38 Matching Results

Results open in a new window/tab.

Multicultural Efforts and Affirmative Action in Brazil: Policies Influencing Education in the Americas (open access)

Multicultural Efforts and Affirmative Action in Brazil: Policies Influencing Education in the Americas

This article explores the intercultural movements toward social justice in education in the Americas, most particularly, North America, and how U.S. multicultural movements and policies influence countries like Brazil.
Date: March 2, 2011
Creator: Murakami-Ramalho, Elizabeth & Auxiliadora Lima Dias da Silva, Maria
System: The UNT Digital Library
Transmission of Information Between Complex Systems: 1/ f resonance (open access)

Transmission of Information Between Complex Systems: 1/ f resonance

In this article, the authors study the transport of information between two complex systems with similar properties.
Date: May 31, 2011
Creator: Aquino, Gerardo; Bologna, Mauro; West, Bruce J. & Grigolini, Paolo
System: The UNT Digital Library
Raman Spectroscopy of UH3 from the Hydrogen Corrosion of Uranium (open access)

Raman Spectroscopy of UH3 from the Hydrogen Corrosion of Uranium

Hydrogen reacts with a uranium surface to form a fine, pyrophoric metal power (UH{sub 3}). Few spectroscopic studies have been conducted to study this reaction. Advances in Raman spectroscopy permit the application of the Raman method to formally difficult areas of chemistry such as the hydrogen corrosion of uranium: availability of multiple laser excitation wavelengths; fiber optics delivery and collection systems; upgraded instrumentation and detection techniques; and development of special enclosed in situ reactor cells. UH{sub 3} vibrations are expected to occur at low frequencies due to extended U-H-U structure.
Date: May 31, 2011
Creator: Smyrl, N. R.; Stowe, A. C. & Powell, G. L.
System: The UNT Digital Library
Characterization of Mo/Si multilayer growth on stepped topographies (open access)

Characterization of Mo/Si multilayer growth on stepped topographies

Mo/Si multilayer mirrors with nanoscale bilayer thicknesses have been deposited on stepped substrate topographies, using various deposition angles. The multilayer morphology at the stepedge region was studied by cross section transmission electron microscopy. A transition from a continuous- to columnar layer morphology is observed near the step-edge, as a function of the local angle of incidence of the deposition flux. Taking into account the corresponding kinetics and anisotropy in layer growth, a continuum model has been developed to give a detailed description of the height profiles of the individual continuous layers. Complementary optical characterization of the multilayer system using a microscope operating in the extreme ultraviolet wavelength range, revealed that the influence of the step-edge on the planar multilayer structure is restricted to a region within 300 nm from the step-edge.
Date: August 31, 2011
Creator: van den Boogaard, A. J. R.; Louis, E.; Zoethout, E.; Goldberg, K. A. & Bijkerk, F.
System: The UNT Digital Library
Towards an Integrated Model of the NIC Layered Implosions (open access)

Towards an Integrated Model of the NIC Layered Implosions

A detailed simulation-based model of the June 2011 National Ignition Campaign (NIC) cryogenic DT experiments is presented. The model is based on integrated hohlraum-capsule simulations that utilize the best available models for the hohlraum wall, ablator, and DT equations of state and opacities. The calculated radiation drive was adjusted by changing the input laser power to match the experimentally measured shock speeds, shock merger times, peak implosion velocity, and bangtime. The crossbeam energy transfer model was tuned to match the measured time-dependent symmetry. Mid-mode mix was included by directly modeling the ablator and ice surface perturbations up to mode 60. Simulated experimental values were extracted from the simulation and compared against the experiment. The model adjustments brought much of the simulated data into closer agreement with the experiment, with the notable exception of the measured yields, which were 15-45% of the calculated yields.
Date: October 31, 2011
Creator: Jones, O. S.; Callahan, D. A.; Cerjan, C. J.; Clark, D. S.; Edwards, M. J.; Glenzer, S. H. et al.
System: The UNT Digital Library
es11_Rappe_final_report_DOE.pdf (open access)

