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Aims. Variability at all observed wavelengths is a distinctive property of active galactic nuclei (AGN). Hard X-rays provide us with a view of the innermost regions of AGN, mostly unbiased by absorption along the line of sight. Characterizing the intrinsic hard X-ray variability of a large AGN sample and comparing it to the results obtained at lower X-ray energies can significantly contribute to our understanding of the mechanisms underlying the high-energy radiation. Methods. Swift/BAT provides us with the unique opportunity to follow, on time scales of days to years and with regular sampling, the 14-195 keV emission of the largest AGN sample available up to date for this kind of investigation. As a continuation of an early work using the first 9 months of BAT data, we study the amplitude of the variations and their dependence on subclass and on energy, for a sample of 110 radio quiet and radio loud AGN selected from the BAT 58-month survey. Results. About 80% of the AGN in the sample are found to exhibit significant variability on month-to-year time scales. In particular, radio loud sources are the most variable, and Seyfert 1.5-2 galaxies are slightly more variable than Seyfert 1, while absorbed and unabsorbed objects show similar timing properties. The amplitude of the variations and their energy dependence are incompatible with variability being driven at hard X-rays by changes in the absorption column density. In general, the variations in the 14-24 and 35-100 keV bands are correlated well, suggesting a common origin to the variability across the BAT energy band. However, radio quiet AGN display on average 10% larger variations at 14-24 keV than at 35-100 keV, and a softer-when-brighter behavior for most of the Seyfert galaxies with detectable spectral variability on a time scale of a month. In addition, sources with harder spectra are found to be more variable than softer ones, unlike what it is observed below 10 keV. These properties are generally consistent with a variable, in flux and shape, power law continuum, pivoting at energies ≳50 keV, to which a constant reflection component is superposed. When the same time scales are considered, the timing properties of AGN at hard X-rays are comparable to those at lower energies, with at least some of the differences possibly ascribable to components contributing differently in the two energy domains (e.g., reflection, absorption). [ABSTRACT FROM AUTHOR]

ABSTRACT SGR 1833−0832 was discovered on 2010 March 19, thanks to the Swift detection of a short hard X-ray burst and follow-up X-ray observations. Since then, it was repeatedly observed with Swift, Rossi X-ray Timing Explorer and XMM-Newton. Using these data, which span about 225 d, we studied the long-term spectral and timing characteristics of SGR 1833−0832. We found evidence for diffuse emission surrounding SGR 1833−0832, which is most likely a halo produced by the scattering of the point-source X-ray radiation by dust along the line of sight, and we show that the source X-ray spectrum is well described by an absorbed blackbody, with temperature kT∼ 1.2 keV and absorbing column NH= (10.4 ± 0.2) × 1022 cm−2, while different or more complex models are disfavoured. The source persistent X-ray emission remained fairly constant at ∼3.7 × 10−12 erg cm−2 s−1 for the first ∼20 d after the onset of the bursting episode, then it faded by a factor of ∼40 in the subsequent ∼140 d, following a power-law trend with index α≃−0.5. We obtained a phase-coherent timing solution with the longest baseline (∼225 d) to date for this source which, besides period P= 7.565 4084(4) s and period derivative s s−1, includes higher order period derivatives. We also report on our search of the counterpart to the soft gamma-ray repeater (SGR) at radio frequencies using the Australia Telescope Compact Array and the Parkes Radio Telescope. No evidence for radio emission was found, down to flux densities of 0.9 mJy (at 1.5 GHz) and 0.09 mJy (at 1.4 GHz) for the continuum and pulsed emissions, respectively, consistently with other observations at different epochs. Finally, the analysis of the field of PSR B1830−08 (J1833−0827), which was serendipitously imaged by the XMM-Newton observations, led to the discovery of the X-ray pulsar wind nebula generated by this 85-ms radio pulsar. We discuss its possible association with the unidentified TeV source HESS J1834−087. [ABSTRACT FROM AUTHOR]

