modelica is an object-oriented acausal modeling language that is well positioned to become a de-facto standard for expressing models of complex physical systems. To simulate a model expressed in Modelica, it needs to be translated into executable code. For generating run-time efficient code, such a translation needs to employ algebraic formula manipulations. As the SPARK solver has been shown to be competitive for generating such code but currently cannot be used with the Modelica language, we report in this paper how SPARK's symbolic and numerical algorithms can be implemented in OpenModelica, an open-source implementation of a Modelica modeling and simulation environment. We also report benchmark results that show that for our air flow network simulation benchmark, the SPARK solver is competitive with Dymola, which is believed to provide the best solver for Modelica.
Date: June 30, 2008
Creator: Wetter, Michael; Wetter, Michael; Haves, Philip; Moshier, Michael A. & Sowell, Edward F.
System: The UNT Digital Library
Glomus intraradices: Status of the Genome Project (open access)

Glomus intraradices: Status of the Genome Project

None
Date: September 1, 2008
Creator: Shapiro, Harris
System: The UNT Digital Library
BDDC for nonsymmetric positive definite and symmetric indefinite problems (open access)

BDDC for nonsymmetric positive definite and symmetric indefinite problems

The balancing domain decomposition methods by constraints are extended to solving both nonsymmetric, positive definite and symmetric, indefinite linear systems. In both cases, certain nonstandard primal constraints are included in the coarse problems of BDDC algorithms to accelerate the convergence. Under the assumption that the subdomain size is small enough, a convergence rate estimate for the GMRES iteration is established that the rate is independent of the number of subdomains and depends only slightly on the subdomain problem size. Numerical experiments for several two-dimensional examples illustrate the fast convergence of the proposed algorithms.
Date: December 10, 2008
Creator: Tu, Xuemin & Li, Jing
System: The UNT Digital Library
Measurement of Fast Voltage Transients in High-Performance Nb3Sn Magnets (open access)

Measurement of Fast Voltage Transients in High-Performance Nb3Sn Magnets

The Superconducting Magnet group at Lawrence Berkeley National Laboratory has been developing Nb{sub 3}Sn high-field accelerator magnet technology for the last fifteen years. In order to support the magnet R&D effort, we are developing a diagnostic system that can help identify the causes of performance limiting quenches by recording small flux-changes within the magnet prior to quench-onset. These analysis techniques were applied to the test results from recent Nb{sub 3}Sn magnets. This paper will examine various types of events and their distinguishing characteristics. The present measurement techniques are discussed along with the design of a new data acquisition system that will substantially improve the quality of the recorded signals.
Date: June 1, 2008
Creator: Lietzke, A. F.; Sabbi, G. L.; Ferracin, P.; Caspi, S.; Zimmerman, S.; Joseph, J. et al.
System: The UNT Digital Library
Initial Operation of the High Temperature Electrolysis Integrated Laboratory Scale Experiment at INL (open access)

Initial Operation of the High Temperature Electrolysis Integrated Laboratory Scale Experiment at INL

An integrated laboratory scale, 15 kW high-temperature electrolysis facility has been developed at the Idaho National Laboratory under the U.S. Department of Energy Nuclear Hydrogen Initiative. Initial operation of this facility resulted in over 400 hours of operation with an average hydrogen production rate of approximately 0.9 Nm3/hr. The integrated laboratory scale facility is designed to address larger-scale issues such as thermal management (feed-stock heating, high-temperature gas handling), multiple-stack hot-zone design, multiple-stack electrical configurations, and other “integral” issues. This paper documents the initial operation of the ILS, with experimental details about heat-up, initial stack performance, as well as long-term operation and stack degradation.
Date: June 1, 2008
Creator: Stoots, C. M.; O'Brien, J. E.; Condie, K. G.; Herring, J. S. & Hartvigsen, J. J.
System: The UNT Digital Library
Three-dimensional lithographically-defined organotypic tissue arrays for quantitative analysis of morphogenesis and neoplastic progression (open access)

