A helium-burning white dwarf binary as a supersoft X-ray source.

Type Ia supernovae are cosmic distance indicators1,2, and the main source of iron in the Universe3,4, but their formation paths are still debated. Several dozen supersoft X-ray sources, in which a white dwarf accretes hydrogen-rich matter from a non-degenerate donor star, have been observed5 and suggested as Type Ia supernovae progenitors6-9. However, observational evidence for hydrogen, which is expected to be stripped off the donor star during the supernova explosion10, is lacking. Helium-accreting white dwarfs, which would circumvent this problem, have been predicted for more than 30 years (refs. 7,11,12), including their appearance as supersoft X-ray sources, but have so far escaped detection. Here we report a supersoft X-ray source with an accretion disk whose optical spectrum is completely dominated by helium, suggesting that the donor star is hydrogen-free. We interpret the luminous and supersoft X-rays as resulting from helium burning near the surface of the accreting white dwarf. The properties of our system provide evidence for extended pathways towards Chandrasekhar-mass explosions based on helium accretion, in particular for stable burning in white dwarfs at lower accretion rates than expected so far. This may allow us to recover the population of the sub-energetic so-called Type Iax supernovae, up to 30% of all Type Ia supernovae13, within this scenario.

Localized thermonuclear bursts from accreting magnetic white dwarfs.

Nova explosions are caused by global thermonuclear runaways triggered in the surface layers of accreting white dwarfs1-3. It has been predicted4-6 that localized thermonuclear bursts on white dwarfs can also take place, similar to type-I X-ray bursts observed in accreting neutron stars. Unexplained rapid bursts from the binary system TV Columbae, in which mass is accreted onto a moderately strong magnetized white dwarf from a low-mass companion, have been observed on several occasions in the past 40 years7-11. During these bursts, the optical/ultraviolet luminosity increases by a factor of more than three in less than an hour and fades in around ten hours. Fast outflows have been observed in ultraviolet spectral lines7, with velocities of more than 3,500 kilometres per second, comparable to the escape velocity from the white dwarf surface. Here we report on optical bursts observed in TV Columbae and in two additional accreting systems, EI Ursae Majoris and ASASSN-19bh. The bursts have a total energy of approximately 10-6  times than those of classical nova explosions (micronovae) and bear a strong resemblance to type-I X-ray bursts12-14. We exclude accretion or stellar magnetic reconnection events as their origin and suggest thermonuclear runaway events in magnetically confined accretion columns as a viable explanation.

A persistent ultraviolet outflow from an accreting neutron star binary transient.

All disc-accreting astrophysical objects produce powerful disc winds. In compact binaries containing neutron stars or black holes, accretion often takes place during violent outbursts. The main disc wind signatures during these eruptions are blue-shifted X-ray absorption lines, which are preferentially seen in disc-dominated 'soft states'1,2. By contrast, optical wind-formed lines have recently been detected in 'hard states', when a hot corona dominates the luminosity3. The relationship between these signatures is unknown, and no erupting system has as yet revealed wind-formed lines between the X-ray and optical bands, despite the many strong resonance transitions in this ultraviolet (UV) region4. Here we report that the transient neutron star binary Swift J1858.6-0814 exhibits wind-formed, blue-shifted absorption lines associated with C IV, N V and He II in time-resolved UV spectroscopy during a luminous hard state, which we interpret as a warm, moderately ionized outflow component in this state. Simultaneously observed optical lines also display transient blue-shifted absorption. Decomposing the UV data into constant and variable components, the blue-shifted absorption is associated with the former. This implies that the outflow is not associated with the luminous flares in the data. The joint presence of UV and optical wind features reveals a multi-phase and/or spatially stratified evaporative outflow from the outer disc5. This type of persistent mass loss across all accretion states has been predicted by radiation-hydrodynamic simulations6 and helps to explain the shorter-than-expected duration of outbursts7.

X-ray quasi-periodic eruptions from two previously quiescent galaxies.

