Can giant radio halos probe the merging rate of galaxy clusters?

Radio and X-ray observations of galaxy clusters probe a direct link between cluster mergers and giant radio halos (RH), suggesting that these sources can be used as probes of the cluster merging rate with cosmic time. In this paper we carry out an explorative study that combines the observed fractions of merging clusters (fm) and RH (fRH) with the merging rate predicted by cosmological simulations and attempt to infer constraints on merger properties of clusters that appear disturbed in X-rays and of clusters with RH. We use morphological parameters to identify merging systems and analyze the currently largest sample of clusters with radio and X-ray data (M500>6d14 Msun, and 0.2<z<0.33, from the Planck SZ cluster catalogue). We found that in this sample fm~62-67% while fRH~44-51%. The comparison of the theoretical f_m with the observed one allows to constrain the combination (xi_m,tau_m), where xi_m and tau_m are the minimum merger mass ratio and the timescale of merger-induced disturbance. Assuming tau_m~ 2-3 Gyr, as constrained by simulations, we find that the observed f_m matches the theoretical one for xi_m~0.1-0.18. This is consistent with optical and near-IR observations of clusters in the sample (xi_m~0.14-0.16). The fact that RH are found only in a fraction of merging clusters may suggest that merger events generating RH are characterized by larger mass ratio; this seems supported by optical/near-IR observations of RH clusters in the sample (xi_min~0.2-0.25). Alternatively, RH may be generated in all mergers but their lifetime is shorter than \tau_m (by ~ fRH/fm). This is an explorative study, however it suggests that follow up studies using the forthcoming radio surveys and adequate numerical simulations have the potential to derive quantitative constraints on the link between cluster merging rate and RH at different cosmic epochs and for different cluster masses.Comment: 10 pages, 3 figures, accepted for publication in A&

Outcome prediction of consciousness disorders and awareness detection in the acute stage based on behavioural responses of existing coma scales

In patients with disorder of consciousness (DOC), awareness preservation is related to a better outcome prognosis (34). The dissociation of identified signs of awareness by laboratory assessment while undetected by bedside behavioural examination, is defined as cognitive motor dissociation (CMD) (1, 22-27). The rate of misdiagnosis is about 30% (18-21). Current researches emphasize enlarged bedside evaluation as it is easily administered and more economical (26). The Motor Behavioural Tool (MBT) had provided accurate insight into the content of consciousness, and had improved significantly the correlation with the outcome prediction during the acute stage, while the CRS-R sub-scores per se did not (1). We propose to further the exploration of supplementary motor behavioural signs by studying the predictability of the emergence defined by the CRS-R as well as the ability to detect CMD of the clinical items of three existing scales: The FOUR, the GCS and the NCS. We enrolled 35 patients with first CRS-R, MBT and the 3 aforementioned scales evaluation performed within 28 days post-injury. One evaluation of each scale was selected for every patient. The FOUR has 4 items, the GCS 3, and the NCS 4, that means 11 items, all rated with a sub-score which were the analysed variables. A first class of 8 group and 4 comparisons were made depending on the first and last CRS-R assessment, the latter defining the emergence: DOC patient emerging (1a) vs not emerged (1b), UWS (1c) and MCS (1e) emerging vs not emerged (1d) and (1f), and patients showing no CRS-R change (1g) vs those showing upper class of CRS-R (1h). A second class of 5 groups with 3 comparisons were made according to the MBT assessment at the admission and the last CRS-R evaluation : CMD patients (2a) vs true DOC (2b) at the entry in the unit, true DOC with DOC at last CRS-R (2c) vs CMD with emergence at last CRS-R (2e), and CMD with DOC at last CRS-R (2d) vs CMD with emergence at last CRS-R (2e). The statistical testing was based on a non-parametric Mann-Whitney U test to see whether there is a difference of sub-scores when comparing two groups for the same item. The p-value was &gt; 0.05 for all comparisons; in other word, none item enables to predict the outcome defined by the last CRS-S classification or to make the CMD diagnosis according to the MBT. Moreover, 26% of CMD patients were classified as DOC on the last CRS-R which can be related to the rate of misdiagnosis found in the literature. Those findings address explicitly the issue of how performing the clinical evaluation to overcome this underestimation of the degree and level of consciousness, and how essential it is to develop and render more accurate the bedside evaluation of awareness

Optical Stark Effect and Dressed Excitonic States in a Mn-doped Quantum Dot

We report on the observation of spin dependent optically dressed states and optical Stark effect on an individual Mn spin in a semiconductor quantum dot. The vacuum-to-exciton or the exciton-to-biexciton transitions in a Mn-doped quantum dot are optically dressed by a strong laser field and the resulting spectral signature is measured in photoluminescence. We demonstrate that the energy of any spin state of a Mn atom can be independently tuned using the optical Stark effect induced by a control laser. High resolution spectroscopy reveals a power, polarization and detuning dependent Autler-Townes splitting of each optical transition of the Mn-doped quantum dot. This experiment demonstrates a complete optical resonant control of the exciton-Mn system

