A WC/WO star exploding within an expanding carbon-oxygen-neon nebula

The final fate of massive stars, and the nature of the compact remnants they leave behind (black holes and neutron stars), are open questions in astrophysics. Many massive stars are stripped of their outer hydrogen envelopes as they evolve. Such Wolf-Rayet stars¹ emit strong and rapidly expanding winds with speeds greater than 1,000 kilometres per second. A fraction of this population is also helium-depleted, with spectra dominated by highly ionized emission lines of carbon and oxygen (types WC/WO). Evidence indicates that the most commonly observed supernova explosions that lack hydrogen and helium (types Ib/Ic) cannot result from massive WC/WO stars^2,3, leading some to suggest that most such stars collapse directly into black holes without a visible supernova explosion⁴. Here we report observations of SN 2019hgp, beginning about a day after the explosion. Its short rise time and rapid decline place it among an emerging population of rapidly evolving transients^5-8. Spectroscopy reveals a rich set of emission lines indicating that the explosion occurred within a nebula composed of carbon, oxygen and neon. Narrow absorption features show that this material is expanding at high velocities (greater than 1,500 kilometres per second), requiring a compact progenitor. Our observations are consistent with an explosion of a massive WC/WO star, and suggest that massive Wolf-Rayet stars may be the progenitors of some rapidly evolving transients.

Cosmological Constraints from Multiple Probes in the Dark Energy Survey

The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy clustering. Here we present combined results from these probes, deriving constraints on the equation of state, w, of dark energy and its energy density in the Universe. Independently of other experiments, such as those that measure the cosmic microwave background, the probes from this single photometric survey rule out a Universe with no dark energy, finding w=-0.80_{-0.11}^{+0.09}. The geometry is shown to be consistent with a spatially flat Universe, and we obtain a constraint on the baryon density of Ω_{b}=0.069_{-0.012}^{+0.009} that is independent of early Universe measurements. These results demonstrate the potential power of large multiprobe photometric surveys and pave the way for order of magnitude advances in our constraints on properties of dark energy and cosmology over the next decade.

Early spectra of the gravitational wave source GW170817: Evolution of a neutron star merger

On 17 August 2017, Swope Supernova Survey 2017a (SSS17a) was discovered as the optical counterpart of the binary neutron star gravitational wave event GW170817. We report time-series spectroscopy of SSS17a from 11.75 hours until 8.5 days after the merger. Over the first hour of observations, the ejecta rapidly expanded and cooled. Applying blackbody fits to the spectra, we measured the photosphere cooling from [Formula: see text] to [Formula: see text] kelvin, and determined a photospheric velocity of roughly 30% of the speed of light. The spectra of SSS17a began displaying broad features after 1.46 days and evolved qualitatively over each subsequent day, with distinct blue (early-time) and red (late-time) components. The late-time component is consistent with theoretical models of r-process-enriched neutron star ejecta, whereas the blue component requires high-velocity, lanthanide-free material.

Light curves of the neutron star merger GW170817/SSS17a: Implications for r-process nucleosynthesis

On 17 August 2017, gravitational waves (GWs) were detected from a binary neutron star merger, GW170817, along with a coincident short gamma-ray burst, GRB 170817A. An optical transient source, Swope Supernova Survey 17a (SSS17a), was subsequently identified as the counterpart of this event. We present ultraviolet, optical, and infrared light curves of SSS17a extending from 10.9 hours to 18 days postmerger. We constrain the radioactively powered transient resulting from the ejection of neutron-rich material. The fast rise of the light curves, subsequent decay, and rapid color evolution are consistent with multiple ejecta components of differing lanthanide abundance. The late-time light curve indicates that SSS17a produced at least ~0.05 solar masses of heavy elements, demonstrating that neutron star mergers play a role in rapid neutron capture (r-process) nucleosynthesis in the universe.

Swope Supernova Survey 2017a (SSS17a), the optical counterpart to a gravitational wave source

On 17 August 2017, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo interferometer detected gravitational waves (GWs) emanating from a binary neutron star merger, GW170817. Nearly simultaneously, the Fermi and INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) telescopes detected a gamma-ray transient, GRB 170817A. At 10.9 hours after the GW trigger, we discovered a transient and fading optical source, Swope Supernova Survey 2017a (SSS17a), coincident with GW170817. SSS17a is located in NGC 4993, an S0 galaxy at a distance of 40 megaparsecs. The precise location of GW170817 provides an opportunity to probe the nature of these cataclysmic events by combining electromagnetic and GW observations.

