We report on the quiescent state of the Soft Gamma Repeater SGR 0501+4516 observed by XMM-Newton on 2009 August 30. The source exhibits an absorbed flux ~75 times lower than that measured at the peak ...of the 2008 outburst, and a rather soft spectrum, with the same value of the blackbody temperature observed with ROSAT back in 1992. This new observation is put into the context of all existing X-ray data since its discovery in August 2008, allowing us to complete the study of the timing and spectral evolution of the source from outburst until its quiescent state. The set of deep XMM-Newton observations performed during the few-years timescale of its outburst allows us to monitor the spectral characteristics of this magnetar as a function of its rotational period, and their evolution along these years. After the first ~10 days, the initially hot and bright surface spot progressively cooled down during the decay. We discuss the behaviour of this magnetar in the context of its simulated secular evolution, inferring a plausible dipolar field at birth of 3x10^14 G, and a current (magneto-thermal) age of ~10 kyr.
The influence of age on plasma growth hormone (HGH) and cortisol response to i.v. insulin (0.1 U/kg of body weight) was evaluated in 32 healthy subjects whose ages ranged between 20 and 84 years. A ...significant reduction in HGH response to insulin was observed with aging. In the young (20-34 years), middel-aged (35-49 years), and elderly (53-84 years) groups, average HGH peaks were 46.51 +/- 7.37, 29.95 +/- 5.35, and 14.31 +/- 2.39 ng/ml while average HGH areas were 2.911 +/- 0.484, 1.654 +/- 0.316, and 0.699 +/- 0.149 mug-min, respectively. Since insulin's hypoglycemic effect became less rapid with aging, this could, in part, explain the progressive decline in the HGH response to insulin. This phenomen may also be attributed to histological changes occurring in the pituitary with aging. Moreover, cortisol response was similar to all three age groups. These findings suggest that, while HGH response to insulin is correlated with age, adrenal response does not show any important modifications with aging.
HD49798/RXJ0648.0-4418 is the only known X-ray binary composed of a hot subdwarf and a massive white dwarf (M=1.28+/-0.05 Msun). This system, with an orbital period of 1.55 days, is the outcome of a ...common envelope evolution, most likely of a pair of stars with initial masses of about 8-10 Msun. When the hot subdwarf, currently in a He-burning phase, will expand again and fill its Roche-lobe, the enhanced mass transfer can rapidly bring the already massive white dwarf above the Chandrasekhar limit. The possible final fate, either a Type Ia supernova explosion or an accretion induced collapse, is particularly interesting in view of the high rotational velocity of this star, which has the shortest spin period (13 s) observed in a white dwarf.
Local-Group galaxies provide access to samples of X-ray source populations of whole galaxies. The XMM-Newton survey of the Small Magellanic Cloud (SMC) completely covers the bar and eastern wing with ...a 5.6 deg^2 area in the (0.2-12.0) keV band. To characterise the X-ray sources in the SMC field, we created a catalogue of point sources and sources with moderate extent. Sources with high extent (>40") have been presented in a companion paper. We searched for point sources in the EPIC images using sliding-box and maximum-likelihood techniques and classified the sources using hardness ratios, X-ray variability, and their multi-wavelength properties. The catalogue comprises 3053 unique X-ray sources with a median position uncertainty of 1.3" down to a flux limit for point sources of ~10^-14 erg cm^-2 s^-1 in the (0.2-4.5) keV band, corresponding to 5x10^33 erg s^-1 for sources in the SMC. We discuss statistical properties, like the spatial distribution, X-ray colour diagrams, luminosity functions, and time variability. We identified 49 SMC high-mass X-ray binaries (HMXB), four super-soft X-ray sources (SSS), 34 foreground stars, and 72 active galactic nuclei (AGN) behind the SMC. In addition, we found candidates for SMC HMXBs (45) and faint SSSs (8) as well as AGN (2092) and galaxy clusters (13). We present the most up-to-date catalogue of the X-ray source population in the SMC field. In particular, the known population of X-ray binaries is greatly increased. We find that the bright-end slope of the luminosity function of Be/X-ray binaries significantly deviates from the expected universal high-mass X-ray binary luminosity function.
