States

The Rapid Cycling Medical Synchrotron RCMS. (open access)

The Rapid Cycling Medical Synchrotron RCMS.

Thirteen hadron beam therapy facilities began operation between 1990 and 2001 - 5 in Europe, 4 in North America, 3 in Japan, and 1 in South Africa [l]. Ten of them irradiate tumors with protons, 2 with Carbon- 12 ions, and 1 with both protons and Carbon-12. The facility with the highest patient throughput - a total of 6 174 patients in 11 years and as many as 150 patient treatments per day -is the Loma Linda University Medical Center, which uses a weak focusing slow cycling synchrotron to accelerate beam for delivery to passive scattering nozzles at the end of rotatable gantries [2, 3,4]. The Rapid Cycling Medical Synchrotron (RCMS) is a second generation synchrotron that, by contrast with the Loma Linda synchrotron, is strong focusing and rapid cycling, with a repetition rate of 30 Hz. Primary parameters for the RCMS are listed in Table 1.
Date: June 2, 2002
Creator: Peggs, S.; Barton, D.; Beebe-Wang, J.; Cardona, J.; Brennan, M.; Fischer, W. et al.
Object Type: Article
System: The UNT Digital Library
Experimental Results in Support of Simulating Progressive Crush in Carbon-Fiber Textile Composites (open access)

Experimental Results in Support of Simulating Progressive Crush in Carbon-Fiber Textile Composites

This report summarizes the findings of an experimental program conducted to support the modeling of the crush behavior of triaxial braid carbon fiber composites. The matrix material as well as braided panels and tubes were characterized in order to determine material properties, to assess failure modes, and to provide a test bed for new analytical and numerical tools developed specifically for braided composites. The matrix material selected by the ACC was an epoxy vinyl ester (Ashland Hetron 922). Tensile tests were used to compare two formulations-one used by the ACC and one recommended by the resin supplier. The latter was a faster reacting system and gelled in one-third the time of the ACC formulation. Both formulations had an average elongation at failure that was only half of the resin supplier's reported value. Only one specimen of each type came close to the reported elongation value and it was shown that failure invariably initiated at both surface and internal defects. Overall, the tensile properties of the two formulations were nearly identical, but those of the ACC system were more consistent. The properties of the ACC matrix formulation were measured in tension, shear, and compression and the average properties obtained in these …
Date: April 2, 2001
Creator: DeTeresa, S J; Allison, L M; Cunningham, B J; Freeman, DC; Saculla, M D; Sanchez, R J et al.
Object Type: Report
System: The UNT Digital Library
Changes of the spin dynamics in perovskite and bilayer manganite. (open access)

Changes of the spin dynamics in perovskite and bilayer manganite.

The authors report a series of {micro}SR measurements performed on single crystals of La{sub 1-x}Sr{sub x}MnO{sub 3} (0 {le} x {le} 0.125) and on a polycrystalline bilayer manganite La{sub 2-2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7} (x = 0.52). They find that the temperature dependence of the spin-lattice relaxation rate is strongly dependent on the hole doping and the associated changes in the magnetic structure. The systems have competing, anisotropic interactions, leading to a complex interplay of charge, spin and orbital order. This has a significant influence on the spin dynamics, both for perovskite and layered manganites.
Date: July 2, 2002
Creator: Coldea, A. I.; Blundell, S. J.; Steer, C. A.; Pratt, F. L.; Prabhakaran, D. & Mitchell, J. F.
Object Type: Article
System: The UNT Digital Library
ISCR FY2005 Annual Report (open access)

ISCR FY2005 Annual Report

Large-scale scientific computation and all of the disciplines that support and help validate it have been placed at the focus of Lawrence Livermore National Laboratory (LLNL) by the Advanced Simulation and Computing (ASC) program of the National Nuclear Security Administration (NNSA) and the Scientific Discovery through Advanced Computing (SciDAC) initiative of the Office of Science of the Department of Energy (DOE). The maturation of simulation as a fundamental tool of scientific and engineering research is underscored in the President's Information Technology Advisory Committee (PITAC) June 2005 finding that ''computational science has become critical to scientific leadership, economic competitiveness, and national security''. LLNL operates several of the world's most powerful computers--including today's single most powerful--and has undertaken some of the largest and most compute-intensive simulations ever performed, most notably the molecular dynamics simulation that sustained more than 100 Teraflop/s and won the 2005 Gordon Bell Prize. Ultrascale simulation has been identified as one of the highest priorities in DOE's facilities planning for the next two decades. However, computers at architectural extremes are notoriously difficult to use in an efficient manner. Furthermore, each successful terascale simulation only points out the need for much better ways of interacting with the resulting avalanche of …
Date: February 2, 2006
Creator: Keyes, D E & McGraw, J R
Object Type: Report
System: The UNT Digital Library
Dynamic neurotransmitter interactions measured with PET (open access)