Electromagnetic evidence that SSS17a is the result of a binary neutron star merger

Eleven hours after the detection of gravitational wave source GW170817 by the Laser Interferometer Gravitational-Wave Observatory and Virgo Interferometers, an associated optical transient, SSS17a, was identified in the galaxy NGC 4993. Although the gravitational wave data indicate that GW170817 is consistent with the merger of two compact objects, the electromagnetic observations provide independent constraints on the nature of that system. We synthesize the optical to near-infrared photometry and spectroscopy of SSS17a collected by the One-Meter Two-Hemisphere collaboration, finding that SSS17a is unlike other known transients. The source is best described by theoretical models of a kilonova consisting of radioactive elements produced by rapid neutron capture (the r-process). We conclude that SSS17a was the result of a binary neutron star merger, reinforcing the gravitational wave result.

Light echoes reveal an unexpectedly cool η Carinae during its nineteenth-century Great Eruption

η Carinae is one of the most massive binary stars in the Milky Way. It became the second-brightest star in our sky during its mid-nineteenth-century 'Great Eruption', but then faded from view (with only naked-eye estimates of brightness). Its eruption is unique in that it exceeded the Eddington luminosity limit for ten years. Because it is only 2.3 kiloparsecs away, spatially resolved studies of the nebula have constrained the ejected mass and velocity, indicating that during its nineteenth-century eruption, η Car ejected more than ten solar masses in an event that released ten per cent of the energy of a typical core-collapse supernova, without destroying the star. Here we report observations of light echoes of η Carinae from the 1838-1858 Great Eruption. Spectra of these light echoes show only absorption lines, which are blueshifted by -210 km s(-1), in good agreement with predicted expansion speeds. The light-echo spectra correlate best with those of G2-to-G5 supergiants, which have effective temperatures of around 5,000 kelvin. In contrast to the class of extragalactic outbursts assumed to be analogues of the Great Eruption of η Carinae, the effective temperature of its outburst is significantly lower than that allowed by standard opaque wind models. This indicates that other physical mechanisms such as an energetic blast wave may have triggered and influenced the eruption.

An optical supernova associated with the X-ray flash XRF 060218

Long-duration gamma-ray bursts (GRBs) are associated with type Ic supernovae that are more luminous than average and that eject material at very high velocities. Less-luminous supernovae were not hitherto known to be associated with GRBs, and therefore GRB-supernovae were thought to be rare events. Whether X-ray flashes--analogues of GRBs, but with lower luminosities and fewer gamma-rays--can also be associated with supernovae, and whether they are intrinsically 'weak' events or typical GRBs viewed off the axis of the burst, is unclear. Here we report the optical discovery and follow-up observations of the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218. Supernova 2006aj is intrinsically less luminous than the GRB-supernovae, but more luminous than many supernovae not accompanied by a GRB. The ejecta velocities derived from our spectra are intermediate between these two groups, which is consistent with the weakness of both the GRB output and the supernova radio flux. Our data, combined with radio and X-ray observations, suggest that XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB observed off-axis. This extends the GRB-supernova connection to X-ray flashes and fainter supernovae, implying a common origin. Events such as XRF 060218 are probably more numerous than GRB-supernovae.

The impact of nutritional depletion in chronic obstructive pulmonary disease

Nutritional depletion is prevalent in patients with advanced chronic obstructive pulmonary disease (COPD). These nutritional abnormalities are pronounced in patients with the "emphysematous" form of COPD on chronic corticosteroid therapy. The pathophysiologic mechanisms for the involuntary weight loss appear to be multifactorial. Clinical research has revealed that nutritional depletion in advanced COPD is associated with an increased morbidity and mortality. This review will address the implications of nutritional depletion in addition to potential therapeutic options.

Laparoscopy in the diagnosis and management of Crohn's disease

We have tried to evaluate the role of laparoscopy and laparoscopic-assisted surgery in the management of Crohn's disease. Over a 4-year period, we had 38 patients, of which 23 patients were suspected to have Crohn's disease and were admitted for diagnostic laparoscopy while 15 patients had already had a biopsy confirmation of Crohn's disease in the past and were admitted for specifically planned procedures. In the first group of 23 patients, 11 were found not to have Crohn's disease. In the remaining 12 patients, three were proven to have Crohn's disease, but no surgical procedure was undertaken. The remaining nine patients underwent laparoscopic-assisted procedures, of which two required conversion to a laparotomy because of intra-abdominal abscesses. All 15 patients in the second group underwent laparoscopic or laparoscopic-assisted procedures. In total, 14 patients were spared a potential diagnostic laparotomy and could go home the next day. The remaining 24 patients underwent procedures requiring longer hospital stays; five had a purely laparoscopic procedure, 17 had a laparoscopic-assisted procedure, and two required a laparotomy. Although there was little difference in the median stay for patients treated laparoscopically or by laparotomy, it is thought that the extent or severity of the disease process influenced the length of the stay rather than the approach used. The complication rate was similar to that found in Crohn's patients undergoing open surgery. It remains to be seen whether those in the laparoscopically treated group have less adhesive complications than those treated by laparotomy. It is our belief that laparoscopy is a valuable aid in the diagnosis of Crohn's disease. It remains to be proven whether or not laparoscopic-assisted surgery will be of significant value in the treatment of this condition.

