About the linearity of the color-magnitude relation of early-type galaxies in the Virgo cluster

We revisit the color-magnitude relation (CMR) of the Virgo cluster early-type galaxies in order to explore its alleged non-linearity. To this aim, we reanalyze the relation already published from data obtained within the ACS Virgo Cluster Survey of the Hubble Space Telescope, and perform our own photometry and analysis of the images of the 100 early-type galaxies observed as part of this survey. In addition, we compare our results with those reported in the literature from data of the Sloan Digital Sky Survey. We have found that when the brightest galaxies and untypical systems are excluded from the sample, a linear relation arises in agreement with what is observed in other groups and clusters. The central regions of the brightest galaxies also follow this relation. In addition, we notice that Virgo contains at least four compact elliptical galaxies besides the well known object VCC 1297 (NGC 4486B). Their locations in the -luminosity diagram define a different trend to that followed by normal early-type dwarf galaxies, setting an upper limit in effective surface brightness and a lower limit in effective radius for their luminosities. Based on the distribution of different galaxy sub-samples in the color-magnitude and -luminosity diagrams we draw some conclusions on their formation and the history of their evolution.Comment: 21 pages, 4 figures, 2 tables. Accepted for publication in Ap

On the properties of the interstellar medium in extremely metal-poor blue compact dwarf galaxies: GMOS-IFU spectroscopy and SDSS photometry of the double-knot galaxy HS 2236+1344

The main goal of this study is to carry out a spatially resolved investigation of the warm interstellar medium (ISM) in the extremely metal-poor Blue Compact Dwarf (BCD) galaxy HS 2236+1344. Special emphasis is laid on the analysis of the spatial distribution of chemical abundances, emission-line ratios and kinematics of the ISM, and to the recent star-forming activity in this galaxy. This study is based on optical integral field unit spectroscopy data from Gemini Multi-Object Spectrograph at the Gemini North telescope and archival Sloan Digital Sky Survey images. The data were obtained in two different positions across the galaxy, obtaining a total 4 arcsec X 8 arcsec field which encompasses most of its ISM. Emission-line maps and broad-band images obtained in this study indicate that HS 2236+1344 hosts three Giant HII regions. Our data also reveal some faint curved features in the BCD periphery that might be due to tidal perturbations or expanding ionized-gas shells. The ISM velocity field shows systematic gradients along the major axis of the BCD, with its south-eastern and north-western half differing by ~80 km/s in their recessional velocity. The Ha and Hb equivalent width distribution in the central part of HS 2236+1344 is consistent with a very young (~3 Myr) burst. Our surface photometry analysis indicates that the ongoing starburst provides ~50% of the total optical emission, similar to other BCDs. It also reveals an underlying lower-surface brightness component with moderately red colors, which suggest that the galaxy has undergone previous star formation. We derive an integrated oxygen abundance of 12+log(O/H)=7.53\pm0.06 and a nitrogen-to-oxygen ratio of log(N/O)=-1.57\pm0.19. Our results are consistent, within the uncertainties, with a homogeneous distribution of oxygen and nitrogen within the ISM of the galaxy. (abridged)Comment: 15 pages, 16 figures, accepted for publication in A&

Definizione, acquisizione sperimentale ed elaborazione di traiettorie di riferimento della mano umana per la sintesi di architetture protesiche di arto superiore

This paper reports an essential part of a wider research activity, which entails the development of a procedure for the Determination of the Optimal Prosthesis Architecture (DOPA) for a given upper limb amputee. A fundamental algorithm of the DOPA procedure performs the kinematic analysis of several prosthetic arm models (also with less than the six degrees of freedom normally required to correctly execute a generic manipulation task). The algorithm must simulate the execution of important daily living activities performed by a prosthesis and thus it requires reference trajectories of the hand. By means of experimental analysis, 59 trajectories of the hand of an able-bodied subject were acquired to identify a modality to correctly perform the corresponding tasks. This paper illustrates in detail the stages of task analysis, experimental acquisition and data processing in order to define the required reference trajectories. The obtained reference trajectories are a temporal succession of the hand pose (position and orientation). A customized algorithm automatically selects the most relevant poses to be considered for the definition of the reference trajectory. The hand pose is reported in the Cartesian Space by means of Natural Coordinates. In order to correctly execute a given task the pose error admitted for the end-effector of the different architectures is associated to each trajectory. In particular, the critical problem to express the orientation error is solved by means of the use of Spherical Rotation Coordinates

