646 research outputs found

    Resolving the Host Galaxy of the Nearby QSO I Zw 1 with Sub-Arcsecond Multi-Transition Molecular Line Observations

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    We present the first sub-kpc 0.7" (~ 850 pc) resolution 12CO(1-0) molecular line observations of the ISM in the host galaxy of the QSO I Zw 1. The observations were obtained with the BIMA mm-interferometer in its compact A configuration. The BIMA data are complemented by new observations of the 12CO(2-1) and 13CO(1-0) line with IRAM Plateau de Bure mm-interferometer (PdBI) at 0.9" and 1.9" resolution, respectively. These measurements, which are part of a multi-wavelength study of the host galaxy of I Zw 1, are aimed at comparing the ISM properties of a QSO host with those of nearby galaxies as well as to obtain constraints on galaxy formation/evolution models. Our images of the 12CO(1-0) line emission show a ring-like structure in the circumnuclear molecular gas distribution with an inner radius of about 1.2 kpc. The presence of such a molecular gas ring was predicted from earlier lower angular resolution PdBI 12CO(1-0) observations. A comparison of the BIMA data with IRAM PdBI 12CO(2-1) observations shows variations in the excitation conditions of the molecular gas in the innermost 1.5" comprising the nuclear region of I Zw 1. The observed properties of the molecular cloud complexes in the disk of the host galaxy suggest that they can be the sites of massive circumnuclear star formation, and show no indications of excitation by the nuclear AGN. This all indicates that the molecular gas in a QSO host galaxy has similar properties to the gas observed in nearby low luminosity AGNs.Comment: to be published in ApJ 1 July 2004 issu

    Programme cantonal diabète dans le canton de Vaud indicateurs pour le suivi et le baromètre : rapport final

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    Le Programme cantonal Diabète souhaite collecter des indicateurs afin d'objectiver son suivi et produire un Baromètre Diabète Vaud qui serait publié et distribué périodiquement à un public large. Ce rapport présente les indicateurs suggérés par l'IUMSP, mandaté afin d'établir une liste raisonnée d'indicateurs sur le diabète pour le canton de Vaud. La sélection d'indicateurs s'est faite d'après plusieurs critères, parmi lesquels la disponibilité des indicateurs actuelle et à long terme, ainsi que leur pertinence avérée par la littérature. Ce rapport décrit les résultats pour les indicateurs sélectionnés, ainsi que les informations nécessaires à leur compréhension : source, fréquence de mise à disposition, méthode de calcul, limites, références éventuelles. Parmi les indicateurs décrits dans ce rapport, certains sont proposés comme spécialement pertinents à inclure dans le futur Baromètre Diabète Vaud. Aussi, une suggestion de présentation de ces indicateurs (fiches descriptives) est articulée pour ce dernier

    The alpha-effect in rotating convection: a comparison of numerical simulations

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    Numerical simulations are an important tool in furthering our understanding of turbulent dynamo action, a process that occurs in a vast range of astrophysical bodies. It is important in all computational work that comparisons are made between different codes and, if non-trivial differences arise, that these are explained. Kapyla et al (2010: MNRAS 402, 1458) describe an attempt to reproduce the results of Hughes & Proctor (2009: PRL 102, 044501) and, by employing a different methodology, they arrive at very different conclusions concerning the mean electromotive force and the generation of large-scale fields. Here we describe why the simulations of Kapyla et al (2010) are simply not suitable for a meaningful comparison, since they solve different equations, at different parameter values and with different boundary conditions. Furthermore we describe why the interpretation of Kapyla et al (2010) of the calculation of the alpha-effect is inappropriate and argue that the generation of large-scale magnetic fields by turbulent convection remains a problematic issue.Comment: Submitted to MNRAS. 5 pages, 3 figure

    Congenital tibial deficiencies: Treatment using the Ilizarov's external fixator

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    SummaryIntroductionCongenital longitudinal deficiency of the tibia is a rare and often syndromic anomaly. Amputation is usually the preferred treatment option in complete absence of the tibia; however, a conservative management might be implemented in partial forms or in case of amputation refusal. Our experience with the Ilizarov fixator, convinced us this device was the best suited for progressive correction of lower limbs length discrepancies and articular or bone angular limb deformities (ALD). The aim of this study is to highlight the interest of the Ilizarov fixator in the multistage conservative treatment of congenital tibial deficiencies.Material and methodsA retrospective study was conducted in nine patients suffering from Type I or II congenital tibial deficiencies (Jones) and sequentially managed using the Ilizarov technique. The functional outcome after treatment completion was then clinically assessed.ResultsThe different stages of correction were recorded for each individual patient. Patients were assessed at a mean follow-up of 18,3 years (4–32 years). The mean maximum knee flexion was 35° (0°–90°) in type I deficiencies and 118° (90°–140°) in type II deficiencies. One patient underwent amputation and a bilateral knee arthrodesis was performed in another case.DiscussionFew series in the literature report a comparable length of follow-up period in the conservative management of severe congenital tibial deficiencies. In our study, the Ilizarov fixator provided satisfactory progressive corrections of severe congenital tibial deficiencies.Level of EvidenceLevel IV therapeutic retrospective study

    Discovery of the INTEGRAL X/Gamma-ray transient IGR J00291+5934: a Comptonised accreting ms pulsar ?

