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Science and Technology Review June 2005
This is the articles in this month's issue: (1) Close Collaborations Advance Progress in Genomic Research--Commentary by Elbert Branscomb; (2) Mining Genomes--Livermore computer programs help locate the stretches of DNA in gene deserts that regulate protein-making genes; (3) Shedding Light on Quantum Physics--Laboratory laser research builds from the foundation of Einstein's description of the quantization of light. (4) The Sharper Image for Surveillance--Speckle imaging-an image-processing technique used in astronomy is bringing long-distance surveillance into sharper focus. (5) Keeping Cool Close to the Sun--The specially coated gamma-ray spectrometer aboard the MESSENGER spacecraft will help scientists determine the abundance of elements in Mercury's crust.
Date:
May 3, 2005
Creator:
Aufderheide, M
Object Type:
Report
System:
The UNT Digital Library
Analysis of Fabry-Perot Velocimeter Records
Program demonstration and user instructions are presented for FabryVB5. This computer program was created for use in analyzing Fabry-Perot interferometer records that detail the velocity time histories of fast moving surfaces. Graphical curves representing peak fringe positions and fiducial timing dots are extracted from a digitized film record or from a CCD digital image. An analysis is demonstrated on a sample velocimeter record along with some mathematical formula and routine operations. Routines used to analyze calibration records on streak camera distortions are illustrated in an appendix. This is a Microsoft Visual Basic{trademark} version for the PC.
Date:
August 3, 2001
Creator:
Avara, G.
Object Type:
Report
System:
The UNT Digital Library
Mid infrared observations of Van Maanen 2: no substellar companion.
The results of a comprehensive infrared imaging search for the putative 0.06 M{sub {circle_dot}} astrometric companion to the 4.4 pc white dwarf van Mannen 2 are reported. Adaptive optics images acquired at 3.8 {micro}m reveal a diffraction limited core of 0.09 inch and no direct evidence of a secondary. Models predict that at 5 Gyr, a 50 M{sub J} brown dwarf would be only 1 magnitude fainter than van Maanen 2 at this wavelength and the astrometric analysis suggested a separation of 0.2 inch. In the case of a chance alignment along the line of sight, a 0.4 mag excess should be measured. An independent photometric observation at the same wavelength reveals no excess. In addition, there exist published ISO observations of van Maanen 2 at 6.8 {micro}m and 15.0 {micro}m which are consistent with photospheric flux of a 6750 K white dwarf. If recent brown dwarf models are correct, there is no substellar companion with T{sub eff} {approx}> 500 K.
Date:
November 3, 2004
Creator:
Farihi, J; Becklin, E & Macintosh, B
Object Type:
Article
System:
The UNT Digital Library
Reviewers Comments on the 5th Symposium and the Status of Fusion Research 2003
Better to understand the status of fusion research in the year 2003 we will first put the research in its historical context. Fusion power research, now beginning its sixth decade of continuous effort, is unique in the field of scientific research. Unique in its mixture of pure and applied research, unique in its long-term goal and its promise for the future, and unique in the degree that it has been guided and constrained by national and international governmental policy. Though fusion research's goal has from the start been precisely defined, namely, to obtain a net release of energy from controlled nuclear fusion reactions between light isotopes (in particular those of hydrogen and helium) the difficulty of the problem has spawned in the past a very wide variety of approaches to the problem. Some of these approaches have had massive international support for decades, some have been pursued only at a ''shoestring'' level by dedicated groups in small research laboratories or universities. In discussing the historical and present status of fusion research the implications of there being two distinctly different approaches to achieving net fusion power should be pointed out. The first, and oldest, approach is the use of strong magnetic …
Date:
February 3, 2005
Creator:
Post, R F
Object Type:
Article
System:
The UNT Digital Library
Hyperspectral Mineral Mapping in Support of Geothermal Exploration: Examples from Long Valley Caldera, CA and Dixie Valley, NV, USA
Growing interest and exploration dollars within the geothermal sector have paved the way for increasingly sophisticated suites of geophysical and geochemical tools and methodologies. The efforts to characterize and assess known geothermal fields and find new, previously unknown resources has been aided by the advent of higher spatial resolution airborne geophysics (e.g. aeromagnetics), development of new seismic processing techniques, and the genesis of modern multi-dimensional fluid flow and structural modeling algorithms, just to name a few. One of the newest techniques on the scene, is hyperspectral imaging. Really an optical analytical geochemical tool, hyperspectral imagers (or imaging spectrometers as they are also called), are generally flown at medium to high altitudes aboard mid-sized aircraft and much in the same way more familiar geophysics are flown. The hyperspectral data records a continuous spatial record of the earth's surface, as well as measuring a continuous spectral record of reflected sunlight or emitted thermal radiation. This high fidelity, uninterrupted spatial and spectral record allows for accurate material distribution mapping and quantitative identification at the pixel to sub-pixel level. In volcanic/geothermal regions, this capability translates to synoptic, high spatial resolution, large-area mineral maps generated at time scales conducive to both the faster pace of …
Date:
March 3, 2004
Creator:
Pickles, W. L.; Martini, B. A.; Silver, E. A. & Cocks, P. A.
