The polarization properties of radio sources at very low frequencies (<200 MHz) have not been widely measured, but the new generation of low-frequency radio telescopes, including the Low Frequency ...Array (LOFAR: a Square Kilometre Array Low pathfinder), now gives us the opportunity to investigate these properties. In this paper, we report on the preliminary development of a data reduction pipeline to carry out polarization processing and Faraday tomography for data from the LOFAR Two-meter Sky Survey (LOTSS) and present the results of this pipeline from the LOTSS preliminary data release region (10h45m–15h30m right ascension, 45°–57° declination, 570 square degrees). We have produced a catalog of 92 polarized radio sources at 150 MHz at 4.′3 resolution and 1 mJy rms sensitivity, which is the largest catalog of polarized sources at such low frequencies. We estimate a lower limit to the polarized source surface density at 150 MHz, with our resolution and sensitivity, of 1 source per 6.2 square degrees. We find that our Faraday depth measurements are in agreement with previous measurements and have significantly smaller errors. Most of our sources show significant depolarization compared to 1.4 GHz, but there is a small population of sources with low depolarization indicating that their polarized emission is highly localized in Faraday depth. We predict that an extension of this work to the full LOTSS data would detect at least 3400 polarized sources using the same methods, and probably considerably more with improved data processing.
We have conducted two pilot surveys for radio pulsars and fast transients with the Low-Frequency Array (LOFAR) around 140 MHz and here report on the first low-frequency fast-radio burst limit and the ...discovery of two new pulsars. The first survey, the LOFAR Pilot Pulsar Survey (LPPS), observed a large fraction of the northern sky, ~ 1.4 × 104 deg2, with 1 h dwell times. Each observation covered ~75 deg2 using 7 independent fields formed by incoherently summing the high-band antenna fields. The second pilot survey, the LOFAR Tied-Array Survey (LOTAS), spanned ~600 deg2, with roughly a 5-fold increase in sensitivity compared with LPPS. Using a coherent sum of the 6 LOFAR “Superterp” stations, we formed 19 tied-array beams, together covering 4 deg2 per pointing. From LPPS we derive a limit on the occurrence, at 142 MHz, of dispersed radio bursts of < 150 day-1 sky-1, for bursts brighter than S> 107 Jy for the narrowest searched burst duration of 0.66 ms. In LPPS, we re-detected 65 previously known pulsars. LOTAS discovered two pulsars, the first with LOFAR or any digital aperture array. LOTAS also re-detected 27 previously known pulsars. These pilot studies show that LOFAR can efficiently carry out all-sky surveys for pulsars and fast transients, and they set the stage for further surveying efforts using LOFAR and the planned low-frequency component of the Square Kilometer Array.
We present a study of the low-frequency radio properties of broad absorption line quasars (BALQSOs) from the LOFAR Two-metre Sky-Survey Data Release 1 (LDR1). The value-added LDR1 catalogue contains ...Pan-STARRS counterparts, which we match with the Sloan Digital Sky Survey (SDSS) DR7 and DR12 quasar catalogues. We find that BALQSOs are twice as likely to be detected at 144 MHz than their non-BAL counterparts, and BALQSOs with low-ionisation species present in their spectra are three times more likely to be detected than those with only high-ionisation species. The BALQSO fraction at 144 MHz is constant with increasing radio luminosity, which is inconsistent with previous results at 1.4 GHz, indicating that observations at the different frequencies may be tracing different sources of radio emission. We cross-match radio sources between the Faint Images of the Radio Sky at Twenty Centimeters (FIRST) survey and LDR1, which provides a bridge via the LDR1 Pan-STARRS counterparts to identify BALQSOs in SDSS. Consequently we expand the sample of BALQSOs detected in FIRST by a factor of three. The LDR1-detected BALQSOs in our sample are almost exclusively radio-quiet (log(R144 MHz) < 2), with radio sizes at 144 MHz typically less than 200 kpc; these radio sizes tend to be larger than those at 1.4 GHz, suggesting more extended radio emission at low frequencies. We find that although the radio detection fraction increases with increasing balnicity index (BI), there is no correlation between BI and either low-frequency radio power or radio-loudness. This suggests that both radio emission and BI may be linked to the same underlying process, but are spatially distinct phenomena.
Spontaneous coronary artery dissection (SCAD) is an acute coronary event of uncertain origin. Clinical features and prognosis remain insufficiently characterized.
