Red-channel (6000-8000 {\AA}) nuclear spectra of 376 local galaxies

We obtained long-slit optical spectra of the nuclear regions of 376 galaxies in the local Universe using the 1.5m Cassini telescope of Bologna Observatory. Of these spectra, 164 were either never taken before by the Sloan Digital Sky Survey (SDSS), or given by the Nasa Extragalactic Database (NED). With these new spectra, we contribute investigating the occurrence of active galactic nuclei (AGNs). Nevertheless, we stress that the present sample is by no means complete, thus, it cannot be used to perform any demographic study. Following the method presented in Gavazzi et al. (2011), we classify the nuclear spectra using a six bin scheme: SEY (Seyfert), sAGN (strong AGN), and wAGN (weak AGN) represent active galactic nuclei of different levels of activity; HII accounts for star-forming nuclei; RET (retired) and PAS (passive) refer to nuclei with poor or no star-formation activity. The spectral classification is performed using the ratio of 6584 {\lambda} [NII] to H{\alpha} lines and the equivalent width (EW) of H{\alpha} versus [NII]/H{\alpha} (WHAN diagnostic introduced by Cid Fernandes and collaborators) after correcting H{\alpha} for underlying absorption. The obtained spectra are made available in machine readable format via the Strasbourg Astronomical Data Center (CDS) and NED.Comment: 8 pages, 6 Figures, 4 Tables, accepted for publication in Astronomy & Astrophysic

CONFRONTO NUMERICO E SPERIMENTALE TRA LA VERSIONE RIVETTATA E INCOLLATA DI UNA GIUNZIONE MECCANICA

Le giunzioni metalliche incollate offrono diversi vantaggi nei confronti dei tradizionali collegamenti meccanici (rivettatura, bullonatura, ecc.), tuttavia richiedono un’estensiva caratterizzazione meccanica al fine di garantire un’adeguata affidabilità delle strutture in cui vengono inserite. In questo lavoro si presentano i risultati delle prove sperimentali e delle simulazioni numeriche condotte nell’ambito della riprogettazione di una giunzione rivettata di un componente reale, sfruttando la tecnologia dell’incollaggio. L’adesivo usato è una resina epossidica bicomponente, caratterizzata attraverso una campagna di prove sperimentali e simulazioni numeriche, su provini di tipo single-lap e T-peel. Si presenta quindi un confronto, sia numerico che sperimentale, delle prestazioni meccaniche della giunzione rivettata con l’analoga giunzione incollata. I risultati hanno evidenziato un sostanziale miglioramento in termini di rigidezza e resistenza con l’uso della tecnica dell’incollaggio

Numerical simulations of an explosion confined inside a cylindrical pipe made of aluminium alloy Al6061-T6

Simulation of the behaviour of structural components subjected to high explosive detonation is one of the current challenges in the field of numerical simulation. Along with experimental tests, numerical analysis is necessary to give an in-depth insight of this event, as well to reduce costs for some further experimental tests. High values of strain rate, temperature and pressure, together with failure phenomenon, govern the complex interaction between the explosion and the structure involved. In a scenario of this type, capabilities and performance of the numerical software used are crucial to the quality and the outcome of the simulation. Besides the simulation itself, this paper provides a comparison between different finite element programs such as ABAQUS, AUTODYN and LS-DYNA in an explosion event. In the event descibed in the paper, the behaviour of tube made of aluminium alloy Al6061-T6 and filled with explosive material is under investigation. A fully coupled Eulerian and Lagrangian formulation is used together with a complete mechanical behaviour and constitutive equations of all the materials involved in the simulation (aluminium alloy Al6061-T6, explosive C4, air). Finally, results and comparison between the mentioned numerical solvers will be reported and critically discussed

Numerical simulations of normal and oblique impact on single and double-layered aluminium Al6061-T6 plates

Studies of ballistic penetration into metal plates and their numerical simulation currently present an important topic in ballistics, however, no congruent results have been presented so far, especially when it comes to impacts on multi-layered plates. Presently, as far as ballistic limits are concerned, the choice between layered and monolithic structures is not completely straightforward and unproblematic. The effect of introducing air gaps between metallic layers is not fully understood and explained either. Furthermore, these issues are more investigated for normal impacts than for oblique impacts for which only limited results are available. Therefore, the aim of this paper is to conduct a numerical analysis in order to evaluate the effect on the ballistic limit on layered targets for both normal and oblique impacts. A validated numerical methodology will be used, though validated with a limited number of experiments. The target material is an Al6061-T6 aluminium alloy the mechanical behaviour of which (hardening, strain rate, failure, etc.) is already known and described. Several configurations will be numerically tested and the results critically evaluated

The environment and distribution of emitting electrons as a function of source activity in Markarian 421

For the high-frequency peaked BL Lac object Mrk 421 we study the variation of the spectral energy distribution (SED) as a function of source activity, from quiescent to active. We use a fully automatized chi-squared minimization procedure, instead of the "eyeball" procedure more commonly used in the literature, to model nine SED datasets with a one-zone Synchrotron-Self-Compton (SSC) model and examine how the model parameters vary with source activity. The latter issue can finally be addressed now, because simultaneous broad-band SEDs (spanning from optical to VHE photon energies) have finally become available. Our results suggest that in Mrk 421 the magnetic field decreases with source activity, whereas the electron spectrum's break energy and the Doppler factor increase -- the other SSC parameters turn out to be uncorrelated with source activity. In the SSC framework these results are interpreted in a picture where the synchrotron power and peak frequency remain constant with varying source activity, through a combination of decreasing magnetic field and increasing number density of electrons below the break energy: since this leads to an increased electron-photon scattering efficiency, the resulting Compton power increases, and so does the total (= synchrotron plus Compton) emission.Comment: Accepted for publication in Astrophysical Journal; 23 pages, 3 figures, 2 table

Emitting electrons and source activity in Markarian 501

We study the variation of the broad-band spectral energy distribution (SED) of the BL Lac object Mrk 501 as a function of source activity, from quiescent to flaring. Through chi-square-minimization we model eight simultaneous SED datasets with a one-zone Synchrotron-Self-Compton (SSC) model, and examine how model parameters vary with source activity. The emerging variability pattern of Mrk 501 is complex, with the Compton component arising from gamma-electron scatterings that sometimes are (mostly) Thomson and sometimes (mostly) extreme Klein-Nishina. This can be seen from the variation of the Compton to synchrotron peak distance according to source state. The underlying electron spectra are faint/soft in quiescent states and bright/hard in flaring states. A comparison with Mrk 421 suggests that the typical values of the SSC parameters are different in the two sources: however, in both jets the energy density is particle dominated in all states.Comment: 8 pages, 4 figures, 1 table; accepted for publication in Ap

kinematic elicitation of basic emotions a validation study in an italian sample

Video clips proved to effectively elicit different emotions. Hewig and colleagues (2005) developed a comprehensive set collecting 20 emotional film clips and investigated the basic emotions elicited in a German sample. In this study, we tested the reproducibility of their findings in Italian nonclinical adult subjects (N = 32) examined individually in an ecological setting; moreover, the differences between presentation modalities (with and without sound) were examined. Clips were rated on 10 emotional states (serene, amused, happy, surprised, sad, scared, angry, disgusted, indignant, tense) and on two bipolar dimensions of valence and intensity. Only little differences between presentation modalities were found; stories depicted proved to be clear enough. Film clips elicited the expected emotional profiles, and their rank order for each emotion is almost comparable with the German ones. However, all the clips elicited more than one emotion: ANCOVA proved that emotions were not fully independent and specific association patterns were found. Implications are discussed in the light of the complexity of emotional activation