Month

On the Significance of the Contribution of Multiple-Electron Capture Processes to Cometary X-Ray Emission (open access)

On the Significance of the Contribution of Multiple-Electron Capture Processes to Cometary X-Ray Emission

We report laboratory studies of the role played by multiple-electron capture (MEC) in solar wind induced cometary X-ray emission. Collisions of Ne{sup 10+} with He, Ne, Ar, CO, and CO{sub 2} have been investigated by means of the traditional singles X-ray spectroscopy in addition to the triple-coincidence measurements of X-rays, scattered projectile, and target recoil ions for the atomic targets. The coincidence measurements enable the reduction of the singles X-ray spectra into partial spectra originating in single-electron capture (SEC) and MEC collisions. The measurements provide unequivocal evidence for a significant role played by MEC, and strongly suggest that models based solely on SEC are bound to yield erroneous conclusions on the solar wind composition and velocities and on cometary atmospheres. The experimental relative importance of MEC collisions is compared with molecular classical-over-the-barrier model (MCBM), classical trajectory Monte Carlo (CTMC), and multi-channel Landau-Zener (MCLZ), calculations which can qualitatively reproduce the experimental trends.
Date: May 12, 2005
Creator: Ali, R.; Neill, P. A.; Beiersdorfer, P.; Harris, C. L.; Rakovi?, M. J.; Wang, J. G. et al.
Object Type: Article
System: The UNT Digital Library
NATO and the European Union (open access)

NATO and the European Union

Report which discusses issues related to the North Atlantic Trade Organization (NATO) and the European Union (EU) including the level of involvement of the entities in using political and military actions to defend against terrorism and proliferation, the types of military forces necessary, the role of the EU in crisis management, the appropriateness of decision-making procedures to respond to emerging threats, and the role of other international institutions.
Date: May 12, 2005
Creator: Archick, Kristin & Gallis, Paul E.
Object Type: Report
System: The UNT Digital Library
FY2005 Supplemental Appropriations for Iraq and Afghanistan, Tsunami Relief, and Other Activities (open access)

FY2005 Supplemental Appropriations for Iraq and Afghanistan, Tsunami Relief, and Other Activities

None
Date: May 12, 2005
Creator: Belasco, Amy & Nowels, Larry
Object Type: Report
System: The UNT Digital Library
New developments for the site-specific attachment of protein to surfaces (open access)

New developments for the site-specific attachment of protein to surfaces

Protein immobilization on surfaces is of great importance in numerous applications in biology and biophysics. The key for the success of all these applications relies on the immobilization technique employed to attach the protein to the corresponding surface. Protein immobilization can be based on covalent or noncovalent interaction of the molecule with the surface. Noncovalent interactions include hydrophobic interactions, hydrogen bonding, van der Waals forces, electrostatic forces, or physical adsorption. However, since these interactions are weak, the molecules can get denatured or dislodged, thus causing loss of signal. They also result in random attachment of the protein to the surface. Site-specific covalent attachment of proteins onto surfaces, on the other hand, leads to molecules being arranged in a definite, orderly fashion and uses spacers and linkers to help minimize steric hindrances between the protein surface. This work reviews in detail some of the methods most commonly used as well as the latest developments for the site-specific covalent attachment of protein to solid surfaces.
Date: May 12, 2005
Creator: Camarero, J A
Object Type: Article
System: The UNT Digital Library
AIDS in Africa (open access)

AIDS in Africa

Sub-Saharan Africa has been far more severely affected by AIDS than any other part of the world. The United Nations reports that 24.5 million adults and children are infected with the HIV virus in the region, which has about 10% of the world's population but more than 64% of the worldwide total of infected people. This report discusses this issue in detail, including the cause of the African AIDS epidemic, the social and economic consequences, response and treatment, and U.S. policy.
Date: May 12, 2005
Creator: Copson, Raymond W.
Object Type: Report
System: The UNT Digital Library
HIV/AIDS International Programs: Appropriations, FY2003-FY2006 (open access)

HIV/AIDS International Programs: Appropriations, FY2003-FY2006

On February 7th, 2005, the Bush Administration requested $3.16 billion for international HIV/AIDS, tuberculosis, and malaria programs in FY2006, a 9% increase over the estimated amount to be provided in FY2005.
Date: May 12, 2005
Creator: Copson, Raymond W.
Object Type: Report
System: The UNT Digital Library
"Fast Track" Congressional Consideration of Recommendations of the Base Realignment and Closure (BRAC) Commission (open access)

