Chromatic periodic activity down to 120 megahertz in a fast radio burst.

Fast radio bursts (FRBs) are extragalactic astrophysical transients1 whose brightness requires emitters that are highly energetic yet compact enough to produce the short, millisecond-duration bursts. FRBs have thus far been detected at frequencies from 8 gigahertz (ref. 2) down to 300 megahertz (ref. 3), but lower-frequency emission has remained elusive. Some FRBs repeat4-6, and one of the most frequently detected, FRB 20180916B7, has a periodicity cycle of 16.35 days (ref. 8). Using simultaneous radio data spanning a wide range of wavelengths (a factor of more than 10), here we show that FRB 20180916B emits down to 120 megahertz, and that its activity window is frequency dependent (that is, chromatic). The window is both narrower and earlier at higher frequencies. Binary wind interaction models predict a wider window at higher frequencies, the opposite of our observations. Our full-cycle coverage shows that the 16.3-day periodicity is not aliased. We establish that low-frequency FRB emission can escape the local medium. For bursts of the same fluence, FRB 20180916B is more active below 200 megahertz than at 1.4 gigahertz. Combining our results with previous upper limits on the all-sky FRB rate at 150 megahertz, we find there are 3-450 FRBs in the sky per day above 50 Jy ms. Our chromatic results strongly disfavour scenarios in which absorption from strong stellar winds causes FRB periodicity. We demonstrate that some FRBs are found in 'clean' environments that do not absorb or scatter low-frequency radiation.

Discrepant results of different tests for antibodies to hepatitis C in children with malignant diseases and in patients on renal replacement therapy.

The serostatus of hepatitis C in pediatric oncological patients and in individuals on renal replacement therapy was tested for circulating antibodies to the c100-3 recombinant antigen of hepatitis C. Upon prescreening, 12 of 82 patients in the pediatric oncological group, 6 of 108 renal transplant recipients, and 17 of 150 patients on chronic intermittent hemodialysis were repeatedly positive. Further testing of these 35 sera by supplemental test assays revealed conflicting data, mostly in the pediatric oncological group and in renal transplant recipients. Only in 10 sera were identical results obtained, suggesting that positive test results in some groups at risk have only a low predictive value.

[Inferior vena cava compression syndrome in cystic kidney. Duplex ultrasonic diagnosis]. / Vena-cava-inferior-Kompressionssyndrome bei Zystennieren. Duplexsonographische Diagnose.

Four months after renal transplantation for polycystic renal degeneration a 38-year-old man developed breathing-related pain in the left upper lung and a sinus tachycardia (130/min). Lung perfusion scintigraphy demonstrated pulmonary emboli from an acute venous thrombosis of the left lower leg. Polycythaemia and impairment of clot-inhibiting factors were excluded. Ultrasound examination of the abdomen revealed stenosis of the inferior vena cava (IVC) distal to the hepatic veins, dorsal to the liver and ventral of a huge right polycystic kidney which had been left in situ at the time of the renal transplantation. Duplex sonography demonstrated a band-like flow profile in the region of the stenosis. Blood flow was clearly increased (0.62 m/s) and not affected by either heart rate or breathing movements. The findings were confirmed by angiography. The right kidney, weighing 5 kg, was removed at surgery. The IVC stenosis was postoperatively found to be relieved and duplex sonography gave normal findings.