es11_Rappe_final_report_DOE.pdf

ES11: the 23rd Annual Workshop on Electronic Structure Methods was held from June 6-9, 2011 at the University of Pennsylvania. The local organizing committee (see Section II) led by PI Andrew M. Rappe supervised the organization of the conference, before, during, and after the meeting itself. The national organizing committee set the technical program of talks, and provided support and advice in various ways. The conference was well-attended (see Section III). An important feature of this conference was a series of panel discussions (see Section IV) to discuss the field of electronic structure and to set new directions. The technical program was of extraordinarily high quality (see Section V). The host institution, the University of Pennsylvania, provided a supportive environment for this meeting (see Section VI).
Date: August 31, 2011
Creator: Rappe, Andrew M.
System: The UNT Digital Library
Shock compression of precompressed deuterium (open access)

Shock compression of precompressed deuterium

Here we report quasi-isentropic dynamic compression and thermodynamic characterization of solid, precompressed deuterium over an ultrafast time scale (< 100 ps) and a microscopic length scale (< 1 {micro}m). We further report a fast transition in shock wave compressed solid deuterium that is consistent with the ramp to shock transition, with a time scale of less than 10 ps. These results suggest that high-density dynamic compression of hydrogen may be possible on microscopic length scales.
Date: July 31, 2011
Creator: Armstrong, M R; Crowhurst, J C; Zaug, J M; Bastea, S; Goncharov, A F & Militzer, B
System: The UNT Digital Library
Comparison of Carbon and Hi-Z Primary Collimators for the LHC Phase II Collimation System (open access)

Comparison of Carbon and Hi-Z Primary Collimators for the LHC Phase II Collimation System

A current issue with the LHC collimation system is single-diffractive, off-energy protons from the primary collimators that pass completely through the secondary collimation system and are absorbed immediately downbeam in the cold magnets of the dispersion suppressor section. Simulations suggest that the high impact rate could result in quenching of these magnets. We have studied replacing the 60 cm primary graphite collimators, which remove halo mainly by inelastic strong interactions, with 5.25 mm tungsten, which remove halo mainly by multiple coulomb scattering and thereby reduce the rate of single-diffractive interactions that cause losses in the dispersion suppressor.
Date: October 31, 2011
Creator: Keller, Lewis; /SLAC; Markiewicz, Thomas; /SLAC; Smith, Jeffrey; /SLAC et al.
System: The UNT Digital Library
AGING PERFORMANCE OF MODEL 9975 PACKAGE FLUOROELASTOMER O-RINGS (open access)

AGING PERFORMANCE OF MODEL 9975 PACKAGE FLUOROELASTOMER O-RINGS

The influence of temperature and radiation on Viton{reg_sign} GLT and GLT-S fluoroelastomer O-rings is an ongoing research focus at the Savannah River National Laboratory. The O-rings are credited for leaktight containment in the Model 9975 shipping package used for transportation of plutonium-bearing materials. At the Savannah River Site, the Model 9975 packages are being used for interim storage. Primary research efforts have focused on surveillance of O-rings from actual packages, leak testing of seals at bounding aging conditions and the effect of aging temperature on compression stress relaxation behavior, with the goal of service life prediction for long-term storage conditions. Recently, an additional effort to evaluate the effect of aging temperature on the oxidation of the materials has begun. Degradation in the mechanical properties of elastomers is directly related to the oxidation of the polymer. Sensitive measurements of the oxidation rate can be performed in a more timely manner than waiting for a measurable change in mechanical properties, especially at service temperatures. Measuring the oxidation rate therefore provides a means to validate the assumption that the degradation mechanisms(s) do not change from the elevated temperatures used for accelerated aging and the lower service temperatures. Monitoring the amount of oxygen uptake …
Date: May 31, 2011
Creator: Hoffman, E.; Daugherty, W.; Skidmore, E.; Dunn, K. & Fisher, D.
System: The UNT Digital Library
FeMn/Fe/Co/Cu(1,1,10) films studied using the magneto-optic Kerr effect and photoemission electron microscopy (open access)

FeMn/Fe/Co/Cu(1,1,10) films studied using the magneto-optic Kerr effect and photoemission electron microscopy