Object Type:
Article
System:
The UNT Digital Library
Seismic Velocities Contain Information About Depth, Lithology, Fluid Content, and Microstructure
Recent advances in field and laboratory methods for measuring elastic wave velocities provide incentive and opportunity for improving interpretation of geophysical data for engineering and environmental applications. Advancing the state-of-the-art of seismic imaging requires developing petrophysical relationships between measured velocities and the hydrogeology parameters and lithology. Our approach uses laboratory data and rock physics methods. Compressional (Vp) and shear (Vs) wave velocities, Vp/Vs ratios, and relative wave amplitudes show systematic changes related to composition, saturation, applied stress (analogous to depth), and distribution of clay for laboratory ultrasonic measurements on soils. The artificial soils were mixtures of Ottawa sand and a second phase, either Wyoming bentonite or peat moss used to represent clay or organic components found in natural soils. Compressional and shear wave velocities were measured for dry, saturated, and partially-saturated conditions, for applied stresses between about 7 and 100 kPa, representing approximately the top 5 m of the subsurface. Analysis of the results using rock physics methods shows the link between microstructure and wave propagation, and implications for future advances in seismic data interpretation. For example, we found that Vp in dry sand-clay mixtures initially increases as clay cements the sand grains and fills porosity, but then Vp decreases …
Date:
January 3, 2002
Creator:
Berge, P A & Bonner, B P
Object Type:
Article
System:
The UNT Digital Library
Implicit Occluders
In this paper we propose a novel visibility-culling technique for optimizing the computation and rendering of opaque isosurfaces. Given a continuous scalar field f (x) over a domain D and an isovalue w, our technique exploits the continuity of f to determine conservative visibility bounds implicitly, i.e., without the need for actually computing the isosurface f{sup -1}(w). We generate Implicit Occluders based on the change in sign of f *(x) = f (x)-w, from positive to negative (or vice versa) in the neighborhood of the isosurface. Consider, for example, the sign of f * along a ray r cast from the current viewpoint. The first change in sign of f * within D must contain an intersection of r with the isosurface. Any additional intersection of the isosurface with r is not visible. Implicit Occluders constitute a general concept that can be exploited algorithmically in different ways depending on the framework adopted for visibility computations. In this paper, we propose a simple from-point approach that exploits well-known hardware occlusion queries.
Date:
February 3, 2004
Creator:
Pesco, S; Lindstrom, P; Pascucci, V & Silva, C T
Object Type:
Article
System:
The UNT Digital Library
Passive Seismic Monitoring for Rockfall at Yucca Mountain: Concept Tests
For the purpose of proof-testing a system intended to remotely monitor rockfall inside a potential radioactive waste repository at Yucca Mountain, a system of seismic sub-arrays will be deployed and tested on the surface of the mountain. The goal is to identify and locate rockfall events remotely using automated data collecting and processing techniques. We install seismometers on the ground surface, generate seismic energy to simulate rockfall in underground space beneath the array, and interpret the surface response to discriminate and locate the event. Data will be analyzed using matched-field processing, a generalized beam forming method for localizing discrete signals. Software is being developed to facilitate the processing. To date, a three-component sub-array has been installed and successfully tested.
