A single-merger scenario for the formation of the giant stream and the warp of M31

We propose that the accretion of a dwarf spheroidal galaxy provides a common origin for the giant southern stream and the warp of M31. We run about 40 full N-body simulations with live M31, infalling galaxies with varying masses and density profiles, and cosmologically-plausible initial orbital parameters. Excellent agreement with a full range of observational data is obtained for a model in which a dark-matter-rich dwarf spheroidal, whose trajectory lies on the thin plane of corotating satellites of M31, is accreted from its turnaround radius of about 200 kpcs into M31 at approximately 3 Gyrs ago. The satellite is disrupted as it orbits in the potential well of the galaxy and forms the giant stream and in return heats and warps the disk of M31. We show that our cosmologically-motivated model is favoured by the kinematic data over the phenomenological models in which the satellite starts its infall from a close distance of M31. Our model predicts that the remnant of the disrupted satellite resides in the region of the North-Eastern shelf of M31. The results here suggest that the surviving satellites of M31 that orbit on the same thin plane, as the disrupted satellite once did, could have all been accreted from an intergalactic filament.Comment: 18 pages, 22 figures, 3 table

M - sigma relation between SMBHs and the velocity dispersion of globular cluster systems

We find evidence that the mass MBH of central supermassive black holes (SMBHs) correlates with the velocity dispersion sigma_GC of globular cluster systems of their host galaxies. This extends the well-known MBH - sigma_sph relation between black hole mass and velocity dispersion of the host spheroidal component. We compile published measurements of both MBH and sigma_GC for a sample of 13 systems and find the relation log(MBH) = alpha + beta log(sigma_GC/200) with alpha = 8.63 \pm 0.09 and beta = 3.76 \pm 0.52. We also consider blue (metal-poor) and red (metal-rich) globular clusters sub-populations separately and obtain a surprisingly tight correlation using only the velocity dispersion sigma_GC^red of the red clusters with alpha = 8.73 \pm 0.09 and beta = 3.84 \pm 0.52 and an intrinsic scatter eps_0 = 0.22 dex compared to eps_0 = 0.27 dex for the MBH - sigma_sph of our sample. We use our MBH - sigma_GC relation to estimate the central black hole mass in five galaxies for which sigma_GC^red is measured.Comment: 6 pages, 3 figures, 3 tables, accepted for publication in MNRA

People management framework using a 2D camera for human-robot social interactions

International audienc

Bayesian time-domain multiple sound source localization for a stochastic machine

International audienc

People management framework using a 2D camera for human-robot social interactions

International audienc

Automatic Extraction and Geospatial Analysis of Lineaments and their Tectonic Significance in South Cameroon Area using Remote Sensing Techniques and GIS

This study investigates the dominant orientations of lineament features and the relationship between these trends and the spatial orientation of tectonic structures in the transition zone of the Congo craton and the Pan African belt in South Cameroon area. Landsat 8 OLI/TIRS and hill-shaded images, constructed from 30 m-resolution SRTM-DEM data, were used for automatically extracting and mapping geological lineaments. Lineament features were analyzed by means of azimuth frequency and length density distributions. Three major sets of lineaments trending W–E, ENE-WSW and WNW-ESE are identified in the South Cameroon area. These trends are probably related to repeated reactivation of pre-existing crustal structures during Eburnean and Pan-African tectonic episodes. The lineaments were formed under the compressional tectonic stress regimes generated during these tectonic events

001 Predictive Value of Post Treatment Platelet Reactivity for Occurrence of Post-discharge Bleeding After Non ST Elevation Acute Coronary Syndrome

AimsWe assessed prospectively the association between occurrence of post-discharge non–CABG-related TIMI major and minor bleedings and post treatment platelet reactivity in patients with Non ST Elevation Acute Coronary Syndrome (NSTE ACS).Methods and Results597 consecutive patients admitted with NSTE ACS were prospectively included. Between hospital discharge and one month follow-up, we observed 16 (2.7%) non–CABG-related TIMI hemorrhagic complications including 5 (0.84%) major and 11 (1.8%) minor bleeds. Patients with bleeding had significantly lower post treatment values of ADP-induced aggregation (43±14% versus. 56±19%, P=0.002) and platelet reactivity index VASP (43±14% versus 54±23%; P=0.04) and a trend for lower values of arachidonic acid-induced aggregation (2.4±5.4 versus 13±21; P=0.27). After stratification by quartiles based on post treatment ADP-induced platelet aggregation, we identified patients in the first quartile as hyper-responders with very low post treatment platelet reactivity, below <40%. The risk of TIMI major and minor bleeding was significantly higher in the first quartile of hyper-responders than in the others quartiles: 10 (6.6%) versus 6 (1.4%), p=0.001.ConclusionOur results suggest that assessment of post treatment platelet reactivity might be used to detect hyper responders to antiplatelet therapy with higher risk of non-CABG related bleedings and tailor antiplatelet therapy according to both ischemic and bleeding risk

Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

International audienceThe relationship between intraplate volcanism and continental tectonics has been investigated for North and East Africa using a high resolution three-dimensional anisotropic tomographic model derived from seismic data of a French experiment ''Horn of Africa'' and existing broadband data. The joint inversion for seismic velocity and anisotropy of the upper 400 km of the mantle, and geochemical data reveals a complex interaction between mantle upwellings, and lithosphere. Two kinds of mantle upwellings can be distinguished: The first one, the Afar ''plume'' originates from deeper than 400 km and is characterized by enrichment in primordial 3 He and 3 He/ 4 He ratios higher than those along mid-ocean ridges (MOR). The second one, associated with other Cenozoic volcanic provinces (Darfur, Tibesti, Hoggar, Cameroon), with 3 He/ 4 He ratios similar to, or lower than MOR, is a consequence of shallower upwelling. The presumed asthenospheric convective instabilities are oriented in an east-west direction, resulting from interaction between south-north asthenospheric mantle flow, main plume head and topography on the base of lithosphere

Gas and dust productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations

Comet 103P/Hartley 2 made a close approach to the Earth in October 2010. It was the target of an extensive observing campaign including ground- and orbit-based observatories and was visited by the Deep Impact spacecraft in the framework of its mission extension EPOXI. We present observations of HCN and CH_3OH emission lines conducted with the IRAM Plateau de Bure interferometer on 22–23, 28 October and 4, 5 November 2010 at 1.1, 1.9 and 3.4 mm wavelengths. The thermal emission from the dust coma and nucleus is detected simultaneously. Interferometric images with unprecedented spatial resolution of ∼100 to ∼500 km are obtained. A sine–wave like variation of the thermal continuum is observed in the 23 October data, that we associate with the nucleus thermal light curve. The nucleus contributes up to 30–55% of the observed continuum emission. The dust thermal emission is used to measure the dust production rate. The inferred large dust-to-gas ratio (in the range 2–6) can be explained by the unusual activity of the comet for its size, which allows decimeter size particles and large boulders to be entrained by the gas due to the small nucleus gravity. The rotational temperature of CH_3OH is measured with beam radii from ∼150 km to ∼1500 km. We attribute the increase from ∼35 K to ∼46 K with increasing beam size to radiative processes. The HCN production rate displays strong rotation-induced temporal variations, varying from ∼0.3 × 10^(25) s^(−1) to ∼2.0 × 10^(25) s^(−1) in the 4–5 November period. The HCN production curve, as well as the CO_2 and H_2O production curves measured by EPOXI, are interpreted with a geometric model which takes into account the complex rotational state of 103P/Hartley 2 and its shape. The HCN and H_2O production curves are in phase, showing that these molecules have common sources. The ∼1.7 h delay, in average, of the HCN and H_2O production curves with respect to the CO_2 production curve suggests that HCN and H_2O are mainly produced by subliming icy grains. The scale length of production of HCN is determined to be on the order of 500–1000 km, implying a mean velocity of 100–200 m s^(−1) for the icy grains producing HCN. From the time evolution of the insolation of the nucleus, we show that the CO_2 production is modulated by the insolation of the small lobe of the nucleus. The three-cycle pattern of the production curves reported earlier is best explained by an overactivity of the small lobe in the longitude range 0–180°. The good correlation between the insolation of the small lobe and CO_2 production is consistent with CO_2 being produced from small depths below the surface. The time evolution of the velocity offset of the HCN lines, as well as the displacement of the HCN photocenter in the interferometric maps, are overall consistent with this interpretation. Other localized sources of gas on the nucleus surface are also suggested