1,721,022 research outputs found
Studi di letteratura italiana in onore di Claudio Scarpati
No full textIn occasione del settantesimo compleanno di Claudio Scarpati, per quattro decenni professore di Letteratura italiana nella Facoltà di Lettere e Filosofia dell'Università Cattolica di Milano, in segno di gratitudine per l'alto contributo offerto nell'ambito della ricerca scientifica e per il prezioso magistero, allievi e colleghi gli rendono omaggio con questa raccolta di studi, che si distende sull'intero arco della storia letteraria italiana
A time-distance reconstruction of the Campanian Ignimbrite pyroclastic current based on lithofacies architecture
No full textS01.36 - Hazard assessment of pyroclastic density currents and lahars current capabilities
and new strategies for comprehensive uncertainty quantification
A time-distance reconstruction of the Campanian Ignimbrite pyroclastic current
based on lithofacies architecture
Claudio Scarpati, Domenico Sparice, Annamaria Perrotta
Dipartimento di Scienze della Terra, dell'Ambiente e delle Risorse (DiSTAR), Università di Napoli Federico II, Italy
Large ignimbrites are the product of high-temperature pyroclastic density currents (PDCs) spreading over huge regions. Understanding the behaviour of these volcanic events is critical to assess the hazard posed to millions of peoples living near volcanoes producing this type of activity. Here we present a detailed examination of the medial (from 30 to 80 km from the source area) ignimbrite sequence of the Campanian Ignimbrite eruption (Campanian Ignimbrite s.s., CI), a caldera-forming Plinian event, occurred 39 ka ago,
whose PDC spread over a huge area from Campi Flegrei (Italy). Ignimbrite deposits have a mass of 1.74*1014 kg and a tephra volume of 54 km3 (25 km3 DRE). We describe CI lithofacies and their vertical and lateral variations. The eruption started with a fluctuating Plinian phase that collapsed irreversibly spreading a pyroclastic density current over a rugged region. Vertical facies variations reflect a temporal evolution of
depositional mechanisms, from traction- to granular- or fluid escape-dominated, that records unsteady conditions and contrast with persistent lateral facies reflecting an overall uniform spatial behaviour of the current. Our lithofacies investigation illustrates how the CI PDC evolved in time and space and the role of internal (eruptive and transport mechanisms) and external (topography, surficial water and rain) factors in
governing its behaviour. Our study may have important implications for assessing the hazards related to the reactivation of the Campi Flegrei caldera with a large ignimbrite-forming Plinian event, like the Campanian Ignimbrite eruption, on the densely populated Campania region
Pre-caldera lateral activity at Somma – Vesuvius
No full textS01.14 - Volcano geology and field observations aimed at validation of numerical models
Pre-caldera lateral activity at Somma- Vesuvius
Claudio Scarpati, Domenico Sparice, Annamaria Perrotta
Dipartimento di Scienze della Terra, dell'Ambiente e delle Risorse (DiSTAR), Università di Napoli Federico II, Italy
Five pre-caldera, scoria- and spatter-cones at Somma-Vesuvius were produced by alternative pulses of Strombolian and Hawaiian activity that emplaced scoria and welded spatter fall deposits, several meters thick. These vents cover a wide azimuth around the volcano. A persistent feature throughout the exposed stratigraphy of the studied parasitic cones is the abundance of coarse, juvenile material (97–100 wt%), a feature suggesting an overall magmatic style during these eruptive episodes. Most of the observed eruptive units show an alternation of unwelded scoria and welded spatter suggesting a repeated variation of the eruptive style. A dominant Strombolian style of fragmentation, with bubble coalescent and rhythmic outbursts, emplaced thick scoriaceous succession; episodically, lava fountaining activity ejected coarse clots of magma which fell near the vent producing spatter horizons. The fragmentary nature (spatter-fed) of lavalike
facies strictly associated (transitional) to less welded to agglutinated facies, as well as the plastic deformation (flattening) of spatter fragments indicate the continuous fall deposition from Hawaiian firefountain episodes alternated with Strombolian phases emplacing loose scoria deposits. The remnants of two
cones show a continuous sequence (no breaks) of pyroclastic beds emplaced as a result of a single coneforming eruptions. This allows us to define them “monogenetic”. Conversely, the presence of thick paleosols, reworked material, exotic tephras and deep erosional surfaces in the pyroclastic succession of the
other three cones has to be regarded as clear, well developed and laterally traceable breaks in the pyroclastic sequence of these small parasitic volcanoes. In light of this, we define such edifices as the result of a polygenetic (multi-phase) evolution. These evidences indicate resumption of activity after a quite long, nonquantifiable period of quiescence. This behaviour should suggest more caution when considering the parasitic volcanoes that erupted in historical time, completely extinct.
S01.1
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
