23 research outputs found

    Pilot KaVA monitoring on the M87 jet: confirming the inner jet structure and superluminal motions at sub-pc scales

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    We report the initial results of our high-cadence monitoring program on the radio jet in the active galaxy M87, obtained by the KVN and VERA Array (KaVA) at 22 GHz. This is a pilot study that preceded a larger KaVA-M87 monitoring program, which is currently ongoing. The pilot monitoring was mostly performed every two to three weeks from December 2013 to June 2014, at a recording rate of 1 Gbps, obtaining the data for a total of 10 epochs. We successfully obtained a sequence of good quality radio maps that revealed the rich structure of this jet from <~1 mas to 20 mas, corresponding to physical scales (projected) of ~0.1-2 pc (or ~140-2800 Schwarzschild radii). We detected superluminal motions at these scales, together with a trend of gradual acceleration. The first evidence for such fast motions and acceleration near the jet base were obtained from recent VLBA studies at 43 GHz, and the fact that very similar kinematics are seen at a different frequency and time with a different instrument suggests these properties are fundamental characteristics of this jet. This pilot program demonstrates that KaVA is a powerful VLBI array for studying the detailed structural evolution of the M87 jet and also other relativistic jets.Comment: 10 pages, 9 figures, accepted for publication in PAS

    The First Very Long Baseline Interferometry Image of 44 GHz Methanol Maser with the KVN and VERA Array (KaVA)

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    We have carried out the first very long baseline interferometry (VLBI) imaging of 44 GHz class I methanol maser (7_{0}-6_{1}A^{+}) associated with a millimeter core MM2 in a massive star-forming region IRAS 18151-1208 with KaVA (KVN and VERA Array), which is a newly combined array of KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry). We have succeeded in imaging compact maser features with a synthesized beam size of 2.7 milliarcseconds x 1.5 milliarcseconds (mas). These features are detected at a limited number of baselines within the length of shorter than approximately 650 km corresponding to 100 Mlambda in the uv-coverage. The central velocity and the velocity width of the 44 GHz methanol maser are consistent with those of the quiescent gas rather than the outflow traced by the SiO thermal line. The minimum component size among the maser features is ~ 5 mas x 2 mas, which corresponds to the linear size of ~ 15 AU x 6 AU assuming a distance of 3 kpc. The brightness temperatures of these features range from ~ 3.5 x 10^{8} to 1.0 x 10^{10} K, which are higher than estimated lower limit from a previous Very Large Array observation with the highest spatial resolution of ~ 50 mas. The 44 GHz class I methanol maser in IRAS 18151-1208 is found to be associated with the MM2 core, which is thought to be less evolved than another millimeter core MM1 associated with the 6.7 GHz class II methanol maser.Comment: 19 pages, 3 figure

    EAVN Astrometry toward the Extreme Outer Galaxy: Kinematic distance with the proper motion of G034.84-00.95

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    We aim to reveal the structure and kinematics of the Outer-Scutum-Centaurus (OSC) arm located on the far side of the Milky Way through very long baseline interferometry (VLBI) astrometry using KaVA, which is composed of KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry). We report the proper motion of a 22 GHz H2_{2}O maser source, which is associated with the star-forming region G034.84-00.95, to be (μαcosδ\mu_{\alpha} \rm{cos}\delta, μδ\mu_{\delta}) = (-1.61±\pm0.18, -4.29±\pm0.16) mas yr1^{-1} in equatorial coordinates (J2000). We estimate the 2D kinematic distance to the source to be 18.6±\pm1.0 kpc, which is derived from the variance-weighted average of kinematic distances with LSR velocity and the Galactic-longitude component of the measured proper motion. Our result places the source in the OSC arm and implies that G034.84-00.95 is moving away from the Galactic plane with a vertical velocity of -38±\pm16 km s1^{-1}. Since the H I supershell GS033+06-49 is located at a kinematic distance roughly equal to that of G034.84-00.95, it is expected that gas circulation occurs between the outer Galactic disk around G034.84-00.95 with a Galactocentric distance of 12.80.9+1.0^{+1.0}_{-0.9} kpc and halo. We evaluate possible origins of the fast vertical motion of G034.84-00.95, which are (1) supernova explosions and (2) cloud collisions with the Galactic disk. However, neither of the possibilities are matched with the results of VLBI astrometry as well as spatial distributions of H II regions and H I gas.Comment: Accepted for publication in PASJ. 14 figures; 8 table

    Additional file 1: Figure S1. of The association of kidney function with repetitive breath-hold diving activities of female divers from Korea, Haenyeo

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    Proportion of subjects categorized by estimated glomerular filtration rate (eGFR) groups before and after propensity (PS) matching in female divers and non-divers. (TIF 864 kb

    Additional file 2: Table S1. of The association of kidney function with repetitive breath-hold diving activities of female divers from Korea, Haenyeo

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    Risk factors for eGFR < 45 ml/min/1.73 m2 on multivariate logistic regression analysis in the unmatched and matched cohort. (DOCX 21 kb

    The Impact of Renin-Angiotensin System Blockade on Renal Outcomes and Mortality in Pre-Dialysis Patients with Advanced Chronic Kidney Disease - Fig 3

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    <p><b>Kaplan-Meier curves for ESRD requiring RRT (A) and composite outcome (ESRD or all-cause mortality or hospitalization for hyperkalemia) (B) in propensity score matching cohort.</b> ACEI/ARB users showed higher risk of renal mortality (A) and composite outcome (B) than non-users.</p
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