Theoretical stellar models for old galactic clusters

We present new evolutionary stellar models suitable for old Population I clusters, discussing both the consequences of the most recent improvements in the input physics and the effect of element diffusion within the stellar structures. Theoretical cluster isochrones are presented, covering the range of ages from 1 to 9 Gyr for the four selected choices on the metallicity Z= 0.007, 0.010, 0.015 and 0.020. Theoretical uncertainties on the efficiency of superadiabatic convection are discussed in some details. Isochrone fitting to the CM diagrams of the two well observed galactic clusters NGC2420 and M67 indicates that a mixing length parameter alpha = 1.9 appears adequate for reproducing the observed color of cool giant stars. The problems in matching theoretical preditions to the observed slope of MS stars are discussed.Comment: 7 pages, 14 postscript figures, accepted for publication on MNRA

Cos’è successo a Siena il 26 maggio 1798 ? Un’iniziativa interdisciplinare per la valutazione del possibile impatto di un futuro «massimo sismico» su una città-monumento

L’importanza di un terremoto non dipende solo dalla sua intensità epicentrale. Quello del 26 maggio 1798 (Io VII MCS secondo CPTI04) non si può dire una catastrofe ma è di certo un evento «strategico». Si tratta, infatti, del massimo terremoto storico conosciuto per Siena, che è una delle maggiori attrazioni turistiche e quindi uno dei luoghi più frequentati di questo paese. Nell’ultimo ventennio il terremoto del 1798 è stato più volte studiato, sia da sismologi storici nell’ambito delle attività di revisione del catalogo PFG promosse dal GNDT e dall’ING/INGV (Castelli e Camassi, 1995; Castelli et al., 1996; Boschi et al., 1997; Boschi et al., 2000), sia da storici dell’architettura (Gennari, 2005). Siamo ancora lontani dall’aver completamente esplorato la copiosissima documentazione storica potenzialmente utile per una ricostruzione degli effetti di questo terremoto nel centro urbano senese. Tuttavia il campione reso disponibile dagli studi fatti finora è abbastanza significativo da rendere possibile l’avvio di un progetto di microzonazione del centro storico senese e di una serie di indagini miranti a comprendere cosa realmente successe a Siena il 26 maggio 1798 e, per conseguenza, quali effetti ci si possa attendere in occasione di un futuro terremoto di analoga portata. Il centro storico senese ha infatti conservato, almeno nelle grandi linee, una fisionomia molto simile a quella che aveva del 1798 e questa circostanza offre l’opportunità di attualizzare l’esperienza del terremoto del 1798 contribuendo alla identificazione delle eventuali criticità attese in caso di terremoti futuri. Si è perciò creato un gruppo di studio interdisciplinare (geofisica, architettura, sismologia storica, ingegneria sismica, geologia, ecc.) che ha cominciato a predisporre gli elementi necessari per questa ricostruzione. La base di dati storici di cui si dispone comprende descrizioni di danno più o meno dettagliate per circa seicento edifici senesi, su un migliaio da cui era composto il centro urbano nel 1798. Questo campione comprende sia edifici monumentali o comunque di vaste proporzioni (palazzi gentilizi e case di abitazione multipla, chiese, conventi, opifici) sia edifici non monumentali. Il nostro primo scopo è una ricostruzione dettagliata della distribuzione del danno del terremoto del 1798 nell’area urbana. Utilizzando cartografia storica pressoché coeva al terremoto (cfr. Gennari, 2005) e grazie all’impiego di un GIS, è stato possibile trasporre le informazioni storiche sottoforma di carte tematiche (Danno, Vulnerabilità, Interventi richiesti, eccetera). Le Figg. 1 e 2 presentano due esempi di tematismi derivati da dati archivistici. In parallelo a questa analisi verrà svolta una indagine a campione su una ventina di edifici rappresentativi per i quali si eseguiranno stime di comportamento dinamico con la tecnica del tremore sismico ambientale. A completamento della caratterizzazione della risposta sismica dei terreni nell’area del centro storico saranno svolte analisi geologiche e sismiche per definire le aree in cui l’assetto del sottosuolo rende ipotizzabili fenomeni di amplificazione del moto sismico del suolo. Tutti i risultati verranno raccolti in una base dati comune e implementati nel GIS (Figura 2) L’analisi congiunta dei dati di danno (opportunamente interpretati in termini di risposta sismica locale utilizzando il metodo proposto da Goretti e Dolce, 2004; Goretti, 2006) e delle analisi geofisiche e geologiche permetterà di individuare quelle parti del patrimonio edilizio storico più esposte a danno in caso di futuri eventi sismici

