Contemporary endovascular management of splenic vascular pathologies.

The spleen is a commonly injured organ and the splenic vasculature is also susceptible to inflammation and trauma, often resulting in aneurysm formation. Splenic artery aneurysms carry a high risk of rupture and are associated with high mortality and morbidity. Due to the advances in endovascular techniques and devices, endovascular management of splenic vascular pathologies is now considered a first-line strategy. Endovascular embolisation and advance techniques including balloon- or stent-assisted coil embolisation enables minimally invasive management option while preserving splenic function.

Relativistic jet activity from the tidal disruption of a star by a massive black hole.

Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events.

A gamma-ray burst at a redshift of z approximately 8.2.

Long-duration gamma-ray bursts (GRBs) are thought to result from the explosions of certain massive stars, and some are bright enough that they should be observable out to redshifts of z > 20 using current technology. Hitherto, the highest redshift measured for any object was z = 6.96, for a Lyman-alpha emitting galaxy. Here we report that GRB 090423 lies at a redshift of z approximately 8.2, implying that massive stars were being produced and dying as GRBs approximately 630 Myr after the Big Bang. The burst also pinpoints the location of its host galaxy.

Presence and absence of non-native fish species in the Wet Tropics region, Australia.

Distributional records of non-native fish species were identified in the Wet Tropics region, Far North Queensland, Australia, through a compilation of published records and expert knowledge. A total of 1106 records were identified comprising 346 presence and four uncertain records for at least 13 species, and 756 absence records. All current presence records consist of six species from the families Cichlidae and Poeciliidae with established self-sustaining populations in the region, probably affecting the highly diverse native fish fauna.

An extremely luminous X-ray outburst at the birth of a supernova.

Massive stars end their short lives in spectacular explosions--supernovae--that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their 'delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion. As a result, the progenitors of some supernovae and the events leading up to their violent demise remain intensely debated. Here we report the serendipitous discovery of a supernova at the time of the explosion, marked by an extremely luminous X-ray outburst. We attribute the outburst to the 'break-out' of the supernova shock wave from the progenitor star, and show that the inferred rate of such events agrees with that of all core-collapse supernovae. We predict that future wide-field X-ray surveys will catch each year hundreds of supernovae in the act of exploding.

Relativistic ejecta from X-ray flash XRF 060218 and the rate of cosmic explosions.

Over the past decade, long-duration gamma-ray bursts (GRBs)--including the subclass of X-ray flashes (XRFs)--have been revealed to be a rare variety of type Ibc supernova. Although all these events result from the death of massive stars, the electromagnetic luminosities of GRBs and XRFs exceed those of ordinary type Ibc supernovae by many orders of magnitude. The essential physical process that causes a dying star to produce a GRB or XRF, and not just a supernova, is still unknown. Here we report radio and X-ray observations of XRF 060218 (associated with supernova SN 2006aj), the second-nearest GRB identified until now. We show that this event is a hundred times less energetic but ten times more common than cosmological GRBs. Moreover, it is distinguished from ordinary type Ibc supernovae by the presence of 10(48) erg coupled to mildly relativistic ejecta, along with a central engine (an accretion-fed, rapidly rotating compact source) that produces X-rays for weeks after the explosion. This suggests that the production of relativistic ejecta is the key physical distinction between GRBs or XRFs and ordinary supernovae, while the nature of the central engine (black hole or magnetar) may distinguish typical bursts from low-luminosity, spherical events like XRF 060218.

Gamma-ray bursts: huge explosion in the early Universe.

Long gamma-ray bursts (GRBs) are bright flashes of high-energy photons that can last for tens of minutes; they are generally associated with galaxies that have a high rate of star formation and probably arise from the collapsing cores of massive stars, which produce highly relativistic jets (collapsar model). Here we describe gamma- and X-ray observations of the most distant GRB ever observed (GRB 050904): its redshift (z) of 6.29 means that this explosion happened 12.8 billion years ago, corresponding to a time when the Universe was just 890 million years old, close to the reionization era. This means that not only did stars form in this short period of time after the Big Bang, but also that enough time had elapsed for them to evolve and collapse into black holes.

The association of GRB 060218 with a supernova and the evolution of the shock wave.