Quasi-periodic eruptions (QPEs) are very-high-amplitude bursts of X-ray radiation recurring every few hours and originating near the central supermassive black holes of galactic nuclei1,2. It is currently unknown what triggers these events, how long they last and how they are connected to the physical properties of the inner accretion flows. Previously, only two such sources were known, found either serendipitously or in archival data1,2, with emission lines in their optical spectra classifying their nuclei as hosting an actively accreting supermassive black hole3,4. Here we report observations of QPEs in two further galaxies, obtained with a blind and systematic search of half of the X-ray sky. The optical spectra of these galaxies show no signature of black hole activity, indicating that a pre-existing accretion flow that is typical of active galactic nuclei is not required to trigger these events. Indeed, the periods, amplitudes and profiles of the QPEs reported here are inconsistent with current models that invoke radiation-pressure-driven instabilities in the accretion disk5-9. Instead, QPEs might be driven by an orbiting compact object. Furthermore, their observed properties require the mass of the secondary object to be much smaller than that of the main body10, and future X-ray observations may constrain possible changes in their period owing to orbital evolution. This model could make QPEs a viable candidate for the electromagnetic counterparts of so-called extreme-mass-ratio inspirals11-13, with considerable implications for multi-messenger astrophysics and cosmology14,15.

Dexamethasone and chronic postsurgical pain: the pendulum meets reductionistic thinking.

Reductionist thinking results in the bulk of anaesthesia trial designs being a single intervention to address what are in fact complex processes. The Perioperative Administration of Dexamethasone and Infection (PADDI) trial assessed the safety of a single preoperative dose of dexamethasone. Surprising to most, in the original report, a single dose of dexamethasone increased the incidence of the secondary outcome chronic postsurgical pain. Was this a chance finding or does dexamethasone increase chronic postsurgical pain? In an attempt to address this question, the PADDI investigators have now analysed this prespecified secondary outcome in two ways: as a substudy published earlier in this Journal, and as a retrospective analysis of the ENIGMA-II chronic pain database in this issue of the Journal. The PADDI investigators have now presented enough data to convince us that indeed a single dose of dexamethasone is safe and effective. However, the increase in chronic postsurgical pain seen in the original PADDI publication highlights the complexities, and the possible immunologic mechanisms, behind the genesis of chronic postsurgical pain. These publications from the PADDI group raise questions about other anti-inflammatory agents we use regularly for long-term postoperative pain management, and highlights the need for well-designed clinical trials to address this critically important patient-centred adverse functional outcome.

Significant and variable linear polarization during the prompt optical flash of GRB 160625B.

Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent-consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source. By contrast, optical and γ-ray observations during the prompt phase have led to discordant and often controversial results, and no definitive conclusions have been reached regarding the origin of the prompt radiation or the configuration of the magnetic field. Here we report the detection of substantial (8.3 ± 0.8 per cent from our most conservative simulation), variable linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt γ-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the jet, closer to its central black hole, and show that the prompt phase is produced via fast-cooling synchrotron radiation in a large-scale magnetic field that is advected from the black hole and distorted by dissipation processes within the jet.

What is in? What is out? Updating the British Society for Cutaneous Allergy facial series.

BACKGROUND: Allergic contact dermatitis (ACD) to cosmetics is widely reported. To ensure we are accurately diagnosing ACD, patch test series should be continually reviewed to identify relevant and emerging allergens and highlight those that are outdated. The current British Society for Cutaneous Allergy (BSCA) facial series recommends 26 allergens and was last modified in 2012. OBJECTIVES: To review and update the BSCA facial series. METHODS: We retrospectively reviewed the results from 12 UK and Ireland patch test centres' facial series from January 2016 to December 2017. We recorded the number of allergens tested in each centre and the detection rate for each allergen. Using a 0·3% positive rate as the inclusion threshold, we established which allergens in the BSCA facial series had positive patch test rates < 0·3% and > 0·3%. Allergens not in the BSCA facial series that had a positive patch test rate > 0·3% were identified. RESULTS: Overall, 4224 patients were patch tested to the facial series. The number of allergens included in individual centres' facial series ranged from 24 to 66, with a total of 103 allergens tested across all centres. Twelve of the 26 allergens in the BSCA facial series had a positive patch test rate < 0·3% and 14 had a rate > 0·3%. Twenty-five allergens not recommended in the BSCA facial series had a positive patch test rate > 0·3%. CONCLUSIONS: This audit has highlighted the significant variation in practice that exists among patch test centres, despite a recommended facial series. The BSCA facial series has been updated and now contains 24 allergens. Fifteen allergens remain, 11 allergens have been dropped and nine new allergens have been added.

