64 research outputs found

    MALS SALT-NOT survey of MIR-selected powerful radio-bright AGN at 0<z<3.5

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    We present results of an optical spectroscopic survey using SALT and NOT to build a WISE mid-infrared color-based, dust-unbiased sample of powerful radio-bright (>>200 mJy at 1.4 GHz) AGN for the MeerKAT Absorption Line Survey (MALS). Our sample has 250 AGN (median z=1.8z=1.8) showing emission lines, 26 with no emission lines, and 27 without optical counterparts. Overall, our sample is fainter (Δi\Delta i=0.6 mag) and redder (Δ(gi)\Delta(g-i)=0.2 mag) than radio-selected quasars, and representative of fainter quasar population detected in optical surveys. About 20% of the sources are narrow line AGN (NLAGN) - 65% of these, at z<0.5z < 0.5 are galaxies without strong nuclear emission, and 10% at z>1.9z>1.9, have emission line ratios similar to radio galaxies. The farthest NLAGN in our sample is M1513-2524 (zem=3.132z_{em}=3.132), and the largest (size\sim330 kpc) is M0909-3133 (zem=0.884z_{em}=0.884). We discuss in detail 110 AGN at 1.9<z<3.51.9 < z < 3.5. Despite representing the radio loudest quasars (median RR=3685), their Eddington ratios are similar to the SDSS quasars having lower RR. We detect 4 CIV BALQSOs, all among AGN with least RR, and highest black hole masses and Eddington ratios. The BAL detection rate (42+34^{+3}_{-2}%) is consistent with that seen in extremely powerful (L1.4GHz>1025L_{1.4GHz}>10^{25} WHz1^{-1}) quasars. Using optical light-curves, radio polarization and γ\gamma-ray detections, we identify 7 high-probability BL Lacs. We also summarize the full MALS footprint to search for HI 21-cm and OH 18-cm lines at z<2z<2.Comment: 62 pages, 15 figures and 3 tables; accepted in ApJ (updated the redshift of M1312-2026 to z=0.977

    The MeerKAT international GHz tiered extragalactic exploration (MIGHTEE) survey

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    The MIGHTEE large survey project will survey four of the most well-studied extragalactic deep fields, totalling 20 square degrees to µJy sensitivity at Giga-Hertz frequencies, as well as an ultra-deep image of a single ∼1 deg2 MeerKAT pointing. The observations will provide radio continuum, spectral line and polarisation information. As such, MIGHTEE, along with the excellent multi-wavelength data already available in these deep fields, will allow a range of science to be achieved. Specifically, MIGHTEE is designed to significantly enhance our understanding of, (i) the evolution of AGN and star-formation activity over cosmic time, as a function of stellar mass and environment, free of dust obscuration; (ii) the evolution of neutral hydrogen in the Universe and how this neutral gas eventually turns into stars after moving through the molecular phase, and how efficiently this can fuel AGN activity; (iii) the properties of cosmic magnetic fields and how they evolve in clusters, filaments and galaxies. MIGHTEE will reach similar depth to the planned SKA all-sky survey, and thus will provide a pilot to the cosmology experiments that will be carried out by the SKA over a much larger survey volume

    Signal transduction underlying the control of urinary bladder smooth muscle tone by muscarinic receptors and β-adrenoceptors

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    The normal physiological contraction of the urinary bladder, which is required for voiding, is predominantly mediated by muscarinic receptors, primarily the M3 subtype, with the M2 subtype providing a secondary backup role. Bladder relaxation, which is required for urine storage, is mediated by β-adrenoceptors, in most species involving a strong β3-component. An excessive stimulation of contraction or a reduced relaxation of the detrusor smooth muscle during the storage phase of the micturition cycle may contribute to bladder dysfunction known as the overactive bladder. Therefore, interference with the signal transduction of these receptors may be a viable approach to develop drugs for the treatment of overactive bladder. The prototypical signaling pathway of M3 receptors is activation of phospholipase C (PLC), and this pathway is also activated in the bladder. Nevertheless, PLC apparently contributes only in a very minor way to bladder contraction. Rather, muscarinic-receptor-mediated bladder contraction involves voltage-operated Ca2+ channels and Rho kinase. The prototypical signaling pathway of β-adrenoceptors is an activation of adenylyl cyclase with the subsequent formation of cAMP. Nevertheless, cAMP apparently contributes in a minor way only to β-adrenoceptor-mediated bladder relaxation. BKCa channels may play a greater role in β-adrenoceptor-mediated bladder relaxation. We conclude that apart from muscarinic receptor antagonists and β-adrenoceptor agonists, inhibitors of Rho kinase and activators of BKCa channels may have potential to treat an overactive bladder

    Genome engineering for improved recombinant protein expression in Escherichia coli

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    VizieR Online Data Catalog: LOFAR Bootes and 3C295 field sources (van Weeren+, 2014)

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    The Bootes and 3C 295 fields were simultaneously observed on 2012 April 12 as part of a multi-beam observation with the LOFAR LBA stations. The idea behind the multi-beam setup is that we use the 3C 295 observations as a calibrator field to transfer the gain amplitudes to the (target) Bootes field. The total integration time on both fields was 10.25 hr. Complete frequency coverage was obtained between 54 and 70 MHz for both fields, while non-contiguous frequency coverage was obtained between 30 and 54 MHz for the 3C 295 only. All four correlation products were recorded. By default, the frequency band was divided into sub-bands, each 195.3125 kHz wide. Each sub-band was further divided in 64 channels and the integration time was 1 s. (1 data file)
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