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Application of a Multidimensional Wavelet Denoising Algorithm for the Detection and Characterization of Astrophysical Sources of Gamma Rays (open access)

Application of a Multidimensional Wavelet Denoising Algorithm for the Detection and Characterization of Astrophysical Sources of Gamma Rays

Zhang, Fadili, & Starck have recently developed a denoising procedure for Poisson data that offers advantages over other methods of intensity estimation in multiple dimensions. Their procedure, which is nonparametric, is based on thresholding wavelet coefficients. The restoration algorithm applied after thresholding provides good conservation of source flux. We present an investigation of the procedure of Zhang et al. for the detection and characterization of astrophysical sources of high-energy gamma rays, using realistic simulated observations with the Large Area Telescope (LAT). The LAT is to be launched in late 2007 on the Gamma-ray Large Area Space Telescope mission. Source detection in the LAT data is complicated by the low fluxes of point sources relative to the diffuse celestial background, the limited angular resolution, and the tremendous variation of that resolution with energy (from tens of degrees at {approx}30 MeV to 0.1{sup o} at 10 GeV). The algorithm is very fast relative to traditional likelihood model fitting, and permits immediate estimation of spectral properties. Astrophysical sources of gamma rays, especially active galaxies, are typically quite variable, and our current work may lead to a reliable method to quickly characterize the flaring properties of newly-detected sources.
Date: December 2, 2005
Creator: Digel, S. W.; /SLAC; Zhang, B.; Chiang, J.; U., /Maryland; Fadili, J. M. et al.
System: The UNT Digital Library
Measurement of the Absolute Branching Fractions of$B^\pm \to K^\pm X_{c\bar c}$ (open access)

Measurement of the Absolute Branching Fractions of$B^\pm \to K^\pm X_{c\bar c}$

We study the two-body decays of B{sup {+-}} mesons to K{sup {+-}} and a charmonium state, X{sub c{bar c}}, in a sample of 210.5 fb{sup -1} of data from the BABAR experiment. We perform measurements of absolute branching fractions {Beta}(B{sup {+-}} {yields} K{sup {+-}} X{sub c{bar c}}) using a missing mass technique, and report several new or improved results. In particular, the upper limit {Beta}(B{sup {+-}} {yields} K{sup {+-}}(3872)) < 3.2 x 10{sup -4} at 90% CL and the inferred lower limit {Beta}(X(3872) {yields} J/{psi}{pi}{sup +}{pi}{sup -}) > 4.2% will help in understanding the nature of the recently discovered X(3872).
Date: November 2, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
A Human Reliability-Centered Approach to the Development of Job Aids for Reviewers of Medical Devices That Use Radiological Byproduct Materials. (open access)

A Human Reliability-Centered Approach to the Development of Job Aids for Reviewers of Medical Devices That Use Radiological Byproduct Materials.

The U.S. Nuclear Regulatory Commission (NRC) is engaged in an initiative to risk-inform the regulation of byproduct materials. Operating experience indicates that human actions play a dominant role in most of the activities involving byproduct materials, which are radioactive materials other than those used in nuclear power plants or in weapons production, primarily for medical or industrial purposes. The overall risk of these activities is strongly influenced by human performance. Hence, an improved understanding of human error, its causes and contexts, and human reliability analysis (HRA) is important in risk-informing the regulation of these activities. The development of the human performance job aids was undertaken by stages, with frequent interaction with the prospective users. First, potentially risk significant human actions were identified based on reviews of available risk studies for byproduct material applications and of descriptions of events for byproduct materials applications that involved potentially significant human actions. Applications from the medical and the industrial domains were sampled. Next, the specific needs of the expected users of the human performance-related capabilities were determined. To do this, NRC headquarters and region staff were interviewed to identify the types of activities (e.g., license reviews, inspections, event assessments) that need HRA support and …
Date: February 2, 2005
Creator: Cooper, S. E.; Brown, W. S. & Wreathall, J.
System: The UNT Digital Library
Innovative Technologies And Vadose Zone Treatment Of Chlorinated Volatile Organic Compounds - Case Study (open access)