Although the link between long gamma-ray bursts (GRBs) and supernovae has been established, hitherto there have been no observations of the beginning of a supernova explosion and its intimate link to a GRB. In particular, we do not know how the jet that defines a gamma-ray burst emerges from the star's surface, nor how a GRB progenitor explodes. Here we report observations of the relatively nearby GRB 060218 (ref. 5) and its connection to supernova SN 2006aj (ref. 6). In addition to the classical non-thermal emission, GRB 060218 shows a thermal component in its X-ray spectrum, which cools and shifts into the optical/ultraviolet band as time passes. We interpret these features as arising from the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the progenitor. We have caught a supernova in the act of exploding, directly observing the shock break-out, which indicates that the GRB progenitor was a Wolf-Rayet star.

An unexpectedly rapid decline in the X-ray afterglow emission of long gamma-ray bursts.

'Long' gamma-ray bursts (GRBs) are commonly accepted to originate in the explosion of particularly massive stars, which give rise to highly relativistic jets. Inhomogeneities in the expanding flow result in internal shock waves that are believed to produce the gamma-rays we see. As the jet travels further outward into the surrounding circumstellar medium, 'external' shocks create the afterglow emission seen in the X-ray, optical and radio bands. Here we report observations of the early phases of the X-ray emission of five GRBs. Their X-ray light curves are characterised by a surprisingly rapid fall-off for the first few hundred seconds, followed by a less rapid decline lasting several hours. This steep decline, together with detailed spectral properties of two particular bursts, shows that violent shock interactions take place in the early jet outflows.

An origin for short gamma-ray bursts unassociated with current star formation.

Two short (< 2 s) gamma-ray bursts (GRBs) have recently been localized and fading afterglow counterparts detected. The combination of these two results left unclear the nature of the host galaxies of the bursts, because one was a star-forming dwarf, while the other was probably an elliptical galaxy. Here we report the X-ray localization of a short burst (GRB 050724) with unusual gamma-ray and X-ray properties. The X-ray afterglow lies off the centre of an elliptical galaxy at a redshift of z = 0.258 (ref. 5), coincident with the position determined by ground-based optical and radio observations. The low level of star formation typical for elliptical galaxies makes it unlikely that the burst originated in a supernova explosion. A supernova origin was also ruled out for GRB 050709 (refs 3, 31), even though that burst took place in a galaxy with current star formation. The isotropic energy for the short bursts is 2-3 orders of magnitude lower than that for the long bursts. Our results therefore suggest that an alternative source of bursts--the coalescence of binary systems of neutron stars or a neutron star-black hole pair--are the progenitors of short bursts.

A short gamma-ray burst apparently associated with an elliptical galaxy at redshift z = 0.225.

Gamma-ray bursts (GRBs) come in two classes: long (> 2 s), soft-spectrum bursts and short, hard events. Most progress has been made on understanding the long GRBs, which are typically observed at high redshift (z approximately 1) and found in subluminous star-forming host galaxies. They are likely to be produced in core-collapse explosions of massive stars. In contrast, no short GRB had been accurately (< 10'') and rapidly (minutes) located. Here we report the detection of the X-ray afterglow from--and the localization of--the short burst GRB 050509B. Its position on the sky is near a luminous, non-star-forming elliptical galaxy at a redshift of 0.225, which is the location one would expect if the origin of this GRB is through the merger of neutron-star or black-hole binaries. The X-ray afterglow was weak and faded below the detection limit within a few hours; no optical afterglow was detected to stringent limits, explaining the past difficulty in localizing short GRBs.

Trophic ecology of northern Australia's terapontids: ontogenetic dietary shifts and feeding classification.

The diets of 21 terapontid species from freshwater environments in northern Australia were investigated to determine the similarity and dissimilarity among species and the extent of any ontogenetic shifts. Distinct ontogenetic dietary shifts occurred in all species for which sufficient data were available, with many species passing through several discrete trophic categories during their life histories. Diets of all juvenile terapontids were similar, mainly comprising aquatic insects and zooplankton. Larger size classes of terapontids diverged into a broad spectrum of feeding groups comprising carnivorous dietary modes (including piscivory and lepidophagy), omnivory (including frugivory and consumption of allochthonous prey), herbivory and detritivory. The results indicate that the terapontids represent Australia's most trophically diverse freshwater fish family.

