Adaptive Covariance Estimation with model selection

We provide in this paper a fully adaptive penalized procedure to select a covariance among a collection of models observing i.i.d replications of the process at fixed observation points. For this we generalize previous results of Bigot and al. and propose to use a data driven penalty to obtain an oracle inequality for the estimator. We prove that this method is an extension to the matricial regression model of the work by Baraud

Femtosecond Spectrotemporal Magneto-Optics

A new method to measure and analyze the time and spectrally resolved polarimetric response of magnetic materials is presented. It allows us to study the ultrafast magnetization dynamics of a CoPt3 ferromagnetic film. The analysis of the pump-induced rotation and ellipticity detected by a broad spectrum probe beam shows that magneto-optical signals predominantly reflect the spin dynamics in ferromagnets

Asteroseismic Theory of Rapidly Oscillating Ap Stars

This paper reviews some of the important advances made over the last decade concerning theory of roAp stars.Comment: 9 pages, 5 figure

L’immunothérapie dans le cancer du rein : un développement clinique en plein essor

CONTEXT: Nivolumab, an anti-PD1 immune control point inhibitor, is the first treatment that has improved the overall survival of patients after first-line metastatic renal cell carcinoma in 2015. Over the past two years, a large number of trials on these treatments and the interest of associations are being evaluated. OBJECTIVE: In this article, we propose to summarize the clinical development of checkpoint inhibitors to assess the direction of clinical research in this area. DOCUMENTARY SOURCE: A systematic review of the literature was performed in PubMed/Medline database and Meeting Library Asco by searching for articles in French or English published on immunotherapy in renal cell carcinoma. The research was limited to abstracts and articles published from 2014 to 2017. SELECTION OF TRIALS: We identified 349 publications and abstracts and selected 17 references from prospective studies. RESULTS: Recent data on checkpoint inhibitors, as well as their combination with tyrosine kinase inhibitors or with anti-angiogenic agents or with indoleamine 2, 3-dioxygenase 1 in renal cell carcinoma and the latest advances in vaccine therapy have been reported. CONCLUSION: In 2017, immunotherapy combined with other treatments is likely to lead to a paradigm shift in the clinical management of patients. The combination of nivolumab and ipilimumab in the first line will revolutionize the therapeutic management of patients with metastatic renal cell carcinoma

Simulations for single-dish intensity mapping experiments

HI intensity mapping is an emerging tool to probe dark energy. Observations of the redshifted HI signal will be contaminated by instrumental noise, atmospheric and Galactic foregrounds. The latter is expected to be four orders of magnitude brighter than the HI emission we wish to detect. We present a simulation of single-dish observations including an instrumental noise model with 1/f and white noise, and sky emission with a diffuse Galactic foreground and HI emission. We consider two foreground cleaning methods: spectral parametric fitting and principal component analysis. For a smooth frequency spectrum of the foreground and instrumental effects, we find that the parametric fitting method provides residuals that are still contaminated by foreground and 1/f noise, but the principal component analysis can remove this contamination down to the thermal noise level. This method is robust for a range of different models of foreground and noise, and so constitutes a promising way to recover the HI signal from the data. However, it induces a leakage of the cosmological signal into the subtracted foreground of around 5%. The efficiency of the component separation methods depends heavily on the smoothness of the frequency spectrum of the foreground and the 1/f noise. We find that as, long as the spectral variations over the band are slow compared to the channel width, the foreground cleaning method still works.Comment: 14 pages, 12 figures. Submitted to MNRA

The fundamental parameters of the roAp star 10 Aql

Due to the strong magnetic field and related abnormal surface layers existing in rapidly oscillating Ap stars, systematic errors are likely to be present when determining their effective temperatures, which potentially compromises asteroseismic studies of these pulsators. Using long-baseline interferometry, our goal is to determine accurate angular diameters of a number of roAp targets to provide a temperature calibration for these stars. We obtained interferometric observations of 10 Aql with the visible spectrograph VEGA at the CHARA array. We determined a limb-darkened angular diameter of 0.275+/-0.009 mas and deduced a linear radius of 2.32+/-0.09 R_sun. We estimated the star's bolometric flux and used it, in combination with its parallax and angular diameter, to determine the star's luminosity and effective temperature. For two data sets of bolometric flux we derived an effective temperature of 7800+/-170 K and a luminosity of 18+/-1 L_sun or of 8000+/-210 K and 19+/-2 L_sun. We used these fundamental parameters together with the large frequency separation to constrain the mass and the age of 10 Aql, using the CESAM stellar evolution code. Assuming a solar chemical composition and ignoring all kinds of diffusion and settling of elements, we obtained a mass of 1.92 M_sun and an age of 780 Gy or a mass of 1.95 M_sun and an age of 740 Gy, depending on the considered bolometric flux. For the first time, we managed to determine an accurate angular diameter for a star smaller than 0.3 mas and to derive its fundamental parameters. In particular, by only combining our interferometric data and the bolometric flux, we derived an effective temperature that can be compared to those derived from atmosphere models. Such fundamental parameters can help for testing the mechanism responsible for the excitation of the oscillations observed in the magnetic pulsating stars

HI intensity mapping with FAST

We discuss the detectability of large-scale HI intensity fluctuations using the FAST telescope. We present forecasts for the accuracy of measuring the Baryonic Acoustic Oscillations and constraining the properties of dark energy. The FAST $19$-beam L-band receivers ($1.05$--$1.45$ GHz) can provide constraints on the matter power spectrum and dark energy equation of state parameters ($w_{0},w_{a}$) that are comparable to the BINGO and CHIME experiments. For one year of integration time we find that the optimal survey area is $6000\,{\rm deg}^2$. However, observing with larger frequency coverage at higher redshift ($0.95$--$1.35$ GHz) improves the projected errorbars on the HI power spectrum by more than $2~\sigma$ confidence level. The combined constraints from FAST, CHIME, BINGO and Planck CMB observations can provide reliable, stringent constraints on the dark energy equation of state.Comment: 7 pages, 3 figures, submitted to "Frontiers in Radio Astronomy and FAST Early Sciences Symposium 2015" conference proceedin

A spectroscopic analysis of the chemically peculiar star HD207561

In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R diagram implies that this is slightly evolved from the main-sequence and located well within the delta-Scuti instability strip. The abundance analysis indicates the star has slight under-abundances of Ca and Sc and mild over-abundances of iron-peak elements. The spectro-polarimetric study of HD207561 shows that the effective magnetic field is within the observational error of 100 gauss (G). The spectroscopic analysis revealed that the star has most of the characteristics similar to an Am star, rather than an Ap star, and that it lies in the delta-Scuti instability strip; hence roAp pulsations are not expected in HD207561, but low-overtone modes might be excited.Comment: 8 pages, 7 figures, 3 tables. Accepted for pubblication in MNRA