443 research outputs found

    Primordial non-Gaussianity with μ\mu-type and yy-type spectral distortions: exploiting Cosmic Microwave Background polarization and dealing with secondary sources

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    Cross-correlations between Cosmic Microwave Background (CMB) temperature and yy-spectral distortions anisotropies have been previously proposed as a way to measure the local bispectrum parameter fNLloc.f_{\rm NL}^{\rm loc.} in a range of scales inaccessible to either CMB (TT, EE) bispectra or TT-μ\mu correlations. This is useful e.g. to test scale dependence of primordial non-Gaussianity. Unfortunately, the primordial yy-T signal is strongly contaminated by the late-time correlation between the Integrated Sachs Wolfe and Sunyaev-Zel'dovich (SZ) effects. Moreover, SZ itself generates a large noise contribution in the yy-parameter map. We consider two original ways to address these issues. In order to remove the bias due to the SZ-CMB temperature coupling, while also adding new signal, we include in the analysis the cross-correlation between yy-distortions and CMB {\em polarization}. In order to reduce the noise, we propose to clean the yy-map by subtracting a SZ template, reconstructed via cross-correlation with external tracers (CMB and galaxy-lensing signals). We combine this SZ template subtraction with the previously adopted solution of directly masking detected clusters. Our final forecasts show that, using yy-distortions, a PRISM-like survey can achieve 1σ(fNLloc.)=3001\sigma(f_{\rm NL}^\text{loc.}) = 300, while an ideal experiment will achieve 1σ(fNLloc.)=1301\sigma(f_{\rm NL}^\text{loc.}) = 130, with improvements of a factor 3\sim 3 from adding the yy-EE signal, and a further 2030%20-30 \% from template cleaning. These forecasts are much worse than current fNLloc.f_{\rm NL}^\text{loc.} boundaries from {\em Planck}, but we stress again that they refer to completely different scales.Comment: 24 pages, 5 figure

    Esecutivo e giurisdizione nell’ amministrazione straordinaria delle imprese in crisi di rilevanti dimensioni

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    la tesi si basa su un'analisi sistematica della procedura di amministrazione straordinaria "speciale",introdotta dal D.L. 347/03 ed innovata con il D.L. 134/08 e il D.L.1/15, ponendo l'attenzione sopratutto ai rapporti ed ai ruoli svolti rispettivamente dall esecutivo e dal Tribunale nelle dinamiche della procedur

    Cost minimization analysis of BoNT-As in the treatment of upper limb spasticity and cervical dystonia

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    Botulinum toxin type A (BoNT-A) injections are recommended for the management of upper limb spasticity (ULS) and cervical dystonia (CD). The main aim of this cost minimization analysis (CMA) was to compare the annual cost per patient for three BoNT-As (Botox®, Dysport® and Xeomin®) in the treatment of ULS or CD in Italy. A budget impact analysis (BIA) was also conducted. Methods The CMA was conducted from the perspective of the Italian National Health Service. Only direct medical costs (BoNT-A and standard therapy) were considered. By using a Delphi panel of twelve Italian Experts in the treatment of ULS and CD, data was collected about BoNT-As (dose, number of administrations and acquisition price) and standard therapy (concomitant medications, visits, Day-Hospital, hospitalizations, etc.). Costs were assessed in Euros 2014. The BIA was conducted to evaluate the pharmaceutical expenditure for the three BoNT-As on a five-year time horizon. A sensitivity analysis was conducted. Results The mean annual cost per patient with ULS was €1,840.20 with Dysport®, €2,067.12 with Botox® and €2,171.05 with Xeomin®. The mean annual cost per patient with CD was €1,353.79 with Dysport®, €1,433.12 with Botox® and €1,503.60 with Xeomin®. In the time horizon considered, the substitution process of Botox® and Xeomin® by Dysport® would result in a total saving of €620,000 when treating ULS and a total saving of €481,000 in the case of CD. Sensitivity and probabilistic analyses showed the robustness of results. Conclusions From the Italian National Health Service's perspective, Dysport® appears to be the cost-saving therapeutic option compared with Botox® and Xeomin® in the treatment of ULS or CD

    Spectro-spatial evolution of the CMB II: generalised Boltzmann hierarchy

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    In this paper, we formulate a generalised photon Boltzmann hierarchy that allows us to model the evolution and creation of spectral distortion anisotropies in the early Universe. We directly build on our first paper in this series, extending the thermalisation Green's function treatment to the anisotropic case. We show that the problem can be described with the common Boltzmann hierarchy for the photon field extended by new spectral parameters -- a step that reduces the complexity of the calculation by at least two orders of magnitude. Our formalism describes the effects of i) Doppler and potential driving, ii) spectral evolution by Compton scattering, iii) perturbed thermalisation and iv) anisotropic heating on the distortion anisotropies. We highlight some of the main physical properties of the equations and also outline the steps for computing CMB power spectra including distortion anisotropies. Limitations and extensions of the formulation are also briefly discussed. The novel Boltzmann hierarchy given here is the basis for a series of companion papers studying how distortion anisotropies evolve in the perturbed Universe and which physical processes could be constrained using future CMB imaging techniques.Comment: 35 pages, 1 figure, to be submitted to JCAP; comments welcom

    Improved calculations of electron–ion bremsstrahlung Gaunt factors for astrophysical applications

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    Electron-ion Bremsstrahlung (free-free) emission and absorption occur in many astrophysical plasmas for a wide range of physical conditions. This classical problem has been studied multiple times, and many analytical and numerical approximations exist. However, accurate calculations of the transition from the non-relativistic to the relativistic regime remain sparse. Here we provide a comprehensive study of the free-free Gaunt factors for ions with low charge (Z<=10). We compute the Gaunt factor using the expressions for the differential cross section given by Elwert & Haug (EH) and compare to various limiting cases. We develop a new software package, BRpack, for direct numerical applications. This package uses a combination of pre-computed tables and analytical approximations to efficiently cover a wide range of electron and photon energies, providing a representation of the EH Gaunt factor to better than 0.03% precision for Z<=2. Our results are compared to those of previous studies highlighting the improvements achieved here. BRpack should be useful in computations of spectral distortions of the cosmic microwave background, radiative transfer problems during reionization or inside galaxy clusters, and the modeling of galactic free-free foregrounds. The developed computational methods can furthermore be extended to higher energies and ion charge.Comment: 12 pages + 5 pages appendix and references, 17 figures, to be submitted to MNRAS, BRpack will be made available at www.chluba.de/BRpac
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