Dynamic neurotransmitter interactions measured with PET

Positron emission tomography (PET) has become a valuable interdisciplinary tool for understanding physiological, biochemical and pharmacological functions at a molecular level in living humans, whether in a healthy or diseased state. The utility of tracing chemical activity through the body transcends the fields of cardiology, oncology, neurology and psychiatry. In this, PET techniques span radiochemistry and radiopharmaceutical development to instrumentation, image analysis, anatomy and modeling. PET has made substantial contributions in each of these fields by providing a,venue for mapping dynamic functions of healthy and unhealthy human anatomy. As diverse as the disciplines it bridges, PET has provided insight into an equally significant variety of psychiatric disorders. Using the unique quantitative ability of PET, researchers are now better able to non-invasively characterize normally occurring neurotransmitter interactions in the brain. With the knowledge that these interactions provide the fundamental basis for brain response, many investigators have recently focused their efforts on an examination of the communication between these chemicals in both healthy volunteers and individuals suffering from diseases classically defined as neurotransmitter specific in nature. In addition, PET can measure the biochemical dynamics of acute and sustained drug abuse. Thus, PET studies of neurotransmitter interactions enable investigators to describe a multitude …
Date: April 2, 2001
Creator: Schiffer, W. K. & Dewey, S. L.
Object Type: Book
System: The UNT Digital Library
Spin Coupling Resonance Study in AGS. (open access)

Spin Coupling Resonance Study in AGS.

In the AGS spin resonances due to coupling may account for as much as a 50 percent loss in polarization at a reduced acceleration rate. The major source of coupling in the AGS is the solenoidal snake. In the past some preliminary work was done to understand this phenomena, and a method to overcome these resonances was attempted. However in the polarized proton run of 2002 we sought to study more thoroughly the response of these coupled spin resonances to the strength of the solenoidal snake, skew quadrupoles and vertical and horizontal betatron tune separation. In this paper we present our results and compare them with those predicted by a modified DEPOL program.
Date: June 2, 2002
Creator: Ranjbar, V.; Ahrens, L.; Bai, M.; Brown, K.; Glenn, W.; Huang, H. et al.
Object Type: Article
System: The UNT Digital Library
ACCELERATING POLARIZED PROTONS TO HIGH ENERGY. (open access)

ACCELERATING POLARIZED PROTONS TO HIGH ENERGY.

The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.
Date: October 2, 2006
Creator: Bai, M.; Ahrens, L.; Alekseev, I. G.; Alessi, J.; Beebe-Wang, J.; Blaskiewicz, M. et al.
Object Type: Article
System: The UNT Digital Library
Chemical Technology Division annual technical report, 2001. (open access)

Chemical Technology Division annual technical report, 2001.

The Chemical Technology Division (CMT) is one of eight engineering research divisions within Argonne National Laboratory, one of the U.S. government's oldest and largest research laboratories. The University of Chicago oversees the laboratory on behalf of the U.S. Department of Energy (DOE). Argonne's mission is to conduct basic scientific research, to operate national scientific facilities, to enhance the nation's energy resources, and to develop better ways to manage environmental problems. Argonne has the further responsibility of strengthening the nation's technology base by developing innovative technology and transferring it to industry. CMT is a diverse early-stage engineering organization, specializing in the treatment of spent nuclear fuel, development of advanced electrochemical power sources, and management of both high- and low-level nuclear wastes. Although this work is often indistinguishable from basic research, our efforts are directed toward the practical devices and processes that are covered by Argonne's mission. Additionally, the Division operates the Analytical Chemistry Laboratory and Environment, Safety, and Health Analytical Chemistry services, which provide a broad range of analytical services to Argonne and other organizations. The Division is multidisciplinary. Its people have formal training as ceramists; physicists; material scientists; electrical, mechanical, chemical, and nuclear engineers; and chemists. They have experience working …
Date: July 2, 2002
Creator: Lewis, D.; Gay, E. C.; Miller, J. C. & Boparai, A. S.
Object Type: Report
System: The UNT Digital Library
Spatial Uncertainty Analysis of Ecological Models (open access)