Three-dimensional lithographically-defined organotypic tissue arrays for quantitative analysis of morphogenesis and neoplastic progression

Here we describe a simple micromolding method to construct three-dimensional arrays of organotypic epithelial tissue structures that approximate in vivo histology. An elastomeric stamp containing an array of posts of defined geometry and spacing is used to mold microscale cavities into the surface of type I collagen gels. Epithelial cells are seeded into the cavities and covered with a second layer of collagen. The cells reorganize into hollow tissues corresponding to the geometry of the cavities. Patterned tissue arrays can be produced in 3-4 h and will undergo morphogenesis over the following one to three days. The protocol can easily be adapted to study a variety of tissues and aspects of normal and neoplastic development.
Date: February 13, 2008
Creator: Nelson, Celeste M.; Inman, Jamie L. & Bissell, Mina J.
System: The UNT Digital Library
Z' Coupling Information From LHeC (open access)

Z' Coupling Information From LHeC

None
Date: April 4, 2008
Creator: Rizzo, Thomas G.
System: The UNT Digital Library
Differentiating neutrino models on the basis of $\theta_{13}$ and lepton flavor violation (open access)

Differentiating neutrino models on the basis of $\theta_{13}$ and lepton flavor violation

The authors show how models of neutrino masses and mixings can be differentiated on the basis of their predictions for {theta}{sub 13} and lepton flavor violation in radiative charged lepton decays and {mu} - e conversion. They illustrate the lepton flavor violation results for five predictive SO(10) SUSY GUT models and point out the relative importance of their heavy right-handed neutrino mass spectra and {theta}{sub 13} predictions.
Date: March 1, 2008
Creator: Albright, Carl H.
System: The UNT Digital Library
Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure (open access)

Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure

We have developed complementary soft x-ray scattering and reflectometry techniques that allow for the morphological analysis of thin polymer films without resorting to chemical modification or isotopic 2 labeling. With these techniques, we achieve significant, x-ray energy-dependent contrast between carbon atoms in different chemical environments using soft x-ray resonance at the carbon edge. Because carbon-containing samples absorb strongly in this region, the scattering length density depends on both the real and imaginary parts of the atomic scattering factors. Using a model polymer film of poly(styrene-b-methyl methacrylate), we show that the soft x-ray reflectivity data is much more sensitive to these atomic scattering factors than the soft x-ray scattering data. Nevertheless, fits to both types of data yield useful morphological details on the polymer?slamellar structure that are consistent with each other and with literature values.
Date: April 4, 2008
Creator: Welch, Cynthia; Welch, Cynthia F.; Hjelm, Rex P.; Mang, Joseph T.; Hawley, Marilyn E.; Wrobleski, Debra A. et al.
System: The UNT Digital Library
The U.S. Department of Energy's Aerial Measuring System (AMS) (open access)

The U.S. Department of Energy's Aerial Measuring System (AMS)

For nearly 40 years, aerial radiological search and survey missions have been performed by the United States Department of Energy's (USDOE) Remote Sensing Laboratory (RSL). Originally created in 1967 as Aerial Measurement Operations (AMO), the AMS mission has expanded to include acquiring baseline measurements, performing periodic area monitoring, and responding to radiological emergencies. In an accident scenario, AMS fixed-wing and/or rotary-wing systems can be deployed to map radiological deposition. A fixed-wing system is on standby twenty-fours per day, seven days per week and can be deployed within four hours of notification. It can quickly evaluate high levels of radiation which may constitute immediate health risks. To accomplish its mission the fixed-wing aircraft utilizes the Spectral Aerial Radiological Computer System (SPARCS) which records gross count and spectral information. Data from SPARCS is telemetered to ground stations and secure websites where it can be viewed and evaluated in near-real time. The rotary-wing system deploys following the critical phase of an accident and supports the DOE's Consequence Management Response Team (CMRT) in determining long term consequences of the accident. The rotary wing aircraft utilizes the Radiation and Environmental Data Acquisition and Recording System (REDAR). A 25-liter sodium iodide (NaI) spectral system and precise …
Date: March 1, 2008
Creator: Marianno, Craig
System: The UNT Digital Library
Future possibilities with Fermilab neutrino beams (open access)

