196,607 research outputs found
Il critico e il marmo: le monografie di Callisto Cosulich
No full textL'articolo è una ricostruzione di tutte le monografia di Callisto Cosulich, inserita in una ricostruzione attenta del contesto storico ed editoriale della cultura cinematografica italian
The Geology of Callisto
No full textThe geology of Callisto is not boring. Although cratered terrain dominates Callisto (a key end-member of the Jovian satellite system), a number of more interesting features are apparent. Cratered terrain is broken into irregular map-able bright and dark subunits that vary in albedo by a factor of 2, and several relatively smooth units are depleted of small craters. Some of these areas may have been volcanically resurfaced. Lineaments, including parallel and radial sets, may be evidence for early global tectonism. Frost deposition occurs in cold traps, and impact scars have formed from tidally disrupted comets. Geologic evidence suggests that Callisto does have a chemically differentiated crust. Central pit and central dome craters and palimpsests are common. The preferred interpretation is that a relatively ice-rich material, at depths of 5 km or more, has been mobilized during impact and exposed as domes or palimpsests. The close similarity in crater morphologies and dimensions indicates that the outermost 10 km or so of Callisto may be as differentiated as on Ganymede. The geology of cratered terrain on Callisto is simpler than that of cratered terrain on Ganymede, however. Orbital evolution and tidal heating may provide the answer to the riddle of why Callisto and Ganymede are so different (Malhotra, 1991). We should expect a few surprises and begins to answer some fundamental questions when Callisto is observed by Galileo in late 1996
La scrittura politico-culturale: Callisto Cosulich tra televisione, critica e lotta alla censura
No full textL'opera di Callisto Cosulich, come risultato di una pratica costante: la scrittura come strumento privilegiato di divulgazione professionale e cinefiliaca dei contenuti, come luogo prediletto d’appassionata enunciazione politico-culturale, mezzo e fine di lotta intellettuale atti alla trasformazione, verso un miglioramento complessivo e istituzionale, attraverso la difesa e la divulgazione del bello e dell’etico nel proprio specifico estetico, quello critico e cinematografico.
La sua scrittura come impegno radical, anche quando mestierante: mai organica, sempre militante, pur libera da specifiche militanze
Magic: a geophysical mission to the galilean moon callisto
No full textThe Magnetics, Altimetry, Gravity, and Imaging of Callisto (MAGIC) mission was conceived to fully characterize the properties of the Galilean moon Callisto from its deep interior to the icy shell. Three main instruments are included as a scientific payload. Extremely accurate measurements of Callisto s topography, magnetic field, and morphology are obtained by the onboard laser altimeter, magnetometer, and camera, respectively. The telecommunication system additionally enables gravity and radio science investigation. A precise characterization of long-And short-wavelength gravity anomalies afford powerful constraints on the internal differentiation and the properties of the hydrosphere. Together these datasets would resolve ambiguities inherent in Galileo flyby data, revealing Callisto s interior structure as well as the existence and properties of its postulated internal ocean
Geology of the Selk crater region on Titan from Cassini VIMS observations
No full textInternational audienceObservations of Titan obtained by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) have revealed Selk crater, a geologically young, bright-rimmed, impact crater located similar to 800 km north-northwest of the Huygens landing site. The crater rim-crest diameter is 90 km; its floor diameter is similar to 60 km. A central pit/peak, 20-30 km in diameter, is seen; the ratio of the size of this feature to the crater diameter is consistent with similarly sized craters on Ganymede and Callisto, all of which are dome craters. The VIMS data, unfortunately, are not of sufficient resolution to detect such a dome. The inner rim of Selk crater is fluted, probably by eolian erosion, while the outer flank and presumed ejecta blanket appear dissected by drainages (particularly to the east), likely the result of fluvial erosion. Terracing is observed on the northern and western walls of Selk crater within a 10-15 km wide terrace zone identified in VIMS data; the terrace zone is bright in SAR data, consistent with it being a rough surface. The terrace zone is slightly wider than those observed on Ganymede and Callisto and may reflect differences in thermal structure and/or composition of the lithosphere. The polygonal appearance of the crater likely results from two preexisting planes of weakness (oriented at azimuths of 21 degrees and 122 degrees east of north). A unit of generally bright terrain that exhibits similar infrared-color variation and contrast to Selk crater extends east-southeast from the crater several hundred kilometers. We informally refer to this terrain as the Selk "bench." Both Selk and the bench are surrounded by the infrared-dark Belet dune field. Hypotheses for the genesis of the optically bright terrain of the bench include: wind shadowing in the lee of Selk crater preventing the encroachment of dunes, impact-induced cryovolcanism, flow of a fluidized-ejecta blanket (similar to the bright crater outflows observed on Venus), and erosion of a streamlined upland formed in the lee of Selk crater by fluid flow. Vestigial circular outlines in this feature just east of Selk's ejecta blanket suggest that this might be a remnant of an ancient, cratered crust. Evidently the southern margin of the feature has sufficient relief to prevent the encroachment of dunes from the Belet dune field. We conclude that this feature either represents a relatively high-viscosity, fluidizedejecta flow (a class intermediate to ejecta blankets and long venusian-style ejecta flows) or a streamlined upland remnant that formed downstream from the crater by erosive fluid flow from the west-northwest
Soil-structure interaction for the seismic design of the Messina Strait Bridge
No full textThis paper illustrates an approach to the study of the seismic soil–structure interaction that was
developed at the verification stage of the design of the Messina Strait Bridge in order to validate its
seismic behaviour. It consisted of a series of two-dimensional, plane strain numerical analyses on models
that included, in addition to the embedded foundation elements, a simplified structural description of
the bridge towers: simplified structural models were specifically designed to reproduce the first
vibrations modes of the towers, that were deemed to have the most significant influence on the
system's dynamic response. Non-linear dynamic analyses were carried out in the time domain, studying
the effects of two different natural records, each characterised by three orthogonal components of the
soil motion. In the first part of the paper, essential information is provided about the foundations layout,
the main properties of the foundation soil resulting from the in situ and laboratory investigation, and the
assessment of the liquefaction potential. Then, the numerical models are discussed in some detail, with
an emphasis on the modelling of the soil and of the structural elements. For sake of conciseness, details
are provided only for one of the two shores. The results obtained with the present approach shed some
light on the complex coupling between the soil's and the structure's behaviour, evidencing the significant
role that the embedded, massive foundations of the bridge play in the dynamic response of the system.
The computed time-histories of the displacements of the foundation elements are used to assess the
seismic performance of the bridge
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