10,703 Matching Results

Results open in a new window/tab.

'Brilliant' Magazine Targets Affluent Texans (open access)

'Brilliant' Magazine Targets Affluent Texans

Article about the launching of Brilliant Magazine by Brilliance Media in Austin, Texas.
Date: December 1, 2003
Creator: Charski, Mindy
System: The UNT Digital Library
[Fox 4 KDFW Good Day, 2004-01-01] (open access)

[Fox 4 KDFW Good Day, 2004-01-01]

Article about Evel Knievel's appearance at Will Rogers Coliseum, Franklin Covey's advice on New Year's resolutions, the launching of Brilliant Magazine, and a recipe by Tim Love.
Date: January 1, 2004
Creator: Fox 4 KDFW
System: The UNT Digital Library
[Christine C. Quinn press release] (open access)

[Christine C. Quinn press release]

Press release from Christine C. Quinn re: Lesbian and Gay Community Organizations / envelope press release was mailed in addressed to Dennis Myrick.
Date: July 1, 2002
Creator: Quinn, Christine C.
System: The UNT Digital Library
The Internet and College Students' Motivation to Vote (open access)

The Internet and College Students' Motivation to Vote

This article investigates the impact of the political information available on-line on college students’ motivation to vote. The results illustrate that not only politicians, but educators should be cognizant of this civic engagement process. Schools and teachers of all levels are one the front lines of the battle to create a more informed, more involved citizenry; higher education has a strong influence on motivation to vote.
Date: March 1, 2004
Creator: White, Amy E. & King, Kimi L.
System: The UNT Digital Library
Preface 2004 (open access)

Preface 2004

Introduction to the 2004 edition of The Eagle Feather.
Date: October 1, 2004
Creator: Cox, Gloria C. & Eve, Susan Brown
System: The UNT Digital Library
Insights into the Dynamic Response of Tunnels in Jointed Rocks (open access)

Insights into the Dynamic Response of Tunnels in Jointed Rocks

Tunnels in jointed rocks can be subjected to severe dynamic loads because of rock bursts, coal bumps, and large earthquakes. A series of 3-dimensional simulations was performed, based on discrete element analysis to gain insights into the parameters that influence the response of such tunnels. The simulations looked at the effect of joint set orientation, the effect of joint spacing, the effect of pulse shape for a given displacement, and the influence of using rigid versus deformable blocks in the analyses. The results of this modeling were also compared to field evidence of dynamic tunnel failures. This comparison reinforced the notion that 3-dimensional discrete element analysis can capture very well the kinematics of structures in jointed rock under dynamic loading.
Date: November 1, 2004
Creator: Heuze, F E
System: The UNT Digital Library
Toward understanding environmental effects in SDSS clusters (open access)

Toward understanding environmental effects in SDSS clusters

We find clusters and superclusters of galaxies using the Data Release 1 of the Sloan Digital Sky Survey. We determine the luminosity function of clusters and find that clusters in a high-density environment have a luminosity a factor of {approx}5 higher than in a low-density environment. We also study clusters and superclusters in numerical simulations. Simulated clusters in a high-density environment are also more massive than those in a low-density environment. Comparison of the density distribution at various epochs in simulations shows that in large low-density regions (voids) dynamical evolution is very slow and stops at an early epoch. In contrast, in large regions of higher density (superclusters) dynamical evolution starts early and continues until the present; here particles cluster early, and by merging of smaller groups very rich systems of galaxies form.
Date: November 1, 2004
Creator: Einasto, Jaan; Tago, E.; Einasto, M.; Saar, E.; Suhhonenko, I.; Heinamaki, P. et al.
System: The UNT Digital Library
The Weak lensing bispectrum (open access)

The Weak lensing bispectrum

Weak gravitational lensing of background galaxies offers an excellent opportunity to study the intervening distribution of matter. While much attention to date has focused on the two-point function of the cosmic shear, the three-point function, the bispectrum, also contains very useful cosmological information. Here, we compute three corrections to the bispectrum which are nominally of the same order as the leading term. We show that the corrections are small, so they can be ignored when analyzing present surveys. However, they will eventually have to be included for accurate parameter estimates from future surveys.
Date: January 1, 2005
Creator: Dodelson, Scott & Zhang, Pengjie
System: The UNT Digital Library
Analysis and Comparison of Test Results from the Small Wind Research Turbine Test Project: Preprint (open access)