Date:
March 3, 2003
Creator:
Cheng, J.; Twilley, K.; Murvosh, H.; Tu, Y.; Luke, B.; Yfantis, A. et al.
Object Type:
Article
System:
The UNT Digital Library
Climate Model Output Rewriter (CMOR)
None
Date:
June 3, 2004
Creator:
Taylor, K E; Doutriaux, C & Peterschmitt, J
Object Type:
Report
System:
The UNT Digital Library
Sheath Physics and Boundary Conditions for Edge Plasmas
The boundary conditions of mass, momentum, energy, and charge appropriate for fluid formulations of edge plasmas are surveyed. We re-visit the classic problem of 1-dimensional flow, and note that the ''Bohm sheath criterion'' is requirement of connectivity of the interior plasma with the external world, not the result of termination of the plasma by a wall. We show that the nature of the interior plasma solution is intrinsically different for ion sources that inject above and below the electron sound speed. We survey the appropriate conditions to apply, and resultant fluxes, for a magnetic field obliquely incident on a wall, including the presence of drifts and radial transport. We discuss the consequences of toroidal asymmetries in wall properties, as well as experimental tests of such effects. Finally, we discuss boundary-condition modifications in the case of rapidly varying plasma conditions.
Date:
September 3, 2003
Creator:
Cohen, R. H. & Ryutov, D. D.
Object Type:
Article
System:
The UNT Digital Library
LORENTZ PHASE IMAGING AND IN-SITU LORENTZ MICROSCOPY OF PATTERNED CO-ARRAYS.
Understanding magnetic structures and properties of patterned and ordinary magnetic films at nanometer length-scale is the area of immense technological and fundamental scientific importance. The key feature to such success is the ability to achieve visual quantitative information on domain configurations with a maximum ''magnetic'' resolution. Several methods have been developed to meet these demands (Kerr and Faraday effects, differential phase contrast microscopy, magnetic force microscopy, SEMPA etc.). In particular, the modern off-axis electron holography allows retrieval of the electron-wave phase shifts down to 2{pi}/N (with typical N = 10-20, approaching in the limit N {approx} 100) in TEM equipped with field emission gun, which is already successfully employed for studies of magnetic materials at nanometer scale. However, it remains technically demanding, sensitive to noise and needs highly coherent electron sources. As possible alternative we developed a new method of Lorentz phase microscopy [1,2] based on the Fourier solution [3] of magnetic transport-of-intensity (MTIE) equation. This approach has certain advantages, since it is less sensitive to noise and does not need high coherence of the source required by the holography. In addition, it can be realized in any TEM without basic hardware changes. Our approach considers the electron-wave refraction in …
Date:
August 3, 2003
Creator:
VOLKOV,V. V. ZHU,Y.
Object Type:
Article
System:
The UNT Digital Library
Arsenic Mobilization from Contaminated Sediments: A Full-scale Experiment in Progress
The mobilization of arsenic was examined in a system where the deposition of iron and arsenic have been substantially modified by large-scale manipulations. This engineering practice was designed to decrease arsenic concentrations in water supplied to the City of Los Angeles. Accomplishing this objective, however, has resulted in significant accumulation of arsenic and iron in the sediments of a reservoir on the Los Angeles Aqueduct. Arsenic and iron are released into the porewater at depth in the sediment, consistent with reductive dissolution of iron(III) oxyhydroxides. Factors influencing the possible re-sorption of arsenic onto residual iron(III) oxyhydroxides solids have been examined. Reduction of As(V) to As(III) alone cannot account for arsenic mobilization since arsenic occurs in the solid phase as As(III) well above the depth at which it is released into the porewater. Competition from other porewater constituents could suppress re-sorption of arsenic released by reductive dissolution.
