282 research outputs found
Blazar Counterparts for 3EG Sources at -40 < decl. < 0: Pushing South Through the Bulge
Supplementing existing survey data with VLA observations, we have extended
ray counterpart identifications down to decl. = -40 using our
Figure of Merit approach. We find blazar counterparts for 70% of EGRET
sources above decl. = -40 away from the Galaxy. Spectroscopic
confirmation is in progress, and spectra for two dozen sources are
presented here. We find evidence that increased exposure in the bulge region
allowed EGRET to detect relatively faint blazars; a clear excess of non-blazar
objects in this region however argues for an additional (new) source class.Comment: ApJ accepte
The Gamma-Ray Blazar Content of the Northern Sky
Using survey data, we have re-evaluated the correlation of flat spectrum
radio sources with EGRET sources in the Northern sky. A likelihood analysis
incorporating the radio and X-ray properties and the Gamma-ray source
localization is used to gauge the reliability of associations and to search for
counterparts of previously unidentified EGRET sources. Above |b|=10deg, where
the classification is complete, we find that 70% of the Northern EGRET sources
have counterparts similar to the bright EGRET blazars. For several of these we
identify known blazar counterparts more likely than the earlier proposed 3EG
association; for ~20 we have new identifications. Spectroscopic confirmation of
these candidates is in progress and we have found flat spectrum radio quasars
and BL Lac counterparts with redshifts as high as 4. We also find strong
evidence for a set of 28 objects with no plausible counterpart like the known
EGRET Blazars. These thus represent either a new extragalactic population or a
population of Galactic objects with a large scale height. The survey has been
extended into the plane, where we find several new blazar candidates; the bulk
of the sources are, however, Galactic. Looking ahead to the GLAST era we
predict that several of the present 3EG sources are composite and that higher
resolution data will break these into multiple Blazar IDs.Comment: 13 pages, 6 figures, submitted to Ap
Improved Constraints on Isotropic Shift and Anisotropies of the Speed of Light using Rotating Cryogenic Sapphire Oscillators
We demonstrate that Michelson-Morley tests, which detect direction-dependent
anisotropies in the speed of light, can also be used to place limits upon
isotropic deviations of the vacuum speed of light from , as described by the
photon sector Standard Model Extension (SME) parameter . A
shift in the speed of light that is isotropic in one inertial frame implies
anisotropic shifts in others. Using observer Lorentz covariance, we derive the
time-dependent variations in the relative resonance frequencies of a pair of
electromagnetic resonators that would be generated by such a shift in the rest
frame of the Sun. A new analysis of a recent experimental test of relativity
using this result constrains with a precision of
. This represents the first constraint on
by a Michelson-Morley experiment and the first analysis
of a single experiment to simultaneously set limits on all nine
non-birefringent terms in the photon sector of the SME
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Efficacy of Atomoxetine in Adult Attention-Deficit/Hyperactivity Disorder: A Drug-placebo Response Curve Analysis
Background: The objective of this study was to evaluate the efficacy of atomoxetine, a new and highly selective inhibitor of the norepinephrine transporter, in reducing symptoms of attention-deficit/hyperactivity disorder (ADHD) among adults by using drug-placebo response curve methods. Methods: We analyzed data from two double-blind, placebo-controlled, parallel design studies of adult patients (Study I, N = 280; Study II, N = 256) with DSM-IV-defined ADHD who were recruited by referral and advertising. Subjects were randomized to 10 weeks of treatment with atomoxetine or placebo, and were assessed with the Conners Adult ADHD Rating Scales and the Clinical Global Impression of ADHD Severity scale before and after treatment. Results: Those treated with atomoxetine were more likely to show a reduction in ADHD symptoms than those receiving placebo. Across all measures, the likelihood that an atomoxetine-treated subject improved to a greater extent than a placebo-treated subject was approximately 0.60. Furthermore, atomoxetine prevented worsening of most symptom classes. Conclusion: From these findings, we conclude that atomoxetine is an effective treatment for ADHD among adults when evaluated using several criteria
Zero Modes for the D=11 Membrane and Five-Brane
There exist extremal p-brane solutions of supergravity for
p=2~and~5. In this paper we investigate the zero modes of the membrane and the
five-brane solutions as a first step toward understanding the full quantum
theory of these objects. It is found that both solutions possess the correct
number of normalizable zero modes dictated by supersymmetry.Comment: Minor typos corrected, one reference added, agrees with published
version. 9 RevTeX pages, 1 figure include
Efficacy of atomoxetine in adult attention-Deficit/Hyperactivity Disorder: a drug-placebo response curve analysis
BACKGROUND: The objective of this study was to evaluate the efficacy of atomoxetine, a new and highly selective inhibitor of the norepinephrine transporter, in reducing symptoms of attention-deficit/hyperactivity disorder (ADHD) among adults by using drug-placebo response curve methods. METHODS: We analyzed data from two double-blind, placebo-controlled, parallel design studies of adult patients (Study I, N = 280; Study II, N = 256) with DSM-IV-defined ADHD who were recruited by referral and advertising. Subjects were randomized to 10 weeks of treatment with atomoxetine or placebo, and were assessed with the Conners Adult ADHD Rating Scales and the Clinical Global Impression of ADHD Severity scale before and after treatment. RESULTS: Those treated with atomoxetine were more likely to show a reduction in ADHD symptoms than those receiving placebo. Across all measures, the likelihood that an atomoxetine-treated subject improved to a greater extent than a placebo-treated subject was approximately 0.60. Furthermore, atomoxetine prevented worsening of most symptom classes. CONCLUSION: From these findings, we conclude that atomoxetine is an effective treatment for ADHD among adults when evaluated using several criteria
A Northern Survey of Gamma-Ray Blazar Candidates
In preparation for GLAST, we have compiled a sample of blazar candidates to
increase the pool of well studied AGN from which GLAST counterparts will be
drawn. Sources were selected with our Figure of Merit (FoM) ranking; thus, they
have radio and X-ray properties very similar to the EGRET blazars.
Spectroscopic confirmation of these candidates is in progress, and more than
70% of these objects have been identified as flat spectrum radio quasars and BL
Lac objects. We present ~250 new optical blazar identifications based on
McDonald Observatory spectroscopy, 224 with redshifts. Of these, 167 are in our
FoM-selected set.
To motivate the Gamma-ray nature of these objects, we analyzed the current
release of the EGRET data for possible point sources at their radio positions.
We develop two distinct methods to combine multiple EGRET observations of a sky
position into a single detection significance. We report a detection of the
signal of the set of blazar candidates in the EGRET data at the > 3 sigma level
by both techniques. We predict that the majority of these blazar candidates
will be found by GLAST due to its increased sensitivity, duty cycle and
resolving power.Comment: ApJ Accepted (to appear 10 June 2005
Finite size effects and error-free communication in Gaussian channels
The efficacy of a specially constructed Gallager-type error-correcting code
to communication in a Gaussian channel is being examined. The construction is
based on the introduction of complex matrices, used in both encoding and
decoding, which comprise sub-matrices of cascading connection values. The
finite size effects are estimated for comparing the results to the bounds set
by Shannon. The critical noise level achieved for certain code-rates and
infinitely large systems nearly saturates the bounds set by Shannon even when
the connectivity used is low
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