Innovative Technologies And Vadose Zone Treatment Of Chlorinated Volatile Organic Compounds - Case Study

Over the last 10 years a mix of innovative and conventional characterization techniques has been used to assess the contamination of vadose zone sediments beneath the pilot-scale test facility known as TNX at the Savannah River Site (SRS) in South Carolina. Shallow soils and groundwater beneath the TNX facility are contaminated with chlorinated volatile organic compounds (CVOCs), trichloroethylene (TCE), carbon tetrachloride (CCl{sub 4}), perchloroethylene (PCE), and chloroform (CHCl{sub 3}). An interim pump and treat remediation system was placed in operation in 1996 to provide hydraulic containment of groundwater containing greater than 500 ug/L dissolved TCE. In 1994, a vadose zone study was initiated to determine the degree and extent of CVOC contamination above the contaminated groundwater. Headspace sampling and analysis, acoustic infrared spectroscopy, cone penetrometry, and vadose zone pumping tests were used to determine contaminant concentrations and physical properties related to soil vapor extraction. In 2001, soil vapor extraction (SVE), a presumptive remedy for CVOCs in soils similar to those present beneath TNX, was selected to treat the CVOC contamination. Cone Penetrometer Testing (CPT) with soil vapor sampling provided a detailed understanding of the subsurface geology and CVOC distribution which was essential for proper well design and placement. Twelve SVE …
Date: August 2, 2005
Creator: NOONKESTER, JAY V.; NICHOLS, RALPH L. & DIXON, KENETH L.
System: The UNT Digital Library
QUARK ANTIQUARK ENERGIES AND THE SCREENING MASS IN A QUARK-GLUON PLASMA AT LOW AND HIGH TEMPERATURES. (open access)

QUARK ANTIQUARK ENERGIES AND THE SCREENING MASS IN A QUARK-GLUON PLASMA AT LOW AND HIGH TEMPERATURES.

We discuss quark antiquark energies and the screening mass in hot QCD using the non-perturbative lattice approach. For this purpose we analyze properties of quark antiquark energies and entropies at infinitely large separation of the quark antiquark pair at low and high temperatures. In the limit of high temperatures these energies and entropies can be related perturbatively to the temperature dependence of the Debye mass and the coupling. On the one hand our analysis thus suggests that the quark antiquark energies at (infinite) large distances are rather related to the Debye screening mass and the coupling than to the temperature dependence of heavy-light meson masses. On the other hand we find no or only little differences in all mass scales introduced by us when changing from quenched to 2-flavor QCD at temperatures which are only moderately above the phase transition.
Date: August 2, 2005
Creator: ZANTOW, F. & KACZMAREK, O.
System: The UNT Digital Library
Determination of MSSM Parameters from LHC and ILCObservables in a Global Fit (open access)

Determination of MSSM Parameters from LHC and ILCObservables in a Global Fit

We present the results of a realistic global fit of the Lagrangian parameters of the Minimal Supersymmetric Standard Model assuming universality for the first and second generation and real parameters. No assumptions on the SUSY breaking mechanism are made. The fit is performed using the precision of future mass measurements of superpartners at the LHC and mass and polarized topological cross-section measurements at the ILC. Higher order radiative corrections are accounted for wherever possible to date. Results are obtained for a modified SPS1a MSSM benchmark scenario but they were checked not to depend critically on this assumption. Exploiting a simulated annealing algorithm, a stable result is obtained without any a priori assumptions on the values of the fit parameters. Most of the Lagrangian parameters can be extracted at the percent level or better if theoretical uncertainties are neglected. Neither LHC nor ILC measurements alone will be sufficient to obtain a stable result. The effects of theoretical uncertainties arising from unknown higher-order corrections and parametric uncertainties are examined qualitatively. They appear to be relevant and the result motivates further precision calculations. The obtained parameters at the electroweak scale are used for a fit of the parameters at high energy scales within …
Date: December 2, 2005
Creator: Bechtle, Philip; /SLAC; Desch, Klaus; U., /Freiburg; Porod, Werner; /Valencia U., IFIC /Zurich U. et al.
System: The UNT Digital Library
Hydrodynamic test problems (open access)

