25,513 research outputs found
Practical applications of interactive voice technologies: Some accomplishments and prospects
A technology assessment of the application of computers and electronics to complex systems is presented. Three existing systems which utilize voice technology (speech recognition and speech generation) are described. Future directions in voice technology are also described
Antiquark nuggets as dark matter: New constraints and detection prospects
Current evidence for dark matter in the universe does not exclude heavy
composite nuclear-density objects consisting of bound quarks or antiquarks over
a significant range of masses. Here we analyze one such proposed scenario,
which hypothesizes antiquark nuggets with a range of log10(B) = 24-30 with
specific predictions for spectral emissivity via interactions with normal
matter. We find that, if these objects make up the majority of the dark matter
density in the solar neighborhood, their radiation efficiency in solids is
marginally constrained, due to limits from the total geothermal energy budget
of the Earth. At allowed radiation efficiencies, the number density of such
objects can be constrained to be well below dark matter densities by existing
radio data over a mass range currently not restricted by other methods.Comment: 6 pages, 3 figures, revised references; submitted to PR
The Cauchy convergence of T and P-approximant templates for test-mass Kerr binary systems
In this work we examine the Cauchy convergence of both post-Newtonian
(T-approximant) and re-summed post-Newtonian (P-approximant) templates for the
case of a test-mass orbiting a Kerr black hole along a circular equatorial
orbit. The Cauchy criterion demands that the inner product between the and
order approximation approaches unity, as we increase the order of
approximation. In previous works, it has been shown that we achieve greater
fitting factors and better parameter estimation using the P-approximant
templates for both Schwarzschild and Kerr black holes. In this work, we show
that the P-approximant templates also display a faster Cauchy convergence
making them a superior template to the standard post-Newtonian templates.Comment: 5 pages, Replaced with shortened published versio
β-adrenergic receptor activation in immortalized human urothelial cells stimulates inflammatory responses by PKA-independent mechanisms
BACKGROUND: Interstitial cystitis (IC) is a debilitating disease characterized by chronic inflammation of the urinary bladder, yet specific cellular mechanisms of inflammation in IC are largely unknown. Multiple lines of evidence suggest that β-adrenergic receptor (AR) signaling is increased in the inflamed urothelium, however the precise effects of these urothelial cell signals have not been studied. In order to better elucidate the AR signaling mechanisms of inflammation associated with IC, we have examined the effects of β-AR stimulation in an immortalized human urothelial cell line (UROtsa). For these studies, UROtsa cells were treated with effective concentrations of the selective β-AR agonist isoproterenol, in the absence or presence of selective inhibitors of protein kinase A (PKA). Cell lysates were analyzed by radioimmunoassay for generation of cAMP or by Western blotting for induction of protein products associated with inflammatory responses. RESULTS: Radioligand binding demonstrated the presence of β-ARs on human urothelial UROtsa cell membranes. Stimulating UROtsa cells with isoproterenol led to concentration-dependent increases of cAMP production that could be inhibited by pretreatment with a blocking concentration of the selective β-AR antagonist propranolol. In addition, isoproterenol activation of these same cells led to significant increases in the amount of phosphorylated extracellular signal-regulated kinase (pERK), inducible nitric oxide synthase (iNOS) and the induced form of cyclooxygenase (COX-2) when compared to control. Moreover, preincubation of UROtsa cells with the selective PKA inhibitors H-89 or Rp-cAMPs did not diminish this isoproterenol mediated phosphorylation of ERK or production of iNOS and COX-2. CONCLUSION: Functional β-ARs expressed on human urothelial UROtsa cell membranes increase the generation of cAMP and production of protein products associated with inflammation when activated by the selective β-AR agonist isoproterenol. However, the increased production of iNOS and COX-2 by isoproterenol is not blocked when UROtsa cells are preincubated with inhibitors of PKA. Therefore, UROtsa cell β-AR activation significantly increases the amount of iNOS and COX-2 produced by a PKA-independent mechanism. Consequently, this immortalized human urothelial cell line can be useful in characterizing potential AR signaling mechanisms associated with chronic inflammatory diseases of the bladder
Can Investors Benefit From Using Morningstar\u27s Stewardship Grades?
