An evolving jet from a strongly magnetized accreting X-ray pulsar.

Relativistic jets are observed throughout the Universe and strongly affect their surrounding environments on a range of physical scales, from Galactic binary systems1 to galaxies and clusters of galaxies2. All types of accreting black hole and neutron star have been observed to launch jets3, with the exception of neutron stars with strong magnetic fields4,5 (higher than 1012 gauss), leading to the conclusion that their magnetic field strength inhibits jet formation6. However, radio emission recently detected from two such objects could have a jet origin, among other possible explanations7,8, indicating that this long-standing idea might need to be reconsidered. But definitive observational evidence of such jets is still lacking. Here we report observations of an evolving jet launched by a strongly magnetized neutron star accreting above the theoretical maximum rate given by the Eddington limit. The radio luminosity of the jet is two orders of magnitude fainter than those seen in other neutron stars with similar X-ray luminosities9, implying an important role for the properties of the neutron star in regulating jet power. Our result also shows that the strong magnetic fields of ultra-luminous X-ray pulsars do not prevent such sources from launching jets.

New methods to constrain the radio transient rate: results from a survey of four fields with LOFAR.

We report on the results of a search for radio transients between 115 and 190 MHz with the LOw-Frequency ARray (LOFAR). Four fields have been monitored with cadences between 15 min and several months. A total of 151 images were obtained, giving a total survey area of 2275 deg2. We analysed our data using standard LOFAR tools and searched for radio transients using the LOFAR Transients Pipeline. No credible radio transient candidate has been detected; however, we are able to set upper limits on the surface density of radio transient sources at low radio frequencies. We also show that low-frequency radio surveys are more sensitive to steep-spectrum coherent transient sources than GHz radio surveys. We used two new statistical methods to determine the upper limits on the transient surface density. One is free of assumptions on the flux distribution of the sources, while the other assumes a power-law distribution in flux and sets more stringent constraints on the transient surface density. Both of these methods provide better constraints than the approach used in previous works. The best value for the upper limit we can set for the transient surface density, using the method assuming a power-law flux distribution, is 1.3 × 10-3 deg-2 for transients brighter than 0.3 Jy with a time-scale of 15 min, at a frequency of 150 MHz. We also calculated for the first time upper limits for the transient surface density for transients of different time-scales. We find that the results can differ by orders of magnitude from previously reported, simplified estimates.

A radio jet from the optical and x-ray bright stellar tidal disruption flare ASASSN-14li.

The tidal disruption of a star by a supermassive black hole leads to a short-lived thermal flare. Despite extensive searches, radio follow-up observations of known thermal stellar tidal disruption flares (TDFs) have not yet produced a conclusive detection. We present a detection of variable radio emission from a thermal TDF, which we interpret as originating from a newly launched jet. The multiwavelength properties of the source present a natural analogy with accretion-state changes of stellar mass black holes, which suggests that all TDFs could be accompanied by a jet. In the rest frame of the TDF, our radio observations are an order of magnitude more sensitive than nearly all previous upper limits, explaining how these jets, if common, could thus far have escaped detection.

An accurate geometric distance to the compact binary SS Cygni vindicates accretion disc theory.

Dwarf novae are white dwarfs accreting matter from a nearby red dwarf companion. Their regular outbursts are explained by a thermal-viscous instability in the accretion disc, described by the disc instability model that has since been successfully extended to other accreting systems. However, the prototypical dwarf nova, SS Cygni, presents a major challenge to our understanding of accretion disc theory. At the distance of 159 ± 12 parsecs measured by the Hubble Space Telescope, it is too luminous to be undergoing the observed regular outbursts. Using very long baseline interferometric radio observations, we report an accurate, model-independent distance to SS Cygni that places the source substantially closer at 114 ± 2 parsecs. This reconciles the source behavior with our understanding of accretion disc theory in accreting compact objects.

Severity scoring in carpal tunnel syndrome helps predict the value of conservative therapy.

A prospective study was performed to assess the outcome of conservative treatment of carpal tunnel syndrome and to establish the predictive value of preoperative Boston carpal tunnel questionnaire scores. Sixty-seven patients with 101 symptomatic hands underwent an evidence-based education and conservative therapy regime prior to surgery. All patients were scored using the Boston carpal tunnel questionnaire at presentation and at 3 months. Fifty-eight of 67 patients completed both assessments providing a complete assessment of 89 symptomatic hands. The mean Boston carpal tunnel questionnaire scores improved significantly from 2.45 to 2.12 and throughout the duration of the study 73% of patients improved with conservative treatment and 14% did not require surgery. Severity scoring at presentation was predictive of outcome with conservative therapy. This work suggests that the Boston carpal tunnel questionnaire can be used to identify patients who are likely to respond to conservative treatment.

Asymptomatic urinary tract colonisation predisposes to superficial wound infection in elective orthopaedic surgery.

There is no evidence surrounding the benefits, effects or clinical outcomes treating asymptomatic urinary tract colonisation. A series of 558 patients undergoing elective admission for orthopaedic surgery were recruited prior to surgery and were screened for urinary tract infection (UTI). Patients had their urine dipstick tested and positive samples were sent for culture and microscopy. Patients with a positive urine culture were treated with antibiotics prior to surgery; 85% of dipsticks tested were positive, while only 7% of the urine samples were culture positive. Over 36% of patients with a pre-operative UTI show some form of post-operative delayed wound healing or confirmed infection versus 16% in the other subgroup giving a relative risk of wound complications of 2:1 (p < 0.02). We have established that patients who present to pre-admission with urinary tract colonisation are a high risk subgroup for wound infection post-operatively.