Analysis and Comparison of Test Results from the Small Wind Research Turbine Test Project: Preprint

Most small wind turbines furl (yaw or tilt out of the wind) as a means of limiting power and rotor speeds in high winds. The Small Wind Research Turbine (SWRT) testing project was initiated in 2003 with the goal of better characterizing both small wind turbine loads (including thrust) and dynamic behavior, specifically as they relate to furling. The main purpose of the testing was to produce high-quality data sets for model development and validation and to help the wind industry further their understanding of small wind turbine behavior. Testing was conducted on a modified Bergey Excel 10-kW wind turbine. A special shaft sensor was designed to measure shaft loads including thrust, torque, and shaft bending. Analysis of 10-minute mean data showed a strong correlation between furling and center of thrust location, as calculated from the shaft-bending and thrust measurements. Data were collected for three different turbine configurations that included a change in the lateral furling offset and the blades. An analysis of inflow conditions indicated that organized atmospheric turbulence had some impact on furling.
Date: November 1, 2004
Creator: Corbus, D. & Prascher, D.
System: The UNT Digital Library
Measurement of the azimuthal angle distribution of leptons from W boson decays as a function of the W transverse momentum in p anti-p collisions at s**(1/2) = 1.8-TeV (open access)

Measurement of the azimuthal angle distribution of leptons from W boson decays as a function of the W transverse momentum in p anti-p collisions at s**(1/2) = 1.8-TeV

We present the first measurement of the A{sub 2} and A{sub 3} angular coefficients of the W boson produced in proton-antiproton collisions. We study W {yields} ev{sub e} and W {yields} {mu}{nu}{sub {mu}} candidate events produced in association with at least one jet at CDF, during Run Ia and Run Ib of the Tevatron at {radical}s = 1.8 TeV. The corresponding integrated luminosity was 110 pb{sup -1}. The jet balances the transverse momentum of the W and introduces QCD effects in W boson production. The extraction of the angular coefficients is achieved through the direct measurement of the azimuthal angle of the charged lepton in the Collins-Soper rest-frame of the W boson. The angular coefficients are measured as a function of the transverse momentum of the W boson. The electron, muon, and combined results are in good agreement with the Standard Model prediction, up to order {alpha}{sub s}{sup 2} in QCD.
Date: April 1, 2005
Creator: Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
System: The UNT Digital Library
Di-boson production and SM SUSY Higgs searches at the Tevatron (open access)

Di-boson production and SM SUSY Higgs searches at the Tevatron

The discovery of the Higgs boson would be a major success for the Standard Model (SM) and would provide further insights into the electroweak symmetry breaking mechanism. This report contains the latest results from the D0 and CDF Tevatron experiments on searches for the SM Higgs produced from gluon fusion with H {yields} WW, and in association with a W boson. It also includes searches for a supersymmetric Higgs in the b{bar b} and {tau}{sup +}{tau}{sup -} decay channels. The study of di-boson production at the Tevatron is important to understand backgrounds in high mass Higgs searches. It also provides a test of the SM through the measurement of the production cross section and the gauge boson self couplings. This paper includes measurements of the WW, W{gamma}, and WZ production cross sections, as well as limits on the anomalous couplings associated with the WW{gamma} and WWZ interactions. The results are based on sets of up to 320 pb{sup -1} of data collected by the D0 and CDF experiments at the {bar p}p Tevatron collider, running at a center-of-mass energy of 1.96 TeV.
Date: July 1, 2005
Creator: Elvira, V. Daniel
System: The UNT Digital Library
Properties of High Efficiency CIGS Thin Film Solar Cells (open access)

Properties of High Efficiency CIGS Thin Film Solar Cells

We present experimental results in three areas. Solar cells with an efficiency of 19% have been fabricated with an absorber bandgap in the range of 1.1-1.2 eV. Properties of solar cells fabricated with and without an undoped ZnO layer were compared. The data show that high efficiency cells can be fabricated without using the high-resistivity or undoped ZnO layer. Properties of CIGS solar cells were fabricated from thin absorbers (1 {micro}m) deposited by the three-stage process and simultaneous co-deposition of all the elements. In both cases, solar cells with efficiencies of 16%-17% are obtained.
Date: February 1, 2005
Creator: Ramanathan, K.; Keane, J. & Noufi, R.
System: The UNT Digital Library
Sub-microsecond beam notching at low energy (open access)

