Breaking the Curse of Cardinality on Bitmap Indexes (open access)

Breaking the Curse of Cardinality on Bitmap Indexes

Bitmap indexes are known to be efficient for ad-hoc range queries that are common in data warehousing and scientific applications. However, they suffer from the curse of cardinality, that is, their efficiency deteriorates as attribute cardinalities increase. A number of strategies have been proposed, but none of them addresses the problem adequately. In this paper, we propose a novel binned bitmap index that greatly reduces the cost to answer queries, and therefore breaks the curse of cardinality. The key idea is to augment the binned index with an Order-preserving Bin-based Clustering (OrBiC) structure. This data structure significantly reduces the I/O operations needed to resolve records that cannot be resolved with the bitmaps. To further improve the proposed index structure, we also present a strategy to create single-valued bins for frequent values. This strategy reduces index sizes and improves query processing speed. Overall, the binned indexes with OrBiC great improves the query processing speed, and are 3 - 25 times faster than the best available indexes for high-cardinality data.
Date: April 4, 2008
Creator: Wu, Kesheng; Wu, Kesheng; Stockinger, Kurt & Shoshani, Arie
System: The UNT Digital Library
Measuring Regional Changes in the Diastolic Deformation of the Left Ventricle of SHR Rats Using microPET Technology and Hyperelastic Warping (open access)

Measuring Regional Changes in the Diastolic Deformation of the Left Ventricle of SHR Rats Using microPET Technology and Hyperelastic Warping

The objective of this research was to assess applicability of a technique known as hyperelastic warping for the measurement of local strains in the left ventricle (LV) directly from microPET image data sets. The technique uses differences in image intensities between template (reference) and target (loaded) image data sets to generate a body force that deforms a finite element (FE) representation of the template so that it registers with the target images. For validation, the template image was defined as the end-systolic microPET image data set from a Wistar Kyoto (WKY) rat. The target image was created by mapping the template image using the deformation results obtained from a FE model of diastolic filling. Regression analysis revealed highly significant correlations between the simulated forward FE solution and image derived warping predictions for fiber stretch (R2 = 0.96), circumferential strain (R2 = 0.96), radial strain (R2 = 0.93), and longitudinal strain (R2 = 0.76) (p<0.001for all cases). The technology was applied to microPET image data of two spontaneously hypertensive rats (SHR) and a WKY control. Regional analysis revealed that, the lateral freewall in the SHR subjects showed the greatest deformation compared with the other wall segments. This work indicates that warping …
Date: April 4, 2008
Creator: Gullberg, Grant T; Veress , Alexander I.; Weiss, Jeffrey A.; Huesman, Ronald H.; Reutter, Bryan W.; Taylor , Scott E. et al.
System: The UNT Digital Library
Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure (open access)

Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure

We have developed complementary soft x-ray scattering and reflectometry techniques that allow for the morphological analysis of thin polymer films without resorting to chemical modification or isotopic 2 labeling. With these techniques, we achieve significant, x-ray energy-dependent contrast between carbon atoms in different chemical environments using soft x-ray resonance at the carbon edge. Because carbon-containing samples absorb strongly in this region, the scattering length density depends on both the real and imaginary parts of the atomic scattering factors. Using a model polymer film of poly(styrene-b-methyl methacrylate), we show that the soft x-ray reflectivity data is much more sensitive to these atomic scattering factors than the soft x-ray scattering data. Nevertheless, fits to both types of data yield useful morphological details on the polymer?slamellar structure that are consistent with each other and with literature values.
Date: April 4, 2008
Creator: Welch, Cynthia; Welch, Cynthia F.; Hjelm, Rex P.; Mang, Joseph T.; Hawley, Marilyn E.; Wrobleski, Debra A. et al.
System: The UNT Digital Library
Song of the Electroweak Penguin (open access)

Song of the Electroweak Penguin

None
Date: April 4, 2008
Creator: Peskin, Michael E.
System: The UNT Digital Library
The Transcriptional Co-activator MBF1c Is a Key Regulator of Thermotolerance in Arabidopsis thaliana (open access)

The Transcriptional Co-activator MBF1c Is a Key Regulator of Thermotolerance in Arabidopsis thaliana

