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.
System: The UNT Digital Library
Sodium laser guide star system at Lawrence Livermore National Laboratory: System description and experimental results (open access)

Sodium laser guide star system at Lawrence Livermore National Laboratory: System description and experimental results

The architecture and major system components of the sodium-layer kw guide star system at LLNL will be described, and experimental results reported. The subsystems include the laser system, the beam delivery system including a pulse stretcher and beam pointing control, the beam director, and the telescope with its adaptive-optics package. The laser system is one developed for the Atomic Vapor Laser Isotope Separation (AVLIS) Program. This laser system can be configured in various ways in support of the AVLIS program objectives, and was made available to the guide star program at intermittent times on a non-interference basis. The first light transmitted into the sky was in July of 1992, at a power level of 1. 1 kW. The laser pulse width is about 32 ns, and the pulse repetition rate was 26 kHz for the 1. 1 kW configuration and 13 kHz for a 400 W configuration. The laser linewidth is tailored to match the sodium D{sub 2} absorption line, and the laser system has active control of beam pointing and wavefront quality. Because of the short pulse length the sodium transition is saturated and the laser power is not efficiently utilized. For this reason a pulse stretcher was developed, …
Date: March 2, 1994
Creator: Avicola, K.; Brase, J. & Morris, J.
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.
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.
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.
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.
System: The UNT Digital Library
Stand-alone microprobe at Livermore (open access)

Stand-alone microprobe at Livermore

Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories/California have jointly constructed a new stand-alone microprobe facility. Although the facility was built to develop a method to rapidly locate and determine elemental concentrations of micron scale particulates on various media using PIXE, the facility has found numerous applications in biology and materials science. The facility is located at LLNL and uses a General Ionex Corporation Model 358 duoplasmatron negative ion source, a National Electrostatics Corporation 5SDH-2 tandem accelerator, and an Oxford triplet lens. Features of the system include complete computer control of the beam transport using LabVIEW<sup>TM</sup> for Macintosh, computer controlled beam collimating and divergence limiting slits, automated sample positioning to micron resolution, and video optics for beam positioning and sample observation. Data collection is accomplished with the simultaneous use of as many as four EG&G Ortec IGLET-X<sup>TM</sup> X-Ray detectors, digital amplifiers made by X-Ray Instruments and Associates (XIA), and LabVIEW<sup>TM</sup> for Macintosh acquisition software.
Date: October 2, 1998
Creator: Antolak, A. J.; Bench, G. S.; Brown, T. A.; Frantz, B. R.; Grant, P. G.; Morse, D. H. et al.
System: The UNT Digital Library
A cytoskeletal function for PBRM1 reading methylated microtubules (open access)

A cytoskeletal function for PBRM1 reading methylated microtubules

This article shows that that the coordinated read-write activity of the epigenetic machinery extends to the cytoskeleton, with PBRM1 in the PBAF chromatin remodeling complex reading microtubule methyl marks written by the SETD2 histone methyltransferase. This article opens a previously unknown window into how chromatin remodeler defects can drive disease via both epigenetic and cytoskeletal dysfunction.
Date: April 2, 2021
Creator: Karki, Menuka; Jangid, Rahul K.; Anish, Ramakrishnan; Seervai, Riyad N. H.; Bertocchio, Jean-Phillipe; Hotta, Takashi et al.
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.
System: The UNT Digital Library
An approach for reliably identifying high-frequency oscillations and reducing false-positive detections (open access)

An approach for reliably identifying high-frequency oscillations and reducing false-positive detections

Article states that high-frequency oscillation (HFO), classified as ripples (80-240 Hz) and fast ripples (240-500 Hz), is regarded as a promising biomarker of epilepsy. The authors presented an integrated, multi-layered procedure capable of automatically rejecting HFOs from a variety of common false positives, such as motion, background signals, and sharp transients.
Date: September 2, 2022
Creator: Zhou, Yufeng; You, Jing; Kumar, Udaya; Weiss, Shennan A.; Bragin, Anatol; Engel Jr., Jerome et al.
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
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
System: The UNT Digital Library
Sensing Current and Forces with SPM (open access)

Sensing Current and Forces with SPM

Atomic force microscopy (AFM) and scanning tunneling microscopy (STM) are well established techniques to image surfaces and to probe material properties at the atomic and molecular scale. In this review, we show hybrid combinations of AFM and STM that bring together the best of two worlds: the simultaneous detection of atomic scale forces and conduction properties. We illustrate with several examples how the detection of forces during STM and the detection of currents during AFM can give valuable additional information of the nanoscale material properties.
Date: July 2, 2010
Creator: Park, Jeong Y.; Maier, Sabine; Hendriksen, Bas & Salmeron, Miquel
System: The UNT Digital Library
Benchmarking Metagenomic Classifiers on Simulated Ancient and Modern Metagenomic Data (open access)

Benchmarking Metagenomic Classifiers on Simulated Ancient and Modern Metagenomic Data

Article describes how taxonomic profiling of ancient metagenomic samples is challenging due to the accumulation of specific damage patterns on DNA over time. The authors performed a comprehensive evaluation on simulated metagenomes representing human dental calculus microbiome, with the level of DNA damage successively raised to mimic modern to ancient metagenomes.
Date: October 2, 2023
Creator: Pusadkar, Vaidehi & Azad, Rajeev K.
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.
System: The UNT Digital Library
Jet Mass and Substructure of Inclusive Jets in $\sqrt{s}=7$ TeV $Pp$ Collisions with the ATLAS Experiment (open access)

Jet Mass and Substructure of Inclusive Jets in $\sqrt{s}=7$ TeV $Pp$ Collisions with the ATLAS Experiment

None
Date: April 2, 2013
Creator: Aad, Georges
System: The UNT Digital Library