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Intraocular Pressure Changes: An Important Determinant of the Biocompatibility of Intravitreous Implants (open access)

Intraocular Pressure Changes: An Important Determinant of the Biocompatibility of Intravitreous Implants

Article discussing intraocular pressure changes and an important determinant of the biocompatibility of intravitreous implants.
Date: December 14, 2011
Creator: Zou, Ling; Nair, Ashwin; Weng, Hong; Tsai, Yi-Ting; Hu, Zhibing & Tang, Liping
System: The UNT Digital Library
A Probabilistic Approach to Classifying Supernovae UsingPhotometric Information (open access)

A Probabilistic Approach to Classifying Supernovae UsingPhotometric Information

This paper presents a novel method for determining the probability that a supernova candidate belongs to a known supernova type (such as Ia, Ibc, IIL, etc.), using its photometric information alone. It is validated with Monte Carlo, and both space- and ground-based data. We examine the application of the method to well-sampled as well as poorly sampled supernova light curves and investigate to what extent the best currently available supernova models can be used for typing supernova candidates. Central to the method is the assumption that a supernova candidate belongs to a group of objects that can be modeled; we therefore discuss possible ways of removing anomalous or less well understood events from the sample. This method is particularly advantageous for analyses where the purity of the supernova sample is of the essence, or for those where it is important to know the number of the supernova candidates of a certain type (e.g., in supernova rate studies).
Date: December 14, 2006
Creator: Kuznetsova, Natalia V. & Connolly, Brian M.
System: The UNT Digital Library
ILC Reference Design Report: Accelerator Executive Summary (open access)

ILC Reference Design Report: Accelerator Executive Summary

The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radiofrequency (SCRF) accelerating cavities. The use of the SCRF technology was recommended by the International Technology Recommendation Panel (ITRP) in August 2004 [1], and shortly thereafter endorsed by the International Committee for Future Accelerators (ICFA). In an unprecedented milestone in high-energy physics, the many institutes around the world involved in linear collider R&D united in a common effort to produce a global design for the ILC. In November 2004, the 1st International Linear Collider Workshop was held at KEK, Tsukuba, Japan. The workshop was attended by some 200 accelerator physicists from around the world, and paved the way for the 2nd ILC Workshop in August 2005, held at Snowmass, Colorado, USA, where the ILC Global Design Effort (GDE) was officially formed. The GDE membership reflects the global nature of the collaboration, with accelerator experts from all three regions (Americas, Asia and Europe). The first major goal of the GDE was to define the basic parameters and layout of the machine--the Baseline Configuration. This was achieved at the first GDE meeting held at INFN, Frascati, Italy in December 2005 with the creation …
Date: December 14, 2007
Creator: Phinney, Nan
System: The UNT Digital Library
New and Novel Nondestructive Neutron and Gamma-Ray Technologies Applied to Safeguards (open access)

New and Novel Nondestructive Neutron and Gamma-Ray Technologies Applied to Safeguards

None
Date: December 14, 2007
Creator: Dougan, A. D.; Snyderman, N. J.; Nakae, L. F.; Dietrich, D. D.; Kerr, P. L.; Wang, T. F. et al.
System: The UNT Digital Library
Investigating Inflation in Type IIA (open access)

Investigating Inflation in Type IIA

We prove that inflation is forbidden in the most well understood class of semi-realistic type IIA string compactifications: Calabi-Yau compactifications with only standard NS-NS 3-form flux, R-R fluxes, D6-branes and O6-planes at large volume and small string coupling. With these ingredients, the first slow-roll parameter satisfies {epsilon} {ge} 27/13 whenever V > 0, ruling out both inflation (including brane/anti-brane inflation) and de Sitter vacua in this limit. Our proof is based on the dependence of the 4-dimensional potential on the volume and dilaton moduli in the presence of fluxes and branes. We also describe broader classes of IIA models which may include cosmologies with inflation and/or de Sitter vacua. The inclusion of extra ingredients, such as NS 5-branes and geometric or non-geometric NS-NS fluxes, evades the assumptions used in deriving the no-go theorem. We focus on NS 5-branes and outline how such ingredients may prove fruitful for cosmology, but we do not provide an explicit model. We contrast the results of our IIA analysis with the rather different situation in IIB.
Date: December 14, 2007
Creator: Hertzberg, Mark P.; /MIT; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC; Taylor, Washington; Tegmark, Max et al.
System: The UNT Digital Library
Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid (open access)

Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

Single crystalline surface such as (100), (111), (110) has been studied as an idealized platform for electrocatalytic reactions since the atomic arrangement affects a catalytic property. The secondary metal deposition on these surfaces also alters the catalytic property often showing improvement such as poisoning decrease. On the other hand, electrocatalysts used for practical purpose usually have a size on the order of nanometers. Therefore, linking the knowledge from single crystalline studies to nanoparticle catalysts is of enormous importance. Recently, the Pt nanoparticles which surface structure was preferentially oriented was synthesized and used as electrocatalysts. Here, we demonstrate a rational design of a binary metallic nanocatalyst based on the single crystalline study.
Date: December 14, 2007
Creator: Lee, Hyunjoo; Habas, Susan; Somorjai, Gabor & Yang, Peidong
System: The UNT Digital Library
Erratum: High power impulse magnetron sputtering:Current-voltage-time characteristics indicate the onset of sustainedself-sputtering (open access)

Erratum: High power impulse magnetron sputtering:Current-voltage-time characteristics indicate the onset of sustainedself-sputtering

None
Date: December 14, 2007
Creator: Anders, Andre; Andersson, Joakim & Ehiasarian, Arutiun
System: The UNT Digital Library
Measurements and Phenomenological Modeling of Magnetic FluxBuildup in Spheromak Plasmas (open access)

Measurements and Phenomenological Modeling of Magnetic FluxBuildup in Spheromak Plasmas

Internal magnetic field measurements and high-speed imaging at the Sustained Spheromak Physics Experiment (SSPX) [E. B. Hooper, L. D. Pearlstein, R. H. Bulmer, Nucl. Fusion 39, 863 (1999)] are used to study spheromak formation and field buildup. The measurements are analyzed in the context of a phenomenological model of magnetic helicity based on the topological constraint of minimum helicity in the open flux before reconnecting and linking closed flux. Two stages are analyzed: (1) the initial spheromak formation, i. e. when all flux surfaces are initially open and reconnect to form open and closed flux surfaces, and (2) the stepwise increase of closed flux when operating the gun on a new mode that can apply a train of high-current pulses to the plasma. In the first stage, large kinks in the open flux surfaces are observed in the high-speed images taken shortly after plasma breakdown, and coincide with large magnetic asymmetries recorded in a fixed insertable magnetic probe that spans the flux conserver radius. Closed flux (in the toroidal average sense) appears shortly after this. This stage is also investigated using resistive magnetohydrodynamic simulations. In the second stage, a time lag in response between open and closed flux surfaces after …
Date: December 14, 2007
Creator: Romero-Talamas, C. A.; Hooper, E. B.; Jayakumar, R.; McLean, H. S.; Wood, R. D. & Moller, J. M.
System: The UNT Digital Library
Synchronous Parallel Kinetic Monte Carlo (open access)

Synchronous Parallel Kinetic Monte Carlo

A novel parallel kinetic Monte Carlo (kMC) algorithm formulated on the basis of perfect time synchronicity is presented. The algorithm provides an exact generalization of any standard serial kMC model and is trivially implemented in parallel architectures. We demonstrate the mathematical validity and parallel performance of the method by solving several well-understood problems in diffusion.
Date: December 14, 2006
Creator: Mart?nez, E.; Marian, J. & Kalos, M. H.
System: The UNT Digital Library
Three-dimensional Dielectric Photonic Crystal Structures for Laser-driven Acceleration (open access)

Three-dimensional Dielectric Photonic Crystal Structures for Laser-driven Acceleration

We present the design and simulation of a three-dimensional photonic crystal waveguide for linear laser-driven acceleration in vacuum. The structure confines a synchronous speed-of-light accelerating mode in both transverse dimensions. We report the properties of this mode, including sustainable gradient and optical-to-beam efficiency. We present a novel method for confining a particle beam using optical fields as focusing elements. This technique, combined with careful structure design, is shown to have a large dynamic aperture and minimal emittance growth, even over millions of optical wavelengths.
Date: December 14, 2007
Creator: Cowan, Benjamin M. & /Tech-X, Boulder /SLAC
System: The UNT Digital Library
Unique Identification of Lee-Wick Gauge Bosons at Linear Colliders (open access)