Persistent Incisional Pain after Noncardiac Surgery: An International Prospective Cohort Study.

BACKGROUND: The purpose of this study was to determine the incidence, characteristics, impact, and risk factors associated with persistent incisional pain. The hypothesis was that patient demographics and perioperative interventions are associated with persistent pain. METHODS: This was a secondary analysis of an international prospective cohort study from 2012 to 2014. This study included patients who were 45 yr of age or older who underwent major inpatient noncardiac surgery. Data were collected perioperatively and at 1 yr after surgery to assess for the development of persistent incisional pain (pain present around incision at 1 yr after surgery). RESULTS: Among 14,831 patients, 495 (3.3%; 95% CI, 3.1 to 3.6) reported persistent incisional pain at 1 yr, with an average pain intensity of 3.6 ± 2.5 (0 to 10 numeric rating scale), with 35% and 14% reporting moderate and severe pain intensities, respectively. More than half of patients with persistent pain reported needing analgesic medications, and 85% reported interference with daily activities (denominator = 495 in the above proportions). Risk factors for persistent pain included female sex (P = 0.007), Asian ethnicity (P < 0.001), surgery for fracture (P < 0.001), history of chronic pain (P < 0.001), coronary artery disease (P < 0.001), history of tobacco use (P = 0.048), postoperative patient-controlled analgesia (P < 0.001), postoperative continuous nerve block (P = 0.010), insulin initiation within 24 h of surgery (P < 0.001), and withholding nonsteroidal anti-inflammatory medication or cyclooxygenase-2 inhibitors on the day of surgery (P = 0.029 and P < 0.001, respectively). Older age (P < 0.001), endoscopic surgery (P = 0.005), and South Asian (P < 0.001), Native American/Australian (P = 0.004), and Latin/Hispanic ethnicities (P < 0.001) were associated with a lower risk of persistent pain. CONCLUSIONS: Persistent incisional pain is a common complication of inpatient noncardiac surgery, occurring in approximately 1 in 30 adults. It results in significant morbidity, interferes with daily living, and is associated with persistent analgesic consumption. Certain demographics, ethnicities, and perioperative practices are associated with increased risk of persistent pain.

Physical and ecological isolation contribute to maintain genetic differentiation between fire salamander subspecies.

Landscape features shape patterns of gene flow among populations, ultimately determining where taxa lay along the continuum between panmixia to complete reproductive isolation. Gene flow can be restricted, leading to population differentiation in two non-exclusive ways: "physical isolation", in which geographic distance in combination with the landscape features restricts movement of individuals promoting genetic drift, and "ecological isolation", in which adaptive mechanisms constrain gene flow between different environments via divergent natural selection. In central Iberia, two fire salamander subspecies occur in parapatry across elevation gradients along the Iberian Central System mountains, while in the adjacent Montes de Toledo Region only one of them occurs. By integrating population and landscape genetic analyses, we show a ubiquitous role of physical isolation between and within mountain ranges, with unsuitable landscapes increasing differentiation between populations. However, across the Iberian Central System, we found strong support for a significant contribution of ecological isolation, with low genetic differentiation in environmentally homogeneous areas, but high differentiation across sharp transitions in precipitation seasonality. These patterns are consistent with a significant contribution of ecological isolation in restricting gene flow among subspecies. Overall, our results suggest that ecological divergence contributes to reduce genetic admixture, creating an opportunity for lineages to follow distinct evolutionary trajectories.

Efficacy of novel aqueous photo-chlorine dioxide against a human norovirus surrogate, bacteriophage MS2 and Clostridium difficile endospores, in suspension, on stainless steel and under greenhouse conditions.

