The LOFAR Two-metre Sky Survey V. Second data release

In this data release from the ongoing LOw-Frequency ARray (LOFAR) Two-metre Sky Survey we present 120a 168 MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44 30a and 1h00m +28 00a and spanning 4178 and 1457 square degrees respectively. The images were derived from 3451 h (7.6 PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4 396 228 radio sources is derived from our total intensity (Stokes I) maps, where the majority of these have never been detected at radio wavelengths before. At 6a resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144 MHz have: a median rms sensitivity of 83 μJy beama 1; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.2a; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8 mJy beama 1. By creating three 16 MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of > a ±a 0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V) 20a resolution 120a168 MHz continuum images have a median rms sensitivity of 95 μJy beama 1, and we estimate a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation (Stokes Q and Stokes U) image cubes consist of 480a A a 97.6 kHz wide planes and have a median rms sensitivity per plane of 10.8 mJy beama 1 at 4a and 2.2 mJy beama 1 at 20a; we estimate the Stokes I to Stokes Q/U leakage to be approximately 0.2%. Here we characterise and publicly release our Stokes I, Q, U and V images in addition to the calibrated uv-data to facilitate the thorough scientific exploitation of this unique dataset

Characterising radio telescope software with the Workload Characterisation Framework

We present a modular framework, the Workload Characterisation Framework (WCF), that is developed to obtain, store and compare key characteristics of radio astronomy processing software in a reproducible way. As a demonstration, we discuss the experiences using the framework to characterise a LOFAR calibration and imaging pipeline

Exercise Capacity in Asymptomatic Adult Patients Treated for Coarctation of the Aorta

A reduced exercise capacity is a common finding in adult congenital heart disease and is associated with cardiovascular morbidity and mortality. However, data on exercise capacity in patients after repair of coarctation of the aorta (CoA) are scarce. Furthermore, a high rate of exercise-induced hypertension has been described in CoA patients. This study sought to assess exercise capacity and blood pressure response in asymptomatic patients long-term after CoA repair in relation to left ventricular and vascular function. Twenty-two CoA patients (age 30 ± 10.6 years) with successful surgical repair (n = 12) or balloon angioplasty (n = 10) between 3 months and 16 years of age with a follow-up of > 10 years underwent cardiopulmonary exercise testing at a mean follow-up of 23.9 years. Exercise capacity (peak oxygen uptake; VO 2peak) and blood pressure response were compared to age- and gender-matched reference values. Left ventricular function and volumetric analysis was performed using cardiovascular magnetic resonance imaging. CoA patients showed preserved exercise capacity compared to the healthy reference group, with a VO 2peak of 41.7 ± 12.0 ml/kg/min versus 44.9 ± 6.7 ml/kg/min. VO 2peak/kg showed a significant association with age (p < 0.001) and male gender (p ≤ 0.001). Exercise-induced hypertension occurred in 82% of CoA patients, and was strongly related to left ventricular mass (p = 0.04). Of the 41% of patients who were normotensive at rest, 78% showed exercise-induced hypertension. No significant correlation was found between peak exercise blood pressure and age, BMI, age at time of repair, LVEF, or LV dimensions. Exercise capacity is well preserved in patients long-term after successful repair of coarctation of the aorta. Nevertheless, a high number of patients develop exercise hypertension, which is strongly related to systemic hypertension. Regular follow-up, including cardiopulmonary exercise testing, and aggressive treatment of hypertension after CoA repair is strongly advised

Salt Marsh Accretion and Storm Tide Variation: an Example from a Barrier Island in the North Sea

We reconstruct past accretion rates of a salt marsh on the island of Sylt, Germany, using measurements of the radioisotopes 210Pb and 137Cs, as well as historical aerial photographs. Results from three cores indicate accretion rates varying between 1 and 16 mm year−1. Comparisons with tide gauge data show that high accretion rates during the 1980s and 1990s coincide with periods of increased storm activity. We identify a critical inundation height of 18 cm below which the strength of a storm seems to positively influence salt marsh accretion rates and above which the frequency of storms becomes the major factor. In addition to sea level rise, we conclude that in low marsh zones subject to higher inundation levels, mean storm strength is the major factor affecting marsh accretion, whereas in high marsh zones with lower inundation levels, it is storm frequency that impacts marsh accretion

LOFAR 150-MHz observations of the Boötes field: catalogue and source counts

We present the first wide area (19 deg 2 ), deep (≈120-150 μJy beam -1 ), high-resolution (5.6 � 7.4 arcsec) LOFAR High Band Antenna image of the Bo�tes field made at 130-169 MHz. This image is at least an order of magnitude deeper and 3-5 times higher in angular resolution than previously achieved for this field at low frequencies. The observations and data reduction, which includes full direction-dependent calibration, are described here. We present a radio source catalogue containing 6 276 sources detected over an area of 19 deg 2 , with a peak flux density threshold of 5σ. As the first thorough test of the facet calibration strategy, introduced by van Weeren et al., we investigate the flux and positional accuracy of the catalogue. We present differential source counts that reach an order of magnitude deeper in flux density than previously achieved at these low frequencies, and show flattening at 150-MHz flux densities below 10 mJy associated with the rise of the low flux density star-forming galaxies and radio-quiet AGN

Expression of class I major histocompatibility antigens switched off by highly oncogenic adenovirus 12 in transformed rat cells

Rat cells transformed by (he highly oncogenic adenovirus 12 lack at least two cellular proteins which are present in cells transformed by the non-oncogenic adenovirus 5 and in untransformed cells. One protein has been identified as the heavy chain of the rat class I major histocompatibility complex. This finding may explain the difference in oncogenicity between adenoviral species