Radio Lobes of Pictor A: an X-ray spatially resolved Study

A new XMM observation has made possible a detailed study of both lobes of the radio galaxy Pictor A. Their X-ray emission is of non thermal origin and due to Inverse Compton scattering of the microwave background photons by relativistic electrons in the lobes, as previously found. In both lobes, the equipartition magnetic field (Beq) is bigger than the Inverse Compton value (Bic), calculated from the radio and X-ray flux ratio. The Beq/Bic ratio never gets below 2, in spite of the large number of reasonable assumptions tested to calculate Beq, suggesting a lobe energetic dominated by particles. The X-ray data quality is good enough to allow a spatially resolved analysis. Our study shows that Bic varies through the lobes. It appears to increase behind the hot spots. On the contrary, a rather uniform distribution of the particles is observed. As a consequence, the radio flux density variation along the lobes appears to be mainly driven by magnetic field changes.Comment: 15 pages, 3 figures, ApJ accepte

A Novel Broadband Measurement Method for the Magnetoimpedance of Ribbons and Thin Films

A novel broad-band measurement method of the MI in thin films and ribbons is presented. It is based on the automated measurement of the reflection coefficient of a cell loaded with the sample. Illustrative results obtained with a permalloy multilayer thin film are presented and discussed.Comment: Paper submitted to International Conference on Magnetism (Rome 2003

The mystery of the 'Kite' radio source in Abell 2626: insights from new Chandra observations

We present the results of a new Chandra study of the galaxy cluster A2626. The radio emission of the cluster shows a complex system of four symmetric arcs without known correlations with the X-ray emission. The mirror symmetry of the radio arcs toward the center and the presence of two optical cores in the central galaxy suggested that they may be created by pairs of precessing radio jets powered by dual AGNs inside the cD galaxy. However, previous observations failed to observe the second jetted AGN and the spectral trend due to radiative age along the radio arcs, thus challenging this interpretation. The new Chandra observation had several scientific objectives, including the search for the second AGN that would support the jet precession model. We focus here on the detailed study of the local properties of the thermal and non-thermal emission in the proximity of the radio arcs, in order to get more insights into their origin. We performed a standard data reduction of the Chandra dataset deriving the radial profiles of temperature, density, pressure and cooling time of the intra-cluster medium. We further analyzed the 2D distribution of the gas temperature, discovering that the south-western junction of the radio arcs surrounds the cool core of the cluster. We studied the X-ray SB and spectral profiles across the junction, finding a cold front spatially coincident with the radio arcs. This may suggest a connection between the sloshing of the thermal gas and the nature of the radio filaments, raising new scenarios for their origin. A possibility is that the radio arcs trace the projection of a complex surface connecting the sites where electrons are most efficiently reaccelerated by the turbulence that is generated by the gas sloshing. In this case, diffuse emission embedded by the arcs and with extremely steep spectrum should be most visible at very low radio frequencies.Comment: 7 pages, 7 figures. Accepted for publication on A&

The Population ageing in Italy: facts and impact on household portfolios

This paper aims to assess the impact of ageing on household portfolios in Italy and hence ultimately on financial markets. To this end, the analysis is carried out in two steps. First, the dimension of population ageing in Italy is assessed by means of both historical and forecast data on the structure of Italian population. Second, based on data taken from the Bank of Italy Survey of Household Income and Wealth (SHIW) over the last decade, we analyse the average household portfolio in relation to demographic characteristics. The main findings are: first, Italy turns out to be one of the countries most affected by ageing; second, financial choices of Italian households are sensibly affected by age. Thus, the exceptional ageing in Italy might have relevant consequences on the Italian financial market

Second homes: households' life dream or (wrong) investment?

While the purchase of a primary home is mainly motivated by essential consumption needs, buying a second house has been generally considered a good investment decision. However, second homes may results in many different final uses, ranging from holidays and profitable uses to definitely unprofitable ones. We contribute to the scant literature on second houses by exploring the case of second homes that remain unrented and represent the most notable unprofitable use. The empirical investigation relies on the 2002-2012 Bank of Italy Survey on Household Income and Wealth which, among other things, provides plenty of information on real estates, including the actual use. Our results on the unprofitable use of second homes highlight: a gender gap, whereby this case tends to be more clearly associated with male decision makers; no association with household’s economic characteristics; and, strong association with the specific real estate features, with inherited dwellings more likely to end up being unprofitably used. Thus our results, besides casting some doubts on the goodness of second homes as an investment decision, may have important policy implications on the housing and rental market and call for policy or regulatory interventions