Hydrodynamic test problems

We present test problems that can be used to check the hydrodynamic implementation in computer codes designed to model the implosion of a National Ignition Facility (NIF) capsule. The problems are simplified, yet one of them is three-dimensional. It consists of a nearly-spherical incompressible imploding shell subjected to an exponentially decaying pressure on its outer surface. We present a semi-analytic solution for the time-evolution of that shell with arbitrary small three-dimensional perturbations on its inner and outer surfaces. The perturbations on the shell surfaces are intended to model the imperfections that are created during capsule manufacturing.
Date: June 2, 2005
Creator: Moran, B
System: The UNT Digital Library
Supersymmetry Parameter Analysis: SPA Convention and Project (open access)

Supersymmetry Parameter Analysis: SPA Convention and Project

High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. A repository for computer programs is provided which connect parameters in different schemes and relate the Lagrangian parameters to physical observables at LHC and high energy e{sup +}e{sup -} linear collider experiments, i.e., masses, mixings, decay widths and production cross sections for supersymmetric particles. In addition, programs for calculating high-precision low energy observables, the density of cold dark matter (CDM) in the universe as well as the cross sections for CDM search experiments are included. The SPA scheme still requires extended efforts on both the theoretical and experimental side before data can be evaluated in the future at the level of the desired precision. We take here an initial step of testing the SPA scheme by applying the techniques involved to a specific supersymmetry reference point.
Date: December 2, 2005
Creator: Aguilar-Saavedra, J. A.; Ali, A.; Allanach, B. C.; Arnowitt, R.; Baer, H. A.; Bagger, J. A. et al.
System: The UNT Digital Library
Photon-Photon Collisions -- Past and Future (open access)

Photon-Photon Collisions -- Past and Future

I give a brief review of the history of photon-photon physics and a survey of its potential at future electron-positron colliders. Exclusive hadron production processes in photon-photon and electron-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes. There are also important high energy {gamma}{gamma} and e{gamma} tests of quantum chromodynamics, including the production of jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Since photons couple directly to all fundamental fields carrying the electromagnetic current including leptons, quarks, W's and supersymmetric particles, high energy {gamma}{gamma} collisions will provide a comprehensive laboratory for Higgs production and exploring virtually every aspect of the Standard Model and its extensions. High energy back-scattered laser beams will thus greatly extend the range of physics of the International Linear Collider.
Date: December 2, 2005
Creator: Brodsky, Stanley J.
System: The UNT Digital Library
Enhanced K(L) ---> Pi0 Nu Anti-Nu From Direct CP Violation in B ---> K Pi With Four Generations (open access)

Enhanced K(L) ---> Pi0 Nu Anti-Nu From Direct CP Violation in B ---> K Pi With Four Generations

Recent CP violation results in B decays suggest that Z penguins may have large weak phase. This can be realized by the four generation (standard) model. Concurrently, B {yields} X{sub s}{ell}{sup +}{ell}{sup -} and B{sub s} mixing allow for sizable V*{sub t's}V{sub t'b} only if it is nearly imaginary. Such large effects in b {leftrightarrow} s transitions would affect s {leftrightarrow} d transitions, as kaon constraints would demand V{sub t'd} {ne} 0. Using {Lambda}(Z {yields} b{bar b}) to bound |V{sub t'b}|, they infer sizable |V{sub t's}| {le} |V{sub t'b}| {le} |V{sub us}|. Imposing {var_epsilon}{sub K}, K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}} and {var_epsilon}'/{var_epsilon} constraints, they find V*{sub t'd} V{sub t's} {approx} few x 10{sup -4} with large phase, enhancing K{sub L} {yields} {pi}{sup 0} {nu}{bar {nu}} to 5 x 10{sup -10} or even higher. Interestingly, {Delta}m{sub B{sub d}} and sin 2{Phi}{sub B{sub d}} are not much affected, as |V*{sub t'd} V{sub t'b} << |V*{sub td} V{sub tb}| {approx} 0.01.
Date: September 2, 2005
Creator: Hou, Wei-Shu; /Taiwan, Natl. Taiwan U. /SLAC; Nagashima, Makiko; /Taiwan, Natl. Taiwan U.; Soddu, Andrea & /Taiwan, Natl. Taiwan U. /Weizmann Inst.
System: The UNT Digital Library
A Rotating Coil Apparatus with Sub-Micrometer Magnetic Center Measurement Stability (open access)