Unique Identification of Lee-Wick Gauge Bosons at Linear Colliders

Grinstein, O'Connell and Wise have recently presented an extension of the Standard Model (SM), based on the ideas of Lee and Wick (LW), which demonstrates an interesting way to remove the quadratically divergent contributions to the Higgs mass induced by radiative corrections. This model predicts the existence of negative-norm copies of the usual SM fields at the TeV scale with ghost-like propagators and negative decay widths, but with otherwise SM-like couplings. In earlier work, it was demonstrated that the LW states in the gauge boson sector of these models, though easy to observe, cannot be uniquely identified as such at the LHC. In this paper, we address the issue of whether or not this problem can be resolved at an e{sup +}e{sup -} collider with a suitable center of mass energy range. We find that measurements of the cross section and the left-right polarization asymmetry associated with Bhabha scattering can lead to a unique identification of the neutral electroweak gauge bosons of the Lee-Wick type.
Date: December 14, 2007
Creator: Rizzo, Thomas G.
System: The UNT Digital Library
Non-Relativistic Superstring Theories (open access)

Non-Relativistic Superstring Theories

We construct a supersymmetric version of the 'critical' non-relativistic bosonic string theory [1] with its manifest global symmetry. We introduce the anticommuting bc CFT which is the super partner of the {beta}{gamma} CFT. The conformal weights of the b and c fields are both 1/2. The action of the fermionic sector can be transformed into that of the relativistic superstring theory. We explicitly quantize the theory with manifest SO(8) symmetry and find that the spectrum is similar to that of Type IIB superstring theory. There is one notable difference: the fermions are non-chiral. We further consider 'noncritical' generalizations of the supersymmetric theory using the superspace formulation. There is an infinite range of possible string theories similar to the supercritical string theories. We comment on the connection between the critical non-relativistic string theory and the lightlike Linear Dilaton theory.
Date: December 14, 2007
Creator: Kim, Bom Soo
System: The UNT Digital Library
HYLIFE-II inertial confinement: Fusion power plant design (open access)

HYLIFE-II inertial confinement: Fusion power plant design

The HYLIFE-2 inertial fusion power plant design study uses a liquid fall, in the form of jets to protect the first structural wall from neutron damage, x rays, and blast to provide a 30-y lifetime. HYLIFE-1 used liquid lithium. HYLIFE 2 avoids the fire hazard of lithium by using a molten salt composed of fluorine, lithium, and beryllium (Li{sub 2}BeF{sub 4}) called Flibe. Access for heavy-ion beams is provided. Calculations for assumed heavy-ion beam performance show a nominal gain of 70 at 5 MJ producing 350 MJ, about 5.2 times less yield than the 1.8 GJ from a driver energy of 4.5 MJ with gain of 400 for HYLIFE-1. The nominal 1 GWe of power can be maintained by increasing the repetition rate by a factor of about 5.2, from 1.5 to 8 Hz. A higher repetition rate requires faster re-establishment of the jets after a shot, which can be accomplished in part by decreasing the jet fall height and increasing the jet flow velocity. Multiple chambers may be required. In addition, although not considered for HYLIFE-1, there is undoubtedly liquid splash that must be forcibly cleared because gravity is too slow, especially at high repetition rates. Splash removal can …
Date: December 14, 1990
Creator: Moir, Ralph W.
System: The UNT Digital Library
Database of average-power damage thresholds at 1064 nm (open access)

Database of average-power damage thresholds at 1064 nm

We have completed a database of average-power, laser-induced, damage thresholds at 1064 nm on a variety of materials. Measurements were made with a newly constructed laser to provide design input for moderate and high average-power laser projects. The measurements were conducted with 16-ns pulses at pulse-repetition frequencies ranging from 6 to 120 Hz. Samples were typically irradiated for time ranging from a fraction of a second up to 5 minutes (36,000 shots). We tested seven categories of samples which included antireflective coatings, high reflectors, polarizers, single and multiple layers of the same material, bare and overcoated metal surfaces, bare polished surfaces, and bulk materials. The measured damage threshold ranged from < 1 J/cm/sup 2/ for some metals to > 46 J/cm/sup 2/ for a bare polished glass substrate. 4 refs., 7 figs., 1 tab.
Date: December 14, 1987
Creator: Rainer, F.; Hildum, E.A. & Milam, D.
System: The UNT Digital Library
Heavy ion beam and reactor chamber interface design (open access)

