A long-period radio transient active for three decades

Several long-period radio transients have recently been discovered, with strongly polarized coherent radio pulses appearing on timescales between tens to thousands of seconds^1,2. In some cases, the radio pulses have been interpreted as coming from rotating neutron stars with extremely strong magnetic fields, known as magnetars; the origin of other, occasionally periodic and less-well-sampled radio transients is still debated³. Coherent periodic radio emission is usually explained by rotating dipolar magnetic fields and pair-production mechanisms, but such models do not easily predict radio emission from such slowly rotating neutron stars and maintain it for extended times. On the other hand, highly magnetic isolated white dwarfs would be expected to have long spin periodicities, but periodic coherent radio emission has not yet been directly detected from these sources. Here we report observations of a long-period (21 min) radio transient, which we have labelled GPM J1839-10. The pulses vary in brightness by two orders of magnitude, last between 30 and 300 s and have quasiperiodic substructure. The observations prompted a search of radio archives and we found that the source has been repeating since at least 1988. The archival data enabled constraint of the period derivative to <3.6 × 10^-13 s s^-1, which is at the very limit of any classical theoretical model that predicts dipolar radio emission from an isolated neutron star.

A radio transient with unusually slow periodic emission

The high-frequency radio sky is bursting with synchrotron transients from massive stellar explosions and accretion events, but the low-frequency radio sky has, so far, been quiet beyond the Galactic pulsar population and the long-term scintillation of active galactic nuclei. The low-frequency band, however, is sensitive to exotic coherent and polarized radio-emission processes, such as electron-cyclotron maser emission from flaring M dwarfs¹, stellar magnetospheric plasma interactions with exoplanets² and a population of steep-spectrum pulsars³, making Galactic-plane searches a prospect for blind-transient discovery. Here we report an analysis of archival low-frequency radio data that reveals a periodic, low-frequency radio transient. We find that the source pulses every 18.18 min, an unusual periodicity that has, to our knowledge, not been observed previously. The emission is highly linearly polarized, bright, persists for 30-60 s on each occurrence and is visible across a broad frequency range. At times, the pulses comprise short-duration (<0.5 s) bursts; at others, a smoother profile is observed. These profiles evolve on timescales of hours. By measuring the dispersion of the radio pulses with respect to frequency, we have localized the source to within our own Galaxy and suggest that it could be an ultra-long-period magnetar.

GaLactic and Extragalactic All-sky Murchison Widefield Array survey eXtended (GLEAM-X) I: Survey Description and Initial Data Release

We describe a new low-frequency wideband radio survey of the southern sky. Observations covering 72-231MHz and Declinations south of +30° have been performed with the Murchison Widefield Array "extended" Phase I I configuration over 2018-2020 and will be processed to form data products including continuum and polarisation images and mosaics, multi-frequency catalogues, transient search data, and ionospheric measurements. From a pilot field described in this work, we publish an initial data release covering 1,447 deg² over 4 h≤ RA≤ 13 h, -32.7° ≤ Dec ≤ -20.7°. We process twenty frequency bands sampling 72-231 MHz, with a resolution of 2'-45″, and produce a wideband source-finding image across 170-231MHz with a root-mean-square noise of 1.27 ± 0.15 mJy beam^-1. Source-finding yields 79,124 components, of which 71,320 are fitted spectrally. The catalogue has a completeness of 98% at ~ 50 mJy, and a reliability of 98.2% at 5σ rising to 99.7% at 7σ. A catalogue is available from Vizier; images are made available on the GLEAM-X VO server and SkyView. This is the first in a series of data releases from the GLEAM-X survey.

Microscope imaging through highly scattering media

Microscopic images of a test chart hidden behind a slab of a highly scattering medium were significantly improved by incorporation of a spatial filter located at the back Fourier-transform plane of the objective lens of a microscope. The image quality was shown to be improved further by detection of only the early-arriving photons through time-resolved detection in combination with spatial filtering.

Clinical accuracy of continuous hemoglobin oxygen saturation monitoring devices

Three devices used to measure hemoglobin oxygen saturation in the extracorporeal circuit were studied and compared to a control. The Baxter Bentley OxySat, Oximetrix Accusat, and Radiometer ABL4 blood gas monitor were compared to a control, the IL 282 Co-Oximeter. Fifty-one sample points were obtained during all phases of cardiopulmonary bypass with results as follows: table: see text. The Accusat was found to be a statistically more accurate means of monitoring hemoglobin oxygen saturations during cardiopulmonary bypass than the ABL4 and the OxySat. All devices had significant correlation with the control and with each other.

Hormonal and metabolic effects of a pancreatic endocrine graft. Vascularized segmental transplantation in insulin-dependent diabetic patients

A new modification of pancreas transplant technique, the vascularized segmental intraperitoneal graft without duct ligation, has provided reversal of insulin-dependent (type I) diabetes mellitus for as long as 2 years of comfortable life. Although the risks associated with immunosuppression remain high (two of the 12 patients have died of early postoperative infection), selected data are presented from six cases to show the following striking hormonal and metabolic results after transplantation and withdrawal of insulin: restoration of normal beta cell function as shown by 24-hour urine C-peptide excretion and acutely responsive serum insulin, restoration of normal suppressibility of plasma glucagon, elimination of ketosis and negative nitrogen balance, normal fasting plasma glucose and glycosylated hemoglobin, and normal or near-normal glucose tolerance. These results provide a standard for current explorations of new ways of treating insulin-dependent diabetes.

Developmental and behavioral changes in the rat during chronic exposure to lead

Young male and female Sprague-Dawley rats were given drinking water containing 5 or 50 ppm Pb for 40 days prior to mating. Pregnant females were continued on these regimens throughout gestation and lactation. After weaning the offspring were similarly exposed through adulthood. Reflex development, body weights, and locomotor activity were measured in the offspring. Significant delays were noted in the development of the righting reflex at 5 and 50 ppm and in eye opening at 50 ppm. No difference was observed in development of the startle reflex at either dose. Mean body weights of treatment groups during this developmental period were not significantly different from controls. Locomotor activity was measured in adult males utilizing a residential maze. Both levels of lead produced a significant reduction in locomotor activity. When groups were treated with d-amphetamine (4.0 mg/kg subcutaneous), lead treatment caused a dose-related diminution in the amphetamine-induced hyperactivity. These results indicate that rats exposed to low levels of lead from conception until adulthood show a delay in nervous system development. As adults, these animals exhibit hypoactivity and decreased responsiveness to amphetamine.