Imaging epilepsy in larval zebrafish.

Our understanding of the genetic aetiology of paediatric epilepsies has grown substantially over the last decade. However, in order to translate improved diagnostics to personalised treatments, there is an urgent need to link molecular pathophysiology in epilepsy to whole-brain dynamics in seizures. Zebrafish have emerged as a promising new animal model for epileptic seizure disorders, with particular relevance for genetic and developmental epilepsies. As a novel model organism for epilepsy research they combine key advantages: the small size of larval zebrafish allows high throughput in vivo experiments; the availability of advanced genetic tools allows targeted modification to model specific human genetic disorders (including genetic epilepsies) in a vertebrate system; and optical access to the entire central nervous system has provided the basis for advanced microscopy technologies to image structure and function in the intact larval zebrafish brain. There is a growing body of literature describing and characterising features of epileptic seizures and epilepsy in larval zebrafish. Recently genetically encoded calcium indicators have been used to investigate the neurobiological basis of these seizures with light microscopy. This approach offers a unique window into the multiscale dynamics of epileptic seizures, capturing both whole-brain dynamics and single-cell behaviour concurrently. At the same time, linking observations made using calcium imaging in the larval zebrafish brain back to an understanding of epileptic seizures largely derived from cortical electrophysiological recordings in human patients and mammalian animal models is non-trivial. In this review we briefly illustrate the state of the art of epilepsy research in zebrafish with particular focus on calcium imaging of epileptic seizures in the larval zebrafish. We illustrate the utility of a dynamic systems perspective on the epileptic brain for providing a principled approach to linking observations across species and identifying those features of brain dynamics that are most relevant to epilepsy. In the following section we survey the literature for imaging features associated with epilepsy and epileptic seizures and link these to observations made from humans and other more traditional animal models. We conclude by identifying the key challenges still facing epilepsy research in the larval zebrafish and indicate strategies for future research to address these and integrate more directly with the themes and questions that emerge from investigating epilepsy in other model systems and human patients.

Memory retrieval from long and short lists.

Reaction time in Sternberg's memory retrieval task with both short and long lists is a bilinear function of list length, changing slope at the limits of memory span. Separate long-term and short-term retrieval processes are implied. An alternative one-process model expressed by a logarithmic function is also considered.

Investigational piscivory of some juvenile Australian freshwater fishes by the introduced Mozambique tilapia Oreochromis mossambicus.

Experimental tanks were used to observe predatory effects in three different size classes of Mozambique tilapia Oreochromis mossambicus (one of the world's most widespread exotic species and generally regarded to be a herbivore or both herbivore and detritivore) when tested against 10 juvenile Australian freshwater fish species, and significant levels of predation against all were recorded. There was a general trend for larger O. mossambicus to kill more prey and this was also reflected in a separate series of experiments using juvenile barramundi Lates calcarifer over a range of size classes. Predatory effects by O. mossambicus broadly reflected the accepted models of predator-prey interactions, being that mortality (and survival) was closely related to relative body size and mouth gape limitation. Experimental evidence for piscivory in O. mossambicus was supported by field sampling that detected prey fish remains in 16% of all fish surveyed (n = 176). The recognition of active piscivory by O. mossambicus in laboratory and field situations is the first such evidence, and suggests a need to re-evaluate the nature of their effects in introduced environments.

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova.

With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. A complete picture of compact object mergers, however, requires the detection of an electromagnetic (EM) counterpart. We report ultraviolet (UV) and x-ray observations by Swift and the Nuclear Spectroscopic Telescope Array of the EM counterpart of the binary neutron star merger GW170817. The bright, rapidly fading UV emission indicates a high mass (≈0.03 solar masses) wind-driven outflow with moderate electron fraction (Ye ≈ 0.27). Combined with the x-ray limits, we favor an observer viewing angle of ≈30° away from the orbital rotation axis, which avoids both obscuration from the heaviest elements in the orbital plane and a direct view of any ultrarelativistic, highly collimated ejecta (a γ-ray burst afterglow).

