Modulation compression for short wavelength harmonic generation (open access)

Modulation compression for short wavelength harmonic generation

Laser modulator is used to seed free electron lasers. In this paper, we propose a scheme to compress the initial laser modulation in the longitudinal phase space by using two opposite sign bunch compressors and two opposite sign energy chirpers. This scheme could potentially reduce the initial modulation wavelength by a factor of C and increase the energy modulation amplitude by a factor of C, where C is the compression factor of the first bunch compressor. Such a compressed energy modulation can be directly used to generate short wavelength current modulation with a large bunching factor.
Date: January 11, 2010
Creator: Qiang, J.
Object Type: Article
System: The UNT Digital Library
Autoignition behavior of unsaturated hydrocarbons in the low and high temperature regions (open access)

Autoignition behavior of unsaturated hydrocarbons in the low and high temperature regions

None
Date: January 11, 2010
Creator: Mehl, M; Pitz, W J; Westbrook, C K; Yasunaga, K & Curran, H J
Object Type: Article
System: The UNT Digital Library
Kinetic Modeling of Gasoline Surrogate Components and Mixtures under Engine Conditions (open access)

Kinetic Modeling of Gasoline Surrogate Components and Mixtures under Engine Conditions

Real fuels are complex mixtures of thousands of hydrocarbon compounds including linear and branched paraffins, naphthenes, olefins and aromatics. It is generally agreed that their behavior can be effectively reproduced by simpler fuel surrogates containing a limited number of components. In this work, an improved version of the kinetic model by the authors is used to analyze the combustion behavior of several components relevant to gasoline surrogate formulation. Particular attention is devoted to linear and branched saturated hydrocarbons (PRF mixtures), olefins (1-hexene) and aromatics (toluene). Model predictions for pure components, binary mixtures and multicomponent gasoline surrogates are compared with recent experimental information collected in rapid compression machine, shock tube and jet stirred reactors covering a wide range of conditions pertinent to internal combustion engines (3-50 atm, 650-1200K, stoichiometric fuel/air mixtures). Simulation results are discussed focusing attention on the mixing effects of the fuel components.
Date: January 11, 2010
Creator: Mehl, M; Pitz, W J; Westbrook, C K & Curran, H J
Object Type: Article
System: The UNT Digital Library
X-ray absorption and magnetic circular dichroism studies of Co2FeAl in magnetic tunnel junctions (open access)

X-ray absorption and magnetic circular dichroism studies of Co2FeAl in magnetic tunnel junctions

The bulk magnetic moment and the element specific magnetic moment of Co{sub 2}FeAl thin films were examined as a function of annealing temperature by alternating gradient magnetometer (AGM) and X-ray absorption spectroscopy (XAS)/X-ray magnetic circular dichroism (XMCD), respectively. A high magnetic moment can be achieved for all annealing temperatures and the predicted bulk and interface magnetic moment of about 5 {tilde A}{sub B} are reached via heating. We will also present tunnel magnetoresistance (TMR) values of up to 153% at room temperature and 260% at 13 K for MgO based magnetic tunnel junctions (MTJs) with Co{sub 2}FeAl and Co-Fe electrodes.
Date: January 11, 2010
Creator: Ebke, D.; Kugler, Z.; Thomas, P.; Schebaum, O.; Schafers, M.; Nissen, D. et al.
Object Type: Article
System: The UNT Digital Library
100-N Area Strontium-90 Treatability Demonstration Project: Phytoextraction Along the 100-N Columbia River Riparian Zone – Field Treatability Study (open access)

100-N Area Strontium-90 Treatability Demonstration Project: Phytoextraction Along the 100-N Columbia River Riparian Zone – Field Treatability Study