"Fast Track" Congressional Consideration of Recommendations of the Base Realignment and Closure (BRAC) Commission

The recommendations of the 2005 Base Realignment and Closure (BRAC) Commission will automatically take effect unless, within a stated period after the recommendations are submitted to the House and Senate, Congress adopts a joint resolution of disapproval rejecting them in their entirety. Congressional consideration of this disapproval resolution is not governed by the regular rules of the House and Senate, but by special expedited or “fast track” procedures laid out in statute. This report describes these expedited parliamentary procedures and explains how they differ from the regular legislative processes of Congress.
Date: May 12, 2005
Creator: Davis, Christopher M.
Object Type: Report
System: The UNT Digital Library
The High Energy Asymptotics of Scattering Processes in QCD (open access)

The High Energy Asymptotics of Scattering Processes in QCD

High energy scattering in the QCD parton model was recently shown to be a reaction-diffusion process, and thus to lie in the universality class of the stochastic Fisher-Kolmogorov-Petrovsky-Piscounov equation. We recall that the latter appears naturally in the context of the parton model. We provide a thorough numerical analysis of the mean field approximation, given in QCD by the Balitsky-Kovchegov equation. In the framework of a simple stochastic toy model that captures the relevant features of QCD, we discuss and illustrate the universal properties of such stochastic models. We investigate in particular the validity of the mean field approximation and how it is broken by fluctuations. We find that the mean field approximation is a good approximation in the initial stages of the evolution in rapidity.
Date: May 12, 2005
Creator: Enberg, Rikard; Golec-Biernat, K. & Munier, S.
Object Type: Article
System: The UNT Digital Library
Agricultural Export and Food Aid Programs (open access)

Agricultural Export and Food Aid Programs

This report discusses projected agricultural imports and exports for FY2005, as well as legislation that deals with federal programs in support of agricultural exports and federal aid dedicated to farms and agricultural reform.
Date: May 12, 2005
Creator: Hanrahan, Charles E.
Object Type: Report
System: The UNT Digital Library
Congressional Budget Actions in 2005 (open access)

Congressional Budget Actions in 2005

During the first session of the 109th Congress, the House and Senate will consider many different budgetary measures. Most of them will pertain to fiscal year (FY) 2006 and beyond, but some will make adjustments to the budget for FY2005. As the session progresses, this report will describe House and Senate actions on major budgetary legislation within the framework of the congressional budget process and other procedural requirements.
Date: May 12, 2005
Creator: Heniff, Bill, Jr.
Object Type: Report
System: The UNT Digital Library
U.S.-China Counter-Terrorism Cooperation: Issues for U.S. Policy (open access)

U.S.-China Counter-Terrorism Cooperation: Issues for U.S. Policy

None
Date: May 12, 2005
Creator: Kan, Shirley A.
Object Type: Report
System: The UNT Digital Library
Postal Reform Bills: A Side-by-Side Comparison of H.R. 22 and S. 662 (open access)

Postal Reform Bills: A Side-by-Side Comparison of H.R. 22 and S. 662

None
Date: May 12, 2005
Creator: Kosar, Kevin R.
Object Type: Report
System: The UNT Digital Library
Orchestrating Shots for the National Ignition Facililty (NIF) (open access)

Orchestrating Shots for the National Ignition Facililty (NIF)

The National Ignition Facility (NIF), currently under construction at the Lawrence Livermore National Laboratory, is a stadium-sized facility containing a 192-beam, 1.8 Megajoule, 500-Terawatt, ultra-violet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. When completed, NIF will be the world's largest and most energetic laser experimental system, providing an international center to study inertial confinement fusion and physics of matter at extreme densities and pressures. The NIF is operated by the Integrated Computer Control System (ICCS), which is a layered architecture of over 700 lower-level front-end processors attached to nearly 60,000 control points and coordinated by higher-level supervisory subsystems in the main control room. A shot automation framework has been developed and deployed during the past year to orchestrate and automate shots performed at the NIF using the ICCS. The Shot Automation framework is designed to automate 4-8 hour shot sequences, that includes deriving shot goals from an experiment definition, set up of the laser and diagnostics, automatic alignment of laser beams, and a countdown to charge and fire the lasers. These sequences consist of set of preparatory verification shots, leading to amplified system shots followed by post-shot analysis and archiving. The …
Date: May 12, 2005
Creator: Mathisen, D G; Bettenhausen, R C; Beeler, R G; Bowers, G A; Carey, R W; Casavant, D D et al.
Object Type: Article
System: The UNT Digital Library
Tritium Effects on Fracture Toughness of Stainless Steel Weldments (open access)