A Rotating Coil Apparatus with Sub-Micrometer Magnetic Center Measurement Stability

A rotating double coil apparatus has been designed and built so that the relative magnetic center change of a quadrupole is measured to an uncertainty smaller than 0.02 micrometers (=micron, {micro}m) for a single measurement. Furthermore, repeated measurements over about an hour vary by less than 0.1 {micro}m and by less than 1 {micro}m for periods of 24 hrs or longer. Correlation analyses of long data runs show that the magnet center measurement is sensitive to mechanical effects, such as vibration and rotating part wear, as well as to environmental effects, such as temperature and relative humidity. Evolving apparatus design has minimized mechanical noise and environmental isolation has reduced the effects of the surrounding environment so that sub-micron level measurement uncertainties and micron level stability have been achieved for multi-day measurement periods. Apparatus design evolution will be described in detail and correlation data taken on water-cooled electromagnet and adjustable permanent quadrupoles, which are about 350 mm in overall length, will be shown. These quads were prototypes for the linac quads of the Next Linear Collider (NLC) that had to meet the requirement that their magnetic centers change less than 1 micron during a 20% change in field strength. Thus it …
Date: December 2, 2005
Creator: Spencer, Cherrill M.; Anderson, Scott D.; Jensen, David R. & Wolf, Zachary R.
System: The UNT Digital Library
Exclusive Two-Photon Processes in QCD (open access)

Exclusive Two-Photon Processes in QCD

Hadron pair production from two-photon annihilation plays an important role in unraveling the perturbative and non-perturbative structure of QCD, first by testing the validity and empirical applicability of leading-twist factorization theorems, second by verifying the structure of the underlying perturbative QCD subprocesses, and third, through measurements of angular distributions and ratios which are sensitive to the shape of the distribution amplitudes. In effect, photon-photon collisions provide a microscope for testing fundamental scaling laws of PQCD and for measuring distribution amplitudes. The determination of the shape and normalization of the distribution amplitude is particularly important in view of their importance in the analysis of exclusive semi-leptonic and two-body hadronic B-decays. The data from the Belle and CLEO collaborations on single and double meson production are in excellent agreement with the QCD predictions. In contrast, the normalization of the nominal leading-order predictions of PQCD for proton pair production appears to be significantly below recent Belle measurements. I also review issues relating to renormalization scale setting.
Date: December 2, 2005
Creator: Brodsky, Stanley J.
System: The UNT Digital Library
Pentaquark Searches at the BaBar Experiment (open access)

Pentaquark Searches at the BaBar Experiment

A review of the results in the inclusive and exclusive searches for pentaquark states obtained from the analysis of the data recorded at the BABAR experiment at the Stanford Linear Accelerator Center PEP-II B-Factory, is presented. Inclusive searches for the strange pentaquark states {Theta}{sub 5}(1540){sup +}, {Xi}{sub 5}(1860){sup --} and {Xi}{sub 5}(1860){sup 0} have been performed in a dataset of e{sup +}e{sup -} annihilations corresponding to 123.4 fb{sup -1} of integrated luminosity. No evidence is found and therefore the corresponding 95% confidence level upper limits on the {Theta}{sub 5}(1540){sup +} and {Xi}{sub 5}(1860){sup --} production rate are set. Additionally the decay {Theta}{sub 5}(1540){sup +} {yields} pK{sub S}{sup 0} has been searched for in events that correspond to interactions of both electrons and hadrons with the inner-most material of the BABAR detector, but then again, no evidence for such a process is found as a result of this analysis. The exclusive search of the {Theta}*{sup ++} pentaquark in the B meson decay B{sup +} {yields} {bar p}{Theta}*{sup ++} where {Theta}*{sup ++} {yields} pK{sup +}, has been carried out in a dataset of 210 fb{sup -1}. The results show no evidence for such a pentaquark in the mass range from 1.43 to …
Date: November 2, 2005
Creator: Grauges, Eugeni & U., /Barcelona
System: The UNT Digital Library
Baryon Number Violation Involving Higher Generations (open access)