Article reporting that the highly conserved transcriptional co-activator, MBF1c (multiprotein bridging factor 1c), is a key regulator of thermotolerance in Arabidopsis thaliana. Results provide evidence for the existence of a tightly coordinated heat stress-response network, involving trehalose-, SA-, and ethylene-signaling pathways, that is under the control of MBF1c.
Date: April 4, 2008
Creator: Suzuki, Nobuhiro; Bajad, Sunil; Shuman, Joel; Shulaev, Vladimir & Mittler, Ron
System: The UNT Digital Library
Z' Coupling Information From LHeC (open access)

Z' Coupling Information From LHeC

None
Date: April 4, 2008
Creator: Rizzo, Thomas G.
System: The UNT Digital Library
ATLAS Metadata Task Force (open access)

ATLAS Metadata Task Force

This document provides an overview of the metadata, which are needed to characterizeATLAS event data at different levels (a complete run, data streams within a run, luminosity blocks within a run, individual events).
Date: April 4, 2007
Creator: Collaboration, ATLAS; Costanzo, D.; Cranshaw, J.; Gadomski, S.; Jezequel, S.; Klimentov, A. et al.
System: The UNT Digital Library
The importance of EBIT data for Z-pinch plasma diagnostics (open access)

The importance of EBIT data for Z-pinch plasma diagnostics

The results from the last six years of x-ray spectroscopy and spectropolarimetry of high energy density Z-pinch plasmas complemented by experiments with the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory (LLNL) are presented. The two topics discussed are the development of M-shell x-ray W spectroscopic diagnostics and K-shell Ti spectropolarimetry of Z-pinch plasmas. The main focus is on radiation from a specific load configuration called an 'X-pinch'. X-pinches are excellent sources for testing new spectral diagnostics and for atomic modelling because of the high density and temperature of the pinch plasmas, which scale from a few {micro}m to several mm in size. They offer a variety of load configurations, which differ in wire connections, number of wires, and wire materials. In this work the study of X-pinches with tungsten wires combined with wires from other, lower-Z materials is reported. Utilizing data produced with the LLNL EBIT at different energies of the electron beam the theoretical prediction of line positions and intensity of M-shell W spectra were tested and calibrated. Polarization-sensitive X-pinch experiments at the University of Nevada, Reno (UNR) provide experimental evidence for the existence of strong electron beams in Ti and Mo X-pinch plasmas and …
Date: April 4, 2007
Creator: Safronova, A S; Kantsyrev, V L; Neill, P; Safronova, U I; Fedin, D A; Ouart, N D et al.
System: The UNT Digital Library
Isochoric Implosions for Fast Ignition (open access)

Isochoric Implosions for Fast Ignition

Various gain models have shown the potentially great advantages of Fast Ignition (FI) Inertial Confinement Fusion (ICF) over its conventional hot spot ignition counterpart [e.g., S. Atzeni, Phys. Plasmas 6, 3316 (1999); M. Tabak et al., Fusion Sci. & Technology 49, 254 (2006)]. These gain models, however, all assume nearly uniform-density fuel assemblies. In contrast, conventional ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hot spot. Hence, to realize fully the advantages of FI, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hot spots. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley [Luftfahrtforschung 19, 302 (1942)] may be employed to yield precisely such quasi-isochoric imploded states. The difficulty remains, however, of accessing these self-similarly imploding configurations from initial conditions representing an actual ICF target, namely a uniform, solid-density shell at rest. Furthermore, these specialized implosions must be realized for practicable drive parameters and at the scales and energies of interest in ICF. A direct-drive implosion scheme is presented which meets all of these requirements and reaches a nearly isochoric assembled density of 300 g=cm{sup 3} and areal …
Date: April 4, 2007
Creator: Clark, D S & Tabak, M
System: The UNT Digital Library
Metastable Vacua and D-branes at the Conifold (open access)

Metastable Vacua and D-branes at the Conifold

We consider quiver gauge theories arising on D-branes at simple Calabi-Yau singularities (quotients of the conifold). These theories have metastable supersymmetry breaking vacua. The field theoretic mechanism is basically the one exhibited by the examples of Intriligator, Seiberg and Shih in SUSY QCD. In a dual description, the SUSY breaking is captured by the presence of anti-branes. In comparison to our earlier related work, the main improvements of the present construction are that we can reach the free magnetic range of the SUSY QCD theory where the existence of the metastable vacua is on firm footing, and we can see explicitly how the small masses for the quark flavors (necessary to the existence of the SUSY breaking vacua) are dynamically stabilized. One crucial mass term is generated by a stringy instanton. Finally, our models naturally incorporate R-symmetry breaking in the non-supersymmetric vacuum, in a way similar to the examples of Kitano, Ooguri and Ookouchi.
Date: April 4, 2007
Creator: Argurio, Riccardo; Bertolini, Matteo; Franco, Sebastian & Kachru, Shamit
System: The UNT Digital Library
AN OVERVIEW OF CESIUM-137 CONTAMINATION IN A SOUTHEASTERN SWAMP ENVIRONMENT (open access)

