Two classes of rotating neutron stars-soft γ-ray repeaters (SGRs) and anomalous X-ray pulsars-are magnetars, whose X-ray emission is powered by a very strong magnetic field (B 1015 G). SGRs ...occasionally become 'active', producing many short X-ray bursts. Extremely rarely, an SGR emits a giant flare with a total energy about a thousand times higher than in a typical burst. Here we report that SGR 1806-20 emitted a giant flare on 27 December 2004. The total (isotropic) flare energy is 2 × 1046 erg, which is about a hundred times higher than the other two previously observed giant flares. The energy release probably occurred during a catastrophic reconfiguration of the neutron star's magnetic field. If the event had occurred at a larger distance, but within 40 megaparsecs, it would have resembled a short, hard γ-ray burst, suggesting that flares from extragalactic SGRs may form a subclass of such bursts.
ABSTRACT V404 Cygni was discovered in 1989 by the Ginga X-ray satellite during its only previously observed X-ray outburst and soon after confirmed as a black hole binary. On 2015 June 15, the ...Gamma-ray Burst Monitor (GBM) triggered on a new outburst of V404 Cygni. We present 13 days of GBM observations of this outburst, including Earth occultation flux measurements and spectral and temporal analysis. The Earth occultation fluxes reached 30 Crab with detected emission to 100 keV and determined, via hardness ratios, that the source was in a hard state. At high luminosity, spectral analysis between 8 and 300 keV showed that the electron temperature decreased with increasing luminosity. This is expected if the protons and electrons are in thermal equilibrium during an outburst with the electrons cooled by the Compton scattering of softer seed photons from the disk. However, the implied seed photon temperatures are unusually high, suggesting a contribution from another source, such as the jet. No evidence of state transitions is seen during this time period. The temporal analysis reveals power spectra that can be modeled with two or three strong, broad Lorentzians, similar to the power spectra of black hole binaries in their hard state.
Abstract Stress and genetic predisposition are two of the major risk factors for a variety of psychiatric illnesses. Inbred mouse strains are considered useful tools in dissecting the genetic basis ...of complex disorders. Indeed, mice of the C57BL/6 and BALB/c strains, differing markedly in anxiety behaviours, are among the most widely used in psychopharmacological research. However, there is a paucity of studies investigating the impact of social stress in these two strains. Moreover, whether these two mouse strains exhibit different sensitivities to chronic social defeat stress remains poorly studied. Thus in this study we compared the impact of repeated (10 days) social defeat stress on a variety of behavioural and endocrine parameters including social interaction, locomotor activity, plasma corticosterone, body weight and stress-related physiological parameters in both mouse strains. Given that the duration of stress exposure may differentially affect such responses we also compared stressors of short (Social Defeat-Short; SD-S) and of long (Social Defeat-Long; SD-L) duration. Our results show that although mice from both strains were defeated in both social defeat paradigms, only BALB/c mice displayed social interaction impairments following SD-S, whereas both strains were behaviourally sensitive to SD-L. Moreover, both strains also differed in some of the physiological alterations induced by social defeat stress. Specifically, SD-S did not induce any change in corticosterone levels in either of the two strains, whereas SD-L was able to induce significant changes in C57BL/6 mice only. SD-S induced differential effects on bodyweight gain in both strains, increasing it in C57BL/6 and decreasing it in BALB/c mice, whereas SD-L had no effect. On the other hand, exposure to SD-S resulted in cardiac hypertrophy in C57BL/6 mice and SD-L induced spleen hypertrophy and thymus atrophy in BALB/c mice in addition to decreasing faecal output. Overall, the innately anxious BALB/c mice were more sensitive to social stress than C57BL/6, with differential behavioural and physiological alterations emerging as a function of stress severity. These data suggest different coping strategies to social interaction stress between the two mouse strains. The genetic basis of this stress-resilience/susceptibility warrants further investigation.
