Spectroscopic identification of r-process nucleosynthesis in a double neutron-star merger.

The merger of two neutron stars is predicted to give rise to three major detectable phenomena: a short burst of γ-rays, a gravitational-wave signal, and a transient optical-near-infrared source powered by the synthesis of large amounts of very heavy elements via rapid neutron capture (the r-process). Such transients, named 'macronovae' or 'kilonovae', are believed to be centres of production of rare elements such as gold and platinum. The most compelling evidence so far for a kilonova was a very faint near-infrared rebrightening in the afterglow of a short γ-ray burst at redshift z = 0.356, although findings indicating bluer events have been reported. Here we report the spectral identification and describe the physical properties of a bright kilonova associated with the gravitational-wave source GW170817 and γ-ray burst GRB 170817A associated with a galaxy at a distance of 40 megaparsecs from Earth. Using a series of spectra from ground-based observatories covering the wavelength range from the ultraviolet to the near-infrared, we find that the kilonova is characterized by rapidly expanding ejecta with spectral features similar to those predicted by current models. The ejecta is optically thick early on, with a velocity of about 0.2 times light speed, and reaches a radius of about 50 astronomical units in only 1.5 days. As the ejecta expands, broad absorption-like lines appear on the spectral continuum, indicating atomic species produced by nucleosynthesis that occurs in the post-merger fast-moving dynamical ejecta and in two slower (0.05 times light speed) wind regions. Comparison with spectral models suggests that the merger ejected 0.03 to 0.05 solar masses of material, including high-opacity lanthanides.

Slowly fading super-luminous supernovae that are not pair-instability explosions.

Super-luminous supernovae that radiate more than 10(44) ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of (56)Ni are synthesized; this isotope decays to (56)Fe via (56)Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10(-6) times that of the core-collapse rate.

[An unusual pneumomediastinum case in a child caused by spontaneous bronchial rupture]. / Un insolito caso di pneumomediastino in un bambino da rottura spontanea di bronco.

We report a case of spontaneous pneumomediastinum (SPM) in a 3 year-old child, admitted to the emergency department because he presented dyspnea for a few hours, after a paroxysm of cough. The SPM is rare in children; the term "spontaneous" is reserved for cases of pneumomediastinum that haven't a traumatic cause. SPM is seen most commonly in asthmatics and in any patient who induces a Valsalva maneuver. The clinical diagnosis is confirmed by chest radiograph. When the diagnosis is uncertain, the chest CT scan is considered the gold standard of imaging tests, capable of detecting pneumomediastinum even in patients with small amounts of mediastinal air. In this case CT images showed the cause: spontaneous bronchial rupture. The direct sign of bronchial injury is the contiguity of the luminal air with that in the mediastinum. In the literature SPM cases are very rare, at least in health patients without tracheobronchial anomalies. The SPM is generally a benign entity that requires supportive care, and resolution occurs spontaneously, such as in our patient. In this article we want to explain the main clinical, diagnostic and therapeutic aspects of SPM, because, even if it's rare in children, it must be considered in the differential diagnosis of dyspnea; then we want to demonstrate as, in this case, a TC scan was important to identifying the SPM cause: a bronchial rupture.

[A sign of the changing times: neonatal scabies]. / Un segno dei tempi che cambiano: scabbia neonatale.

Scabies is an itchy-parasitic cutaneous infection; it can spread from person to person directly or through clothing, sheets or mattresses. The incidence had fallen a lot during the last ten years, but recently it is growing up again; this is due to immigration of people coming from countries where local hygienic and social conditions are very poor. In this contest it is more frequent to observe the infection in pediatric age, sometimes also newborn. In this particular case the diagnosis can be more difficult because the clinical manifestations are different from pathognomonic lesions we usually see in adult age. We report the clinical case of a newborn, 30-day-old, born in Italy from an Indian family. When the baby was admitted in our department she looked in good physical conditions but she presented a pustular dermatitis all over the body, scalp excluded. The presence in the mother of typical skin lesion and baby's eosinophilia at blood test, induced us to suspect the diagnosis of scabies. However, both the search for acarus at optical microscope on a skin sample obtained with "scarification" and clinical response to a treatment with PAF, were unsuccessful. Moreover, we found in the baby a persistent trombopenia; this fact induced us to think of other hypothesis. Finally the child's positive response to permethrina topical treatment and normalization of the number of platelets let us confirm the initial diagnosis of scabies.

A low-energy core-collapse supernova without a hydrogen envelope.