AIMS: The efficacy of a novel photochemical method for generating chlorine dioxide (photoClO2 ) was evaluated against human noroviruses (HuNoV) surrogate, bacteriophage MS2, and Clostridium difficile endospores. METHODS AND RESULTS: Chlorine dioxide was generated by mixing 1% sodium chlorite with 10 parts-per-million (ppm) Eosin Y and irradiating with a photo-activator-excitable light. PhotoClO2 efficacy was assessed against bacteriophage MS2 and C. difficile endospores in suspension, on hard surfaces and greenhouse conditions under soiled and unsoiled conditions. The estimated effective photoClO2 produced and consumed was 20·39 ± 0·16 ppm at a rate of 8·16 ppm per min in a 1% sodium chlorite solution. In suspension, MS2 phage was reduced by 3·35 and >5·10 log10 PFU per ml in 120 and 90 min, with and without soil, respectively. At the same time, when dried on stainless steel surface, MS2 phage was reduced by >4·53 log10 PFU per carrier in 30 min under both conditions. On the other hand, C. difficile endospores in suspension were reduced by 2·26 and 3·65 log10 CFU per ml in 120 min with and without soiling, respectively. However, on stainless steel surface, maximal reductions of the C. difficile endospores were 0·8 and 1·5 log10 CFU per carrier with and without soiling, respectively, and a maximal reduction of 2·97 log10 CFU per carrier under greenhouse conditions at 24 h. CONCLUSIONS: Overall, photoClO2 showed promise as a technology to control HuNoV contamination on environmental surfaces but requires further optimization and testing against C. difficile endospores. SIGNIFICANCE AND IMPACT OF THE STUDY: Results from this investigation will serve as a model for how to generate and quantify photoClO2 and how to appropriately evaluate this new class of disinfectants against environmentally resilient pathogens: viruses and bacterial endospores.

Response to "understanding the behavioural determinants of opioid prescribing among family physicians: a qualitative study".

The 2017 Canadian opioid Guideline made both strong recommendations, indicating that all or almost all fully informed patients would choose the recommended course of action, and weak recommendations, in which different choices are appropriate for individual patients based on their values and preferences. The Guideline's recommendation to taper legacy patients prescribed high-dose opioid therapy is weak, and mandatory tapering is expressly discouraged.

Recommendation to include hydroxyethyl (meth)acrylate in the British baseline patch test series.

BACKGROUND: (Meth)acrylates are potent sensitizers and a common cause of allergic contact dermatitis (ACD). The frequency of (meth)acrylate ACD has increased with soaring demand for acrylic nails. A preliminary audit has suggested a significant rate of positive patch tests to (meth)acrylates using aimed testing in patients providing a clear history of exposure. To date, (meth)acrylates have not been routinely tested in the baseline patch test series in the U.K. and Europe. OBJECTIVES: To determine whether inclusion of 2-hydroxyethyl methacrylate (2-HEMA) 2% in petrolatum (pet.) in the baseline series detects cases of treatable (meth)acrylate ACD. METHODS: During 2016-2017, 15 U.K. dermatology centres included 2-HEMA in the extended baseline patch test series. Patients with a history of (meth)acrylate exposure, or who tested positive to 2-HEMA, were selectively tested with a short series of eight (meth)acrylate allergens. RESULTS: In total 5920 patients were consecutively patch tested with the baseline series, of whom 669 were also tested with the (meth)acrylate series. Overall, 102 of 5920 (1·7%) tested positive to 2-HEMA and 140 (2·4%) to at least one (meth)acrylate. Had 2-HEMA been excluded from the baseline series, (meth)acrylate allergy would have been missed in 36 of 5920 (0·6% of all patients). The top (meth)acrylates eliciting a positive reaction were 2-HEMA (n = 102, 1·7%), 2-hydroxypropyl methacrylate (n = 61, 1·0%) and 2-hydroxyethyl acrylate (n = 57, 1·0%). CONCLUSIONS: We recommend that 2-HEMA 2% pet. be added to the British baseline patch test series. We also suggest a standardized short (meth)acrylate series, which is likely to detect most cases of (meth)acrylate allergy.

Somatosensory rehabilitation for allodynia in complex regional pain syndrome of the upper limb: A retrospective cohort study.