Date:
February 3, 2004
Creator:
O'Day, P A; Campbell, K; Dixit, S & Hering, J G
Object Type:
Article
System:
The UNT Digital Library
Scientific Presentations: 10th Meeting of the Management Steering Committee of the Riken Bnl Collaboration (Rbrc Scientific Articles, Volume 10)
None
Date:
September 3, 2004
Creator:
Samios, N. P.
Object Type:
Report
System:
The UNT Digital Library
Designers Workbench: Towards Real-Time Immersive Modeling
This paper introduces the DesignersWorkbench, a semi-immersive virtual environment for two-handed modeling, sculpting and analysis tasks. The paper outlines the fundamental tools, design metaphors and hardware components required for an intuitive real-time modeling system. As companies focus on streamlining productivity to cope with global competition, the migration to computer-aided design (CAD), computer-aided manufacturing (CAM), and computer-aided engineering (CAE) systems has established a new backbone of modern industrial product development. However, traditionally a product design frequently originates from a clay model that, after digitization, forms the basis for the numerical description of CAD primitives. The DesignersWorkbench aims at closing this technology or ''digital gap'' experienced by design and CAD engineers by transforming the classical design paradigm into its filly integrated digital and virtual analog allowing collaborative development in a semi-immersive virtual environment. This project emphasizes two key components from the classical product design cycle: freeform modeling and analysis. In the freeform modeling stage, content creation in the form of two-handed sculpting of arbitrary objects using polygonal, volumetric or mathematically defined primitives is emphasized, whereas the analysis component provides the tools required for pre- and post-processing steps for finite element analysis tasks applied to the created models.
Date:
October 3, 2001
Creator:
Kuester, F; Duchaineau, M A; Hamann, B; Joy, K I & Ma, K L
Object Type:
Article
System:
The UNT Digital Library
Strongly Non-Arrhenius Self-Interstitial Diffusion in Vanadium
None
Date:
February 3, 2004
Creator:
Zepeda-Ruiz, L A; Rottler, J; Han, S; Ackland, G J; Car, R & Srolovitz, D J
Object Type:
Article
System:
The UNT Digital Library
Photometric Calibration of an EUV Flat Field Spectrometer at the Advanced Light Source
The photometric calibration of ail extreme ultraviolet flat field spectrometer has been done at the Advanced Light Source at LBNL. This spectrometer is used to record spectrum for atomic physics research from highly charged ions in plasmas created in the Livermore electron beam ion traps EBIT-I and SUPEREBIT. Two calibrations were done each with a different gold-coated grating, a 1200 {ell}/mm and a 2400 {ell}/mm, that covered 75-300{angstrom} and 15-160{angstrom}, respectively. The detector for this calibration was a back thinned CCD. The relative calibration was determined for several different incident angles for both gratings. Within the scatter of the data, the calibration was roughly insensitive to the incidence angle for the range of angles investigated.
Date:
July 3, 2002
Creator:
May, M.; Lepson, J.; Beiersdorfer, P.; Thorn, D.; Chen, H.; Hey, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Results from the First {sup 249}Cf + {sup 48}Ca Experiment
The present paper reports the results of an attempt aimed at the synthesis of element 118 in the reaction {sup 249}Cf({sup 48}Ca,3n){sup 294}118. The experiment was performed employing the Dubna Gas-filled Recoil Separator and the U400 heavy-ion cyclotron at FLNR, JINR, Dubna. In the course of a 2300-hour irradiation of an enriched {sup 249}Cf target (0.23 mg/cm{sup 2}) with a beam of 245-MeV {sup 48}Ca ions, we accumulated a total beam dose of 2.5 x 10{sup 19} ions. We detected two events that may be attributed to the formation and decay of nuclei with Z=118. For one event, we observed a decay chain of two correlated {alpha}-decays with corresponding energies and correlation times of E{sub {alpha}1} = 11.65 {+-} 0.06 MeV, t{sub {alpha}1} = 2.55 ms and E{sub {alpha}2} = 10.71 {+-} 0.17 MeV, t{sub {alpha}2} = 42.1 ms and, finally, a spontaneous fission with the sum of the kinetic energies of the fission fragments E{sub tot} = 207 MeV (TKE {approx} 230 MeV) and t{sub SF} = 0.52 s. In the second event chain, the recoil nucleus decayed into two fission fragments with E{sub tot} = 223 MeV (TKE {approx} 245 MeV) 3.16 ms later, without intervening {alpha} decays. …
Date:
February 3, 2003
Creator:
Oganessian, Y T; Utyonkov, V K; Lobanov, Y V; Abdullin, F S; Polyakov, A N; Shirokovsky, I V et al.