This study aimed to assess the foodborne diseases (FBD) outbreaks reported in Brazil between 2000 and 2018, based on data from the Brazilian Ministry of Health (official data) and from scientific ...literature. According to official data, 13,163 FBD outbreaks were reported in the country during this period, involving 247,570 cases and 195 deaths. The largest prevalence of FBD outbreaks was observed in the Southeast region of Brazil (45.6%). In most outbreaks it was not possible to determine the food implicated (45.9%) but among those identified, water was the most frequently associated (12.0%). The etiological agent was not identified in most outbreaks (38.0%), while Salmonella (14.4%) was the most frequently reported among those identified. Homes were the main site of FBD occurrence (12.5%). Regarding data obtained from the scientific literature, 57 articles dealing with FBD in the country throughout the same period were selected and analyzed. Based on these articles, mixed foods were the most prevalent in the outbreaks (31.6%), Salmonella spp. was the pathogen most frequently reported (22.8%) and homes were also the main site of FBD occurrence (45.6%). Despite under-notification, the records of FBD outbreaks that have occurred in Brazil in the past recent years show alarming data, requiring attention from health authorities. The notification of outbreaks is essential to facilitate public health actions.
The Enhanced Resolution Imager and Spectrograph (ERIS) is an instrument that both extends and enhances the fundamental diffraction limited imaging and spectroscopy capability for the VLT. It replaces ...two instruments that were being maintained beyond their operational lifetimes, combines their functionality on a single focus, provides a new wavefront sensing module for natural and laser guide stars that makes use of the Adaptive Optics Facility, and considerably improves on their performance. The observational modes ERIS provides are integral field spectroscopy at 1–2.5 μm, imaging at 1–5 μm with several options for high-contrast imaging, and long-slit spectroscopy at 3–4 μm. The instrument is installed at the Cassegrain focus of UT4 at the VLT and, following its commissioning during 2022, has been made available to the community.
ABSTRACT The Fermi Gamma-ray Burst Monitor (GBM) is an all-sky gamma-ray monitor well known in the gamma-ray burst (GRB) community. Although GBM excels in detecting the hard, bright extragalactic ...GRBs, its sensitivity above 8 keV and its all-sky view make it an excellent instrument for the detection of rare, short-lived Galactic transients. In 2010 March, we initiated a systematic search for transients using GBM data. We conclude this phase of the search by presenting a three-year catalog of 1084 X-ray bursts. Using spectral analysis, location, and spatial distributions we classified the 1084 events into 752 thermonuclear X-ray bursts, 267 transient events from accretion flares and X-ray pulses, and 65 untriggered gamma-ray bursts. All thermonuclear bursts have peak blackbody temperatures broadly consistent with photospheric radius expansion (PRE) bursts. We find an average rate of 1.4 PRE bursts per day, integrated over all Galactic bursters within about 10 kpc. These include 33 and 10 bursts from the ultra-compact X-ray binaries 4U 0614+09 and 2S 0918-549, respectively. We discuss these recurrence times and estimate the total mass ejected by PRE bursts in our Galaxy.
After about 18 yr of steadily spinning down, the accretion-powered pulsar 4U 1626-67 experienced a new torque reversal at the beginning of 2008. For the present study, we have used all available ...Fermi/Gamma-ray Burst Monitor data since its launch in 2008 June 11 and over 5 yr of hard X-ray Swift/Burst Alert Telescope observations (starting from 2004 October up to the present time). From 2004 up to the end of 2007 the spin-down rate averaged at a mean rate of Hz s-1 until the torque reversal reported here. This second detected torque reversal was centered near MJD 54500 (2008 February 4) and it lasted approximately 150 days. During the reversal, the source also underwent an increase in flux by a fraction of ~2.5. Since then it has been following a steady spin-up at a mean rate of Hz s-1. We present a detailed long-term timing analysis of this source and a long-term spectral hardness ratio study in order to see whether there are spectral changes around this new observed torque reversal.