Baryon Number Violation Involving Higher Generations

None
Date: September 2, 2005
Creator: Hou, Wei-Shu; /Taiwan, Natl. Taiwan U. /SLAC; Nagashima, Makiko; /Taiwan, Natl. Taiwan U.; Soddu, Andrea & /Taiwan, Natl. Taiwan U. /Weizmann Inst.
System: The UNT Digital Library
A WDM/Optical-CDMA (WDM/O-CDMA) Concept for Avionics Integration (open access)

A WDM/Optical-CDMA (WDM/O-CDMA) Concept for Avionics Integration

We describe a concept where WDM and O-CDMA share a set of discrete wavelengths and components while using similar modulation formats. O-CDMA acts as a channel multiplier. Experiments show the feasibility of >2X channel multiplication.
Date: June 2, 2005
Creator: Mendez, A. J.; Hernandez, V. J.; Gagliardi, R. M.; Braun, S. W.; Bennett, C. V. & Lennon, W. J.
System: The UNT Digital Library
Recent and Future Observations in the X-ray and Gamma-ray Bands: Chandra, Suzaku, GLAST, and NuSTAR (open access)

Recent and Future Observations in the X-ray and Gamma-ray Bands: Chandra, Suzaku, GLAST, and NuSTAR

This paper presents a brief overview of the accomplishments of the Chandra satellite that are shedding light on the origin of high energy particles in astrophysical sources, with the emphasis on clusters of galaxies. It also discusses the prospects for the new data to be collected with instruments recently launched--such as Suzaku--or those to be deployed in the near future, and this includes GLAST and NuSTAR.
Date: December 2, 2005
Creator: Madejski, Greg
System: The UNT Digital Library
QCD CORRECTIONS TO DILEPTON PRODUCTION NEAR PARTONIC THRESHOLD IN PP SCATTERING. (open access)

QCD CORRECTIONS TO DILEPTON PRODUCTION NEAR PARTONIC THRESHOLD IN PP SCATTERING.

We present a recent study of the QCD corrections to dilepton production near partonic threshold in transversely polarized {bar p}p scattering, We analyze the role of the higher-order perturbative QCD corrections in terms of the available fixed-order contributions as well as of all-order soft-gluon resummations for the kinematical regime of proposed experiments at GSI-FAIR. We find that perturbative corrections are large for both unpolarized and polarized cross sections, but that the spin asymmetries are stable. The role of the far infrared region of the momentum integral in the resummed exponent and the effect of the NNLL resummation are briefly discussed.
Date: October 2, 2005
Creator: SHIMIZU, H.; STERMAN, G.; VOGELSANG, W. & YOKOYA, H.
System: The UNT Digital Library
Modeling aerosol-cloud interactions with a self-consistent cloud scheme in a general circulation model (open access)

Modeling aerosol-cloud interactions with a self-consistent cloud scheme in a general circulation model

This paper describes a self-consistent prognostic cloud scheme that is able to predict cloud liquid water, amount and droplet number (N{sub d}) from the same updraft velocity field, and is suitable for modeling aerosol-cloud interactions in general circulation models (GCMs). In the scheme, the evolution of droplets fully interacts with the model meteorology. An explicit treatment of cloud condensation nuclei (CCN) activation allows the scheme to take into account the contributions to N{sub d} of multiple types of aerosol (i.e., sulfate, organic and sea-salt aerosols) and kinetic limitations of the activation process. An implementation of the prognostic scheme in the Geophysical Fluid Dynamics Laboratory (GFDL) AM2 GCM yields a vertical distribution of N{sub d} characteristic of maxima in the lower troposphere differing from that obtained through diagnosing N{sub d} empirically from sulfate mass concentrations. As a result, the agreement of model-predicted present-day cloud parameters with satellite measurements is improved compared to using diagnosed N{sub d}. The simulations with pre-industrial and present-day aerosols show that the combined first and second indirect effects of anthropogenic sulfate and organic aerosols give rise to a global annual mean flux change of -1.8 W m{sup -2} consisting of -2.0 W m{sup -2} in shortwave and …
Date: May 2, 2005
Creator: Ming, Y; Ramaswamy, V; Donner, L J; Phillips, V T; Klein, S A; Ginoux, P A et al.
System: The UNT Digital Library
Scanning Hall Probe Imaging of ErNi2B2C (open access)

