727 research outputs found
A Detection of the Integrated Sachs-Wolfe Effect
We have detected statistically significant correlations between the cosmic
microwave background and two tracers of large-scale structure, the HEAO1 A2
full sky hard X-ray map and the NVSS 1.4 GHz, nearly full sky radio galaxy
survey. The level of correlations in these maps is consistent with that
predicted for the integrated Sachs-Wolfe (ISW) effect in the context of a
Lambda CDM cosmological model and, therefore, provides independent evidence for
a cosmological constant. A maximum likelihood fit to the amplitude of the ISW
effect relative to the predicted value is 1.13 +- 0.35 (statistical error
only).Comment: 4 pages, 4 figures, presented at 6th UCLA Dark Matter/Dark Energy
Symposiu
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Markets for reactor-produced non-fission radioisotopes
Current market segments for reactor produced radioisotopes are developed and reported from a review of current literature. Specific radioisotopes studied in is report are the primarily selected from those with major medical or industrial markets, or those expected to have strongly emerging markets. Relative market sizes are indicated. Special emphasis is given to those radioisotopes that are best matched to production in high flux reactors such as the Advanced Test Reactor (ATR) at the Idaho National Engineering Laboratory or the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory. A general bibliography of medical and industrial radioisotope applications, trends, and historical notes is included
Exponential lower bound on the highest fidelity achievable by quantum error-correcting codes
On a class of memoryless quantum channels which includes the depolarizing
channel, the highest fidelity of quantum error-correcting codes of length n and
rate R is proven to be lower bounded by 1-exp[-nE(R)+o(n)] for some function
E(R). The E(R) is positive below some threshold R', which implies R' is a lower
bound on the quantum capacity.Comment: Ver.4. In vers.1--3, I claimed Theorem 1 for general quantum
channels. Now I claim this only for a slight generalization of depolarizing
channel in this paper because Lemma 2 in vers.1--3 was wrong; the original
general statement is proved in quant-ph/0112103. Ver.5. Text sectionalized.
Appeared in PRA. The PRA article is typographically slightly crude: The LaTeX
symbol star, used as superscripts, was capriciously replaced by the asterisk
in several places after my proof readin
Crossing w=-1 in Gauss-Bonnet Brane World with Induced Gravity
Recent type Ia supernovas data seemingly favor a dark energy model whose
equation of state crosses -1 very recently, which is a much more amazing
problem than the acceleration of the universe. In this paper we show that it is
possible to realize such a crossing without introducing any phantom component
in a Gauss-Bonnet brane world with induced gravity, where a four dimensional
curvature scalar on the brane and a five dimensional Gauss-Bonnet term in the
bulk are present. In this realization, the Gauss-Bonnet term and the mass
parameter in the bulk play a crucial role.Comment: Revtex 16 pages including 10 eps files, references added, to appear
in Comm. Theor. Phy
Three-dimensional Aeroelastic and Aerothermoelastic Behavior in Hypersonic Flow
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76667/1/AIAA-2005-2175-915.pd
Generalized Second Law of Thermodynamics on the Event Horizon for Interacting Dark Energy
Here we are trying to find the conditions for the validity of the generalized
second law of thermodynamics (GSLT) assuming the first law of thermodynamics on
the event horizon in both cases when the FRW universe is filled with
interacting two fluid system- one in the form of cold dark matter and the other
is either holographic dark energy or new age graphic dark energy. Using the
recent observational data we have found that GSLT holds both in quintessence
era as well as in phantom era for new age graphic model while for holographic
dark energy GSLT is valid only in phantom era.Comment: 8 pages, 2 figure
Cross-Correlation of the Cosmic Microwave Background with the 2MASS Galaxy Survey: Signatures of Dark Energy, Hot Gas, and Point Sources
We cross-correlate the Cosmic Microwave Background (CMB) temperature
anisotropies observed by the Wilkinson Microwave Anisotropy Probe (WMAP) with
the projected distribution of extended sources in the Two Micron All Sky Survey
(2MASS). By modelling the theoretical expectation for this signal, we extract
the signatures of dark energy (Integrated Sachs-Wolfe effect;ISW), hot gas
(thermal Sunyaev-Zeldovich effect;thermal SZ), and microwave point sources in
the cross-correlation. Our strongest signal is the thermal SZ, at the 3.1-3.7
\sigma level, which is consistent with the theoretical prediction based on
observations of X-ray clusters. We also see the ISW signal at the 2.5 \sigma
level, which is consistent with the expected value for the concordance LCDM
cosmology, and is an independent signature of the presence of dark energy in
the universe. Finally, we see the signature of microwave point sources at the
2.7 \sigma level.Comment: 35 pages (preprint format), 8 figures. In addition to minor revisions
based on referee's comments, after correcting for a bug in the code, the SZ
detection is consistent with the X-ray observations. Accepeted for
publication in Physical Review
EPUAP classification system for pressure ulcers: European reliability study
âThe definitive version is available at www3.interscience.wiley.com .' Copyright Blackwell PublishingPeer reviewe
Correlations in Cosmic String Networks
We investigate scaling and correlations of the energy and momentum in an
evolving network of cosmic strings in Minkowski space. These quantities are of
great interest, as they must be understood before accurate predictions for the
power spectra of the perturbations in the matter and radiation in the early
Universe can be made. We argue that Minkowski space provides a reasonable
approximation to a Friedmann background for string dynamics and we use our
results to construct a simple model of the network, in which it is considered
to consist of randomly placed segments moving with random velocities. This
model works well in accounting for features of the two-time correlation
functions, and even better for the power spectra.Comment: 20pp Plain LaTeX, 11 EPS figures, uses epsf.st
Probing mSUGRA via the Extreme Universe Space Observatory
An analysis is carried out within mSUGRA of the estimated number of events
originating from upward moving ultra-high energy neutralinos that could be
detected by the Extreme Universe Space Observatory (EUSO). The analysis
exploits a recently proposed technique that differentiates ultra-high energy
neutralinos from ultra-high energy neutrinos using their different absorption
lengths in the Earth's crust. It is shown that for a significant part of the
parameter space, where the neutralino is mostly a Bino and with squark mass
TeV, EUSO could see ultra-high energy neutralino events with
essentially no background. In the energy range 10^9 GeV < E < 10^11 GeV, the
unprecedented aperture of EUSO makes the telescope sensitive to neutralino
fluxes as low as 1.1 \times 10^{-6} (E/GeV)^{-1.3} GeV^{-1} cm^{-2} yr^{-1}
sr^{-1}, at the 95% CL. Such a hard spectrum is characteristic of supermassive
particles' -body hadronic decay. The case in which the flux of ultra-high
energy neutralinos is produced via decay of metastable heavy particles with
uniform distribution throughout the universe is analyzed in detail. The
normalization of the ratio of the relics' density to their lifetime has been
fixed so that the baryon flux produced in the supermassive particle decays
contributes to about 1/3 of the events reported by the AGASA Collaboration
below 10^{11} GeV, and hence the associated GeV gamma-ray flux is in complete
agreement with EGRET data. For this particular case, EUSO will collect between
4 and 5 neutralino events (with 0.3 of background) in ~ 3 yr of running. NASA's
planned mission, the Orbiting Wide-angle Light-collectors (OWL), is also
briefly discussed in this context.Comment: Some discussion added, final version to be published in Physical
Review
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