AN OVERVIEW OF CESIUM-137 CONTAMINATION IN A SOUTHEASTERN SWAMP ENVIRONMENT

In the early 1960s, an area of privately owned swamp adjacent to the Savannah River Site (SRS) was contaminated by site operations. Studies conducted in 1974 estimated that approximately 925 GBq of {sup 137}Cs and 37 GBq of {sup 60}Co were deposited in the swamp. Subsequently, a series of surveys was initiated to characterize the contaminated environment. These surveys--composed of 52 monitoring locations--allow for continued monitoring at a consistent set of locations. Initial survey results indicated maximum {sup 137}Cs concentrations of 19.5 Bq g{sup -1} in soil and 8.7 Bq g{sup -1} in vegetation. By the 2004-2005 surveys, maximum concentrations had declined to 1-2 Bq g{sup -1} in soil and 0.4 Bq g{sup -1} in vegetation.
Date: April 4, 2007
Creator: Fledderman, P; Tim Jannik, T & Michael Paller, M
System: The UNT Digital Library
Scientific Computing Kernels on the Cell Processor (open access)

Scientific Computing Kernels on the Cell Processor

The slowing pace of commodity microprocessor performance improvements combined with ever-increasing chip power demands has become of utmost concern to computational scientists. As a result, the high performance computing community is examining alternative architectures that address the limitations of modern cache-based designs. In this work, we examine the potential of using the recently-released STI Cell processor as a building block for future high-end computing systems. Our work contains several novel contributions. First, we introduce a performance model for Cell and apply it to several key scientific computing kernels: dense matrix multiply, sparse matrix vector multiply, stencil computations, and 1D/2D FFTs. The difficulty of programming Cell, which requires assembly level intrinsics for the best performance, makes this model useful as an initial step in algorithm design and evaluation. Next, we validate the accuracy of our model by comparing results against published hardware results, as well as our own implementations on a 3.2GHz Cell blade. Additionally, we compare Cell performance to benchmarks run on leading superscalar (AMD Opteron), VLIW (Intel Itanium2), and vector (Cray X1E) architectures. Our work also explores several different mappings of the kernels and demonstrates a simple and effective programming model for Cell's unique architecture. Finally, we propose modest …
Date: April 4, 2007
Creator: Williams, Samuel W.; Shalf, John; Oliker, Leonid; Kamil, Shoaib; Husbands, Parry & Yelick, Katherine
System: The UNT Digital Library
Sequestering in String Theory (open access)

Sequestering in String Theory

We study sequestering, a prerequisite for flavor-blind supersymmetry breaking in several high-scale mediation mechanisms, in compactifications of type IIB string theory. We find that although sequestering is typically absent in unwarped backgrounds, strongly warped compactifications do readily sequester. The AdS/CFT dual description in terms of conformal sequestering plays an important role in our analysis, and we establish how sequestering works both on the gravity side and on the gauge theory side. We pay special attention to subtle compactification effects that can disrupt sequestering. Our result is a step toward realizing an appealing pattern of soft terms in a KKLT compactification.
Date: April 4, 2007
Creator: Kachru, Shamit; McAllister, Liam & Sundrum, Raman
System: The UNT Digital Library
Storage Ring Optics Measurement, Model, and Correction (open access)

Storage Ring Optics Measurement, Model, and Correction

To improve the optics of a storage ring, it is very helpful if one has an accurate lattice model. Although the ideal lattice may serve such a purpose to some extent, in most cases, real accelerator optics improvement requires accurate measurement of optics parameters. In this section, we present precision measurements of a complete set of linear orbits from which we can form a linear optics model to match the linear optics of the real machine. We call such a model a virtual machine. We have used a model-independent analysis (MIA) for accurate orbit and phase advance measurement and then used an SVD-enhanced Least Square fitting for building accurate virtual models for PEP-II e+, e- storage rings. The MIA virtual machine matches very well the real-machine linear optics including dispersion. It has successfully improved PEP-II beta beats, linear couplings, half-integer working tunes, and dispersion.
Date: April 4, 2007
Creator: Yan, Yiton T.
System: The UNT Digital Library
USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE (open access)

USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE

A bench-scale feasibility study on the use of a Wet Air Oxidation (WAO) process to destroy a slurry laden with tetraphenylborate (TPB) compounds has been undertaken. WAO is an aqueous phase process in which soluble and/or insoluble waste constituents are oxidized using oxygen or oxygen in air at elevated temperatures and pressures ranging from 150 C and 1 MPa to 320 C and 22 MPa. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). Test results indicate WAO is a feasible process for destroying TPB, its primary daughter products [triphenylborane (3PB), diphenylborinic acid (2PB), and phenylboronic acid (1PB)], phenol, and most of the biphenyl byproduct. The required conditions are a temperature of 300 C, a reaction time of 3 hours, 1:1 feed slurry dilution with 2M NaOH solution, the addition of CuSO{sub 4}.5H{sub 2}O solution (500 mg/L Cu) as catalyst, and the addition of 2000 mL/L of antifoam. However, for the destruction of TPB, its daughter compounds (3PB, 2PB, and 1PB), and phenol without consideration for biphenyl destruction, less severe conditions (280 C and 1-hour reaction time with similar remaining above conditions) are adequate.
Date: April 4, 2007
Creator: Adu-Wusu, K; Daniel McCabe, D & Bill Wilmarth, B
System: The UNT Digital Library
A sampling-based Bayesian model for gas saturation estimationusing seismic AVA and marine CSEM data (open access)

A sampling-based Bayesian model for gas saturation estimationusing seismic AVA and marine CSEM data

We develop a sampling-based Bayesian model to jointly invertseismic amplitude versus angles (AVA) and marine controlled-sourceelectromagnetic (CSEM) data for layered reservoir models. The porosityand fluid saturation in each layer of the reservoir, the seismic P- andS-wave velocity and density in the layers below and above the reservoir,and the electrical conductivity of the overburden are considered asrandom variables. Pre-stack seismic AVA data in a selected time windowand real and quadrature components of the recorded electrical field areconsidered as data. We use Markov chain Monte Carlo (MCMC) samplingmethods to obtain a large number of samples from the joint posteriordistribution function. Using those samples, we obtain not only estimatesof each unknown variable, but also its uncertainty information. Thedeveloped method is applied to both synthetic and field data to explorethe combined use of seismic AVA and EM data for gas saturationestimation. Results show that the developed method is effective for jointinversion, and the incorporation of CSEM data reduces uncertainty influid saturation estimation, when compared to results from inversion ofAVA data only.
Date: April 4, 2006
Creator: Chen, Jinsong; Hoversten, Michael; Vasco, Don; Rubin, Yoram & Hou,Zhangshuan
System: The UNT Digital Library
Scaling laws for collisionless laser-plasma interactions of relevance for laboratory astrophysics (open access)

Scaling laws for collisionless laser-plasma interactions of relevance for laboratory astrophysics

Scaling laws for interaction of ultra-intense laser beams with a collisionless plasmas are discussed. Special attention is paid to the problem of the collective ion acceleration. Symmetry arguments in application to the generation of the poloidal magnetic field are presented. A heuristic model for evaluating the magnetic field strength is proposed.
Date: April 4, 2006
Creator: Ryutov, D. D. & Rermington, B. A.
System: The UNT Digital Library
A Universe Without Weak Interactions (open access)

A Universe Without Weak Interactions

None
Date: April 4, 2006
Creator: Harnik, Roni; Kribs, Graham D. & Perez, Gilad
System: The UNT Digital Library
Auxiliary basis expansions for large-scale electronic structure calculations (open access)

Auxiliary basis expansions for large-scale electronic structure calculations

One way to reduce the computational cost of electronic structure calculations is to employ auxiliary basis expansions to approximate 4 center integrals in terms of 2 and 3-center integrals, usually using the variationally optimum Coulomb metric to determine the expansion coefficients. However the long-range decay behavior of the auxiliary basis expansion coefficients has not been characterized. We find that this decay can be surprisingly slow. Numerical experiments on linear alkanes and a toy model both show that the decay can be as slow as 1/r in the distance between the auxiliary function and the fitted charge distribution. The Coulomb metric fitting equations also involve divergent matrix elements for extended systems treated with periodic boundary conditions. An attenuated Coulomb metric that is short-range can eliminate these oddities without substantially degrading calculated relative energies. The sparsity of the fit coefficients is assessed on simple hydrocarbon molecules, and shows quite early onset of linear growth in the number of significant coefficients with system size using the attenuated Coulomb metric. This means it is possible to design linear scaling auxiliary basis methods without additional approximations to treat large systems.
Date: April 4, 2005
Creator: Jung, Yousung; Sodt, Alexander; Gill, Peter W. M. & Head-Gordon, Martin
System: The UNT Digital Library
BIBLIOGRAPHIC DATABASES IN SUPPORT OF NSDD EVALUATIONS. (open access)

BIBLIOGRAPHIC DATABASES IN SUPPORT OF NSDD EVALUATIONS.

