2,191 research outputs found
Response to an invited commentary on âImpact of a bundle on surgical infections after hip arthroplasty. A cohort study in Italyâ [Int. J. Surg. (2020) Epub ahead of print] The reality of bundles in a resource-limited environment
Response to a commentary on âSurgical site infection prevention through bundled interventions in hip replacement surgery: A systematic reviewâ (Int J Surg 2021; 106149)
Average fractional polarization of extragalactic sources at Planck frequencies
Recent detailed simulations have shown that an insufficiently accurate
characterization of the contamination of unresolved polarized extragalactic
sources can seriously bias measurements of the primordial cosmic microwave
background (CMB) power spectrum if the tensor-to-scalar ratio as
predicted by models currently of special interest (e.g., Starobinsky's
and Higgs inflation). This has motivated a reanalysis of the median
polarization fraction of extragalactic sources (radio-loud AGNs and dusty
galaxies) using data from the \textit{Planck} polarization maps. Our approach,
exploiting the intensity distribution analysis, mitigates or overcomes the most
delicate aspects of earlier analyses based on stacking techniques. By means of
simulations, we have shown that the residual noise bias on the median
polarization fraction, , of extragalactic sources is
generally \simlt 0.1\%. For radio sources, we have found , with no significant dependence on either frequency or flux
density, in good agreement with the earlier estimate and with high-sensitivity
measurements in the frequency range 5--40\,GHz. No polarization signal is
detected in the case of dusty galaxies, implying 90\% confidence upper limits
of \Pi_{\rm dusty}\simlt 2.2\% at 353\,GHz and of \simlt 3.9\% at 217\,GHz.
The contamination of CMB polarization maps by unresolved point sources is
discussed.Comment: 10 pages, 3 figures, 7 tables; revised version. In press on Astronomy
and Astrophysic
Colonization of dental unit waterlines by Helicobacter pylori: Risk of exposure in dental practices
Polarization Properties of Extragalactic Radio Sources and Their Contribution to Microwave Polarization Fluctuations
We investigate the statistical properties of the polarized emission of
extragalactic radio sources and estimate their contribution to the power
spectrum of polarization fluctuations in the microwave region. The basic
ingredients of our analysis are the NVSS polarization data, the multifrequency
study of polarization properties of the B3-VLA sample (Mack et al. 2002) which
has allowed us to quantify Faraday depolarization effects, and the 15 GHz
survey by Taylor et al. (2001), which has provided strong constraints on the
high-frequency spectral indices of sources. The polarization degree of both
steep- and flat-spectrum at 1.4 GHz is found to be anti-correlated with the
flux density. The median polarization degree at 1.4 GHz of both steep- and
flat-spectrum sources brighter than mJy is . The data by Mack et al. (2002) indicate a substantial mean Faraday
depolarization at 1.4 GHz for steep spectrum sources, while the depolarization
is undetermined for most flat/inverted-spectrum sources. Exploiting this
complex of information we have estimated the power spectrum of polarization
fluctuations due to extragalactic radio sources at microwave frequencies. We
confirm that extragalactic sources are expected to be the main contaminant of
Cosmic Microwave Background (CMB) polarization maps on small angular scales. At
frequencies GHz the amplitude of their power spectrum is expected to be
comparable to that of the -mode of the CMB. At higher frequencies, however,
the CMB dominates.Comment: 10 pages, A&A in pres
Analysis of the fatality rate in relation to testing capacity during the first 50 days of the COVID-19 epidemic in Italy
Failure to eradicate non-tuberculous mycobacteria upon disinfection of heaterâcooler units: results of a microbiological investigation in northwestern Italy
Data quality assessment and subsampling strategies to correct distributional bias in prevalence studies
Astrophysical and Cosmological Information from Large-scale sub-mm Surveys of Extragalactic Sources
We present a quantitative analysis of the astrophysical and cosmological
information that can be extracted from the many important wide-area, shallow
surveys that will be carried out in the next few years. Our calculations
combine the predictions of the physical model by Granato et al. (2004) for the
formation and evolution of spheroidal galaxies with up-to-date phenomenological
models for the evolution of starburst and normal late-type galaxies and of
radio sources. We compute the expected number counts and the redshift
distributions of these source populations separately and then focus on
proto-spheroidal galaxies. For the latter objects we predict the counts and
redshift distributions of strongly lensed sources at 250, 350, 500, and 850
micron, the angular correlation function of sources detected in the surveys
considered, the angular power spectra due to clustering of sources below the
detection limit in Herschel and Planck surveys. An optimal survey for selecting
strongly lensed proto-spheroidal galaxies is described, and it is shown how
they can be easily distinguished from the other source populations. We also
discuss the detectability of the imprints of the 1-halo and 2-halo regimes on
angular correlation functions and clustering power spectra, as well as the
constraints on cosmological parameters that can be obtained from the
determinations of these quantities. The novel data relevant to derive the first
sub-millimeter estimates of the local luminosity functions of starburst and
late-type galaxies, and the constraints on the properties of rare source
populations, such as blazars, are also briefly described.Comment: 16 pages, 10 figures. Accepted for publication on MNRA
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