Scanning Hall Probe Imaging of ErNi2B2C

We report scanning Hall probe imaging of ErNi{sub 2}B{sub 2}C in the superconducting, antiferromagnetic, and weakly ferromagnetic regimes in magnetic fields up to 20 Oe, well below H{sub c1}, with two results. First, imaging isolated vortices shows that they spontaneously rearrange on cooling through the antiferromagnetic transition temperature T{sub N} = 6 K to pin on twin boundaries, forming a striped pattern. Second, a weak, random magnetic signal appears in the ferromagnetic phase below T{sub WFM} = 2.3 K, and no spontaneous vortex lattice is present down to 1.9 K. We conclude that ferromagnetism coexists with superconductivity either by forming small ferromagnetic domains or with oscillatory variation of the magnetization on sub-penetration depth length scales.
Date: December 2, 2005
Creator: Bluhm, Hendrik; Sebastian, Suchitra; Guikema, Janice W.; Fisher, I.R.; Moler, Kathryn A. & /Stanford U., Appl. Phys. Dept.
System: The UNT Digital Library
A Search for the Decay B+ ---> Tau+ Nu/Tau at BaBar (open access)

A Search for the Decay B+ ---> Tau+ Nu/Tau at BaBar

Based on an 87-fb{sup -1} dataset collected by the Babar detector at the PEP-II asymmetric-energy B-Factory, a search for D{sup 0}-{bar D}{sup 0} mixing has been made using the semileptonic decay modes D*{sup +} {yields} {pi}{sup +}D{sup 0}, D{sup 0} {yields} Ke{nu} (+c.c.). The use of these modes allows unambiguous flavor tagging and a combined fit of the D{sup 0} decay time and D*{sup +}-D{sup 0} mass difference ({Delta}M) distributions. The high-statistics sample of unmixed semileptonic D{sup 0} decays is used to model the {Delta}M distribution and time-dependence of mixed events directly from the data. Neural networks are used to select events and reconstruct the D{sup 0}. A result consistent with no charm mixing has been obtained, R{sub mix} = 0.0023 {+-} 0.0012 {+-} 0.0004. This corresponds to an upper limit of R{sub mix} < 0.0042 (90% CL).
Date: November 2, 2005
Creator: Datta, M.
System: The UNT Digital Library
The Back End of the Fuel Cycle Moves Front and Center (open access)

The Back End of the Fuel Cycle Moves Front and Center

For many years, the commercial nuclear business has remained relatively stable in many ways. That is unlikely to be the case in the coming years. While some countries have called for the phase out of nuclear power and others have ordered a small number of new plants, the overall profile of the nuclear power business has changed little. The number of countries with nuclear power plants is not much different than 10 years ago and the total number of operating plants has increased only slightly. Commercial enrichment and reprocessing services have remained the province of a few countries and consortia. Repository programs have moved forward slowly in some cases, backward in others, with a very small number making substantial progress. We are now witnessing the beginnings of serious change, with significant consequences for the future nuclear regime. Business as usual will not be the business of the future. The way the nuclear and policy community respond will have much to do with energy adequacy, national security, international stability, and environmental consequences including waste management and disposal. A number of events and trends are becoming increasingly apparent and are cause for both opportunity and caution: (1) New nuclear power plant orders …
Date: November 2, 2005
Creator: Isaacs, T & Choi, J
System: The UNT Digital Library
The Ring System of Uranus: Flat as a Pancake, Sprinkled with Dust (open access)