Heavy ion beam and reactor chamber interface design

The design of the heavy-ion beam and the HYLIFE-II reactor chamber interface must provide final focusing quadruple triplets, neutron shielding, fast shutters, vapor condensation and pumping, thermal insulation, and blast resistant structures. The smallest half angle encompassing all beams striking the target might be {plus minus}14{degrees} for an array of 4 {times} 4 beams or {plus minus}9{degrees} if the four corner beams are eliminated, giving a 12-beam array. The target gain drops considerably from the 0{degree} published values because of this finite angle. The assumed one-sided irradiation reduces the number of bending magnets. A 350-MJ yield might be achieved with a 6-MJ driver (gain of 58) (nominal 1000 MWe net power with a repetition rate of 8 Hz). For either lower repetition rate or lower gain the yield must be increased by increasing the driver energy. The beam ports are protected from radiation by an array of vertical and horizontal, neutronically-thick, liquid jets. 6 refs., 7 figs.
Date: December 14, 1990
Creator: Moir, Ralph W.
System: The UNT Digital Library
Oscillating liquid flow ICF Reactor (open access)

Oscillating liquid flow ICF Reactor

Oscillating liquid flow in a falling molten salt inertial confinement fusion reactor is predicted to rapidly clear driver beam paths of residual liquid droplets. Oscillating flow will also provide adequate neutron and x-ray protection for the reactor structure with a short (2-m) fall distance permitting an 8 Hz repetition rate. A reactor chamber configuration is presented with specific features to clear the entire heavy-ion beam path of splashed molten salt. The structural components, including the structure between beam ports, are shielded. 3 refs., 12 figs.
Date: December 14, 1990
Creator: Petzoldt, R.W.
System: The UNT Digital Library
Results from hadron colliders (open access)

Results from hadron colliders

The present status of hadron collider physics is reviewed. The total cross section for {bar p} + p has been measured at 1.8 TeV: {sigma}{sub tot} = 72.1 {plus minus} 3.3 mb. New data confirm the UA2 observation of W/Z {yields} {bar q}q. Precision measurements of M{sub W} by UA2 and CDF give an average value M{sub W} = 80.13 {plus minus} 0.30 GeV/c{sup 2}. When combined with measurements of M{sub Z} from LEP and SLC this number gives sin{sup 2}{theta}{sub W} = 0.227 {plus minus} 0.006, or m{sub top} = 130{sub {minus}60}{sup +40} GeV/c{sup 2} from the EWK radiative correction term {Delta}r. Evidence for hadron colliders as practical sources of b quarks has been strengthened, while searches for t quarks have pushed the mass above M{sub W}: m{sub top} > 89 GeV/c{sup 2} 95% cl (CDF Preliminary). Searches beyond the standard model based on the missing E{sub T} signature have not yet produced any positive results. Future prospects for the discovery of the top quark in the range m{sub top} < 200 GeV/c{sup 2} look promising. 80 refs., 35 figs., 7 tabs.
Date: December 14, 1990
Creator: Pondrom, L.G. (Wisconsin Univ., Madison, WI (USA))
System: The UNT Digital Library
HYLIFE-II inertial confinement fusion reactor design (open access)

HYLIFE-II inertial confinement fusion reactor design

The HYLIFE-2 inertial fusion power plant design study uses a liquid fall, in the form of jets to protect the first structural wall from neutron damage, x rays, and blast to provide a 30-y lifetime. HYLIFE-1 used liquid lithium. HYLIFE 2 avoids the fire hazard of lithium by using a molten salt composed of fluorine, lithium, and beryllium (Li{sub 2}BeF{sub 4}) called Flibe. Access for heavy-ion beams is provided. Calculations for assumed heavy-ion beam performance show a nominal gain of 70 at 5 MJ producing 350 MJ, about 5.2 times less yield than the 1.8 GJ from a driver energy of 4.5 MJ with gain of 400 for HYLIFE-1. The nominal 1 GWe of power can be maintained by increasing the repetition rate by a factor of about 5.2, from 1.5 to 8 Hz. A higher repetition rate requires faster re-establishment of the jets after a shot, which can be accomplished in part by decreasing the jet fall height and increasing the jet flow velocity. Multiple chambers may be required. In addition, although not considered for HYLIFE-1, there is undoubtedly liquid splash that must be forcibly cleared because gravity is too slow, especially at high repetition rates. Splash removal can …
Date: December 14, 1990
Creator: Moir, Ralph W.
System: The UNT Digital Library
Machining of uranium and uranium alloys (open access)