FeMn/Fe/Co/Cu(1,1,10) films were grown epitaxially and investigated using the magneto-optic Kerr effect and photoemission electron microscopy. We found that FeMn/Fe/Co/Cu(1,1,10) exhibits the same properties as FeMn/Co/Cu(1,1,10) for the ferromagnetic phase of the face centered cubic (fcc) Fe film but a different property for the non-ferromagnetic phase of the fcc Fe film. This result indicates that the characteristic property reported in the literature for FeMn/Co/Cu(001) comes from the FeMn spin structure and is independent of the ferromagnetic layer.
Date: July 31, 2011
Creator: Meng, Y.; Li, J.; Tan, A.; Park, J.; Jin, E.; Son, H. et al.
System: The UNT Digital Library
AlGaN UV LED and Photodiodes Radiation Hardness and Space Qualifications and Their Applications in Space Science and High Energy Density Physics (open access)

AlGaN UV LED and Photodiodes Radiation Hardness and Space Qualifications and Their Applications in Space Science and High Energy Density Physics

This presentation provides an overview of robust, radiation hard AlGaN optoelectronic devices and their applications in space exploration & high energy density physics. Particularly, deep UV LED and deep UV photodiodes are discussed with regard to their applications, radiation hardness and space qualification. AC charge management of UV LED satellite payload instruments, which were to be launched in late 2012, is covered.
Date: May 31, 2011
Creator: Sun, K. X.
System: The UNT Digital Library
Incorporating Experience Curves in Appliance Standards Analysis (open access)

Incorporating Experience Curves in Appliance Standards Analysis

The technical analyses in support of U.S. energy conservation standards for residential appliances and commercial equipment have typically assumed that manufacturing costs and retail prices remain constant during the projected 30-year analysis period. There is, however, considerable evidence that this assumption does not reflect real market prices. Costs and prices generally fall in relation to cumulative production, a phenomenon known as experience and modeled by a fairly robust empirical experience curve. Using price data from the Bureau of Labor Statistics, and shipment data obtained as part of the standards analysis process, we present U.S. experience curves for room air conditioners, clothes dryers, central air conditioners, furnaces, and refrigerators and freezers. These allow us to develop more representative appliance price projections than the assumption-based approach of constant prices. These experience curves were incorporated into recent energy conservation standards for these products. The impact on the national modeling can be significant, often increasing the net present value of potential standard levels in the analysis. In some cases a previously cost-negative potential standard level demonstrates a benefit when incorporating experience. These results imply that past energy conservation standards analyses may have undervalued the economic benefits of potential standard levels.
Date: October 31, 2011
Creator: Garbesi, Karina; Chan, Peter; Greenblatt, Jeffery; Kantner, Colleen; Lekov, Alex; Meyers, Stephen et al.
System: The UNT Digital Library
Using synthetic biology to screen for functional diversity of GH1 enzymes (open access)

Using synthetic biology to screen for functional diversity of GH1 enzymes

Advances in next-generation sequencing technologies have enabled single genomes as well as complex environmental samples (metagenomes) to be comprehensively sequenced on a routine basis. Bioinformatics analysis of the resulting sequencing data reveals a continually expanding catalogue of predicted proteins ( 14 million as of April 2011), 75 percent of which are associated with functional annotation (COG, Pfam, Enzyme, Kegg, etc). These predicted proteins cover the full spectrum of known pathways and functional activities, including many novel biocatalysts that are expected to significantly contribute to the development of clean technologies including biomass degradation, lipid transformation for biodiesel generation, intermediates for polymer production, carbon capture, and bioremediation.
Date: May 31, 2011
Creator: Deutsch, Sam; Datta, Supratim; Hamilton, Matthew; Friedland, Greg; D'Haeseleer, Patrik; Chen, Jan-Fang et al.
System: The UNT Digital Library
Image processing and control of a programmable spatial light modulator (open access)

Image processing and control of a programmable spatial light modulator

None
Date: January 31, 2011
Creator: Awwal, A.; Leach, R.; Brunton, G.; Tse, E.; Matone, J. & Heebner, J.
System: The UNT Digital Library
Agave: a biofuel feedstock for arid and semi-arid environments (open access)

