2,076 research outputs found
Parameter extraction by Planck for a CDM model with broken scale invariance and cosmological constant
We consider a class of spatially flat cold dark matter (CDM) models, with a
cosmological constant and a broken-scale-invariant (BSI) steplike primordial
spectrum of adiabatic perturbations, previously found to be in very good
agreement with observations. Performing a Fisher matrix analysis, we show that
in case of a large gravitational waves (GW) contribution some free parameters
(defining the step) of our BSI model can be extracted with remarkable accuracy
by the Planck satellite, thanks to the polarisation anisotropy measurements.
Further, cosmological parameters can still be found with very good precision,
despite a larger number of free parameters than in the simplest inflationary
models.Comment: Final version to appear in MNRAS. Minor changes. 5 pages, 1 LaTeX
figure, uses mn.st
Enterprise model verification and validation : an approach
This article presents a verification and validation approach which is used here in order to complete the classical tool box the industrial user may utilize in enterprise modeling and integration domain. This approach, which has been defined independently from any application domain is based on several formal concepts and tools presented in this paper. These concepts are property concepts, property reference matrix, properties graphs, enterprise modeling domain ontology, conceptual graphs and formal reasoning mechanisms
Study of cascade ring-closing metathesis reactions en route to an advanced intermediate of Taxol
A highly functionalized intermediate in the synthesis of Taxol has been synthesized, which features the tricyclic core and the required oxygen substituents at C1, C2, C7, C10 and C13. The key step, a ring-closing dienyne metathesis (RCDEYM) reaction, has been thoroughly optimized to favor the tricyclic product over the undesired bicyclic product resulting from diene metathesis
Topology beyond the horizon: how far can it be probed?
The standard cosmological model does not determine the spatial topology of
the universe. This article revisits the signature of a non-trivial topology on
the properties of the cosmic microwave background anisotropies. We show that
the correlation function of the coefficients of the expansion of the
temperature and polarization anisotropies in spherical harmonics, encodes a
topological signature that can be used to distinguish a multi-connected space
from an infinite space on sizes larger than the last scattering surface. The
effect of the instrumental noise and of a galactic cut are estimated. We thus
establish boundaries for the size of the biggest torus dintinguisable with
temperature and polarization CMB data. We also describe the imprint of the
spatial topology on the 3-point function and on non-Gaussianity.Comment: 20 pages, 24 figure
Galactic dust polarized emission at high latitudes and CMB polarization
We estimate the dust polarized emission in our galaxy at high galactic
latitudes, which is the dominant foreground for measuring CMB polarization
using the high frequency instrument (HFI) aboard Planck surveyor. We compare it
with the level of CMB polarization and conclude that, for angular scales , the scalar-induced CMB polarization and temperature-polarization
cross-correlation are much larger than the foreground level at . The tensor-induced signals seem to be at best comparable to the
foreground level.}Comment: Latex document, 4 pages, 2 figures, to appear in "Fundamental
parameters in Cosmology", Rencontres de Moriond, 199
CMB anisotropy power spectrum using linear combinations of WMAP maps
In recent years the goal of estimating different cosmological parameters
precisely has set new challenges in the effort to accurately measure the
angular power spectrum of CMB. This has required removal of foreground
contamination as well as detector noise bias with reliability and precision.
Recently, a novel {\em model-independent} method for the estimation of CMB
angular power spectrum solely from multi-frequency observations has been
proposed and implemented on the first year WMAP data by Saha et al. 2006. All
previous estimates of power spectrum of CMB are based upon foreground templates
using data sets from different experiments. However our methodology
demonstrates that {\em CMB angular spectrum can be reliably estimated with
precision from a self contained analysis of the WMAP data}. In this work we
provide a detailed description of this method. We also study and identify the
biases present in our power spectrum estimate. We apply our methodoly to
extract the power spectrum from the WMAP 1 year and 3 year data.Comment: 38 pages, 17 figure
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