STUDY DESIGN: Retrospective cohort study. INTRODUCTION: Somatosensory rehabilitation is a standardized method of evaluation and conservative treatment of painful disorders of vibrotactile sensation, including the mechanical allodynia and burning pain of complex regional pain syndrome (CRPS). PURPOSE OF THE STUDY: The purpose of this study was to examine the effectiveness of somatosensory rehabilitation for reducing allodynia in persons with CRPS of 1 upper limb in a retrospective consecutive cohort of patients. METHODS: An independent chart review of all client records (May 2004-August 2015) in the Somatosensory Rehabilitation Centre (Fribourg, Switzerland) identified 48 persons meeting the Budapest criteria for CRPS of 1 limb who had undergone assessment and treatment. Outcomes of interest were the French version of the McGill Pain Questionnaire (Questionnaire de la Douleur St-Antoine [QDSA]), total area of allodynia as recorded by mapping the area of skin where a 15-g monofilament was perceived as painful, and the allodynia threshold (minimum pressure required to elicit pain within the allodynic territory). RESULTS: This cohort was primarily women (70%), with a mean age of 45 years (range: 18-74). Mean duration of burning pain was 31 months (range: 1 week-27.5 years), and baseline QDSA core was 48. The average primary area of allodynia was 66 cm2 (range: 2.6-320), and the most common allodynia threshold was 4.0 g. The average duration of treatment was 81 days. At cessation of treatment, the average QDSA score was 20 (effect size Cohen's d = 1.64). Allodynia completely resolved in 27 persons (56% of the total sample where only 58% completed treatment). DISCUSSION: This uncontrolled retrospective study suggests that somatosensory rehabilitation may be an effective treatment with a large effect size for reducing the allodynia and painful sensations associated with CRPS of the upper limb. More work is in progress to provide estimates of reliability and validity for the measurement tools for allodynia employed by this method. LEVEL OF EVIDENCE: 2c.

Recommendation to test limonene hydroperoxides 0·3% and linalool hydroperoxides 1·0% in the British baseline patch test series.

BACKGROUND: There is a significant rate of sensitization worldwide to the oxidized fragrance terpenes limonene and linalool. Patch testing to oxidized terpenes is not routinely carried out; the ideal patch test concentration is unknown. OBJECTIVES: To determine the best test concentrations for limonene and linalool hydroperoxides, added to the British baseline patch test series, to optimize detection of true allergy and to minimize irritant reactions. METHODS: During 2013-2014, 4563 consecutive patients in 12 U.K. centres were tested to hydroperoxides of limonene in petrolatum (pet.) 0·3%, 0·2% and 0·1%, and hydroperoxides of linalool 1·0%, 0·5% and 0·25% pet. Irritant reactions were recorded separately from doubtful reactions. Concomitant reactions to other fragrance markers and clinical relevance were documented. RESULTS: Limonene hydroperoxide 0·3% gave positive reactions in 241 (5·3%) patients, irritant reactions in 93 (2·0%) and doubtful reactions in 110 (2·4%). Linalool hydroperoxide 1·0% gave positive reactions in 352 (7·7%), irritant reactions in 178 (3·9%) and doubtful reactions in 132 (2·9%). A total of 119 patients with crescendo reactions to 0·3% limonene would have been missed if only tested with 0·1% and 131 patients with crescendo reactions to 1·0% linalool would have been missed if only tested with 0·25%. In almost two-thirds of patients with positive patch tests to limonene and linalool the reaction was clinically relevant. The majority of patients did not react to any fragrance marker in the baseline series. CONCLUSIONS: We recommend that limonene hydroperoxides be tested at 0·3% and linalool hydroperoxides at 1·0% in the British baseline patch test series.

Stevens - Johnson Syndrome Induced by Combination of Lamotrigine and Valproic Acid in a 9-Year-Old Boy.

We describe the case history of a 9-year-old boy who developed Stevens-Johnson syndrome (SJS) following concomitant use of valproic acid and lamotrigine. He presented with rash and fever several weeks after introduction of lamotrigine, having been on valproic acid for seizure disorder. SJS happens to be one of the rare adverse reactions of antiepilepsy drugs (AED). Management is mainly supportive with care escalation when necessary because of the significant morbidity.