50 research outputs found

    The thick disk rotation-metallicity correlation, comparison with Galactic cosmological simulations

    Get PDF
    Although the existence of a thick disc in the Milky Way was revealed 35 years ago and its spatial, kinematic, and chemical properties are today better defined, its origin is still matter of debate. Proposed scenarios include the heating of a pre-existing thin disc through a minor merger, accretion of dwarf galaxies stars from disrupted satellites, or stars formed in situ from gas-rich mergers at high redshift.In order to better understand these processes, we have investigated the chemo-dynamical evolution of a Milky Way-like disk galaxy, as produced by the recent cosmological simulations, integrating a sub-resolution ISM model, published by Murante et al. (2015). In particular, we evidence a global inside-out and top-down disk evolution.Recently, Re Fiorentin, Lattanzi & Spagna (2019) analysed a new chemo-kinematic catalogue based on Gaia DR2 and APOGEE DR14 and showed evidence that the thick disk rotation-metallicity correlation is persistently positive from R=5 kpc to 13 kpc, in spite of a quasi-flat metallicity gradient.Our simulation at redshift z=0 shows very similar properties when we look at the "thick disk" stellar particles at 1 kpc 2) with a negative rotation-metallicity correlation associated with a negative radial metallicity gradient (cfr. also Schoenrich & McMillan 2017; Kawata et al. 2018)

    Chemo-dynamical signatures in simulated Milky Way-like galaxies

    Get PDF
    We have investigated the chemo-dynamical evolution of a Milky Way-like disk galaxy, AqC4, produced by a cosmological simulation integrating a sub-resolution ISM model. We evidence a global inside-out and upside-down disk evolution, that is consistent with a scenario where the ``thin disk'' stars are formed from the accreted gas close to the galactic plane, while the older ``thick disk'' stars are originated in situ at higher heights. Also, the bar appears the most effective heating mechanism in the inner disk. Finally, no significant metallicity-rotation correlation has been observed, in spite of the presence of a negative [Fe/H] radial gradient

    The campaign on Facebook for the 2016 roman administrative election from a Mixed-Methods perspective. The M5S/PD Face-Off

    No full text
    While the internet offers up great masses of both textual and numerical data that can be analyzed using the automatic features of powerful software programs, this does not on its own represent a viable work strategy. The wealth of available data should in fact mark the beginning of a varied and complex process of research and analysis that looks to combine a plurality of investigative tools and techniques, both traditional and of the latest generation. The presentation here of the key findings of an empirical investigation offers an opportunity to highlight the advantages of a mixed-methods approach

    Tra big e small data. La partecipazione politica degli utenti Twitter

    No full text
    This article aims to show how an approach with a mixed method orientation, combining big and small data, can be fruitfully used to study political participation. The limits of using exclusively of Big Data downloaded from the web (in particular from Twitter) can be partially overcome through a pluralist methodological approach. This case of empirical research, a web survey conducted during the campaign for the parliamentary elections in 2013, highlights the value of this approach in the study of political participation, online and offline, in relation to all its conceptual dimensions, as well as to other social phenomena

    Big Text Corpora & Mixed Methods. The roman Five Star Movement blog

    No full text
    This paper presents the most significant results of a study into the political communication of the Rome branch of the M5S, or Five Stars Movement, conducted through analysis of its blog, a big text corpus, comprising posts, comments and images, which brought together between the period immediately prior to the May 2013 administrative elections and the present day. This corpus was subjected to advanced statistical text analysis, and targeted hermeneutic and content analysis. Semiotic analyses of visual material were also performed, in addition to network analyses of blog contributors and analyses of communicational efficacy. Research team members from several disciplines and a variety of institutions, worked in constant collaboration, adopting a mixed-method approach

    Tradurre Michelangelo della Sistina: dall'immagine fissa all'immagine in movimento