Spatial Uncertainty Analysis of Ecological Models

The authors evaluated the sensitivity of a habitat model and a source-sink population model to spatial uncertainty in landscapes with different statistical properties and for hypothetical species with different habitat requirements. Sequential indicator simulation generated alternative landscapes from a source map. Their results showed that spatial uncertainty was highest for landscapes in which suitable habitat was rare and spatially uncorrelated. Although, they were able to exert some control over the degree of spatial uncertainty by varying the sampling density drawn from the source map, intrinsic spatial properties (i.e., average frequency and degree of spatial autocorrelation) played a dominant role in determining variation among realized maps. To evaluate the ecological significance of landscape variation, they compared the variation in predictions from a simple habitat model to variation among landscapes for three species types. Spatial uncertainty in predictions of the amount of source habitat depended on both the spatial life history characteristics of the species and the statistical attributes of the synthetic landscapes. Species differences were greatest when the landscape contained a high proportion of suitable habitat. The predicted amount of source habitat was greater for edge-dependent (interior) species in landscapes with spatially uncorrelated(correlated) suitable habitat. A source-sink model demonstrated that, although …
Date: September 2, 2000
Creator: Jager, H.I.; Ashwood, T.L.; Jackson, B.L. & King, A.W.
Object Type: Article
System: The UNT Digital Library
Vadose Zone Transport Field Study: FY 2002 Status Report (open access)

Vadose Zone Transport Field Study: FY 2002 Status Report

This work reported here is part of the U. S. Department of Energy’s Science and Technology Initiative to develop improved conceptual models of flow and transport in the vadose zone, particularly for the Hanford Site, Washington. The National Academy of Sciences has identified significant knowledge gaps in conceptual model development as one reason for discovery of subsurface contamination in unexpected places. Inadequate conceptualizations limits, not only the understanding of long-term fate and transport, but also the selection and design of remediation technologies. Current conceptual models are limited partly because they do not account for the random heterogeneity that occurs under the extremes of very nonlinear flow behavior typical of the Hanford vadose zone. A major improvement in conceptual modeling of the Hanford vadose zone includes a better understanding and description of soil anisotropy, a property that appears to control much of the subsurface flow and transport in layered sediments at the Hanford Site.
Date: January 2, 2003
Creator: Ward, Anderson L.; Gee, Glendon W.; Zhang, Z. F. & Keller, Jason M.
Object Type: Report
System: The UNT Digital Library
Discovery of a 66 mas Ultracool Binary with Laser Guide Star Adaptive Optics (open access)

Discovery of a 66 mas Ultracool Binary with Laser Guide Star Adaptive Optics

We present the discovery of 2MASS J21321145+1341584AB as a closely separated (0.066'') very low-mass field dwarf binary resolved in the near-infrared by the Keck II Telescope using laser guide star adaptive optics. Physical association is deduced from the angular proximity of the components and constraints on their common proper motion. We have obtained a near-infrared spectrum of the binary and find that it is best described by an L5{+-}0.5 primary and an L7.5{+-}0.5 secondary. Model-dependent masses predict that the two components straddle the hydrogen burning limit threshold with the primary likely stellar and the secondary likely substellar. The properties of this sytem - close projected separation (1.8{+-}0.3AU) and near unity mass ratio - are consistent with previous results for very low-mass field binaries. The relatively short estimated orbital period of this system ({approx}7-12 yr) makes it a good target for dynamical mass measurements. Interestingly, the system's angular separation is the tightest yet for any very low-mass binary published from a ground-based telescope and is the tightest binary discovered with laser guide star adaptive optics to date.
Date: February 2, 2007
Creator: Siegler, N; Close, L; Burgasser, A; Cruz, K; Marois, C; Macintosh, B et al.
Object Type: Article
System: The UNT Digital Library
Hydrodynamic phenomena of gas-filled chamber due to target implosion in fusion reactors. (open access)

Hydrodynamic phenomena of gas-filled chamber due to target implosion in fusion reactors.