A retrospective single-center cohort ...study identified 87 patients with angiographically confirmed SCAD. Incidence, clinical characteristics, treatment modalities, in-hospital outcomes, and long-term risk of SCAD recurrence or major adverse cardiac events were evaluated. Mean age was 42.6 years; 82% were female. Extreme exertion at SCAD onset was more frequent in men (7 of 16 versus 2 of 71; P<0.001), and postpartum status was observed in 13 of 71 women (18%). Presentation was ST-elevation myocardial infarction in 49%. Multivessel SCAD was found in 23%. Initial conservative management (31 of 87) and coronary artery bypass grafting (7 of 87) were associated with an uncomplicated in-hospital course, whereas percutaneous coronary intervention was complicated by technical failure in 15 of 43 patients (35%) and 1 death. During a median follow-up of 47 months (interquartile range, 18-106 months), SCAD recurred in 15 patients, all female. Estimated 10-year rate of major adverse cardiac events (death, heart failure, myocardial infarction, and SCAD recurrence) was 47%. Fibromuscular dysplasia of the iliac artery was identified incidentally in 8 of 16 femoral angiograms (50%) undertaken before closure device placement and in the carotid arteries of 2 others with carotid dissection.
SCAD affects a young, predominantly female population, frequently presenting as ST-elevation myocardial infarction. Although in-hospital mortality is low regardless of initial treatment, percutaneous coronary intervention is associated with high rates of complication. Risks of SCAD recurrence and major adverse cardiac events in the long term emphasize the need for close follow-up. Fibromuscular dysplasia is a novel association and potentially causative factor.
ABSTRACT
Radio-loud active galaxies have two accretion modes radiatively inefficient (RI) and radiatively efficient (RE), with distinct optical and infrared signatures, and two jet dynamical ...behaviours, which in arcsec- to arcmin-resolution radio surveys manifest primarily as centre- or edge-brightened structures Fanaroff–Riley (FR) class I and II. The nature of the relationship between accretion mode and radio morphology (FR class) has been the subject of long debate. We present a comprehensive investigation of this relationship for a sample of 286 well-resolved radio galaxies in the LOFAR Two-metre Sky Survey Deep Fields (LoTSS-Deep) first data release, for which robust morphological and accretion mode classifications have been made. We find that two-thirds of luminous FRII radio galaxies are RI, and identify no significant differences in the visual appearance or source dynamic range (peak/mean surface brightness) of the RI and RE FRIIs, demonstrating that both RI and RE systems can produce FRII structures. We also find a significant population of low-luminosity FRIIs (predominantly RI), supporting our earlier conclusion that FRII radio structures can be produced at all radio luminosities. We demonstrate that in the luminosity range where both morphologies are present, the probability of producing FRI or FRII radio morphology is directly linked to stellar mass, while across all morphologies and luminosities, RE accretion occurs in systems with high specific star formation rate, presumably because this traces fuel availability. In summary, the relationship between accretion mode and radio morphology is very indirect, with host-galaxy environment controlling these two key parameters in different ways.
Aims/hypothesis Fenofibrate caused an acute, sustained plasma creatinine increase in the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) and Action to Control Cardiovascular Risk in ...Diabetes (ACCORD) studies. We assessed fenofibrate's renal effects overall and in a FIELD washout sub-study. Methods Type 2 diabetic patients (n = 9,795) aged 50 to 75 years were randomly assigned to fenofibrate (n = 4,895) or placebo (n = 4,900) for 5 years, after 6 weeks fenofibrate run-in. Albuminuria (urinary albumin/creatinine ratio measured at baseline, year 2 and close-out) and estimated GFR, measured four to six monthly according to the Modification of Diet in Renal Disease Study, were pre-specified endpoints. Plasma creatinine was re-measured 8 weeks after treatment cessation at close-out (washout sub-study, n = 661). Analysis was by intention-to-treat. Results During fenofibrate run-in, plasma creatinine increased by 10.0 μmol/l (p < 0.001), but quickly reversed on placebo assignment. It remained higher on fenofibrate than on placebo, but the chronic rise was slower (1.62 vs 1.89 μmol/l annually, p = 0.01), with less estimated GFR loss (1.19 vs 2.03 ml min⁻¹ 1.73 m⁻² annually, p < 0.001). After washout, estimated GFR had fallen less from baseline on fenofibrate (1.9 ml min⁻¹ 1.73 m⁻², p = 0.065) than on placebo (6.9 ml min⁻¹ 1.73 m⁻², p < 0.001), sparing 5.0 ml min⁻¹ 1.73 m⁻² (95% CI 2.3-7.7, p < 0.001). Greater preservation of estimated GFR with fenofibrate was observed with baseline hypertriacylglycerolaemia (n = 169 vs 491 without) alone, or combined with low HDL-cholesterol (n = 140 vs 