Aims. In this Letter we present results from INTEGRAL and RXTE observations of the spectral and timing behavior of the High Mass X-ray Binary A 0535+26 during its August/September 2005 normal (type ...I) outburst with an average flux $F_{(5-100)}\,_{\mathrm{keV}} \sim400$ mCrab. The search for cyclotron resonance scattering features (fundamental and harmonic) is one major focus of the paper. Methods. Our analysis is based on data from INTEGRAL and RXTE Target of Opportunity Observations performed during the outburst. The pulse period is determined. X-ray pulse profiles in different energy ranges are analyzed. The broad band INTEGRAL and RXTE pulse phase averaged X-ray spectra are studied. The evolution of the fundamental cyclotron line at different luminosities is analyzed. Results.The pulse period P is measured to be 103.39315(5) s at MJD 53614.5137. Two absorption features are detected in the phase averaged spectra at $E_{1}\sim 45$ keV and $E_{2}\sim 100$ keV. These can be interpreted as the fundamental cyclotron resonance scattering feature and its first harmonic and therefore the magnetic field can be estimated to be $B\sim 4\times 10^{12}$ G.
We have discovered four X-ray bursts, recorded with the Rossi X-ray Timing Explorer Proportional Counter Array between 2003 September and 2004 April, that we show to originate from the transient ...magnetar candidate XTE J1810-197. The burst morphologies consist of a short spike or multiple spikes lasting 61 s each, followed by extended tails of emission where the pulsed flux from XTE J1810-197 is significantly higher. The burst spikes are likely correlated with the pulse maxima, having a chance probability of a random phase distribution of 0.4%. The burst spectra are best fitted to a blackbody with temperatures 4-8 keV, considerably harder than the persistent X-ray emission. During the X-ray tails following these bursts, the temperature rapidly cools as the flux declines, maintaining a constant emitting radius after the initial burst peak. During the brightest X-ray tail, we detect a narrow emission line at 12.6 keV, with an equivalent width of 1.4 keV and a probability of chance occurrence of less than 4 x 10 super(-6). The temporal and spectral characteristics of these bursts closely resemble the bursts seen from 1E 1048.1-5937 and a subset of the bursts detected from 1E 2259+586, thus establishing XTE J1810-197 as a magnetar candidate. The bursts detected from these three objects are sufficiently similar to one another, yet significantly different from those seen from soft gamma repeaters, that they likely represent a new class of bursts from magnetar candidates exclusive (thus far) to the anomalous X-ray pulsar-like sources.
To describe the occurrence of discrete arcs of increased fundus autofluorescence (FAF) associated with various retinal dystrophies and to assess their functional significance by fundus-controlled ...microperimetry.
Seven patients, three with pigmented paravenous retinochoroidal atrophy (PPRCA), one with sector retinitis pigmentosa (RP), one with typical RP, and two with macular dystrophy were assessed by retinal imaging including FAF imaging. Serial images were obtained within a review period of 6 and 10 years in a patient with PPRCA and macular dystrophy, respectively. Fundus-controlled microperimetry was performed in eight eyes of five patients to determine light increment sensitivity.
A discrete arched line of increased FAF was observed without obvious correlate on fundus biomicroscopy. The orientation of this line differed from ring shape in RP and macular dystrophy, a semi-circle structure in sector RP to crescent shape with tiplike extensions towards branching retinal veins in PPRCA. Longitudinal investigation revealed slight migration of the arc in PPRCA and peripheral extension of the ring diameter in macular dystrophy. Microperimetry revealed that the arc of increased FAF sharply delineated areas of severely impaired retinal sensitivity.
The findings indicate that arcs of increased FAF in PPRCA and other retinal dystrophies demarcate areas of impaired retinal function and may migrate over time. FAF imaging may therefore reveal the exact extent of neurosensory dysfunction that may exceed the dimensions anticipated by conventional examinations.
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