    No full text
    La giornata di studi “Tradurre la Sistina: dall’immagine fissa all’immagine in movimento”, ha indagato il ponte creatosi tra la riproduzione fotografica e filmografica della Sistina, quest’ultima sin dagli inizi dell’utilizzo della macchina da presa all’interno della cappella con lo specifico obiettivo storico-artistico, non escludendone la concomitanza di usi documentaristici per le funzioni religiose che risalgono agli anni ‘30. La documentazione fotografica conservata presso la Fototeca dei Musei Vaticani, posta a confronto con il suo uso nella societĂ  di massa, e quella filmografia presente nelle cineteche dell’Istituto Luce, della Cineteca Nazionale, della Filmoteca Vaticana, del CTV (Centro televisivo vaticano), di RAI Teche, e altre cineteche internazionali (Unesco, Ina), sono state oggetto di un’indagine selettiva e di studio, con la proiezione di una selezione di immagini e filmati piĂč rilevanti. E' prevista la pubblicazione degli atti e di un catalogo ragionato occasione per una riflessione storica e metodologica sul linguaggio critico utilizzato, sull’uso dei mezzi tecnici per la resa degli affreschi, e sull’impatto sociale che i mezzi foto-cinematografico e audiovisivo hanno avuto sulle modalitĂ  di ricezione dell’opera michelangiolesca nell’ultimo secolo, da un punto di vista specialistico e divulgativo, ipotizzandone anche i possibili sviluppi

    Big Data testuali. La campagna Facebook per le elezioni amministrative romane 2016 in una prospettiva mixed-methods

    No full text
    L’articolo, mirato a evidenziare i vantaggi di un approccio mixed-methods con specifico riferimento a dati testuali, presenta alcuni dei principali risultati di un’indagine empirica relativa alla campagna elettorale condotta su Facebook dai candidati sindaco delle elezioni amministrative romane del 2016. Gli autori sottolineano alcuni aspetti critici emersi sul piano metodologico rispetto all’uso di Big Data testuali, mettendoli in connessione con la ricostruzione delle modalità di svolgimento della campagna elettorale, con la definizione del ruolo di Facebook, con lo studio dei toni, dei contenuti, dello stile comunicativo dei leader scesi in campo e con l’analisi delle reazioni, dei commenti e delle interazioni-relazioni online degli internauti maggiormente presenti sul web. L’obiettivo ù quello di mostrare i limiti delle tecniche di rilevazione su big e small data, ma anche gli aspetti virtuosi che si generano dalla fusione e dalla complementarietà tra i due

    The development of the pediatric NAFLD fibrosis score (PNFS) to predict the presence of advanced fibrosis in children with nonalcoholic fatty liver disease.

    No full text
    BACKGROUND: Noninvasive hepatic fibrosis scores that predict the presence of advanced fibrosis have been developed and validated in adult patients with NAFLD. The aims of our study were to assess the utility of commonly used adult fibrosis scores in pediatric NAFLD and to develop a pediatric specific fibrosis score that can predict advanced fibrosis. METHODS: Consecutive children with biopsy-proven NAFLD were included. Fibrosis was determined by an experienced pathologist (F0-4). Advanced fibrosis was defined as fibrosis stage ≄ 3. The following adult fibrosis scores were calculated for each child: AST/ALT ratio, AST/platelet ratio index (APRI), NAFLD fibrosis score (NFS), and FIB-4 Index. Multivariable logistic regression analysis was performed to build a new pediatric model for predicting advanced fibrosis. RESULTS: Our cohort consisted of 242 children with a mean age of 12.4 ± 3.1 years and 63% were female. 36 (15%) subjects had advanced fibrosis. APRI and FIB-4 were higher in patients with advanced fibrosis compared to those with fibrosis stage 0-2; however, AST/ALT ratio and NFS were not different between the two groups. We used our data to develop a new model to predict advanced fibrosis which included: ALT, alkaline phosphatase, platelet counts and GGT. The multivariable logistic regression model (z) was defined as follows: z = 1.1+(0.34*sqrt(ALT))+(0.002*alkaline phosphatase) - (1.1*log(platelets) - (0.02*GGT). This value was then converted into a probability distribution (p) with a value between 0 to 100 by the following formula: p = 100 × exp(z)/[1+exp(z)]. The AUCROC for this model was 0.74 (95% CI: 0.66, 0.82). This was found to be significantly better than APRI, NAFLD Fibrosis Score and FIB-4 Index. CONCLUSION: Noninvasive hepatic fibrosis scores developed in adults had poor performance in diagnosing advanced fibrosis in children with NAFLD. We developed a new pediatric NAFLD fibrosis score with improved performance characteristics
    corecore