Use of an intermediate gas in the reaction chamber of an inertial fusion power reactor is under consideration to decrease the thermal shock to the walls resulting from target implosions. A model was developed and implemented in HEIGHTS package to simulate hydrodynamic and radiation shock waves in the chamber and used to determine the effect of xenon gas at various densities ranging from mtorr up to tens of torr. Numerical calculations for the dense-gas case indicated that two pressure peaks result from the shock wave interacting with the chamber wall, and radiation energy accumulates directly in front of the hydrodynamic shock wave. The shock wave should reach a maximum pressure peak when the chamber gas has a density between the two extremes analyzed. In general, calculated results with our model compared favorably with previously published data.
Date: July 2, 2003
Creator: Sizyuk, V. & Hassanein, A.
Object Type: Report
System: The UNT Digital Library
Laboratory Directed Research and Development FY2002 Annual Report (open access)

Laboratory Directed Research and Development FY2002 Annual Report

None
Date: May 2, 2003
Creator: Al-Ayat, R
Object Type: Report
System: The UNT Digital Library
Proceedings of the 3rd US-Japan Workshop on Plasma Polarization Spectroscopy (open access)

Proceedings of the 3rd US-Japan Workshop on Plasma Polarization Spectroscopy

The third US-Japan Workshop on Plasma Polarization Spectroscopy was held at the Lawrence Livermore National Laboratory in Livermore, California, on June 18-21, 2001. The talks presented at this workshop are summarized in these proceedings. The papers cover both experimental investigation and applications of plasma polarization spectroscopy as well as the theoretical foundation and formalisms to understand and describe the polarization phenomena. The papers give an overview of the history of plasma polarization spectroscopy, derive the formal aspects of polarization spectroscopy, including the effects of electric and magnetic fields, discuss spectra perturbed by intense microwave fields, charge exchange, and dielectronic recombination, and present calculations of various collisional excitation and ionization cross sections and the modeling of plasma polarization spectroscopy phenomena. Experimental results are given from the WT-3 tokamak, the MST reverse field pinch, the Large Helical Device, the GAMMA 10 mirror machine, the Nevada Terrawatt Facility, the Livermore EBIT-II electron beam ion trap, and beam-foil spectroscopy. In addition, results were presented from studies of several laser-produced plasma experiments and new instrumental techniques were demonstrated.
Date: January 2, 2002
Creator: Beiersdorfer, P & Flyimoto, T
Object Type: Report
System: The UNT Digital Library
Scanning Hall Probe Microscopy of Magnetic Vortices inVery Underdoped yttrium-barium-copper-oxide (open access)

Scanning Hall Probe Microscopy of Magnetic Vortices inVery Underdoped yttrium-barium-copper-oxide

Since their discovery by Bednorz and Mueller (1986), high-temperature cuprate superconductors have been the subject of intense experimental research and theoretical work. Despite this large-scale effort, agreement on the mechanism of high-T{sub c} has not been reached. Many theories make their strongest predictions for underdoped superconductors with very low superfluid density n{sub s}/m*. For this dissertation I implemented a scanning Hall probe microscope and used it to study magnetic vortices in newly available single crystals of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} (Liang et al. 1998, 2002). These studies have disproved a promising theory of spin-charge separation, measured the apparent vortex size (an upper bound on the penetration depth {lambda}{sub ab}), and revealed an intriguing phenomenon of ''split'' vortices. Scanning Hall probe microscopy is a non-invasive and direct method for magnetic field imaging. It is one of the few techniques capable of submicron spatial resolution coupled with sub-{Phi}{sub 0} (flux quantum) sensitivity, and it operates over a wide temperature range. Chapter 2 introduces the variable temperature scanning microscope and discusses the scanning Hall probe set-up and scanner characterizations. Chapter 3 details my fabrication of submicron GaAs/AlGaAs Hall probes and discusses noise studies for a range of probe sizes, which suggest …
Date: December 2, 2005
Creator: Guikema, Janice Wynn & /SLAC, SSRL
Object Type: Report
System: The UNT Digital Library
Photoproduction of charm pairs (open access)

Photoproduction of charm pairs

A large sample of events containing fully and partially reconstructed pairs of charmed D mesons has been studied by the Fermilab photoproduction experiment FOCUS (FNAL-E831). Correlations between photoproduced D and {bar D} mesons are used to study heavy quark production dynamics. Correlation results are presented for fully and partially reconstructed pairs of charmed D mesons. The results are compared to Monte Carlo predictions based on a recent version of PYTHIA with default settings.
Date: September 2, 2003
Creator: Gottschalk, Erik E
Object Type: Article
System: The UNT Digital Library
Moisture characteristics of Hanford gravels: Bulk, grain-surface, and intragranular components (open access)

Moisture characteristics of Hanford gravels: Bulk, grain-surface, and intragranular components

None
Date: May 2, 2003
Creator: Tokunaga, Tetsu K.; Olson, Keith R. & Wan, Jiamin
Object Type: Article
System: The UNT Digital Library
Connecting Galaxies, Halos, and Star Formation Rates Across Cosmic Time (open access)