Bibliographic databases useful to nuclear structure and decay data (NSDD) evaluators are briefly described, along with examples of their usage. Authors' reference listings are also discussed. Nuclear Science References is recognized as the major bibliographic resource, and therefore most of the presentation is devoted to this database.
Date: April 4, 2005
Creator: BURROWS, T.
System: The UNT Digital Library
Characterization and Compensation of High Speed Digitizers (open access)

Characterization and Compensation of High Speed Digitizers

Increasingly, ADC technology is being pressed into service for single single-shot instrumentation applications that were formerly served by vacuum-tube based oscilloscopes and streak cameras. ADC technology, while convenient, suffers significant performance impairments. Thus, in these demanding applications, a quantitative and accurate representation of these impairments is critical to an understanding of measurement accuracy. We have developed a phase-plane behavioral model, implemented it in SIMULINK and applied it to interleaved, high-speed ADCs (up to 4 gigasamples/sec). We have also developed and demonstrated techniques to effectively compensate for these impairments based upon the model.
Date: April 4, 2005
Creator: Fong, P; Teruya, A & Lowry, M
System: The UNT Digital Library
ENSDF ANALYSIS AND UTILITY CODES. (open access)

ENSDF ANALYSIS AND UTILITY CODES.

The ENSDF analysis and checking codes are briefly described, along with their uses with various types of ENSDF datasets. For more information on the programs see ''Read Me'' entries and other documentation associated with each code.
Date: April 4, 2005
Creator: BURROWS, T.
System: The UNT Digital Library
Groundwater Profession in Transition: Discovery toAdaptation (open access)

Groundwater Profession in Transition: Discovery toAdaptation

Over the past century and half, groundwater has played an important role in the economic prosperity of the United States. The groundwater profession which has contributed to this prosperity has grown through the contributions of the U.S. and State Geological Surveys,academia, and industry. A century ago, the energies of the profession were channeled towards discovering new sources of groundwater in a largely unexplored land, and exploiting the resources for maximum economic benefit. Experience has since revealed that groundwater systems are finite, and are intimately linked to surface water bodies and the biosphere. A consequence is that aggressive exploitation of groundwater can lead to unacceptable environmental degradation and social cost. At present, the groundwater profession is in a state of transition from one of discovery and exploitation, to one of balancing resource development with avoiding unacceptable damage to the environment. This paper outlines the history of the groundwater profession in the United States since the late nineteenth century, and speculates on what may lie ahead in the near future, as the profession makes the transition from discovering new sources of groundwater to one of better understanding and adapting to nature's constraints.
Date: April 4, 2005
Creator: Narasimhan, T. N.
System: The UNT Digital Library
Groundwater Profession in Transition: Discovery toAdaptation (open access)

Groundwater Profession in Transition: Discovery toAdaptation

Over the past century and half, groundwater has played an important role in the economic prosperity of the United States. The groundwater profession which has contributed to this prosperity has grown through the contributions of the U.S. and State Geological Surveys,academia, and industry. A century ago, the energies of the profession were channeled towards discovering new sources of groundwater in a largely unexplored land, and exploiting the resources for maximum economic benefit. Experience has since revealed that groundwater systems are finite, and are intimately linked to surface water bodies and the biosphere. A consequence is that aggressive exploitation of groundwater can lead to unacceptable environmental degradation and social cost. At present, the groundwater profession is in a state of transition from one of discovery and exploitation, to one of balancing resource development with avoiding unacceptable damage to the environment. This paper outlines the history of the groundwater profession in the United States since the late nineteenth century, and speculates on what may lie ahead in the near future, as the profession makes the transition from discovering new sources of groundwater to one of better understanding and adapting to nature's constraints.
Date: April 4, 2005
Creator: Narasimhan, T. N.
System: The UNT Digital Library