Tritium Effects on Fracture Toughness of Stainless Steel Weldments

The effects of tritium on the fracture toughness properties of Type 304L and Type 21-6-9 stainless steel weldments were measured. Weldments were tritium-charged-and-aged and then tested in order to measure the effect of the increasing decay helium content on toughness. The results were compared to uncharged and hydrogen-charged samples. For unexposed weldments having 8-12 volume percent retained delta ferrite, fracture toughness was higher than base metal toughness. At higher levels of weld ferrite, the fracture toughness decreased to values below that of the base metal. Hydrogen-charged and tritium-charged weldments had lower toughness values than similarly charged base metals and toughness decreased further with increasing weld ferrite content. The effect of decay helium content was inconclusive because of tritium off-gassing losses during handling, storage and testing. Fracture modes were dominated by the dimpled rupture process in unexposed weldments. In hydrogen and tritium-exposed weldments, the fracture modes depended on the weld ferrite content. At high ferrite contents, hydrogen-induced transgranular fracture of the weld ferrite phase was observed.
Date: May 12, 2005
Creator: Morgan, Michael; Chapman, G. K.; Tosten, M. H. & West, S. L.
Object Type: Article
System: The UNT Digital Library
Armenia, Azerbaijan, and Georgia: Political Developments and Implications for U.S. Interests (open access)

Armenia, Azerbaijan, and Georgia: Political Developments and Implications for U.S. Interests

The United States recognized the independence of all the former Soviet republics by the end of 1991, including the South Caucasus states of Armenia, Azerbaijan, and Georgia. The United States has fostered these states' ties with the West in part to end the dependence of these states on Russia for trade, security, and other relations. The FREEDOM Support Act of 1992 provides authorization for assistance to the Eurasian states for humanitarian needs, democratization, and other purposes. In the aftermath of the September 11, 2001, terrorist attacks on the United States, the Administration appealed for a national security waiver of the prohibition on aid to Azerbaijan, in consideration of Azerbaijan's assistance to the international coalition to combat terrorism. Azerbaijani and Georgian troops participate in stabilization efforts in Afghanistan and Iraq, and Armenian personnel serve in Iraq.
Date: May 12, 2005
Creator: Nichol, Jim
Object Type: Report
System: The UNT Digital Library
Coast Guard Deepwater Program: Background and Issues for Congress (open access)

Coast Guard Deepwater Program: Background and Issues for Congress

The Deepwater program is a $24 billion, 25-year acquisition program to replace or modernize 93 Coast Guard ships and 207 Coast Guard aircraft. The Coast Guard's FY2007 budget requests $934.431 million for the program. Some Members of Congress have criticized and expressed strong concerns over the Deepwater program on several grounds. The House-reported version of H.R. 5441, the FY2007 Department of Homeland Security (DHS) appropriations bill, recommends $892.64 million for the Deepwater program.
Date: May 12, 2005
Creator: O'Rourke, Ronald
Object Type: Report
System: The UNT Digital Library
Navy Ship Deployments: New Approaches - Background and Issues for Congress (open access)

Navy Ship Deployments: New Approaches - Background and Issues for Congress

None
Date: May 12, 2005
Creator: O'Rourke, Ronald
Object Type: Report
System: The UNT Digital Library
Unmanned Vehicles for U.S. Naval Forces:  Background and Issues for Congress (open access)

Unmanned Vehicles for U.S. Naval Forces: Background and Issues for Congress

None
Date: May 12, 2005
Creator: O'Rourke, Ronald
Object Type: Report
System: The UNT Digital Library
Flash X-ray (FXR) Accelerator Optimization Injector Voltage-variation Compensation via Beam-induced Gap Voltage (open access)

Flash X-ray (FXR) Accelerator Optimization Injector Voltage-variation Compensation via Beam-induced Gap Voltage