Strontium-90 (90Sr) is present both in the aquifer near the river and in the vadose and riparian zones of the river’s shore at 100-NR-2. Phytoextraction of 90Sr is being considered as a potential remediation system along the riparian zone of the Columbia River. Phytoextraction would employ coyote willow (Salix exigua). Past studies have shown that willow roots share uptake mechanisms for Sr with Ca, a plant macronutrient as well as no discrimination between Sr and 90Sr. Willow 90Sr concentration ratios [CR’s; (pCi 90Sr/g dry wt. of new growth tissue)/(pCi 90Sr/g soil porewater)] were consistently greater than 65 with three-quarters of the assimilated label partitioned into the above ground shoot. Insect herbivore experiments also demonstrated no significant potential for bioaccumulation or food chain transfer from their natural activities. The objectives of this field study were three-fold: (1) to demonstrate that a viable, “managed” plot of coyote willows can be established on the shoreline of the Columbia River that would survive the same microenvironment to be encountered at the 100-NR-2 shoreline; (2) to show through engineered barriers that large and small animal herbivores can be prevented from feeding on these plants; and (3) to show that once established, the plants will provide …
Date: January 11, 2010
Creator: Fellows, Robert J.; Fruchter, Jonathan S.; Driver, Crystal J. & Ainsworth, Calvin C.
Object Type: Report
System: The UNT Digital Library
Site Determination and Magnetism of Mn Doping in Protein Encapsulated Iron Oxide Nanoparticles (open access)

Site Determination and Magnetism of Mn Doping in Protein Encapsulated Iron Oxide Nanoparticles

Soft-X-ray absorption spectroscopy, soft-X-ray magnetic circular dichroism, and alternating current magnetic susceptibility were performed on 6.7 nm iron oxide nanoparticles doped with (5-33%) Mn grown inside the horse-spleen ferritin protein cages and compared to similarly protein encapsulated pure Fe-oxide and Mn-oxide nanoparticles to determine the site of the Mn dopant and to quantify the magnetic behavior with varying Mn concentration. The Mn dopant is shown to substitute preferentially as Mn{sup +2} and prefers the octahedral site in the defected spinel structure. The Mn multiplet structure for the nanoparticles is simpler than for the bulk standards, suggesting that the nanoparticle lattices are relaxed from the distortions present in the bulk. Addition of Mn is found to alter the host Fe-oxide lattice from a defected ferrimagnetic spinel structure similar to {gamma}-Fe{sub 2}O{sub 3} to an non-ferromagnetic spinel structure with a local Fe environment similar to Fe{sub 3}O{sub 4}.
Date: January 11, 2010
Creator: Pool, V.; Klem, M.; Jolley, C.; Arenholz, E. A.; Douglas, T.; Young, M. et al.
Object Type: Article
System: The UNT Digital Library
Fermi Surface of Superconducting LaFePO Determined by Quantum Oscillations (open access)

Fermi Surface of Superconducting LaFePO Determined by Quantum Oscillations

We report extensive measurements of quantum oscillations in the normal state of the Fe-based superconductor LaFePO, (T{sub c} {approx} 6 K) using low temperature torque magnetometry and transport in high static magnetic fields (45 T). We find that the Fermi surface is in broad agreement with the band-structure calculations with the quasiparticle mass enhanced by a factor {approx}2. The quasi-two dimensional Fermi surface consist of nearly-nested electron and hole pockets, suggesting proximity to a spin/charge density wave instability.
Date: January 11, 2010
Creator: Coldea, A. I.; Fletcher, J. D.; Carrington, A.; U., /Bristol; Analytis, J. G.; /Stanford U., Geballe Lab. /Stanford U., Appl. Phys. Dept. et al.
Object Type: Article
System: The UNT Digital Library
Hi-Q Rotor - Low Wind Speed Technology (open access)

Hi-Q Rotor - Low Wind Speed Technology

The project objective was to optimize the performance of the Hi-Q Rotor. Early research funded by the California Energy Commission indicated the design might be advantageous over state-of-the-art turbines for collecting wind energy in low wind conditions. The Hi-Q Rotor is a new kind of rotor targeted for harvesting wind in Class 2, 3, and 4 sites, and has application in areas that are closer to cities, or 'load centers.' An advantage of the Hi-Q Rotor is that the rotor has non-conventional blade tips, producing less turbulence, and is quieter than standard wind turbine blades which is critical to the low-wind populated urban sites. Unlike state-of-the-art propeller type blades, the Hi-Q Rotor has six blades connected by end caps. In this phase of the research funded by DOE's Inventions and Innovation Program, the goal was to improve the current design by building a series of theoretical and numeric models, and composite prototypes to determine a best of class device. Development of the rotor was performed by aeronautical engineering and design firm, DARcorporation. From this investigation, an optimized design was determined and an 8-foot diameter, full-scale rotor was built and mounted using a Bergey LX-1 generator and furling system which were …
Date: January 11, 2010
Creator: Mills, Todd E. & Tatum, Judy
Object Type: Report
System: The UNT Digital Library
Exclusive B Decays into Final States with Two Charmed Baryons (open access)

