An X-ray view of Mrk 705: A borderline narrow-line Seyfert 1 galaxy

Mrk 705 exhibits optical properties of both narrow- and broad-line Seyfert 1 galaxies. We examine the X-ray properties of this borderline object utilising proprietary and public data from Chandra, ASCA, ROSAT and RXTE, spanning more than twelve years. Though long-term flux variability from the pointed observations appears rather modest (about 3 times), we do find examples of rare large amplitude outbursts in the RXTE monitoring data. There is very little evidence of long-term spectral variability as the low- and high-energy spectra appear constant with time. A 6.4 keV emission line is detected in the ASCA spectra of Mrk 705, but not during the later, higher flux state Chandra observation. However, the upper limit on the equivalent width of a line in the Chandra spectrum is consistent with a constant-flux emission line and a brighter continuum, suggesting that the line is emitted from distant material such as the putative torus. Overall, the X-ray properties of Mrk 705 appear typical of BLS1 activity.Comment: 7 pages, 7 figures. Accepted for publication in A&A (Research Note

The inelastic hard dimer gas: a non-spherical model for granular matter

We study a two-dimensional gas of inelastic smooth hard dimers. Since the collisions between dimers are dissipative, being characterized by a coefficient of restitution $\alpha<1$, and no external driving force is present, the energy of the system decreases in time and no stationary state is achieved. However, the resulting non equilibrium state of the system displays several interesting properties in close analogy with systems of inelastic hard spheres, whose relaxational dynamics has been thoroughly explored. We generalise to inelastic systems a recently method introduced [G.Ciccotti and G.Kalibaeva, J. Stat. Phys. {\bf 115}, 701 (2004)] to study the dynamics of rigid elastic bodies made up of different spheres hold together by rigid bonds. Each dimer consists of two hard disks of diameter $d$, whose centers are separated by a fixed distance $a$. By describing the rigid bonds by means of holonomic constraints and deriving the appropriate collision rules between dimers, we reduce the dynamics to a set of equations which can be solved by means of event driven simulation. After deriving the algorithm we study the decay of the total kinetic energy, and of the ratio between the rotational and the translational kinetic energy of inelastic dimers. We show numerically that the celebrated Haff's homogeneous cooling law $t^{-2}$, describing how the kinetic energy of an inelastic hard sphere system with constant coefficient of restitution decreases in time, holds even in the case of these non spherical particles. We fully characterize this homogeneous decay process in terms of appropriate decay constants and confirm numerically the scaling behavior of the velocity distributions.Comment: 21 pages, 6 figures and 2 tables, submitted to JC

XMM-Newton observation of the ULIRG NGC 6240: The physical nature of the complex Fe K line emission

We report on an XMM-Newton observation of the ultraluminous infrared galaxy NGC 6240. The 0.3-10 keV spectrum can be successfully modelled with: (i) three collisionally ionized plasma components with temperatures of about 0.7, 1.4, and 5.5 keV; (ii) a highly absorbed direct power-law component; and (iii) a neutral Fe K_alpha and K_beta line. We detect a significant neutral column density gradient which is correlated with the temperature of the three plasma components. Combining the XMM-Newton spectral model with the high spatial resolution Chandra image we find that the temperatures and the column densities increase towards the center. With high significance, the Fe K line complex is resolved into three distinct narrow lines: (i) the neutral Fe K_alpha line at 6.4 keV; (ii) an ionized line at about 6.7 keV; and (iii) a higher ionized line at 7.0 keV (a blend of the Fe XXVI and the Fe K_beta line). While the neutral Fe K line is most probably due to reflection from optically thick material, the Fe XXV and Fe XXVI emission arises from the highest temperature ionized plasma component. We have compared the plasma parameters of the ultraluminous infrared galaxy NGC 6240 with those found in the local starburst galaxy NGC 253. We find a striking similarity in the plasma temperatures and column density gradients, suggesting a similar underlying physical process at work in both galaxies.Comment: 8 pages including 9 figures. Accepted for publication in A&

Determinants of Sovereign Bond Yield Spreads in the EMU. An Optimal Currency Area Perspective