Future possibilities with Fermilab neutrino beams

We will start with a brief overview of neutrino oscillation physics with emphasis on the remaining unanswered questions. Next, after mentioning near future reactor and accelerator experiments searching for a non zero {theta}{sub 13}, we will introduce the plans for the next generation of long-baseline accelerator neutrino oscillation experiments. We will focus on experiments utilizing powerful (0.7-2.1 MW) Fermilab neutrino beams, either existing or in the design phase.
Date: January 1, 2008
Creator: Saoulidou, Niki
System: The UNT Digital Library
Multi-Megajoule NIF: Ushering In a New Era in High Energy Density Science (open access)

Multi-Megajoule NIF: Ushering In a New Era in High Energy Density Science

This paper describes the status of the stadium-sized National Ignition Facility (NIF), the world's largest laser system and first operational multi-megajoule laser. The 192-beam NIF, located at Lawrence Livermore National Laboratory (LLNL), is 96% complete and scheduled for completion in March 2009. The NIF laser will produce nanosecond laser pulses with energies up to approximately 4 MJ in the infrared (laser wavelength = 1.053-{micro}m) and 2MJ in the ultraviolet (laser wavelength = 0.35-{micro}m). With these energies NIF will access conditions of pressure and temperature not previously available on earth, allowing it to conduct experiments in support of the nation's national security, energy, and fundamental science goals. First ignition experiments at NIF are scheduled for FY2010. This paper will provide an overview of the NIF laser and the ignition, energy, and fundamental science activities at NIF.
Date: April 30, 2008
Creator: Keane, C & Moses, E I
System: The UNT Digital Library
Evolution of the Surface Science of Catalysis from Single Crystals to Metal Nanoparticles under Pressure (open access)

Evolution of the Surface Science of Catalysis from Single Crystals to Metal Nanoparticles under Pressure

Vacuum studies of metal single crystal surfaces using electron and molecular beam scattering revealed that the surface atoms relocate when the surface is clean (reconstruction) and when it is covered by adsorbates (adsorbate induced restructuring). It was also discovered that atomic steps and other low coordination surface sites are active for breaking chemical bonds (H-H, O=O, C-H, C=O and C-C) with high reaction probability. Investigations at high reactant pressures using sum frequency generation (SFG)--vibrational spectroscopy and high pressure scanning tunneling microscopy (HPSTM) revealed bond breaking at low reaction probability sites on the adsorbate-covered metal surface, and the need for adsorbate mobility for continued turnover. Since most catalysts (heterogeneous, enzyme and homogeneous) are nanoparticles, colloid synthesis methods were developed to produce monodispersed metal nanoparticles in the 1-10 nm range and controlled shapes to use them as new model catalyst systems in two-dimensional thin film form or deposited in mesoporous three-dimensional oxides. Studies of reaction selectivity in multipath reactions (hydrogenation of benzene, cyclohexene and crotonaldehyde) showed that reaction selectivity depends on both nanoparticle size and shape. The oxide-metal nanoparticle interface was found to be an important catalytic site because of the hot electron flow induced by exothermic reactions like carbon monoxide oxidation.
Date: March 6, 2008
Creator: Somorjai, Gabor A. & Park, Jeong Y.
System: The UNT Digital Library
How to Calculate Colourful Cross Sections Efficiently (open access)

How to Calculate Colourful Cross Sections Efficiently

Different methods for the calculation of cross sections with many QCD particles are compared. To this end, CSW vertex rules, Berends-Giele recursion and Feynman-diagram based techniques are implemented as well as various methods for the treatment of colours and phase space integration. We find that typically there is only a small window of jet multiplicities, where the CSW technique has efficiencies comparable or better than both of the other two methods.
Date: September 3, 2008
Creator: Gleisberg, Tanju; Hoeche, Stefan & Krauss, Frank
System: The UNT Digital Library
Status of Offshore Wind Energy Projects, Policies and Programs in the United States (open access)