Object Type:
Report
System:
The UNT Digital Library
Properties of Fluid Deuterium under Double-Shock Compression to Several Mbar
The compressibility of fluid deuterium up to several Mbar has been probed using laser-driven shock waves reflected from a quartz anvil. Combining high-precision ({approx} 1 %) shock velocity measurements with the double-shock technique, where differences in equation of state (EOS) models are magnified, has allowed us to accurately discriminate between various theoretical predictions. Our data are consistent with EOS models that show approximately fourfold compression on the principal Hugoniot from 0.7 to 1 Mbar; however, our results indicate that deuterium has a higher compressibility than predicted by these models for single shock pressures between 1 and 2.5 Mbar.
Date:
February 3, 2004
Creator:
Vianello, E; Celliers, P M; Hicks, D G; Boehly, T R; Collins, T B; Moon, S J et al.
Object Type:
Article
System:
The UNT Digital Library
Science and Technology and Counterterorrism
Major scientific and technological breakthroughs played a pivotal role in our ability to win the Cold War. The possibility of a different type of war, in response to terrorism, has long been recognized. Indeed, countermeasures to address specific terrorist acts have been developed and are deployed, for example, at special sporting and political events. The current threat environment, however, has created an intense and compelling set of concerns; consequently, the challenge to the scientific Community to develop new concepts and products on an accelerated timeframe is clear. Also, the spectrum of terrorist threats is broad. It includes the use of conventional, chemical, biological, and nuclear and radiological weapons, not to mention cyber-based attacks. The imperatives for advances have been amplified now that attacks are clearly possible within the U.S. borders. For example, advanced sensors and detectors that are able to monitor the proliferation of all the above warfare agents and their movement at entry points into the U.S. are clearly needed. The investments over the last decades in research and development efforts at the U.S. Department of Energy (DOE) national laboratories in nonproliferation have led unique technologies and detection capabilities that have proved useful; yet, many challenges remain. In particular, …
Date:
April 3, 2002
Creator:
Wadsworth, J
Object Type:
Article
System:
The UNT Digital Library
Many amino acid substitution variants identified in DNA repair genes during human population screenings are predicted to impact protein function
Over 520 different amino acid substitution variants have been previously identified in the systematic screening of 91 human DNA repair genes for sequence variation. Two algorithms were employed to predict the impact of these amino acid substitutions on protein activity. Sorting Intolerant From Tolerant (SIFT) classified 226 of 508 variants (44%) as ''Intolerant''. Polymorphism Phenotyping (PolyPhen) classed 165 of 489 amino acid substitutions (34%) as ''Probably or Possibly Damaging''. Another 9-15% of the variants were classed as ''Potentially Intolerant or Damaging''. The results from the two algorithms are highly associated, with concordance in predicted impact observed for {approx}62% of the variants. Twenty one to thirty one percent of the variant proteins are predicted to exhibit reduced activity by both algorithms. These variants occur at slightly lower individual allele frequency than do the variants classified as ''Tolerant'' or ''Benign''. Both algorithms correctly predicted the impact of 26 functionally characterized amino acid substitutions in the APE1 protein on biochemical activity, with one exception. It is concluded that a substantial fraction of the missense variants observed in the general human population are functionally relevant. These variants are expected to be the molecular genetic and biochemical basis for the associations of reduced DNA repair …
Date:
November 3, 2003
Creator:
Xi, T; Jones, I M & Mohrenweiser, H W
Object Type:
Article
System:
The UNT Digital Library
Biased deposition of nanocrystalline Be1-x Cux coatings
Coatings of Be{sub 1-x}Cu{sub x} are prepared by magnetron sputter deposition onto spherical polymer mandrels. The application of an applied bias during deposition refines the columnar morphology of the coating and surface finish to the nanoscale. A mechanical testing technique is developed to load the thin-walled spherical capsules under uniaxial tension at constant strain to fracture. The bias-deposited material exhibits an increase in strength by a factor of three or more following a Hall-Petch type relationship with surface roughness.