Sub-microsecond beam notching at low energy

A technique for creating a burst of 100 ns notches (beam extinctions) in an H{sup -} beam at 454 kHz has been developed at {le} 20 keV utilizing a Magnetron ion source with a slit extraction system and a split extractor. Each half of the extractor is treated as part of a 50 ohm transmission line which can be pulsed at {+-} 700 volts creating a 1400 volt gradient across the extractor. A beam current reduction of better than 95% has been observed at the end of the Fermilab 400 MeV Linac. Notched multi-turn charge-exchange injection into the Booster, a 400 MeV to 8 GeV synchrotron, has been demonstrated with a charge reduction in the resulting beam gap of 83%. Presently, the trailing edge of the notch may be adversely affected by space charge resulting in a beam recovery with two different time constants. Efforts to minimize this effect are discussed.
Date: September 1, 2005
Creator: Moehs, D. P.
System: The UNT Digital Library
a-SiGe:H Materials and Devices Deposited by Hot Wire CVD Using a Tantalum Filament Operated at Low Temperature (open access)

a-SiGe:H Materials and Devices Deposited by Hot Wire CVD Using a Tantalum Filament Operated at Low Temperature

We report the deposition of improved hydrogenated amorphous silicon germanium (a-SiGe:H) films by the hot wire CVD (HWCVD) technique using a tantalum filament operating at a low temperature. We gauge the material quality of the a-SiGe:H films by comparing infrared, small angle X-ray scattering (SAXS), photocapacitance, and conductivity measurements to earlier results, and fabricate single-junction n-i-p solar cell devices using these i-layers.
Date: February 1, 2005
Creator: Mahan, A. H.; Xu, Y.; Gedvilas, L. M.; Reedy, R. C.; Williamson, D. L.; Datta, S. et al.
System: The UNT Digital Library
Fitting the luminosity decay in the Tevatron (open access)

Fitting the luminosity decay in the Tevatron

This paper explores how to fit the decay of the luminosity in the Tevatron. The standard assumptions of a fixed-lifetime exponential decay are only appropriate for very short time intervals. A ''1/time'' functional form fits well, and is supported by analytical derivations. A more complex form, assuming a time-varying lifetime-like term, also produces good results. Changes in the luminosity can be factored into two phenomena: The luminosity burn-off rate, and the burn-off rate from non-luminosity effects. This is particularly relevant for the antiprotons in the Tevatron. The luminous and the non-luminous burn rate of the antiprotons are shown for Tevatron stores.
Date: May 1, 2005
Creator: McCrory, E.; Shiltsev, V.; Slaughter, A. J. & Xiao, A.
System: The UNT Digital Library
A Simple test for the existence of two accretion modes in active galactic nuclei (open access)

A Simple test for the existence of two accretion modes in active galactic nuclei

By analogy to the different accretion states observed in black-hole X-ray binaries (BHXBs), it appears plausible that accretion disks in active galactic nuclei (AGN) undergo a state transition between a radiatively efficient and inefficient accretion flow. If the radiative efficiency changes at some critical accretion rate, there will be a change in the distribution of black hole masses and bolometric luminosities at the corresponding transition luminosity. To test this prediction, the author considers the joint distribution of AGN black hole masses and bolometric luminosities for a sample taken from the literature. The small number of objects with low Eddington-scaled accretion rates m < 0.01 and black hole masses M{sub BH} < 10{sup 9} M{sub {circle_dot}} constitutes tentative evidence for the existence of such a transition in AGN. Selection effects, in particular those associated with flux-limited samples, systematically exclude objects in particular regions of the (M{sub BH}, L{sub bol}) plane. Therefore, they require particular attention in the analysis of distributions of black hole mass, bolometric luminosity, and derived quantities like the accretion rate. The author suggests further observational tests of the BHXB-AGN unification scheme which are based on the jet domination of the energy output of BHXBs in the hard state, …
Date: February 1, 2005
Creator: Jester, Sebastian
System: The UNT Digital Library
Interconnection Testing of Distributed Resources: Preprint (open access)