Status of Offshore Wind Energy Projects, Policies and Programs in the United States

This paper provides the status of the offshore wind energy project proposals in the United States and describes strategic issues faced by the U.S. wind industry.
Date: January 1, 2008
Creator: Musial, W. & Ram, B.
System: The UNT Digital Library
INTEGRAL BENCHMARKS AVAILABLE THROUGH THE INTERNATIONAL REACTOR PHYSICS EXPERIMENT EVALUATION PROJECT AND THE INTERNATIONAL CRITICALITY SAFETY BENCHMARK EVALUATION PROJECT (open access)

INTEGRAL BENCHMARKS AVAILABLE THROUGH THE INTERNATIONAL REACTOR PHYSICS EXPERIMENT EVALUATION PROJECT AND THE INTERNATIONAL CRITICALITY SAFETY BENCHMARK EVALUATION PROJECT

Interest in high-quality integral benchmark data is increasing as efforts to quantify and reduce calculational uncertainties accelerate to meet the demands of next generation reactor and advanced fuel cycle concepts. The International Reactor Physics Experiment Evaluation Project (IRPhEP) and the International Criticality Safety Benchmark Evaluation Project (ICSBEP) continue to expand their efforts and broaden their scope to identify, evaluate, and provide integral benchmark data for method and data validation. Benchmark model specifications provided by these two projects are used heavily by the international reactor physics, nuclear data, and criticality safety communities. Thus far, 14 countries have contributed to the IRPhEP, and 20 have contributed to the ICSBEP. The status of the IRPhEP and ICSBEP is discussed in this paper, and the future of the two projects is outlined and discussed. Selected benchmarks that have been added to the IRPhEP and ICSBEP handbooks since PHYSOR’06 are highlighted, and the future of the two projects is discussed.
Date: September 1, 2008
Creator: Briggs, J. Blair; Scott, Lori; Sartori, Enrico & Rugama, Yolanda
System: The UNT Digital Library
High Penetration, Grid Connected Photovoltaic Technology Codes and Standards: Preprint (open access)

High Penetration, Grid Connected Photovoltaic Technology Codes and Standards: Preprint

This paper reports the interim status in identifying and reviewing photovoltaic (PV) codes and standards (C&S) and related electrical activities for grid-connected, high-penetration PV systems with a focus on U.S. electric utility distribution grid interconnection.
Date: May 1, 2008
Creator: Basso, T. S.
System: The UNT Digital Library
Use of microphysical relationships to discern growth/decay mechanisms of cloud droplets with focus on Z-LWC relationships. (open access)

Use of microphysical relationships to discern growth/decay mechanisms of cloud droplets with focus on Z-LWC relationships.

Cloud droplet size distributions hence the key microphysical quantities (e.g., radar reflectivity, droplet concentration, liquid water content, relative dispersion, and mean-volume radius) are determined by different physical mechanisms, including pre-cloud aerosols as CCNs, cloud updraft, and various turbulent entrainment-mixing processes. Therefore, different relationships among these microphysical properties are expected in response to these various mechanisms. The effect of turbulent entrainment-mixing processes is particularly vexing, with different entrainment-mixing processes likely leading to different microphysical relationships. Cloud radar has been widely used to infer the cloud liquid water content (L) from the measurement of radar reflectivity (Z) using a Z-L relationship. Existing Z-L expressions have been often obtained empirically, and differ substantially (Khain et al. 2008). The discrepancy among Z-L relations, which has been hindering the application of cloud radar in measuring cloud properties, likely stems from the different relationships between the relevant microphysical properties caused by different physical processes. This study first analyzes the Z-L relationship theoretically, and identify the key microphysical properties that affect this relationship, and then address the effects of various processes on the Z-L relationship by discerning the characteristics of the relationships between the relative dispersion, droplet concentration, liquid water content, and mean-volume radius calculated from in-situ …
Date: May 1, 2008
Creator: Liu, Y.; Daum, P. H.; Yum, S. S. & Wang, J.
System: The UNT Digital Library