Machining of uranium and uranium alloys

Uranium and uranium alloys can be readily machined by conventional methods in the standard machine shop when proper safety and operating techniques are used. Material properties that affect machining processes and recommended machining parameters are discussed. Safety procedures and precautions necessary in machining uranium and uranium alloys are also covered. 30 figures.
Date: December 14, 1981
Creator: Morris, T. O.
System: The UNT Digital Library
Quark gluon plasma: Overview and experimental results from E-735 (open access)

Quark gluon plasma: Overview and experimental results from E-735

A brief review of the phenomenology associated with the effort to produce and observe quark-gluon plasma in particle collisions is presented. E-735 has taken data during the 1987 Tevatron-Collider run at /square root/s = 1.8 TeV in pursuit of this goal. Results in the correlation of < p/sub t/ > with multiplicity for charged particles and p/sub t/ distributions for ..lambda../sup o/ and /bar Lambda//sup o/ are presented. 32 refs., 10 figs., 2 tabs.
Date: December 14, 1988
Creator: Turkot, F.; Alexopoulos, T.; Allen, C.; Anderson, E.W.; Areti, H.; Banerjee, S. et al.
System: The UNT Digital Library
Measurements of optical loss in transparent solids using a novel spectrometer based on optical cavity decay (open access)

Measurements of optical loss in transparent solids using a novel spectrometer based on optical cavity decay

Recent advances in High Average Power (HAP) solid state lasers and the development of new concept lasers with the potential of ultra- high average power output have put increasing demands on the transparency of optical window materials. To gain a better understanding of the current status of window materials and to direct research toward more nearly transparent materials, we have constructed an optical characterization facility with the purpose of making quantitative optical loss measurements in the sensitivity range of 10/sup /minus/3/ to 10/sup /minus/6/ cm/sup /minus/1/. The cornerstone of this facility is a scanning optical lossmeter in which loss is determined by comparing the decay time of an optical cavity with and without a transparent solid present. The lossmeter has been successfully applied to measurements of the optical loss of witness samples of highly transparent fused silica. A description of the lossmeter and a compilation of preliminary loss measurements are presented here. 3 refs.
Date: December 14, 1988
Creator: Milanovich, F. P.; Hunt, J. T. & Roe, J. N.
System: The UNT Digital Library
Waveguide Fabrication in Fused Silica Using Tightly Focused Femtosecond Laser Pulses (open access)

Waveguide Fabrication in Fused Silica Using Tightly Focused Femtosecond Laser Pulses

Refractive index changes have been induced inside bulk fused silica by using femtosecond (fs) laser pulses tightly focused inside the material. Waveguides have been fabricated inside the glass by scanning the glass with respect to the focal point of the laser beam. The refractive index change is estimated to be {approx} 10{sup -4}. Other more complex three-dimensional structures have also been fabricated (curved waveguides, splitters, and interferometers). We also report on fluorescence spectroscopy of the fs-modified fused silica using a confocal microscopy setup. Using a 488 nm excitation source, a fluorescence at 630 nm is observed from the modified glass, which is attributed to the presence of non-bridging oxygen hole center (NBOHC) defects created by the fs pulses. The fluorescence decays with prolonged exposure to the 488 nm light, indicating that the defects are being photobleached by the excitation light.
Date: December 14, 2001
Creator: Chan, J W; Huser, T; Risbud, S H & Krol, D M
System: The UNT Digital Library
Surface Based Differential Forms (open access)

Surface Based Differential Forms

Higher-order basis functions have been constructed for surface-based differential forms that are used in engineering simulations. These surface-based forms have been designed to complement the volume-based forms present in EMSolve[1], a finite element code. The basis functions are constructed on a reference element and transformed, as necessary, for each element in space. Lagrange polynomials are used to create the basis functions. This approach is a necessary step in creating a hybrid finite-element/integral-equation time-domain code for electromagnetic analysis.
Date: December 14, 2004
Creator: Pingenot, J.; Yang, C.; Jandhyala, V.; Champagne, N.; White, D.; Stowell, M. et al.
System: The UNT Digital Library
Systematic Uncertainties in NLO PS Matching (open access)

Systematic Uncertainties in NLO PS Matching

None
Date: December 14, 2012
Creator: Schonherr, Marek; Hoeche, Stefan; Krauss, Frank & Siegert, Frank
System: The UNT Digital Library