Agave: a biofuel feedstock for arid and semi-arid environments

Efficient production of plant-based, lignocellulosic biofuels relies upon continued improvement of existing biofuel feedstock species, as well as the introduction of newfeedstocks capable of growing on marginal lands to avoid conflicts with existing food production and minimize use of water and nitrogen resources. To this end, specieswithin the plant genus Agave have recently been proposed as new biofuel feedstocks. Many Agave species are adapted to hot and arid environments generally unsuitable forfood production, yet have biomass productivity rates comparable to other second-generation biofuel feedstocks such as switchgrass and Miscanthus. Agavesachieve remarkable heat tolerance and water use efficiency in part through a Crassulacean Acid Metabolism (CAM) mode of photosynthesis, but the genes andregulatory pathways enabling CAM and thermotolerance in agaves remain poorly understood. We seek to accelerate the development of agave as a new biofuelfeedstock through genomic approaches using massively-parallel sequencing technologies. First, we plan to sequence the transcriptome of A. tequilana to provide adatabase of protein-coding genes to the agave research community. Second, we will compare transcriptome-wide gene expression of agaves under different environmentalconditions in order to understand genetic pathways controlling CAM, water use efficiency, and thermotolerance. Finally, we aim to compare the transcriptome of A.tequilana with that of other …
Date: May 31, 2011
Creator: Gross, Stephen; Martin, Jeffrey; Simpson, June; Wang, Zhong & Visel, Axel
System: The UNT Digital Library
Single-Particle Dynamics in Electron Storage Rings with Extremely Low Emittance (open access)

Single-Particle Dynamics in Electron Storage Rings with Extremely Low Emittance

Electron storage rings are widely used for high luminosity colliders, damping rings in high-energy linear colliders, and synchrotron light sources. They have become essential facilities to study high-energy physics and material and medical sciences. To further increase the luminosity of colliders or the brightness of synchrotron light sources, the beam emittance is being continually pushed downward, recently to the nanometer region. In the next decade, another order of reduction is expected. This requirement of ultra-low emittance presents many design challenges in beam dynamics, including better analysis of maps and improvement of dynamic apertures. To meet these challenges, we have refined transfer maps of common elements in storage rings and developed a new method to compute the resonance driving terms as they are built up along a beamline. The method is successfully applied to a design of PEP-X as a future light source with 100-pm emittance. As a result, we discovered many unexpected cancelations of the fourth-order resonance terms driven by sextupoles within an achromat.
Date: May 31, 2011
Creator: Cai, Yunhai
System: The UNT Digital Library
A 12 GHZ 50 MW Klystron for Support of Accelerator Research (open access)

A 12 GHZ 50 MW Klystron for Support of Accelerator Research

A 12 GHz 50MW X-band klystron is under development at the SLAC National Accelerator Laboratory Klystron Department. The klystron will be fabricated to support programs currently underway at three European Labs; CERN, PSI, and INFN Trieste. The choice of frequency selection was due to the CLIC RF frequency changing from 30 GHz to the European X-band frequency of 11.99 GHz in 2008. Since the Klystron Department currently builds 50MW klystrons at 11.424 GHz known collectively as the XL4 klystrons, it was deemed cost-effective to utilize many XL4 components by leaving the gun, electron beam transport, solenoid magnet and collector unchanged. To realize the rf parameters required, the rf cavities and rf output hardware were necessarily altered. Some improvements to the rf design have been made to reduce operating gradients and increase reliability. Changes in the multi-cell output structure, waveguide components, and the window will be discussed along with testing of the devices. Five klystrons known as XL5 klystrons are scheduled for production over the next two years.
Date: May 31, 2011
Creator: Sprehn, Daryl; Haase, Andrew; Jensen, Aaron; Jongewaard, Erik; Nantista, Christopher & Vlieks, Arnold
System: The UNT Digital Library
Hemicellulolytic organisms in the particle-associated microbiota of the hoatzin crop (open access)

Hemicellulolytic organisms in the particle-associated microbiota of the hoatzin crop