The Ring System of Uranus: Flat as a Pancake, Sprinkled with Dust

We present a high quality image of the uranian ring system, obtained in July 2004 at 2.2 {micro}m with the adaptive optics camera NIRC2 on the Keck II telescope. Using these data, we report the first ground-based image of the ring 1986U2R, seen only once before by the Voyager spacecraft. We show that this ring extends inward to {approx} 7000 km above the Uranus cloud deck. Its VIF (total vertically integrated I/F) is {approx} 100 m. We further detected narrow sheets of dust in between the {delta} and {epsilon} rings, and in between rings 4 and {alpha}, with a VIF of 14 and 20 m, respectively. Surprisingly, we find that the particles in Uranus' 9 main rings are distributed within a mono-layer, rather than the usually adopted poly-layer model. We come to this conclusion via a comparison of the VIF as derived from our 2003 data at a ring opening angle B {approx} 18{sup o} (from Gibbard et al. 2004) with those derived in this paper at B {approx} 11{sup o}. We show that the VIF increases approximately as 1/sinB at the ring ansae, but is independent of sinB in front of the disk. This combination of factors can only …
Date: February 2, 2005
Creator: de Pater, I; Gibbard, S G & Hammel, H B
System: The UNT Digital Library
Evidence for K ---> K* L+ L- and Measurement of B ---> K L+ L- (open access)

Evidence for K ---> K* L+ L- and Measurement of B ---> K L+ L-

The authors present evidence for the flavor-changing neutral current decay B {yields} K*{ell}{sup +}{ell}{sup -} and a measurement of the B {yields} K{ell}{sup +}{ell}{sup -} branching fraction, where {ell}{sup +}{ell}{sup -} is either an e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -} pair. The data sample analyzed comprises 88.5 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. Averaging over K{sup (*)} isospin and lepton flavor, we obtain {Beta}(B {yields} K*{ell}{sup +}{ell}{sup -}) = (1.40{sub -0.49}{sup +0.57} {+-} 0.21) x 10{sup -6} and {Beta}(B {yields} K{ell}{sup +}{ell}{sup -}) = (0.68{sub -0.15}{sup +0.17} {+-} 0.04) x 10{sup -6}, where the uncertainties are statistical and systematic. The significance for the B {yields} K*{ell}{sup +}{ell}{sup -} signal is 3.0{sigma} and for B {yields} K{ell}{sup +}{ell}{sup -} the signal significance is over 7{sigma}.
Date: August 2, 2005
Creator: Ryd, A.
System: The UNT Digital Library
Dynamic force spectroscopy of parallel individual mucin1-antibody bonds (open access)

Dynamic force spectroscopy of parallel individual mucin1-antibody bonds

We used atomic force microscopy (AFM) to measure the binding forces between Mucin1 (MUC1) peptide and a single chain antibody fragment (scFv) selected from a scFv library screened against MUC1. This binding interaction is central to the design of the molecules for targeted delivery of radioimmunotherapeutic agents for prostate and breast cancer treatment. Our experiments separated the specific binding interaction from non-specific interactions by tethering the antibody and MUC1 molecules to the AFM tip and sample surface with flexible polymer spacers. Rupture force magnitude and elastic characteristics of the spacers allowed identification of the bond rupture events corresponding to different number of interacting proteins. We used dynamic force spectroscopy to estimate the intermolecular potential widths and equivalent thermodynamic off rates for mono-, bi-, and tri-valent interactions. Measured interaction potential parameters agree with the results of molecular docking simulation. Our results demonstrate that an increase of the interaction valency leads to a precipitous decline in the dissociation rate. Binding forces measured for mono and multivalent interactions match the predictions of a Markovian model for the strength of multiple uncorrelated bonds in parallel configuration. Our approach is promising for comparison of the specific effects of molecular modifications as well as for determination …
Date: May 2, 2005
Creator: Sulchek, T A; Friddle, R W; Langry, K; Lau, E; Albrecht, H; Ratto, T et al.
System: The UNT Digital Library