In the light of the recent financial crisis, we take a panel cointegration approach that allows for structural breaks to the analysis of the determinants of sovereign bond yield spreads in nine economies of the European Monetary Union. While we find evidence for a level break in the cointegrating relationship, we do not find empirical support for a regime shift and hence for a change in the pricing of the determinants of sovereign spreads. Moreover, results show that (i) fiscal imbalances (namely expected government debt-to-GDP differentials) are the main long-run drivers of sovereign spreads; (ii) liquidity risks and cumulated inflation differentials have non-negligible weights; but (iii) all conclusions are ultimately connected to whether or not the sample of countries is composed of members of an Optimal Currency Area (OCA). In particular, we establish (i) that results are overall driven by those countries not passing the OCA test; and (ii) that investors closely monitor and severely punish the deterioration of expected debt positions of those economies exhibiting significant gaps in competitiveness

Emovo Corpus: an Italian Emotional Speech Database

This article describes the first emotional corpus, named EMOVO, applicable to Italian language,. It is a database built from the voices of up to 6 actors who played 14 sentences simulating 6 emotional states (disgust, fear, anger, joy, surprise, sadness) plus the neutral state. These emotions are the well-known Big Six found in most of the literature related to emotional speech. The recordings were made with professional equipment in the Fondazione Ugo Bordoni laboratories. The paper also describes a subjective validation test of the corpus, based on emotion-discrimination of two sentences carried out by two different groups of 24 listeners. The test was successful because it yielded an overall recognition accuracy of 80%. It is observed that emotions less easy to recognize are joy and disgust, whereas the most easy to detect are anger, sadness and the neutral state

The warm absorber in NGC 5548: The lean years

We study the variability of the warm absorber and the gas responsible for the emission lines in the Seyfert 1 galaxy NGC 5548, in order to constrain the location and physical properties of these components. Using X-ray spectra taken with the \textit{Chandra}$-$LETGS in 2002 and 2005, we study variability in the ionic column densities and line intensities. We find a lower \ion{O}{vii} forbidden emission line flux in 2005, while the Fe K$\alpha$ line flux stays constant. The warm absorber is less ionized in 2005, allowing us to constrain its location to within 7 pc of the central source. Using both the observed variability and the limit on the FWHM of the \ion{O}{vii} f line, we have constrained the location of the narrow line region to a distance of 1 pc from the central source. The apparent lack of variability of the Fe K$\alpha$ line flux does not allow for a unique explanation.Comment: 6 pages, 6 figures, accepted by A&

Delbruck scattering and the g-factor of a bound electron

The leading contribution of the light-by-light scattering effects to g-factor of a bound electron is derived. The corresponding amplitude is expressed in terms of low-energy Delbruck scattering of a virtual photon. The result reads Delta g = (7/216) alpha (Z alpha)^5

Deterministic ratchets: route to diffusive transport

The rectification efficiency of an underdamped ratchet operated in the adiabatic regime increases according to a scaling current-amplitude curve as the damping constant approaches a critical threshold; below threshold the rectified signal becomes extremely irregular and eventually its time average drops to zero. Periodic (locked) and diffusive (fully chaotic) trajectories coexist on fine tuning the amplitude of the input signal. The transition from regular to chaotic transport in noiseless ratchets is studied numerically.Comment: 9 pages, 5 figures, to be published in Phys. Rev.

Progetto Terra più Sicura: i rischi geologici e la loro prevenzione spiegati agli studenti delle scuole secondarie di primo grado

L'associazione Geologia Senza Frontiere onlus (www.gsf.it) è nata nel 2003 dalla volontà di un gruppo di geologi, ambientalisti e naturalisti di dare una prospettiva comune alle competenze conseguite nell'ambito della ricerca universitaria, dell'attività professionale e della cooperazione. Durante l'anno scolastico 2013-2014 Geologia Senza Frontiere ha ideato e realizzato il progetto Terra più Sicura (TpS), volto all'insegnamento dei rischi geologici in scuole secondarie di primo grado di Lazio, Toscana e Veneto. Gli obiettivi del progetto sono stati in particolare l'avvicinamento di studenti ed insegnanti ai problemi della sicurezza del territorio, dei rischi in esso presenti, oltre a come prevenire ed affrontare in maniera consapevole e corretta le emergenze naturali

MySQL extension automatic porting to PDO for PHP migration and security improvement

In software management, the upgrade of programming languages may introduce critical issues. This is the case of PHP, the fifth version of which is going towards the end of the support. The new release improves on different aspects, but removes the old deprecated MySQL extensions, and supports only the newer library of functions for the connection to the databases. The software systems already in place need to be renewed to be compliant with respect to the new language version. The conversion of the source code, to be safe against injection attacks, should involve also the transformation of the query code. The purpose of this work is the design of specific tool that automatically applies the required transformation yielding to a precise and efficient conversion procedure. The tool has been applied to different projects to provide evidence of its effectiveness