Interconnection Testing of Distributed Resources: Preprint

With the publication of IEEE 1547-2003(TM) Standard for Interconnecting Distributed Resources With Electric Power Systems, the electric power industry has a need to develop tests and procedures to verify that interconnection equipment meets 1547 technical requirements. A new standard, IEEE P1547.1(TM), is being written to give detailed tests and procedures for confirming that equipment meets the interconnection requirements. The National Renewable Energy Laboratory has been validating test procedures being developed as part of IEEE P1547.1. As work progresses on the validation of those procedures, information and test reports are passed on to the working group of IEEE P1547.1 for future revisions.
Date: February 1, 2004
Creator: Kroposki, B.; Basso, T. & DeBlasio, R.
System: The UNT Digital Library
Diagnostic potential of cosmic-neutrino absorption spectroscopy (open access)

Diagnostic potential of cosmic-neutrino absorption spectroscopy

Annihilation of extremely energetic cosmic neutrinos on the relic-neutrino background can give rise to absorption lines at energies corresponding to formation of the electroweak gauge boson Z{sup 0}. The positions of the absorption dips are set by the masses of the relic neutrinos. Suitably intense sources of extremely energetic (10{sup 21} - 10{sup 25}-eV) cosmic neutrinos might therefore enable the determination of the absolute neutrino masses and the flavor composition of the mass eigenstates. Several factors--other than neutrino mass and composition--distort the absorption lines, however. We analyze the influence of the time-evolution of the relic-neutrino density and the consequences of neutrino decay. We consider the sensitivity of the lineshape to the age and character of extremely energetic neutrino sources, and to the thermal history of the Universe, reflected in the expansion rate. We take into account Fermi motion arising from the thermal distribution of the relic-neutrino gas. We also note the implications of Dirac vs. Majorana relics, and briefly consider unconventional neutrino histories. We ask what kinds of external information would enhance the potential of cosmic-neutrino absorption spectroscopy, and estimate the sensitivity required to make the technique a reality.
Date: December 1, 2004
Creator: Barenboim, Gabriela; U., /Valencia; Mena Requejo, Olga; Quigg, Chris & /Fermilab
System: The UNT Digital Library
The SAMGrid monitoring service and its integration with MonALISA (open access)

The SAMGrid monitoring service and its integration with MonALISA

The SAMGrid team is in the process of implementing a monitoring and information service, which fulfills several important roles in the operation of the SAMGrid system, and will replace the first generation of monitoring tools in the current deployments. The first generation tools are in general based on text log-files and represent solutions which are not scalable or maintainable. The roles of the monitoring and information service are: (1) providing diagnostics for troubleshooting the operation of SAMGrid services; (2) providing support for monitoring at the level of user jobs; (3) providing runtime support for local configuration and other information which currently must be stored centrally (thus moving the system toward greater autonomy for the SAMGrid station services, which include cache management and job management services); (4) providing intelligent collection of statistics in order to enable performance monitoring and tuning. The architecture of this service is quite flexible, permitting input from any instrumented SAMGrid application or service. It will allow multiple backend storage for archiving of (possibly) filtered monitoring events, as well as real time information displays and active notification service for alarm conditions. This service will be able to export, in a configurable manner, information to higher level Grid monitoring …
Date: December 1, 2004
Creator: Lyon, A.; Vokac, P.; Zimmler, M.; Baranovski, G.; Garzoglio, G.; Loebel-Carpenter, L. et al.
System: The UNT Digital Library
Using star tracks to determine the absolute pointing of the Fluorescence Detector telescopes of the Pierre Auger Observatory (open access)

Using star tracks to determine the absolute pointing of the Fluorescence Detector telescopes of the Pierre Auger Observatory

To accurately reconstruct a shower axis from the Fluorescence Detector data it is essential to establish with high precision the absolute pointing of the telescopes. To d that they calculate the absolute pointing of a telescope using sky background data acquired during regular data taking periods. The method is based on the knowledge of bright star's coordinates that provide a reliable and stable coordinate system. it can be used to check the absolute telescope's pointing and its long-term stability during the whole life of the project, estimated in 20 years. They have analyzed background data taken from January to October 2004 to determine the absolute pointing of the 12 telescopes installed both in Los Leones and Coihueco. The method is based on the determination of the mean-time of the variance signal left by a star traversing a PMT's photocathode which is compared with the mean-time obtained by simulating the track of that star on the same pixel.
Date: May 1, 2005
Creator: De Donato, Cinzia; Sanchez, Federico; /Milan U. /INFN, Milan; Santander, Marcos; Natl.Tech.U., San Rafael; Camin, Daniel et al.
System: The UNT Digital Library
Double Pomeron physics at the LHC (open access)

