Radio emission from dark matter annihilation in the Large Magellanic Cloud

The Large Magellanic Cloud, at only 50 kpc away from us and known to be dark matter dominated, is clearly an interesting place where to search for dark matter annihilation signals. In this paper, we estimate the synchrotron emission due to WIMP annihilation in the halo of the LMC at two radio frequencies, 1.4 and 4.8 GHz, and compare it to the observed emission, in order to impose constraints in the WIMP mass vs. annihilation cross section plane. We use available Faraday rotation data from background sources to estimate the magnitude of the magnetic field in different regions of the LMC's disc, where we calculate the radio signal due to dark matter annihilation. We account for the e+ e- energy losses due to synchrotron, Inverse Compton Scattering and bremsstrahlung, using the observed hydrogen and dust temperature distribution on the LMC to estimate their efficiency. The extensive use of observations, allied with conservative choices adopted in all the steps of the calculation, allow us to obtain very realistic constraints.Comment: 9 pages, 7 figure

ELECTRON SPIN RESONANCE INVESTIGATION OF THE EFFECTS OF THE H2+ IMPLANTATION AND DIFFUSION ONE THE LASER INDUCED DEFECTS IN VIRGIN SILICON

Electron paramagnetic resonance of the defects induced by laser annealing at high power density (2 J/cm-2) has been investigated in virgin FZ semi-insulating Silicon. A further H2+ implantation and diffusion is inactive on the signal observed at gx = 2.0055 ± 0.0005. This is consistent with the attribution of X to the dangling bonds, created by the mechanical stresses during the thermal shock, as they are not passivated by molecular hydrogen

Prevention of recurrent hip fracture

Our objective was to describe the interventions aimed at preventing a recurrent hip fracture, and other injurious falls, which were provided during hospitalization for a first hip fracture and during the two following years. A secondary objective was to study some potential determinants of these preventive interventions. The design of the study was an observational, two-year follow-up of patients hospitalized for a first hip fracture at the University Hospital of Lausanne, Switzerland. The participants were 163 patients (median age 82 years, 83% women) hospitalized in 1991 for a first hip fracture, among 263 consecutively admitted patients (84 did not meet inclusion criteria, e.g., age >50, no cancer, no high energy trauma, and 16 refused to participate). Preventive interventions included: medical investigations performed during the first hospitalization and aimed at revealing modifiable pathologies that raise the risk of injurious falls; use of medications acting on the risk of falls and fractures; preventive recommendations given by medical staff; suppression of environmental hazards; and use of home assistance services. The information was obtained from a baseline questionnaire, the medical record filled during the index hospitalization, and an interview conducted 2 years after the fracture. Potential predictors of the use of preventive interventions were: age; gender; destination after discharge from hospital; comorbidity; cognitive functioning; and activities of daily living. Bi- and multivariate associations between the preventive interventions and the potential predictors were measured. Inhospital investigations to rule out medical pathologies raising the risk of fracture were performed in only 20 patients (12%). Drugs raising the risk of falls were reduced in only 17 patients (16%). Preventive procedures not requiring active collaboration by the patient (e.g., modifications of the environment) were applied in 68 patients (42%), and home assistance was provided to 67 patients (85% of the patients living at home). Bivariate analyses indicated that prevention was less often provided to patients in poor general conditions, but no ascertainment of this association was found in multivariate analyses. In conclusion, this study indicates that, in the study setting, measures aimed at preventing recurrent falls and injuries were rarely provided to patients hospitalized for a first hip fracture at the time of the study. Tertiary prevention could be improved if a comprehensive geriatric assessment were systematically provided to the elderly patient hospitalized for a first hip fracture, and passive preventive measures implemente

Photometric type Ia supernova surveys in narrow band filters

We study the characteristics of a narrow band type Ia supernova survey through simulations based on the upcoming Javalambre Physics of the accelerating universe Astrophysical Survey (J-PAS). This unique survey has the capabilities of obtaining distances, redshifts, and the SN type from a single experiment thereby circumventing the challenges faced by the resource-intensive spectroscopic follow-up observations. We analyse the flux measurements signal-to-noise ratio and bias, the supernova typing performance, the ability to recover light curve parameters given by the SALT2 model, the photometric redshift precision from type Ia supernova light curves and the effects of systematic errors on the data. We show that such a survey is not only feasible but may yield large type Ia supernova samples (up to 250 supernovae at $z<0.5$ per month of search) with low core collapse contamination ($\sim 1.5$ per cent), good precision on the SALT2 parameters (average $\sigma_{m_B}=0.063$, $\sigma_{x_1}=0.47$ and $\sigma_c=0.040$) and on the distance modulus (average $\sigma_{\mu}=0.16$, assuming an intrinsic scatter $\sigma_{\mathrm{int}}=0.14$), with identified systematic uncertainties $\sigma_{\mathrm{sys}}\lesssim 0.10 \sigma_{\mathrm{stat}}$. Moreover, the filters are narrow enough to detect most spectral features and obtain excellent photometric redshift precision of $\sigma_z=0.005$, apart from $\sim$ 2 per cent of outliers. We also present a few strategies for optimising the survey's outcome. Together with the detailed host galaxy information, narrow band surveys can be very valuable for the study of supernova rates, spectral feature relations, intrinsic colour variations and correlations between supernova and host galaxy properties, all of which are important information for supernova cosmological applications.Comment: 20 pages, 12 tables and 26 figures. Version accepted by MNRAS, with results slightly different from previous on

Operations of and Future Plans for the Pierre Auger Observatory

Technical reports on operations and features of the Pierre Auger Observatory, including ongoing and planned enhancements and the status of the future northern hemisphere portion of the Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200