Connecting Galaxies, Halos, and Star Formation Rates Across Cosmic Time

A simple, observationally-motivated model is presented for understanding how halo masses, galaxy stellar masses, and star formation rates are related, and how these relations evolve with time. The relation between halo mass and galaxy stellar mass is determined by matching the observed spatial abundance of galaxies to the expected spatial abundance of halos at multiple epochs--i.e. more massive galaxies are assigned to more massive halos at each epoch. This 'abundance matching' technique has been shown previously to reproduce the observed luminosity- and scale-dependence of galaxy clustering over a range of epochs. Halos at different epochs are connected by halo mass accretion histories estimated from N-body simulations. The halo-galaxy connection at fixed epochs in conjunction with the connection between halos across time provides a connection between observed galaxies across time. With approximations for the impact of merging and accretion on the growth of galaxies, one can then directly infer the star formation histories of galaxies as a function of stellar and halo mass. This model is tuned to match both the observed evolution of the stellar mass function and the normalization of the observed star formation rate--stellar mass relation to z {approx} 1. The data demands, for example, that the star …
Date: June 2, 2008
Creator: Conroy, Charlie & Wechsler, Risa H.
Object Type: Article
System: The UNT Digital Library
Congressional Investigations: Subpoenas and Contempt Power (open access)

Congressional Investigations: Subpoenas and Contempt Power

When conducting investigations of the executive branch, congressional committees and Members of Congress generally receive the information required for legislative needs. If agencies fail to cooperate or the President invokes executive privilege, Congress can turn to a number of legislative powers that are likely to compel compliance. The two techniques described in this report are the issuance of subpoenas and the holding of executive officials in contempt. These techniques usually lead to an accommodation that meets the needs of both branches. Litigation is used at times, but federal judges generally encourage congressional and executive parties to settle their differences out of court. The specific examples in this report explain how information disputes arise and how they are resolved.
Date: April 2, 2003
Creator: Fisher, Louis
Object Type: Report
System: The UNT Digital Library
In situ nanoindentation in a transmission electron microscope (open access)

In situ nanoindentation in a transmission electron microscope

This dissertation presents the development of the novel mechanical testing technique of in situ nanoindentation in a transmission electron microscope (TEM). This technique makes it possible to simultaneously observe and quantify the mechanical behavior of nano-scale volumes of solids.
Date: December 2, 2002
Creator: Minor, Andrew M.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Plant Wide Assessment for Johns Manville Waterville Ohio Plant 1 (open access)

Plant Wide Assessment for Johns Manville Waterville Ohio Plant 1

The report describes activites carried out at the palnt to identify energy savings in various energy user systems. The results list areas of energy savings potential and metods of energy savings.
Date: July 2, 2006
Creator: Kissock, Kelly & Thekdi, Arvind
Object Type: Report
System: The UNT Digital Library
Privacy: An Overview of Federal Statutes Governing Wiretapping and Electronic Eavesdropping (open access)

Privacy: An Overview of Federal Statutes Governing Wiretapping and Electronic Eavesdropping

This report provides an overview of federal law governing wiretapping and electronic eavesdropping. It also appends citations to state law in the area and contains a bibliography of legal commentary as well as the text of the Electronic Communications Privacy Act (ECPA) and the Foreign Intelligence Surveillance Act (FISA). This report also includes a brief summary of the recently expired Protect America Act, P.L. 110-55 and of the Foreign Intelligence Surveillance Act of 1978 Amendments Act of 2008, P.L. 110-261 (H.R. 6304).
Date: September 2, 2008
Creator: Stevens, Gina & Doyle, Charles
Object Type: Report
System: The UNT Digital Library
The CoStar Office Report Mid-Year 2004 (open access)

The CoStar Office Report Mid-Year 2004

The CoStar Office Report Mid-Year 2004 Washington, D.C. Office Market. From the CoStar Group(Real Estate Information).
Date: August 2, 2005
Creator: United States. Department of Defense.
Object Type: Book
System: The UNT Digital Library
BRAC  Public Affairs Issue Book Office of Communications Commissioner's Issue Book (open access)

BRAC Public Affairs Issue Book Office of Communications Commissioner's Issue Book

BRAC Public Affairs Issue Book Office of Communications Commissioner's Issue Book
Date: November 2, 2005
Creator: United States. Defense Base Closure and Realignment Commission.
Object Type: Book
System: The UNT Digital Library