The final fate of massive stars depends on many factors. Theory suggests that some with initial masses greater than 25 to 30 solar masses end up as Wolf-Rayet stars, which are deficient in hydrogen in their outer layers because of mass loss through strong stellar winds. The most massive of these stars have cores which may form a black hole and theory predicts that the resulting explosion of some of them produces ejecta of low kinetic energy, a faint optical luminosity and a small mass fraction of radioactive nickel. An alternative origin for low-energy supernovae is the collapse of the oxygen-neon core of a star of 7-9 solar masses. No weak, hydrogen-deficient, core-collapse supernovae have hitherto been seen. Here we report that SN 2008ha is a faint hydrogen-poor supernova. We propose that other similar events have been observed but have been misclassified as peculiar thermonuclear supernovae (sometimes labelled SN 2002cx-like events). This discovery could link these faint supernovae to some long-duration gamma-ray bursts, because extremely faint, hydrogen-stripped core-collapse supernovae have been proposed to produce such long gamma-ray bursts, the afterglows of which do not show evidence of associated supernovae.

[Linear IgA bullous dermatosis: the importance of a correct differential diagnosis]. / Dermatosi bollosa a IgA lineari: l'importanza di una corretta diagnosi differenziale.

Linear IgA bullous dermatosis is an acquired subepidermal blistering disease which belongs to bullous autoimmune diseases, along with dermatitis herpetiformis and bullous pemphigoid. Inflammatory blisters are the main clinical characteristics and the areas of common involvement are: perioral region, abdomen, perineum, buttocks and the interior side of thighs. Essential for the diagnosis is to find by direct immunofluorescence the presence of a linear band of IgA antibodies at the level of the basement membrane. We present the case of a 5 year-old Moroccan girl which arrived at our First Aid Department for bullous dermatitis, localized mainly on the abdomen, legs and thighs. During a short stay in Morocco, a month before, the little girl was stung by an insect and developed bullous dermatitis by a residual lesion. The child was in a good state of health but blood exams showed an increase of total IgE antibodies. The girl was admitted and during her hospitalisation we made a skin biopsy which led to a diagnosis of linear IgA dermatosis. She began a steroid therapy and there was a progressive regression of the lesions. At present, she does not take medicines anymore, she feels well and is submitted to ambulatory medical follow-up.

A very faint core-collapse supernova in M85.

An anomalous transient in the early Hubble-type (S0) galaxy Messier 85 (M85) in the Virgo cluster was discovered by Kulkarni et al. on 7 January 2006 that had very low luminosity (peak absolute R-band magnitude M(R) of about -12) that was constant over more than 80 days, red colour and narrow spectral lines, which seem inconsistent with those observed in any known class of transient events. Kulkarni et al. suggest an exotic stellar merger as the possible origin. An alternative explanation is that the transient in M85 was a type II-plateau supernova of extremely low luminosity, exploding in a lenticular galaxy with residual star-forming activity. This intriguing transient might be the faintest supernova that has ever been discovered.

Detection of circumstellar material in a normal type Ia supernova.

Type Ia supernovae are important cosmological distance indicators. Each of these bright supernovae supposedly results from the thermonuclear explosion of a white dwarf star that, after accreting material from a companion star, exceeds some mass limit, but the true nature of the progenitor star system remains controversial. Here we report the spectroscopic detection of circumstellar material in a normal type Ia supernova explosion. The expansion velocities, densities, and dimensions of the circumstellar envelope indicate that this material was ejected from the progenitor system. In particular, the relatively low expansion velocities suggest that the white dwarf was accreting material from a companion star that was in the red-giant phase at the time of the explosion.

A giant outburst two years before the core-collapse of a massive star.

The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported (see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations.

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.

Is pressure dressing necessary after ear surgery?

Compressive bandages carry intrinsic risks and complications. The purpose of this study was to assess whether compressive head bandages are necessary after ear surgery to prevent complications such as hematoma or wound infection. A prospective, randomized, controlled study was conducted from August 1, 1993, to June 1, 1999. We randomly assigned 420 consecutive middle ear or mastoid operations to either a pressure bandage group or to a no-pressure bandage group. A careful follow-up was planned, and complications were recorded. In the pressure bandage group, 3 patients had bruising over the pinna and 70 patients had minor skin erythema when the dressing was removed. No patient had bruising or erythema in the no-pressure bandage group. No patient had hematoma, wound infection, or any other wound complication in either group. As a result of this study, we have decided to abandon the use of compression bandages after uncomplicated ear surgery.

The Properties of Supernova 1997cy Associated with GRB 970514.

The extraordinary SN 1997cy associated with GRB 970514 has been observed photometrically and spectroscopically for nearly 2 yr. At the time of discovery, SN 1997cy was the brightest supernova (SN) ever observed (MV