1,720,969 research outputs found
IDENTIFICATION AND INVESTIGATION OF SHALLOW PALEOCHANNELS IN THE CHAMELECON VALLEY (HONDURAS): 1D VS 2D ELECTRICAL RESISTIVITY SURVEYS
No full textElectrical Resistivity Tomography (ERT) and resistivity depth sounding surveys were undertaken at two sites located along the Chamelecòn Valley (Honduras). The objective of the surveys was to determine the occurrence, geometry and lithological properties of the Chamelecòn River’s shallow paleochannels. Following the interpretation of aerial photograms which indicated the likely presence of paleochannels, two sites were selected for the surveys. Resistivity depth soundings were used to achieve electro-stratigraphic sections obtained by interpolating 1D inverted data that would assist with assessing the occurrence of paleochannels at a large scale. The presence of paleochannels at the two sites was assessed through interpretation of the electro-stratigraphic sections. At Site 2, the abundant 1D data, the small distance between the soundings and the shallow target, allowed determining the course of the paleoriver as shown by resistivity and electrical transmissivity maps. The results from the 1D data, although affected by strong heterogeneities, are congruent with the 2D inverted models. ERT surveys confirmed the presence of paleochannels and allowed achieving detailed imaging of the alluvial geological bodies. Paleochannel deposits show resistivity values ranging between 70 and 100 ohm m at Site 1, while resistivity values range between 90 and 120 ohm m at Site 2. The latter resistivity values were affected by the presence of coarser deposits. Resistivity values suggest that at both sites paleochannel deposits have a clay content that is lower than 3 %. Other alluvial deposits in the area show resistivity values that range between 19 and 70 ohm m at Site 1, while resistivity values range between 30 and 90 ohm m at Site 2. These lower values suggest that clay content can be as high as 29 %. The presence of paleochannels assessed by means of 1D surveys and the lithological characterisation assessed by means of 2D surveys were confirmed by logs from boreholes drilled at the sites
Application of 1D-2D electrical resistivity surveys to the identification and investigation of shallow paleochannels in the Chamelecòn Valley (Honduras)
No full textIl lavoro confronta i risultati ottenuti dall’utilizzo di due differenti metodi di prospezione elettrica, nell’ambito di uno studio finalizzato alla ricerca e caratterizzazione di paleoalvei presenti in due siti opportunamente selezionati lungo la valle del Rio Chamelecòn (Honduras). L’applicazione di sondaggi elettrici verticali (1D) ha permesso di determinare la presenza di paleoalvei; la caratterizzazione geometrica e litologica di questi è stata invece ottenuta mediante applicazione di indagini di tomografia elettrica 2D (ERT)
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
Seismic amplification effects induced by ancient shallow cavities underneath the urban area of the historical city center of Chieti, Italy
No full textAnthropogenic cavities excavated just beneath the walkable floor (about 1–6 m depth) are present in many
ancient urban centres, particularly in Europe and along the Mediterranean basin. The oldest caves are Roman
constructions and have been used for different purposes over time (i.e., water storage, secret pathways, shelters
against sieges, and wars). For this reason, Seismic Microzonation (SM) studies performed in urban areas must
consider the presence of these holes in the subsoil, with their effects predicted through numerical simulations of
local seismic response on the surface. In this study, we investigate the seismic effects of ancient anthropogenic
cavities in Chieti city centre (Italy) through the cavity amplification factor (CAF). A parametric study was carried
out on several different dynamic subsoil models. We define CAF as the ratio between the Acceleration Spectral
Intensities on the surface and at the bedrock calculated in the period range of 0.1–0.5 s. The 2-dimensional
parametric simulations were performed adopting the soil equivalent linear constitutive law by varying: (1)
shear wave velocity values of subsoil, (2) cavity dimensions, (3) cavity depths, (4) cavity lining shear wave
velocity values. The CAF plots were calculated on the surface for cavity sizes (width x height) varying from 4 × 5
m to 7 × 9 m. Our study demonstrates that CAF values are relevant only in the period range of 0.1–0.5 s. In
particular, results show that: (1) CAF values vary from 1% to 15%; (2) the maximum CAF is felt away from the
cavity axis at a distance equal to about 1.5 times the cavity width (L); (3) the maximum difference in CAF values
at the surface is equal to 40% within a horizontal distance from the cavity axis ranging from 6 to 14 m. Finally,
the case study of the city centre of Chieti (Abruzzo Region) is considered to show how to draw CAF maps for
microzonation purposes
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
Application of 1D-2D electrical resistivity surveys to the identification and investigation of shallow paleochannels in the Chamelecòn Valley (Honduras)
No full textIl lavoro confronta i risultati ottenuti dall’utilizzo di due differenti metodi di prospezione elettrica, nell’ambito di uno studio finalizzato alla ricerca e caratterizzazione di paleoalvei presenti in due siti opportunamente selezionati lungo la valle del Rio Chamelecòn (Honduras). L’applicazione di sondaggi elettrici verticali (1D) ha permesso di determinare la presenza di paleoalvei; la caratterizzazione geometrica e litologica di questi è stata invece ottenuta mediante applicazione di indagini di tomografia elettrica 2D (ERT)
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
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