Exclusive B Decays into Final States with Two Charmed Baryons

This Thesis presents measurements of the decays B{sup -} {yields} {Xi}{sub c}{sup 0}{bar {Lambda}}{sub c}{sup -}, {bar B}{sup 0} {yields} {Xi}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -}, B{sup -} {yields} {Lambda}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -} K{sup -}, and {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -} K{sub s}{sup 0} based on 228 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory.
Date: January 11, 2010
Creator: Chai, Xuedong
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Local Measurement of the Penetration Depth in the Pnictide Superconductor Ba(Fe_0.95 Co_0.05)_2 As_2 (open access)

Local Measurement of the Penetration Depth in the Pnictide Superconductor Ba(Fe_0.95 Co_0.05)_2 As_2

We use magnetic force microscopy (MFM) to measure the local penetration depth {lambda} in Ba(Fe{sub 0.95}Co{sub 0.05}){sub 2}As{sub 2} single crystals and use scanning SQUID susceptometry to measure its temperature variation down to 0.4 K. We observe that superfluid density {rho}{sub s} over the full temperature range is well described by a clean two-band fully gapped model. We demonstrate that MFM can measure the important and hard-to-determine absolute value of {lambda}, as well as obtain its temperature dependence and spatial homogeneity. We find {rho}{sub s} to be uniform on the submicron scale despite the highly disordered vortex pinning.
Date: January 11, 2010
Creator: Matsushita, Y.
Object Type: Article
System: The UNT Digital Library
Evidence for charge Kondo effect in superconducting Tl-doped PbTe (open access)

Evidence for charge Kondo effect in superconducting Tl-doped PbTe

We report results of low-temperature thermodynamic and transport measurements of Pb{sub 1-x}Tl{sub x}Te single crystals for Tl concentrations up to the solubility limit of approximately x = 1.5%. For all doped samples, we observe a low-temperature resistivity upturn that scales in magnitude with the Tl concentration. The temperature and field dependence of this upturn are consistent with a charge Kondo effect involving degenerate Tl valence states differing by two electrons, with a characteristic Kondo temperature T{sub K} {approx} 6 K. The observation of such an effect supports an electronic pairing mechanism for superconductivity in this material and may account for the anomalously high T{sub c} values.
Date: January 11, 2010
Creator: Fisher, I
Object Type: Article
System: The UNT Digital Library
Low Prevalence of Chronic Beryllium Disease among Workers at a Nuclear Weapons Research and Development Facility (open access)

Low Prevalence of Chronic Beryllium Disease among Workers at a Nuclear Weapons Research and Development Facility

To study the prevalence of beryllium sensitization (BeS) and chronic beryllium disease (CBD) in a cohort of workers from a nuclear weapons research and development facility. We evaluated 50 workers with BeS with medical and occupational histories, physical examination, chest imaging with HRCT (N=49), and pulmonary function testing. Forty of these workers also underwent bronchoscopy for bronchoalveolar lavage (BAL) and transbronchial biopsies. The mean duration of employment at the facility was 18 yrs and the mean latency (from first possible exposure) to time of evaluation was 32 yrs. Five of the workers had CBD at the time of evaluation (based on histology or HRCT); three others had evidence of probable CBD. These workers with BeS, characterized by a long duration of potential Be exposure and a long latency, had a low prevalence of CBD.
Date: January 11, 2010
Creator: Arjomandi, M; Seward, J P; Gotway, M B; Nishimura, S; Fulton, G P; Thundiyil, J et al.
Object Type: Article
System: The UNT Digital Library
CRS Issue Statement on Animal Welfare (open access)

CRS Issue Statement on Animal Welfare

This report discusses the questions whether additional measures are needed to protect the health and well-being of animals.
Date: January 11, 2010
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
Medicare Physician Payment Updates and the Sustainable Growth Rate (SGR) System (open access)