Date:
November 3, 2000
Creator:
Jankowski, Alan Frederic
Object Type:
Article
System:
The UNT Digital Library
Theoretical Model for the EM Effects Induced by High-Energy Photons (Gamma, X-ray) in Dielectric Materials and Electronic Systems
During last twenty years, a number of models have been used to calculate the change of conductivity and dielectric strength in materials caused by the passage of high-energy photons, such as Gamma-rays and X-rays. In these models, the electromagnetic fields generated in the electronic system created by the high-energy photons have not been investigated. That is, the solution of Maxwell's equations has not been obtained for these kinds of problems. We constructed a theoretical model, described by a set of equations to solve such a problem. The model includes the equations that describe the physics of the recombination and generation of electron-hole pairs by the high-energy photons in the dielectric materials, the Compton electron generation rates, and Maxwell's equations. When a beam of gamma photons penetrates into a transmission line or cables, energetic electrons and holes (carriers) are created in the metals and dielectrics of the system by the Compton and photoelectric effects. These energetic electrons and holes in turn create many low-energy holes and electrons through the interaction of the high-energy electrons with the atoms in the solids. Since the density of the solids is very high, the mean free path of the high-energy electrons is very short. In …
Date:
August 3, 2001
Creator:
Yee, J H; Mayhall, D J & Bland, M F
Object Type:
Report
System:
The UNT Digital Library
RadHeat V1 User's Manual
RadHeat is a one dimensional finite difference heat transfer code that can determine the transient temperature evolution of layered targets in pulsed penetrating radiation environments. It makes use of energy dependent opacity and stopping data to model the volumetric deposition of any number of photon or ion spectra each incident at arbitrary angles. Convective and radiative boundary conditions are handled as well as the ability to impose any initial temperature profile. The heat diffusion equation is formulated implicitly to eliminate timestep dependent stability issues. Simulations are, therefore, able to achieve high fidelity during times of thermal activity and greater speed elsewhere. The prototypical physical situation simulated by RadHeat is illustrated. RadHeat was originally written to study the temperature response of tungsten-armored target-facing walls to the pulsed photon and ion radiation emanating from fusion microexplosions in future IFE power plants. RadHeat's implementation is quite general, though, and the code can be applied to a very broad range of problems. Anything from the heating of the Earth's crust on a warm summer day to the temperature rise in a mirror after a laser pulse could potentially be modeled. This manual was written to help new users learn how to run the code …
Date:
January 3, 2005
Creator:
Abbott, R P
Object Type:
Text
System:
The UNT Digital Library
Superconducting Combined Function Magnet System for J-PARC Neutrino Experiment.
The J-PARC Neutrino Experiment, the construction of which starts in JFY 2004, will use a superconducting magnet system for its primary proton beam line. The system, which bends the 50 GeV 0.75 MW proton beam by about 80 degrees, consists of 28 superconducting combined function magnets. The magnets utilize single layer left/right asymmetric coils that generate a dipole field of 2.6 T and a quadrupole field of 18.6 T/m with the operation current of about 7.35 kA. The system also contains a few conduction cooled superconducting corrector magnets that serve as vertical and horizontal steering magnets. All the magnets are designed to provide a physical beam aperture of 130 mm in order to achieve a large beam acceptance. Extensive care is also required to achieve safe operation with the high power proton beam. The paper summarizes the system design as well as some safety analysis results.
Date:
October 3, 2004
Creator:
Ogitsu, T.; Ajima, Y.; Anerella, M.; Escallier, J.; Ganetis, G.; Gupta, R. et al.
Object Type:
Article
System:
The UNT Digital Library