1,721,013 research outputs found
Structural settings of the carbonatic "basament" and its relationship with magma uprising in the gulf of Naples (Southern Italy)
No full textThe carbonatic "basement" of the Gulf of Naples, a peri-tyrrhenian basin located on the western side of the Southern Apenninic chain, was studied in detail by means of seismic reflection profiles both on the mainland and in the sea. The carbonatic "basement" dips toward the north-west with an angle of 100 and is affected by brittle extensional tectonics. This structural setting is related to the extension of the Tyrrhenian Sea, which caused the development of horst and graben-like structure along the western margin of the Apennines. Some normal faults with a regional relevance were recognised: 1 ) a N 110° trending fault responsible for the sinking of the carbonic "basement" below Mount Somma-Vesuvius; 2) a N 1O° trending fault, along which five sub- marine volcanoes are aligned; 3) a N70° fault, which separates the Gulf of Naples from the Gulf of Salerno. The first two faults, arranged radially with respect to the shallow magmatic chamber of Phlegraean Fields, are interpreted as the main uprising route for magma in this area. The carbonatic "basement"cannot be recognized in seismic profiles in the Phlegraean area; a tectonic feature responsible for this is hypothesised.JCR Journalope
Vertical radar profiling for the assessment of landfill capping effectiveness
No full textIn this paper we present the results of the characterization of a large landfill cap by means of ground-penetrating radar (GPR) measurements. The GPR data were collected in boreholes, using a vertical radar profile (VRP) configuration, where one antenna was kept at the ground surface while the other was progressively lowered into the borehole. This yields a vertical profile of GPR velocity from which a moisture content profile can be obtained. VRPs were conducted in 15 boreholes available on-site, all having been drilled through the protective cap and the waste mass into the underlying native soil. The separation between the boreholes (many tens of metres) makes it infeasible to characterize the site via other forms of hole-to-hole GPR measurements, with the exception of a few pairs of holes drilled at the periphery of the waste mass and therefore of limited usefulness. The VRP data allowed for the characterization of the moisture content profile across the waste body down to the water table, very close to the natural land surface, providing evidence that the waste is generally fairly dry (moisture content less than 10% on average). In order to assess the effectiveness of the cap, two surveys where conducted in March and April 2005 using all the boreholes with the aim of identifying moisture content changes due to natural rainfall and especially artificial irrigation over a limited area surrounding one of the boreholes. The time-lapse VRP results show that in the irrigated area a measurable amount of water seeps through the cap and changes the waste moisture content. Elsewhere, we basically observed no changes in moisture content due to natural infiltration during the same period: this fact does not confirm or exclude that some degree of leakage can occur. Direct in-situ permeability measurements, albeit more localized than VRP data, confirm that the landfill cap is not totally impermeable, thus corroborating the results derived from geophysical measurements
Slow-to-fast transition of giant creeping rockslides modulated by undrained loading in basal shear zones
Full text linkGiant rockslides are widespread and sensitive to hydrological forcing, especially in climate change scenarios. They creep slowly for centuries and then can fail catastrophically posing major threats to society. However, the mechanisms regulating the slow-to-fast transition toward their catastrophic collapse remain elusive. We couple laboratory experiments on natural rockslide shear zone material and in situ observations to provide a scale-independent demonstration that short-term pore fluid pressure variations originate a full spectrum of creep styles, modulated by slip-induced undrained conditions. Shear zones respond to pore pressure increments by impulsive acceleration and dilatancy, causing spontaneous deceleration followed by sustained steady-rate creep. Increasing pore pressure results in high creep rates and eventual collapse. Laboratory experiments quantitatively capture the in situ behavior of giant rockslides and lay physically-based foundations to understand the collapse of giant rockslides
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
A saline trace test monitored via time-lapse surface electrical resistivity tomography.
No full textA saline tracer test has been performed at an industrial site, located in the Po River delta region (North-Eastern Italy). This tracer test was aimed at identifying possible hydraulic connections between a shallow unconfined aquifer and a deeper confined aquifer. Hydraulic head difference between the two aquifers is maintained via an active hydraulic barrier (pumping wells) screened in the deeper formation. The movement of the tracer in the subsurface has been monitored via electrical resistivity tomography (ERT) from the surface, using a network of twelve 48-electrode lines, for a total time period of about 45 days. This non-invasive geophysical method offers several advantages over direct water sampling from monitoring boreholes: (a) a wide area is investigated in a relatively short time; (b) a 2D picture of the subsurface is produced, in this case to a depth of about 15–20 m; (c) because of the above, it is possible to follow the tracer motion even if the tracer does not reach the few boreholes where water can be sampled. The latter is a major advantage over traditional methods, where it is not uncommon to miss the tracer plume altogether, or sample it only partially. The site is characterized by fairly saline groundwater, and the presence of diffuse silt and clay, that make the system rather conductive. Under such unfavourable conditions, careful inversion of resistance ratios was needed to identify changes in resistivity of as much as 50% with respect to background. The migration of the tracer was successfully monitored and confirmed by direct sampling of water from few boreholes. The results of the time lapse survey confirm that the system is very heterogeneous, and that some downward migration of the tracer through the confining layer can take place over relatively short time periods, maybe through some manmade connections
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
- …
