Stochastic background from extra-galactic double neutron stars

We present Monte Carlo simulations of the extra galactic population of inspiralling double neutron stars, and estimate its contribution to the astrophysical gravitational wave background, in the frequency range of ground based interferometers, corresponding to the last thousand seconds before the last stable orbit when more than 96 percent of the signal is released. We show that sources at redshift z>0.5 contribute to a truly continuous background which may be detected by correlating third generation interferometers.Comment: 13 pages, 7 figures - proceeding of a talk given at the 11th GWDAW, to appear in CQ

EIT Observations of the Extreme Ultraviolet Sun

The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft has been operational since 2 January 1996. EIT observes the Sun over a 45 x 45 arc min field of view in four emission line groups: Feix, x, Fexii, Fexv, and Heii. A post-launch determination of the instrument flatfield, the instrument scattering function, and the instrument aging were necessary for the reduction and analysis of the data. The observed structures and their evolution in each of the four EUV bandpasses are characteristic of the peak emission temperature of the line(s) chosen for that bandpass. Reports on the initial results of a variety of analysis projects demonstrate the range of investigations now underway: EIT provides new observations of the corona in the temperature range of 1 to 2 MK. Temperature studies of the large-scale coronal features extend previous coronagraph work with low-noise temperature maps. Temperatures of radial, extended, plume-like structures in both the polar coronal hole and in a low latitude decaying active region were found to be cooler than the surrounding material. Active region loops were investigated in detail and found to be isothermal for the low loops but hottest at the loop tops for the large loops

La qualité de vie du patient brûlé, entre soins contraignants et séquelles

National audienc

Asymmetric standing posture after stroke is related to a biased egocentric coordinate system.

International audienceBACKGROUND: Weakness and somatosensory deficits have long been known to be involved in the postural instability of subjects with stroke. Recently, it has been shown that impaired representations of the orientation of the longitudinal axis of the body (LBA, egocentric reference) and of verticality (allocentric reference) may also play a role. The objective of the present study was to determine whether these two references were independently linked to postural asymmetry in standing stroke patients. METHODS: Twenty-two subjects were tested after a first hemispheric stroke (13 +/- 7.5 weeks). The LBA perception was investigated in the supine position by adjusting the orientation of a luminous rod in the frontal plane to correspond to the subjective LBA. The subjective visual vertical (SVV) was assessed by adjusting the orientation of a luminous line in the frontal plane to correspond to the SVV in upright patients. Weight distribution was measured in the standing position for about 2 minutes and 45 seconds by two separate force platforms under the feet. RESULTS: LBA and SVV were strongly associated (r = 0.7; p < 0.001). The estimate of the LBA was a better predictor (r = -0.52: p < 0.02) of weight bearing asymmetry than was SVV (r = -0.41; p = 0.074) when adjusted for motor weakness and hypoesthesia. CONCLUSION: Contralesional rotation of the longitudinal axis of the body could lead to unequal distribution of loading on the feet. This novel interpretation of weight bearing asymmetry underlines the complexity of control of the erect stance following stroke and brings new perspectives for rehabilitation programs

Réflectivité et sélectivité spectrale de multicouches B/Si dans le domaine des X-UV. Approche théorique et expérimentale

Le contraste d'indices des deux éléments (B,Si) est en général petit dans le domaine spectral des X-UV, ce qui fait que des écarts d'indices, même faibles, de chacun des éléments constitutifs de la bicouche vont modifier les propriétés optiques du miroir. Il est donc nécessaire d'étudier le mieux possible les caractéristiques de l'empilement afin de prévoir les conditions optimales de réalisation et d'utilisation (de 100 eV à 1 keV

Imaging the solar corona in the EUV

The SOHO (SOlar and Heliospheric Observatory) satellite was launched on December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point on February 14th 1996, it began to continuously observe the Sun. As one of the instruments onboard SOHO, the EIT (Extreme ultraviolet Imaging Telescope) images the Sun's corona in 4 EUV wavelengths. The He II filter at 304 AË images the chromosphere and the base of the transition region at a temperature of 5 - 8 x 10^4 K; the Fe IX-X filter at 171 AË images the corona at a temperature of ~ 1.3 x 10^6 K; the Fe XII filter at 195 AË images the quiet corona outside coronal holes at a temperature of ~ 1.6 x 10^6 K; and the Fe XV filter at 284 AË images active regions with a temperature of ~ 2.0 x 10^6 K. About 5000 images have been obtained up to the present. In this paper, we describe also some aspects of the telescope and the detector performance for application in the observations. Images and movies of all the wavelengths allow a look at different phenomena present in the Sun's corona, and in particular, magnetic field reconnection