Use of a laparoscopic trocar for percutaneous introduction of drains into intra-abdominal abscesses

Drainage of an intra-abdominal abscess is a difficult problem. Laparotomy with open drainage, although effective, carries a certain morbidity and mortality rate. Percutaneous drainage using one of the various pigtail catheters is often ineffective, especially when there is debris within the abscess. These catheters tend to become blocked unless they are flushed regularly owing to a smaller lumen1. A method is described for introducing a wide-bore Robinson drain under ultrasonographic guidance using local anaesthesia.

Day case laparoscopic cholecystectomy: a safe and cost effective procedure

OBJECTIVE

To evaluate the safety and cost effectiveness of laparoscopic cholecystectomy as a day case procedure.

SETTING

District hospital, England.

SUBJECTS

103 patients undergoing laparoscopic cholecystectomy.

INTERVENTIONS

Laparoscopic cholecystectomy by a standard four cannula technique. Propofol anaesthesia, prophylactic antiemetics and pre-emptive analgesia were given in all cases.

MAIN OUTCOME MEASURES

Morbidity and cost.

RESULTS

103 patients have undergone laparoscopic cholecystectomy, 51 of them as day cases. Patients were selected for day treatment if they were under 60 years old, they wanted to go home the same day, they had no history of jaundice or any anaesthetic contraindication, and if there was an adult at home to look after them. Three of those selected as day cases required overnight admission, one because of severe pain and two who required a drain overnight. The median hospital stay was 12 hours (range 10-28 hours) and the cost of the operation was about pounds 419.

CONCLUSION

This is a safe and cost-effective procedure and should be considered in selected patients.

Nephrotoxicity from nonsteroidal anti-inflammatory drugs

We categorize the three types of renal dysfunction associated with the use of nonsteroidal anti-inflammatory drugs (NSAID): acute renal failure, acute interstitial nephritis, and hyperkalemia. The paper provides clinical examples of each type, discusses pathophysiology, and describes response to therapy, in addition to outlining the usefulness of labeled leukocyte nuclear studies and kidney biopsy. We conclude that these drugs are relatively common causes of renal dysfunction, particularly in selected subpopulations.

Acute anaphylactoid reactions in hemodialysis

Our recent experience with membrane reactions in three hemodialysis patients is reported. We believe that two distinct populations manifest this reaction. First, well-known chronic hemodialysis patients may be exposed to inadequately rinsed new membranes. The etiology may be related to ethylene oxide either as a direct toxin or as a hapten attached to serum proteins. Adequate attention to dialysis membrane priming should eliminate this particular reaction. In the second group, the patients are new to the unit (transients) and frequently arrive with little information on prior care. Two of our patients and at least one other in the literature demonstrate markedly elevated IgE levels. This suggests an IgE-mediated mechanism; whether this is related to the membrane type, ethylene oxide, or a currently undetermined allergen remains uncertain.

Hyperthyroidism in end-stage renal disease

We report the 2nd patient to have hyperthyroidism while on maintenance hemodialysis. This case is instructive because the diagnosis of hyperthyroidism in uremic patients is difficult due to similar signs and symptoms. This case report describes, for the first time, the unique interaction between hemodialysis and thyrotoxic heart disease. Paroxysmal atrial fibrillation and severe hypotension interfered with all hemodialyses. Only the correction of the hyperthyroid state and withdrawal of all beta-blocking agents allowed resumption of normal hemodialysis. The delayed gastric emptying and hypercalcemia ultimately resolved with return to the euthyroid state and did not recur during 10 months of follow-up.

Serum potassium concentrations in cyclosporine- and azathioprine-treated renal transplant patients

Hyperkalemia was commonly observed in successful renal transplant patients treated with cyclosporine and prednisone. At 1, 3 and 6 months after transplantation, 13 of 50, 9 of 50, and 5 of 50 patients, respectively, had serum concentrations of potassium greater than 5 mEq/1. This contrasts with the finding of hyperkalemia in only 1 of 13 comparable patients treated with azathioprine and prednisone. Mean serum concentrations of potassium at these dates were significantly higher in cyclosporine-treated patients than azathioprine-treated patients. The 2 patient groups had similar mean serum concentrations of chloride, bicarbonate and creatinine, and mean creatinine clearances at 1 and 3 months. Exposure to diuretic agents and antihypertensive agents was similar in the 2 groups. Serum concentrations of electrolytes and renal function data in hyperkalemic and normokalemic transplant patients receiving cyclosporine were similar. These observations suggest an association between cyclosporine administration and hyperkalemia in renal transplant recipients.

Amphetamine-induced acute renal failure

A 32-year-old man had acute renal failure after ingesting amphetamines. The renal biopsy findings indicated acute interstitial nephritis. In contrast to other reports, which indicate an association between coexisting rhabdomyolysis, hyperpyrexia, or necrotizing angiitis and acute renal failure in amphetamine abusers, our case suggests that amphetamine alone may cause acute renal injury.