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    We report the discovery of a high-energy transient with the IBIS/ISGRI detector on board the INTEGRAL observatory. The source, namely IGR J00291+5934, was first detected on 2nd December 2004 in the routine monitoring of the IBIS/ISGRI 20--60 keV images. The observations were conducted during Galactic Plane Scans, which are a key part of the INTEGRAL Core Programme observations. After verifying the basic source behaviour, the discovery was announced on 3rd December. The transient shows a hard Comptonised spectrum, with peak energy release at about 20 keV and a total luminosity of ~ 0.9E36 erg/s in the 5--100 keV range, assuming a distance of 3 kpc. Following the INTEGRAL announcement of the discovery of IGR J00291+5934, a number of observations were made by other instruments. We summarise the results of those observations and, together with the INTEGRAL data, identifiy IGR J00291+5934 as the 6th member of a class of accreting X-ray millisecond pulsars.Comment: Accepted for publication as an A&A Letter 24/01/2005. 5 pages, 2 figure

    Sending femtosecond pulses in circles: highly non-paraxial accelerating beams

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    We use caustic beam shaping on 100 fs pulses to experimentally generate non-paraxial accelerating beams along a 60 degree circular arc, moving laterally by 14 \mum over a 28 \mum propagation length. This is the highest degree of transverse acceleration reported to our knowledge. Using diffraction integral theory and numerical beam propagation simulations, we show that circular acceleration trajectories represent a unique class of non-paraxial diffraction-free beam profile which also preserves the femtosecond temporal structure in the vicinity of the caustic

    Filamentation with nonlinear Bessel vortices

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    International audienceWe present a new type of ring-shaped filaments featured by stationary nonlinear high-order Bessel solutions to the laser beam propa-gation equation. Two different regimes are identified by direct numerical simulations of the nonlinear propagation of axicon focused Gaussian beams carrying helicity in a Kerr medium with multiphoton absorption: the stable nonlinear propagation regime corresponds to a slow beam reshaping into one of the stationary nonlinear high-order Bessel solutions, called nonlinear Bessel vortices. The region of existence of nonlinear Bessel vortices is found semi-analytically. The influence of the Kerr nonlinearity and non-linear losses on the beam shape is presented. Direct numerical simulations highlight the role of attractors played by nonlinear Bessel vortices in the stable propagation regime. Large input powers or small cone angles lead to the unstable propagation regime where nonlinear Bessel vortices break up into an helical multiple filament pattern or a more irregular structure. Nonlinear Bessel vortices are shown to be sufficiently intense to generate a ring-shaped filamentary ionized channel in the medium which is foreseen as opening the way to novel applications in laser material processing of transparent dielectrics. OCIS codes: (190.7110) Ultrafast nonlinear optics; (190.5940) Self-action effects; (190.3270) Kerr effect

    INTEGRAL and XMM-Newton observations of the weak GRB 030227

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    We present INTEGRAL and XMM-Newton observations of the prompt gamma-ray emission and the X-ray afterglow of GRB030227, the first GRB for which the quick localization obtained with the INTEGRAL Burst Alert System (IBAS) has led to the discovery of X-ray and optical afterglows. GRB030227 had a duration of about 20 s and a peak flux of 1.1 photons cm^-2 s^-1 in the 20-200 keV energy range. The time averaged spectrum can be fit by a single power law with photon index about 2 and we find some evidence for a hard to soft spectral evolution. The X-ray afterglow has been detected starting only 8 hours after the prompt emission, with a 0.2-10 keV flux decreasing as t^-1 from 1.3x10e-12 to 5x10e-13 erg cm^-2 s^-1. The afterglow spectrum is well described by a power law with photon index 1.94+/-0.05 modified by a redshifted neutral absorber with column density of several 10e22 cm^-2. A possible emission line at 1.67 keV could be due to Fe for a redshift z=3, consistent with the value inferred from the absorption.Comment: 16 pages, 5 figures, latex, Accepted for publication in The Astrophysical Journal Letter

    The first outburst of the black hole candidate MAXI J1836-194 observed by INTEGRAL, Swift, and RXTE

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    MAXI J1836-194 is a transient black-hole candidate discovered in outburst by MAXI on 30 August 2011. We report on the available INTEGRAL, Swift, and RXTE observations performed in the direction of the source during this event before 55 864 MJD. Combining the broad band (0.6-200 keV) spectral and timing information obtained from these data with the results of radio observations, we show that the event displayed by MAXI J1836-194 is another example of "failed" outburst. During the first ~20 days after the onset of the event, the source underwent a transition from the canonical low/hard to the hard intermediate state, while reaching the highest X-ray flux. In the ~40 days following the peak of the outburst, the source displayed a progressive spectral hardening and a decrease of the X-ray flux, thus it entered again the low/hard state and began its return to quiescence.Comment: Accepted for A&A Letters on 22 Dec. 201
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