Lawrence Livermore National Laboratory (LLNL) is evaluating design alternatives to improve the voltage regulation in our injector and accelerator cells of our Flash X-Ray (FXR) machine. The operational peak electron beam current and energy at the x-ray generating target are 3.2 kA and 17 MeV. The goal is to create a more mono-energetic electron beam with variation of less than 1%-root-mean-squared (rms). This would allow the beam to be focused more tightly and create an x-ray source with a smaller spot-size. Our injector appears to have significant voltage-variation, and this report describes a technique to appreciably correct the deviations. When an electron beam crosses the energized gap of an accelerator cell, the energy increases. However, the beam with the associated electromagnetic wave also loses a small amount of energy because of the increased impedance seen across each gap. The phenomenon is sometimes called beam loading. It can also be described as a beam-induced voltage at the gap which is time varying. The polarity of this induced voltage is the opposite of the voltage in the injector. The time varying profiles of the injector and induced gap voltage are related through the beam current. However, while the change in magnitude is …
Date: May 12, 2005
Creator: Ong, M. M.
Object Type: Article
System: The UNT Digital Library
Flash X-Ray (FXR) Accelerator Optimization Beam-induced Voltage Simulation and TDR Measurements (open access)

Flash X-Ray (FXR) Accelerator Optimization Beam-induced Voltage Simulation and TDR Measurements

Lawrence Livermore National Laboratory (LLNL) is evaluating design alternatives to improve the voltage regulation in our Flash X-Ray (FXR) accelerator cell and pulse-power system. The goal is to create a more mono-energetic electron beam. When an electron beam crosses the energized gap of an accelerator cell, the electron energy is increased. However, the beam with the associated electromagnetic wave also looses a small amount of energy because of the increased impedance seen across the gap. The beam-induced voltage at the gap is time varying. This creates beam energy variations that we need to understand and control. A high-fidelity computer simulation of the beam and cell interaction has been completed to quantify the time varying induced voltage at the gap. The cell and pulse-power system was characterized using a Time-domain Reflectometry (TDR) measurement technique with a coaxial air-line to drive the cell gap. The beam-induced cell voltage is computed by convoluting the cell impedance with measured beam current. The voltage was checked against other measurements to validate the accuracy.
Date: May 12, 2005
Creator: Ong, M. M. & Vogtlin, G. E.
Object Type: Article
System: The UNT Digital Library
Hydropower Licenses and Alternative Licensing Conditions in H.R. 6, 109th Congress (open access)

Hydropower Licenses and Alternative Licensing Conditions in H.R. 6, 109th Congress

In the next ten years, nearly 20% of the nation’s nonfederal hydropower projects will require new federal licenses to continue operating. New licenses will establish facilities’ operating parameters for the next 30 to 50 years. These operating parameters will affect the total quantity and timing of electricity production. They will also affect flood control, irrigation, municipal and industrial water supplies, recreation, fish and wildlife habitat, and transportation.
Date: May 12, 2005
Creator: Powers, Kyna
Object Type: Report
System: The UNT Digital Library
Upper Mississippi River System: Proposals to Restore an Inland Waterway’s Ecosystem (open access)

Upper Mississippi River System: Proposals to Restore an Inland Waterway’s Ecosystem

This report explains what is meant by restoration, the Corps' restoration plan, and some of the issues in the debate over federal investment in this restoration.
Date: May 12, 2005
Creator: Powers, Kyna & Carter, Nicole T.
Object Type: Report
System: The UNT Digital Library
Indexing Social Security Benefits: The Effects of Price and Wage Indexes (open access)

Indexing Social Security Benefits: The Effects of Price and Wage Indexes

None
Date: May 12, 2005
Creator: Purcell, Patrick; Haltzel, Laura & Ranade, Neela
Object Type: Report
System: The UNT Digital Library
Verification of high-order mixed FEM solution of transient Magnetic diffusion problems (open access)

Verification of high-order mixed FEM solution of transient Magnetic diffusion problems

We develop and present high order mixed finite element discretizations of the time dependent electromagnetic diffusion equations for solving eddy current problems on 3D unstructured grids. The discretizations are based on high order H(grad), H(curl) and H(div) conforming finite element spaces combined with an implicit and unconditionally stable generalized Crank-Nicholson time differencing method. We develop three separate electromagnetic diffusion formulations, namely the E (electric field), H (magnetic field) and the A-{phi} (potential) formulations. For each formulation, we also provide a consistent procedure for computing the secondary variables F (current flux density) and B (magnetic flux density), as these fields are required for the computation of electromagnetic force and heating terms. We verify the error convergence properties of each formulation via a series of numerical experiments on canonical problems with known analytic solutions. The key result is that the different formulations are equally accurate, even for the secondary variables J and B, and hence the choice of which formulation to use depends mostly upon relevance of the Natural and Essential boundary conditions to the problem of interest. In addition, we highlight issues with numerical verification of finite element methods which can lead to false conclusions on the accuracy of the methods.
Date: May 12, 2005
Creator: Rieben, R. & White, D. A.
Object Type: Article
System: The UNT Digital Library