Double Pomeron physics at the LHC

The author discusses central exclusive production, also known as Double Pomeron Exchange DIPE, from the ISR through the Tevatron to the LHC. There the author emphasizes the interest of exclusive Higgs and W{sup +}W{sup -}/ZZ production.
Date: July 1, 2005
Creator: Albrow, Michael G.
System: The UNT Digital Library
Advances in the understanding and operations of superconducting colliders (open access)

Advances in the understanding and operations of superconducting colliders

Chromaticity drift during injection is a well-known phenomenon in superconducting colliders, such as the Tevatron, HERA and RHIC. Imperfect compensation of the drift effects can contribute to beam loss and emittance growth. It is caused by the drift of the sextupole component in the dipole magnets due to current redistribution in its superconducting coils. Recently extensive studies of chromaticity drift were conducted at the Tevatron, aiming at the improvement of the luminosity performance in the ongoing run II. These studies included not only beam experiments, but also extensive off-line magnetic measurements on spare Tevatron dipoles. Less known, until recently, is that chromaticity drift is often accompanied by tune and coupling drift. This was recently discovered in the Tevatron. We believe that these effects are the product of systematic beam offset in conjunction with the sextupole drifts (and their compensation in the chromaticity correctors). These discoveries are most relevant to the upcoming LHC, where the drift effects will have even more dramatic consequences given the high beam current. It is therefore not a surprise that CERN has been the source of major advances in the understanding of dynamic effects during the LHC superconducting magnet development. The following will briefly review the …
Date: May 1, 2005
Creator: Annala, G.; Bauer, P.; Bottura, L.; Martens, M. A.; Sammut, N.; Velev, G. et al.
System: The UNT Digital Library
e+ e- collider in the VLHC tunnel. Proceedings, Workshop, Chicago, USA, March 9-11, 2001 (open access)

e+ e- collider in the VLHC tunnel. Proceedings, Workshop, Chicago, USA, March 9-11, 2001

This document is a collection of the contributions made to the March IIT workshop on an e{sup +}e{sup -} collider in the VLHC tunnel. This machine, which is based on a relatively conservative extrapolation of LEP technology, has a baseline luminosity of 10{sup 33}/cm{sup 2}/s at a CM energy of 370 GeV. The overall parameters and general description of such a machine is described in T. Sen and J. Norem, ''A Very Large Lepton Collider in the VLHC Tunnel'', to be published. A preprint of this paper is included as Appendix 2 of this report. The intention of the workshop was to define the parameters of such a collider and make them available to the community for use in further physics studies. It is clear that the machine cannot compete with a full scale linear collider. Its main interest would be if a VLHC were built and if a linear collider did not already exist. In this case, it could provide a limited and perhaps crucial view of low mass Higgs states. Although the study is incomplete, it does define rather well the parameters of the machine, as well as the challenges that the design faces. The study benefited greatly …
Date: July 1, 2001
Creator: Dugan, D., (ed.); /Cornell U., LEPP; Tollestrup, A., (ed.) & /Fermilab
System: The UNT Digital Library
Study of the decay asymmetry parameter and CP violation parameter in the Lambda(c)+ ---> Lambda pi+ decay (open access)

Study of the decay asymmetry parameter and CP violation parameter in the Lambda(c)+ ---> Lambda pi+ decay

Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter a{sub {Lambda}{sub c}} in {Lambda}{sub c}{sup +} {yields} {Lambda}{pi}{sup +} decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter {Alpha} {triple_bond} a{sub {Lambda}{sub c}} + a{sub {ovr {Lambda}{sub c}}}/a{sub {Lambda}{sub c}} - a{sub {ovr {Lambda}{sub c}}}. We obtain a{sub {Lambda}{sub c}} = -0.78 {+-} 0.16 {+-} 0.13 and {Alpha} = -0.07 {+-} 0.19 {+-} 0.12 where errors are statistical and systematic.
Date: September 1, 2005
Creator: Link, J. M.; Yager, P. M.; /UC, Davis; Anjos, J. C.; Bediaga, I.; Castromonte, C. et al.
System: The UNT Digital Library