Professional soccer players are susceptible to amyotrophic lateral sclerosis. Strenuous physical activity has been associated with persistent inflammatory conditions and elevation of systemic cytokine levels, which could contribute to the vulnerability of these athletes. To investigate changes induced by playing soccer in the systemic profiles of growth factors and of the principal cytokines involved in the inflammatory response, we compared the serum concentrations of these factors in Italian professional soccer players and sedentary subjects. We also investigated the effects of the sera on primary cultured motor neurons in relation to their cytokine and growth factor content. Serum concentrations of cytokines and growth factors were measured by a biochip array analyzer. Neurotoxicity of sera was assessed by immunocytochemical assays in primary motor neuron cultures from mouse embryos. Circulating levels of interleukin-8, tumor necrosis factor-alpha and interleukin-4 were lower in soccer players than controls. However, the viability of primary cultured mouse motor neurons treated with sera from the two groups did not differ significantly. Vascular endothelial growth factor (VEGF) independently emerged as a systemic protective factor for motor neurons. We found significant alterations in circulating pro-inflammatory cytokines in Italian professional soccer players, showing an unbalanced inflammatory condition in these subjects. VEGF was a protective serum factor affecting motor neuron survival. [ABSTRACT FROM AUTHOR]

Purpose. To provide a translation and cultural adaptation of the Spinal Cord Independence Measure version III scale for Italy (i-SCIM3) and to validate this version of the scale. Method. i-SCIM3 was developed involving a forward-backward translation and administered to patients with spinal cord lesions (SCL) admitted to two centers. Two raters for each center evaluated patients at admission and discharge. Psychometric testing included reliability by internal consistency (Cronbach's alpha) and test-retest reliability. The validity of i-SCIM3 was assessed by comparing it with the Italian version of Functional Independence Measure (FIM). Results. One hundred three adult patients with SCL (84 males) with a mean age of 50.33 +/- 15.35 years were recruited. Seventy-four patients were paraplegic and 29 patients were tetraplegic. The median time elapsed between the two evaluations was 77.5 days (interquartile range, 53-144 days). Internal consistency, inter-rater reliability, and test-retest reliability were satisfactory overall, showing values higher than 0.90. The validity of i-SCIM3 was confirmed by the close correlation with FIM results both at admission and discharge (r = 0.91, p < 0.01). The sensitivity to change of i-SCIM3 was similar to that of FIM. Conclusion. i-SCIM3 was found to be a consistent, reliable, and valid scale for use in the clinical setting. It is the first validated scale in Italian for patients with SCL. [ABSTRACT FROM AUTHOR]

Emission of two short hard X-ray bursts on 2009 June 5 disclosed the existence of a new soft gamma-ray repeater, now catalogued as SGR 0418+5729. After a few days, X-ray pulsations at a period of 9.1 s were discovered in its persistent emission. SGR 0418+5729 was monitored almost since its discovery with the Rossi X-ray Timing Explorer (2–10 keV energy range) and observed many times with Swift (0.2–10 keV). The source persistent X-ray emission faded by a factor of ∼10 in about 160 d, with a steepening in the decay about 19 d after the activation. The X-ray spectrum is well described by a simple absorbed blackbody, with a temperature decreasing in time. A phase-coherent timing solution over the ∼160 d time-span yielded no evidence for any significant evolution of the spin period, implying a 3σ upper limit of on the period derivative and of on the surface dipole magnetic field. Phase-resolved spectroscopy provided evidence for a significant variation of the spectrum as a function of the stellar rotation, pointing to the presence of two emitting caps, one of which became hotter during the outburst. Finally, a deep observation of the field of SGR 0418+5729 with the new Gran Telescopio Canarias 10.4-m telescope allowed us to set an upper limit on the source optical flux of , corresponding to an X-ray-to-optical flux ratio exceeding , consistent with the characteristics of other magnetars. [ABSTRACT FROM AUTHOR]

Using Chandra data taken in 2008 June, we detected pulsations at 2.594 39(4) s in the soft gamma-ray repeater SGR 41. This is the second measurement of the source spin period and allows us to derive for the first time a long-term spin-down rate of . From this value, we infer for SGR 41 a characteristic age of ∼2.2 kyr, a spin-down luminosity of (one of the highest among sources of the same class), and a surface dipole magnetic field strength of G. These properties confirm the magnetar nature of SGR 41; however, they should be considered with caution since they were derived on the basis of a period derivative measurement made using two epochs only, and magnetar spin-down rates are generally highly variable. The pulse profile, double-peaked and with a pulsed fraction of per cent in the 2–10 keV range, closely resembles that observed by XMM–Newton in 2008 September. Having for the first time a timing model for this soft gamma-ray repeater (SGR), we also searched for a pulsed signal in archival radio data collected with the Parkes radio telescope 9 months after the previous X-ray outburst. No evidence for radio pulsations was found, down to a luminosity level ∼10–20 times fainter (for a 10 per cent duty cycle and a distance of 11 kpc) than the peak luminosity shown by the known radio magnetars. [ABSTRACT FROM AUTHOR]