Medicare Physician Payment Updates and the Sustainable Growth Rate (SGR) System

None
Date: January 11, 2010
Creator: unknown
Object Type: Report
System: The UNT Digital Library
CRS Issue Statement on Agriculture Appropriations (open access)

CRS Issue Statement on Agriculture Appropriations

This report discusses about the agricultural appropriations bill that is formally known as the Agriculture, Rural Development, Food and Drug Administration, and Related agencies Appropriations Act.
Date: January 11, 2010
Creator: Monke, Jim
Object Type: Report
System: The UNT Digital Library
The Individuals with Disabilities Education Act (IDEA): Supreme Court Decisions (open access)

The Individuals with Disabilities Education Act (IDEA): Supreme Court Decisions

None
Date: January 11, 2010
Creator: Jones, Nancy Lee & Toland, Carol J.
Object Type: Report
System: The UNT Digital Library
The Individuals with Disabilities Education Act (IDEA): Statutory Provisions and Recent Legal Issues (open access)

The Individuals with Disabilities Education Act (IDEA): Statutory Provisions and Recent Legal Issues

This report examines the major provisions of the Individuals with Disabilities Education Act and legal issues that have risen.
Date: January 11, 2010
Creator: Jones, Nancy Lee
Object Type: Report
System: The UNT Digital Library
Central Asia: Regional Developments and Implications for U.S. Interests (open access)

Central Asia: Regional Developments and Implications for U.S. Interests

This report discusses the current status of Central Asian states and U.S. policy, which has been aimed at facilitating their cooperation with U.S. and NATO stabilization efforts in Afghanistan and their efforts to combat terrorism, proliferation, and trafficking in arms, drugs, and persons. Congress will be considering an increase in support for the programs in Central Asia.
Date: January 11, 2010
Creator: Nichol, Jim
Object Type: Report
System: The UNT Digital Library
Gangs in Central America (open access)

Gangs in Central America

This report describes the gang problem in Central America, discusses country and regional approaches to deal with the gangs, and analyzes U.S. policy with respect to gangs in Central America.
Date: January 11, 2010
Creator: Seelke, Clare Ribando
Object Type: Report
System: The UNT Digital Library
Water Infrastructure Funding in the American Recovery and Reinvestment Act of 2009 (open access)

Water Infrastructure Funding in the American Recovery and Reinvestment Act of 2009

This report identifies funding for water infrastructure programs and projects included in American Recovery and Reinvestment Act of 2009 (P.L. 111-5). The legislation directs additional appropriations to a number of existing federal programs that either directly invest in water infrastructure projects or provide assistance to states and localities for such activities.
Date: January 11, 2010
Creator: Copeland, Claudia; Carter, Nicole T.; Cody, Betsy A. & Stubbs, Megan
Object Type: Report
System: The UNT Digital Library
Automatic Cost of Living Adjustments: Some Economic and Practical Considerations (open access)

Automatic Cost of Living Adjustments: Some Economic and Practical Considerations

This report looks at how automatic cost-of-living adjustments (COLAs) influence the budget and identifies major programs that have indexing provisions. It also explains what price indexes attempt to measure and discusses some of their weaknesses. Finally, it points out some practical things to keep in mind when establishing an indexing provision.
Date: January 11, 2010
Creator: Cashell, Brian W.
Object Type: Report
System: The UNT Digital Library
Afghanistan: Politics, Elections, and Government Performance (open access)

Afghanistan: Politics, Elections, and Government Performance

This report discusses the current political state of Afghanistan, as well as the Afghan government. This report also discusses Afghanistan's relationship with the United States, particularly U.S. efforts to urge President Hamid Karzai to address corruption within the Afghan government.
Date: January 11, 2010
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Federal Register, Volume 75, Number 6, January 11, 2010, Pages 1269-1524 (open access)

Federal Register, Volume 75, Number 6, January 11, 2010, Pages 1269-1524

Daily publication of the U.S. Office of the Federal Register contains rules and regulations, proposed legislation and rule changes, and other notices, including "Presidential proclamations and Executive Orders, Federal agency documents having general applicability and legal effect, documents required to be published by act of Congress, and other Federal agency documents of public interest" (p. ii). Table of Contents starts on page iii.
Date: January 11, 2010
Creator: United States. Office of the Federal Register.
Object Type: Journal/Magazine/Newsletter
System: The UNT Digital Library