520 without) and reductions of ≥0.48 mmol/l in triacylglycerol over the active run-in period (pre-randomisation) (n = 356 vs 303 without). Fenofibrate reduced urine albumin concentrations and hence albumin/creatinine ratio by 24% vs 11% (p < 0.001; mean difference 14% 95% CI 9-18; p < 0.001), with 14% less progression and 18% more albuminuria regression (p < 0.001) than in participants on placebo. End-stage renal event frequency was similar (n = 21 vs 26, p = 0.48). Conclusions/interpretation Fenofibrate reduced albuminuria and slowed estimated GFR loss over 5 years, despite initially and reversibly increasing plasma creatinine. Fenofibrate may delay albuminuria and GFR impairment in type 2 diabetes patients. Confirmatory studies are merited. Trial registration ISRCTN64783481 Funding The study was funded by grants from Laboratoires Fournier SA (Dijon, France; now part of Abbott Pharmaceuticals) and the National Health and Medical Research Council, Australia
Abstract
We present the results of a new study of the relationship between infrared excess (IRX ≡ LIR/LUV), ultraviolet (UV) spectral slope (β) and stellar mass at redshifts 2 < z < 3, based on a ...deep Atacama Large Millimeter Array (ALMA) 1.3-mm continuum mosaic of the Hubble Ultra Deep Field. Excluding the most heavily obscured sources, we use a stacking analysis to show that z ≃ 2.5 star-forming galaxies in the mass range $9.25\le \log (M_{\ast }/\rm M_{{\odot }}) \le 10.75$ are fully consistent with the IRX–β relation expected for a relatively grey attenuation curve, similar to the commonly adopted Calzetti law. Based on a large, mass-complete sample of 2 ≤ z ≤ 3 star-forming galaxies drawn from multiple surveys, we proceed to derive a new empirical relationship between β and stellar mass, making it possible to predict UV attenuation (A1600) and IRX as a function of stellar mass, for any assumed attenuation law. Once again, we find that z ≃ 2.5 star-forming galaxies follow A1600–M* and IRX–M* relations consistent with a relatively grey attenuation law, and find no compelling evidence that star-forming galaxies at this epoch follow a reddening law as steep as the Small Magellanic Cloud (SMC) extinction curve. In fact, we use a simple simulation to demonstrate that previous determinations of the IRX–β relation may have been biased towards low values of IRX at red values of β, mimicking the signature expected for an SMC-like dust law. We show that this provides a plausible mechanism for reconciling apparently contradictory results in the literature and that, based on typical measurement uncertainties, stellar mass provides a cleaner prediction of UV attenuation than β. Although the situation at lower stellar masses remains uncertain, we conclude that for 2 < z < 3 star-forming galaxies with $\log (M_{\ast }/\rm M_{{\odot }}) \ge 9.75$, both the IRX–β and IRX–M* relations are well described by a Calzetti-like attenuation law.
Context. Remnant radio galaxies represent the final dying phase of radio galaxy evolution in which the jets are no longer active. Remnants are rare in flux-limited samples, comprising at most a few ...percent. As a result of their rarity and because they are difficult to identify, this dying phase remains poorly understood and the luminosity evolution is largely unconstrained. Aims. Here we present the discovery and detailed analysis of a large (700 kpc) remnant radio galaxy with a low surface brightness that has been identified in LOFAR images at 150 MHz. Methods. By combining LOFAR data with new follow-up Westerbork observations and archival data at higher frequencies, we investigated the source morphology and spectral properties from 116 to 4850 MHz. By modelling the radio spectrum, we probed characteristic timescales of the radio activity. Results. The source has a relatively smooth, diffuse, amorphous appearance together with a very weak central compact core that is associated with the host galaxy located at z = 0.051. From our ageing and morphological analysis it is clear that the nuclear engine is currently switched off or, at most, active at a very low power state. We find that the source has remained visible in the remnant phase for about 60 Myr, significantly longer than its active phase of 15 Myr, despite being located outside a cluster. The host galaxy is currently interacting with another galaxy located at a projected separation of 15 kpc and a radial velocity offset of ~ 300 km s-1. This interaction may have played a role in the triggering and/or shut-down of the radio jets. Conclusions. The spectral shape of this remnant radio galaxy differs from most of the previously identified remnant sources, which show steep or curved spectra at low to intermediate frequencies. Our results demonstrate that remnant radio galaxies can show a wide range of evolutionary paths and spectral properties. In light of this finding and in preparation for new-generation deep low-frequency surveys, we discuss the selection criteria to be used to select representative samples of these sources.
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