The Distance of the First Overtone RR Lyrae Variables in the MACHO LMC Database: A New Method to Correct for the Effects of Crowding

Previous studies have indicated that many of the RR Lyrae variables in the LMC have properties similar to the ones in the Galactic globular cluster M3. Assuming that the M3 RR Lyrae variables follow the same relationships among period, temperature, amplitude and Fourier phase parameter phi31 as their LMC counterparts, we have used the M3 phi31-logP relation to identify the M3-like unevolved first overtone RR Lyrae variables in 16 fields near the LMC bar. The temperatures of these variables were calculated from the M3 logP-logTe relation so that the extinction could be derived for each star separately. Since blended stars have lower amplitudes for a given period, the period amplitude relation should be a useful tool for identifying which stars are affected by crowding. We find that the low amplitude stars are brighter. We remove them from the sample and derive an LMC distance modulus 18.49+/-0.11.Comment: 30 pages, 7 figures, accepted for publication in the Astronomical Journa

Utility of the Diagnostic Criteria for Psychosomatic Research in assessing psychological disorders in fibromyalgia patients

The data confirmed the clinical utility of the DCPR in detecting psychological disorders in FM patients. The results highlighted a very high prevalence of psychosomatic syndromes in FM patients, who displayed an average of more than 4 psychosomatic syndromes each, with every patient displaying at least one. Furthermore, psychosomatic syndromes indicated predictive validity with respect to a poor health-related quality of life in FM patients

Polaris B, an optical companion of Polaris (alpha UMi) system: atmospheric parameters, chemical composition, distance and mass

We present an analysis of high-resolution spectroscopic observations of Polaris B, the optical companion of the Polaris Ab system. The star has a radial velocity V_r of -16.6km/s to -18.9km/s, and a projected rotational velocity vsini=110 km/s. The derived atmospheric parameters are: Teff=6900K; logg=4.3; V_t=2.5km/s. Polaris B has elemental abundances generally similar to those of the Cepheid Polaris A (Usenko et al. 2005a), although carbon, sodium and magnesium are close to the solar values. At a spectral type of F3V Polaris B has a luminosity of 3.868L_sun, an absolute magnitude of +3.30mag, and a distance of 109.5pc. The mass of the star is estimated to be 1.39M_sun, close to a mass of 1.38+/-0.61M_sun for the recently-resolved orbital periods companion Polaris Ab observed by Evans et al. (2007).Comment: 6 pages, 3 figures, 1 tabl

A simplified semi-quantitative procedure based on the SLIP model for landslide risk assessment: the case study of Gioiosa Marea (Sicily, Italy)

Landslide risk assessment is fundamental in identifying risk areas, where mitigation measures must be introduced. Most of the existing methods are based on susceptibility assessment strongly site-specific and require information often unavailable for damage quantification. This study proposes a simplified methodology, specific for rainfall-induced shallow landslides, that tries to overcome both these limitations. Susceptibility assessed from a physically-based model SLIP (shallow landslides instability prediction) is combined with distance derived indices representing the interference probability with elements at risk in the anthropized environment. The methodology is applied to Gioiosa Marea municipality (Sicily, south Italy), where shallow landslides are often triggered by rainfall causing relevant social and economic damage because of their interference with roads. SLIP parameters are first calibrated to predict the spatial and temporal occurrence of past surveyed phenomena. Susceptibility is then assessed in the whole municipality and validated by comparison with areas affected by slide movements according to the regional databases of historical landslides. It is shown that all the detected areas are covered by points where the SLIP safety factor ranges between 0 and 2. Risk is finally assessed after computation of distances from elements at risk, selected from the land use map. In this case, results are not well validated because of lack of details in the available regional hydrogeological plan, both in terms of extension and information. Further validation of the proposed interference indices is required, e.g., with studies of landslide propagation, which can also allow considerations on the provoked damage