The hoatzin (Opisthocomus hoazin) is a South American herbivorous bird, that has an enlarged crop analogous to the rumen, where foregut microbes degrade the otherwise indigestible plant materials, providing energy to the host. The crop harbors an impressive array of microorganisms with potentially novel cellulolytic enzymes. Thie study describes the composition ofthe particle-associated microbiota in the hoatzin crop, combining a survey of 16S rRNA genes in 7 adult birds and metagenome sequencing of two animals. The pyrotag survey demonstrates that Prevotellaceae, are the most abundant and ubiquitous taxa, suggesting that the degradation of hemicellulose is an important activity in the crop. Nonetheless, preliminary results from the metagnome of the particle-associated microbiota of two adult birds show that the crop microbiome contains a high number of genes encoding cellulases (such as GH5) more abundant than those of the termite gut, as well as genes encoding hemicellulases. These preliminary results show that the carbohydate-active enzyme genes in the cropmetagenome could be a source of biochemical catalysts able to deconstruct plant biomass.
Date: May 31, 2011
Creator: Godoy-Vitorino, Filipa; Malfatti, Stephanie; Garcia-Amado, Maria A.; Dominguez-Bello, Maria Gloria; Hugenholtz, Phillip & Tringe, Susannah
System: The UNT Digital Library
LLNL's Experience with the 3rd ITWG Nuclear Forensics Round Robin - INMM 2011 (open access)

LLNL's Experience with the 3rd ITWG Nuclear Forensics Round Robin - INMM 2011

None
Date: May 31, 2011
Creator: Kristo, M J
System: The UNT Digital Library
Application of Analytical Heat Transfer Models of Multi-layered Natural and Engineered Barriers in Potential High-Level Nuclear Waste Repositories (open access)

Application of Analytical Heat Transfer Models of Multi-layered Natural and Engineered Barriers in Potential High-Level Nuclear Waste Repositories

None
Date: October 31, 2011
Creator: Greenberg, H. R.; Blink, J. A.; Sutton, M.; Fratoini, M. & Ross, A. D.
System: The UNT Digital Library
Precision X-Band Linac Technologies for Nuclear Photonics Gamma-Ray Sources (open access)

Precision X-Band Linac Technologies for Nuclear Photonics Gamma-Ray Sources

Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabled by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, …
Date: August 31, 2011
Creator: Hartemann, F. V.; Albert, F.; Anderson, S. G.; Bayramian, A. J.; Cross, R. R.; Ebbers, C. A. et al.
System: The UNT Digital Library
The RNA-Seq Analysis pipeline on Galaxy (open access)

The RNA-Seq Analysis pipeline on Galaxy

Q: How do I know my RNA-Seq experiments worked well A: RNA-Seq QC PipelineQ: How do I detect transcripts which are over expressed or under expressed in my samples A: Counting and Statistic AnalysisQ: What do I do if I don't have a reference genome A: Rnnotator de novo Assembly.
Date: May 31, 2011
Creator: Meng, Xiandong; Martin, Jeffrey & Wang, Zhong
System: The UNT Digital Library
Experimental X-Ray Characterization of Gekko XII Laser Propagation Through Very Low Density Aerogels (2-5 mg/cc) Creating Multi-keV Photons from a Titanium Solid Foil (open access)

Experimental X-Ray Characterization of Gekko XII Laser Propagation Through Very Low Density Aerogels (2-5 mg/cc) Creating Multi-keV Photons from a Titanium Solid Foil

Describes measurements of laser propagations through low density aerogels.
Date: January 31, 2011
Creator: Girard, F; Primout, M; Villette, B; Brebion, D; Nishimura, H & Fournier, K B
System: The UNT Digital Library
A compact neutron generator using a field ionization source (open access)

A compact neutron generator using a field ionization source

Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-#12;bers promise the high #12;eld-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of #12;field emitters with a density up to 10{sup 6} tips/cm{sup 2} and measure their performance characteristics using electron field emission. The critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties.
Date: October 31, 2011
Creator: Persaud, Arun; Waldmann, Ole; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali & Schenkel, Thomas
System: The UNT Digital Library