A pseudo-outbreak of purified protein derivative skin-test conversions caused by inappropriate testing materials.

OBJECTIVE: To investigate a cluster of newly identified tuberculosis infections. DESIGN: A field study was conducted including interviews; medical record reviews; checking of bills and invoices, pharmacy records, and drug manufacturer information; and clinical retesting. SETTING: Community residential facilities providing comprehensive services to retarded adults. PARTICIPANTS: Twenty residential facility staff (not previously known to be purified protein derivative [PPD] positive). RESULTS: Staff had been tested with 250 TU of PPD, and 9 of 20 were tuberculin positive. Retesting with 5 TU yielded no reaction. CONCLUSIONS: Reactions were attributable to testing with a product not recommended for routine PPD screening. Healthcare workers planting PPD Mantoux tests always should check the vials to ensure that the appropriate strength solution is being used.

Successful twin pregnancy after renal transplant maintained on cyclosporine A immunosuppression.

Cyclosporine A has recently been reported to be an effective immunosuppressant agent for use in renal allograft recipients. Questions have been raised regarding its effects during pregnancy, in light of an increased life span and return of fertility in renal transplant patients. A preterm delivery is reported in a cadaveric renal allograft recipient chronically immunosuppressed with cyclosporine A and methylprednisolone. Dizygotic twins were delivered at 35 weeks' gestation, weighing 2452 and 2386 g. Maternal cyclosporine A levels were determined weekly by whole blood radioimmunoassay, with little increase in requirement found before delivery. No indication of maternal renal compromise was apparent, as evidenced by stable weekly creatinine clearance studies. Cyclosporine A, at the doses used, was passed transplacentally, with cord blood values of 34 and 57% of the maternal cyclosporine A level found at delivery. No adverse effects were noted at birth in the average for gestational age neonates, nor at nine-month follow-up evaluation. Given careful monitoring, cyclosporine A may be an effective immunosuppressant agent for use in pregnancies complicated by renal transplantation.

Induction of periodic breathing during sleep causes upper airway obstruction in humans.

To test the hypothesis that occlusive apneas result from sleep-induced periodic breathing in association with some degree of upper airway compromise, periodic breathing was induced during non-rapid-eye-movement (NREM) sleep by administering hypoxic gas mixtures with and without applied external inspiratory resistance (9 cmH2O X l-1 X s) in five normal male volunteers. In addition to standard polysomnography for sleep staging and respiratory pattern monitoring, esophageal pressure, tidal volume (VT), and airflow were measured via an esophageal catheter and pneumotachograph, respectively, with the latter attached to a tight-fitting face mask, allowing calculation of total pulmonary system resistance (Rp). During stage I/II NREM sleep minimal period breathing was evident in two of the subjects; however, in four subjects during hypoxia and/or relief from hypoxia, with and without added resistance, pronounced periodic breathing developed with waxing and waning of VT, sometimes with apneic phases. Resistive loading without hypoxia did not cause periodicity. At the nadir of periodic changes in VT, Rp was usually at its highest and there was a significant linear relationship between Rp and 1/VT, indicating the development of obstructive hypopneas. In one subject without added resistance and in the same subject and in another during resistive loading, upper airway obstruction at the nadir of the periodic fluctuations in VT was observed. We conclude that periodic breathing resulting in periodic diminution of upper airway muscle activity is associated with increased upper airway resistance that predisposes upper airways to collapse.

T-cell subset assay. A useful differentiating marker of atopic and seborrheic eczema in infancy?

To confirm T-cell changes previously reported in atopic eczema, to compare T-cell subset values in atopic and seborrheic infants, and to determine whether T-cell subset assay would be a useful differentiating marker between atopic and seborrheic infants, three age- and sex-matched groups of normal, seborrheic, and atopic infants were recruited. T-cell subset values, total serum IgE, and serum IgE to specific allergens (Dermatophagoides pteronyssimus, cat epithelium, dog dander, rye grass, egg white, and milk) were measured. The results showed that total and allergen-specific IgE levels were higher in atopic disease in infancy, but no statistical differences in T-cell subset values between seborrheic and atopic infants were found. T-cell subset values are therefore not a reliable differentiating marker between atopic and seborrheic eczema in infancy.