2,510 research outputs found
Preparation to the CMB PLANCK data analysis, estimation of the contamination due to the galactic polarized emissions
This work is point of the preparation to the analysis of the PLANCK satellite
data. The PLANCK satellite is an ESA mission which has been launched the 14th
of may 2009 and is dedicaced to the measurement of the Cosmic Microwave
Background (CMB) in temperature and polarization. The presence of diffuse
Galactic polarized emissions disturb the measurement of the CMB anisotropies,
in particular in polarization. Therefore a precise knowledge of these emissions
is needed to obtain the level of accuracy required for PLANCK. In this context,
we have developed and implemented a coherent 3D model of the two mains
polarized Galactic emissions : synchrotron and thermal dust. We have compared
these models to preexisting data: the 23 GHz band of the WMAP data, the 353 GHz
Archeops data and the 408 MHz all-sky continuum survey. We extrapolate these
models to the frequencies where the CMB dominates and we are able to estimate
the contribution of polarized foreground emissions to the polarized CMB
emission measured with PLANCK.Comment: Proceeding of the International Workshop on Cosmic Structure and
Evolution - Cosmology2009, September 23-25, 2009 Bielefeld, German
Thermal effects on the resonance fluorescence of doubly dressed artificial atoms
In this work, robustness of controlled density of optical states in doubly
driven artificial atoms is studied under phonon dissipation. By using both
perturbative and polaron approaches, we investigate the influence of
carrier-phonon interactions on the emission properties of a two-level
solid-state emitter, simultaneously coupled to two intense distinguishable
lasers. Phonon decoherence effects on the emission spectra are found modest up
to neon boiling temperatures ( K), as compared with photon generation
at the Fourier transform limit obtained in absence of lattice vibrations (zero
temperature). These results show that optical switching and photonic modulation
by means of double dressing, do not require ultra low temperatures for
implementation, thus boosting its potential technological applications.Comment: Submitted versio
Small-Scale Structure of Spacetime: Bounds and Conjectures
This review consists of two parts. The first part establishes certain
astrophysical bounds on the smoothness of classical spacetime. Some of the best
bounds to date are based on the absence of vacuum Cherenkov radiation in
ultrahigh-energy cosmic rays. The second part discusses possible implications
of these bounds for the quantum structure of spacetime. One conjecture is that
the fundamental length scale of quantum spacetime may be different from the
Planck length.Comment: 20 pages; invited talk at the Third Mexican Meeting on Mathematical
and Experimental Physics, September 10-14, 2007, El Colegio Nacional, Mexico
City; v3: final versio
Bayesian blind component separation for Cosmic Microwave Background observations
We present a technique for the blind separation of components in CMB data.
The method uses a spectral EM algorithm which recovers simultaneously component
templates, their emission law as a function of wavelength, and noise levels. We
test the method on Planck HFI simulated observations featuring 3 astrophysical
components.Comment: 15 pages, 5 figures, to appear in the Proceedings of the MAXENT 2001
international worksho
Metric-affine gauge theory of gravity II. Exact solutions
In continuing our series on metric-affine gravity (see Gronwald IJMP D6
(1997) 263 for Part I), we review the exact solutions in this theory.Comment: Revtex file, 25 pages, final version to appear in IJMP
Porokeratosis of Mibelli. A Case Report
As poroqueratoses resultam de uma hiper-proliferação clonal dos queratinócitos, encontrando-se pelo menos descritas seis formas clÃnicas, que partilham o achado da lamela cornóide no exame histopatológico.
Os autores descrevem o caso de uma poroqueratose de Mibelli numa mulher de 27 anos, raça negra, com inÃcio na infância, eficazmente tratada com retinóide tópico, apresentando-se as manifestações tÃpicas de uma dermatose pouco frequente e destacando-se a importância da histopatologia na confirmação do seu diagnóstico. A poroqueratose de Mibelli é uma dermatose crónica e progressiva, raramente com remissão espontânea. A sua evolução para neoplasia maligna, particularmente carcinoma espino-celular, pode ocorrer em cerca de 7% dos doentes, reforçando-se a importância de uma adequada vigilância
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