Interest in governance led Morningstar to develop a summary measure for mutual fund governance. In contrast to previous work in this area, we focus on whether and how individual investors can use the Stewardship Grade Overall to improve mutual fund selection. We find that regardless of fee structure, top overall governance grade funds impose lower costs on investors regardless of fund investment style. We also find some evidence that choosing funds with the highest stewardship grade may earn positive risk adjusted returns. Stewardship Grade overall may therefore help less sophisticated investors identify better-performing mutual funds
Distribution of the spacing between two adjacent avoided crossings
We consider the frequency at which avoided crossings appear in an energy
level structure when an external field is applied to a quantum chaotic system.
The distribution of the spacing in the parameter between two adjacent avoided
crossings is investigated. Using a random matrix model, we find that the
distribution of these spacings is well fitted by a power-law distribution for
small spacings. The powers are 2 and 3 for the Gaussian orthogonal ensemble and
Gaussian unitary ensemble, respectively. We also find that the distributions
decay exponentially for large spacings. The distributions in concrete quantum
chaotic systems agree with those of the random matrix model.Comment: 11 page
Detecting gravitational waves from test-mass bodies orbiting a Kerr black hole with P-approximant templates
In this study we apply post-Newtonian (T-approximants) and resummed
post-Newtonian (P-approximants) to the case of a test-particle in equatorial
orbit around a Kerr black hole. We compare the two approximants by measuring
their effectualness (i.e. larger overlaps with the exact signal), and
faithfulness (i.e. smaller biases while measuring the parameters of the signal)
with the exact (numerical) waveforms. We find that in the case of prograde
orbits, T-approximant templates obtain an effectualness of ~0.99 for spins q <
0.75. For 0.75 < q < 0.95, the effectualness drops to about 0.82. The
P-approximants achieve effectualness of > 0.99 for all spins up to q = 0.95.
The bias in the estimation of parameters is much lower in the case of
P-approximants than T-approximants. We find that P-approximants are both
effectual and faithful and should be more effective than T-approximants as a
detection template family when q > 0. For q < 0 both T- and P-approximants
perform equally well so that either of them could be used as a detection
template family. However, for parameter estimation, the P-approximant templates
still outperforms the T-approximants.Comment: 11 Pages - 9 figures. Accepted for publication. Proceedings of GWDAW
9. Special edition of Classical and Quantum Gravit
A Revised Validation Process for Ice Accretion Codes
A research project is underway at NASA Glenn to produce computer software that can accurately predict ice growth under any meteorological conditions for any aircraft surface. This report will present results from the latest LEWICE release, version 3.5. This program differs from previous releases in its ability to model mixed phase and ice crystal conditions such as those encountered inside an engine. It also has expanded capability to use structured grids and a new capability to use results from unstructured grid flow solvers. A quantitative comparison of the results against a database of ice shapes that have been generated in the NASA Glenn Icing Research Tunnel (IRT) has also been performed. This paper will extend the comparison of ice shapes between LEWICE 3.5 and experimental data from a previous paper. Comparisons of lift and drag are made between experimentally collected data from experimentally obtained ice shapes and simulated (CFD) data on simulated (LEWICE) ice shapes. Comparisons are also made between experimentally collected and simulated performance data on select experimental ice shapes to ensure the CFD solver, FUN3D, is valid within the flight regime. The results show that the predicted results are within the accuracy limits of the experimental data for the majority of cases
Planning research in the area of launch vehicle and propulsion programs Progress report, 1-31 Mar. 1968
Program and report reviews on launch vehicle upper stages and propulsion of advanced reentry spacecraf
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