Relationships among natriuresis, atrial natriuretic peptide and insulin in insulin-dependent diabetes. Insulin-dependent diabetic patients have a large exchangeable body sodium pool, secondary to ...sodium retention. The pathogenesis of impaired natriuresis in insulin dependent diabetes remains to be elucidated. The present study examines the role of hyperinsulinemia, impaired atrial natriuretic release, and resistance to atrial natriuretic peptide action in determining sodium retention in normotensive and hypertensive insulin-dependent diabetic patients. Eight insulin-dependent diabetic patients had significantly higher daily sodium excretion rate (147 ± 16mmol/day; mean ± SE) during conventional insulin treatment (daily plasma glucose: 11.6 ± 1.2 mmol/liter; daily plasma insulin: 27 ± 3 μU/ml) than during intensified insulin treatment (daily sodium excretion rate: 91 ± 12, P < 0.01; daily plasma glucose: 6.8 ± 0.7, P < 0.01; daily plasma insulin: 44 ± 4, P < 0.01). Daily sodium excretion rate was also significantly lower (107 ± 13, P < 0.01) in the same diabetic patients during intensified insulin treatment along with hyperglycemic clamp (daily plasma glucose: 12.8 ± 0.3, NS; plasma insulin 48 ± 4, P < 0.01). Seven control subjects had lower extracellular liquid volume than eight insulin-dependent diabetic patients (11.0 ± 0.8 1/ 1.73m2 vs. 14.8 ± 0.9, P < 0.05) and also had baseline plasma atrial natriuretic peptide concentrations (18 ± 5 pg/ml vs. 37 ± 4, P < 0.05). Atrial natriuretic peptide response to saline challenge was blunted in insulin-dependent diabetic patients when saline was administered on the basis of body surface area (90mmol/1.73 m2 · 90 min) but not when administered on the basis of extracellular liquid volume (ECV) (8.2 mmol/liter ECV · 90 min). Continuous infusion of atrial natriuretic peptide in the same control and diabetic subjects (0.06 µg/kg min · 120 min) resulted in similar circulating concentrations of the hormone but in significantly lower sodium excretion rate in diabetic (from 185 ± 19 to 193 ± 21 µmol/1.73m2 · min) than in control subjects (199 ± 14 to 341 ± 22, P < 0.01). Natriuretic action of atrial natriuretic peptide was similarly impaired in a group of eighteen hypertensive insulin-dependent diabetic patients in comparison with a matched group of seven hypertensive control patients. Angiotensin converting enzyme inhibitor treatment in these hypertensive diabetic patients decreased extracellular liquid volume and improved natriuretic response to atrial natriuretic peptide. We conclude that refractoriness to natriuretic action rather than impaired release of atrial natriuretic peptide can further deteriorate sodium retention in insulin dependent diabetes. This altered hormonal behavior could be primarily due to insulin-induced sodium retention and extracellular liquid volume expansion.
Long-duration gamma-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterised by an initial phase of bright and highly ...variable radiation in the keV-MeV band that is likely produced within the jet and lasts from milliseconds to minutes, known as the prompt emission. Subsequently, the interaction of the jet with the external medium generates external shock waves, responsible for the afterglow emission, which lasts from days to months, and occurs over a broad energy range, from the radio to the GeV bands. The afterglow emission is generally well explained as synchrotron radiation by electrons accelerated at the external shock. Recently, an intense, long-lasting emission between 0.2 and 1 TeV was observed from the GRB 190114C. Here we present the results of our multi-frequency observational campaign of GRB~190114C, and study the evolution in time of the GRB emission across 17 orders of magnitude in energy, from \(5\times10^{-6}\) up to \(10^{12}\)\,eV. We find that the broadband spectral energy distribution is double-peaked, with the TeV emission constituting a distinct spectral component that has power comparable to the synchrotron component. This component is associated with the afterglow, and is satisfactorily explained by inverse Compton upscattering of synchrotron photons by high-energy electrons. We find that the conditions required to account for the observed TeV component are not atypical, supporting the possibility that inverse Compton emission is commonly produced in GRBs.
The effects of two different plasma glucose concentrations (5 and 10 mmol/L) on lipolysis and ketogenesis during baseline and in response to epinephrine infusion were evaluated in insulin-dependent ...diabetic patients. Each insulin-dependent diabetic subject was studied during euglycemia, hyperglycemia with hypoinsulinemia, and hyperglycemia with hyperinsulinemia. Total ketone body (TKB) concentrations were significantly higher in hyperglycemic-hypoinsulinemic diabetics than in hyperglycemic-hyperinsulinemic and normoglycemic diabetics. Hyperglycemic-hyperinsulinemics had higher TKB concentrations than euglycemic diabetics. During epinephrine infusion, the ketone body rate of appearance and concentration significantly increased in all groups. Plasma FFA concentrations were significantly higher in hyperglycemic-hypoinsulinemic diabetics than in the other groups. During epinephrine infusion, the plasma FFA rate of appearance and concentration significantly increased in all groups. The apparent fraction of FFA converted to ketones was increased by epinephrine in all groups, except in hyperglycemic-hyperinsulinemic diabetics. In conclusion, this study demonstrates that although insulin alone decreases FFA and TKB concentrations, it does not affect the fraction of FFA converted to ketones. If hyperinsulinemia is superimposed on hyperglycemia, there is both a reduction of ketogenesis capacity, compared to hyperglycemia alone, and a decrease in the apparent fraction of FFA converted to ketone bodies.
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