1,721,305 research outputs found
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
Chronostratigraphic and lithologic features of the Tiber River sediments (Rome, Italy): Implications on the post-glacial sea-level rise and Holocene climate
No full textRapid and permanent granulometric changes within the clastic sedimentary deposits of the Tiber River are directly linked to changes in sediment transport capacity and give insight on climate fluctuations and related sea-level oscillations during Late Pleistocene-Holocene times. In this work, we investigate the stratigraphic features of the sedimentary fill of the Tiber River channel as far as 30km from the coast, and of one tributary, the Grottaperfetta stream. Through direct observation and core sampling of ten, 30 to 80m deep boreholes, and the analysis of a large number of stratigraphic log data, we reconstruct a series of transverse sections and correlate them along a longitudinal profile of the Tiber River course. We provide geochronologic constraints to the deposition of distinct lithostratigraphic units by means of 8 newly acquired 14C ages and 21 previously reported ages of intercalated peat layers and wood fragments. Moreover, we review and select 28 radiocarbon ages from literature on the deposits of the Tiber River in the coastal plain, in order to reconstruct the aggradational history throughout the distal portion of the basin. Finally, we provide curves of sediment aggradation vs. time during the last 19,000yr for the different investigated portions of the Tiber River course. We compare them to sea-level curves from the literature. To perform this comparison, we use a rigorous geotechnical approach to estimate the subsidence due to sediment compaction, and we apply a correction to the Present-day elevation of the dated samples of organic material interbedded with the sedimentary deposits.Two significant sedimentary events at around 13,800. yr. BP and 7500. yr. BP, marked by sharp stratigraphic and granulometric changes, are recognized and correlate to important variations in the rate of sea-level rise. Moreover, we show evidence of an erosional event coupled to a reversal of the granulometry (increase in gain size of sediments) affecting the whole investigated tract of the Tiber River channel between 5500 and 3500. yr. BP and discuss its possible causes. In particular, we discuss whether besides the change in capacity of transport due to a climatic change, also a drop in sea level, in the order of 2-3 meters, may have occurred in this time span, either in response to an increase in global ice volume, glacial isostatic adjustment, or local tectonic uplift. © 2013 Elsevier B.V
Increased risk of cardiovascular disease in non-alcoholic fatty liver disease: causal effect or epiphenomenon?
No full textAbstract Non-alcoholic fatty liver disease (NAFLD),
comprising a spectrum of conditions ranging from pure
steatosis to steatohepatitis and cirrhosis, has reached
epidemic proportions and represents the most common
cause of chronic liver disease in the community. The
prevalence of NAFLD has been estimated to be between
20% and 30% in the general population, but this value is
much higher (∼70–80%) in type 2 diabetic patients, who
are also at higher risk of developing advanced fibrosis and
cirrhosis. Increasing recognition of the importance of
NAFLD and its strong relationship with the metabolic
syndrome has stimulated an interest in the possible role
of NAFLD in the development of cardiovascular disease
(CVD). Several epidemiological studies indicate that NAFLD,
especially in its more severe forms, is linked to an increased
risk of CVD, independently of underlying cardiometabolic
risk factors. This suggests that NAFLD is not merely a
marker of CVD, but may also be actively involved in its
pathogenesis. The possible molecular mediators linking
NAFLD and CVD include the release of pro-atherogenic
factors from the liver (C-reactive protein, fibrinogen,
plasminogen activator inhibitor-1 and other inflammatory
cytokines) as well as the contribution of NAFLD per se to
whole-body insulin resistance and atherogenic dyslipidemia,
in turn favouring CVD progression. The clinical impact of
NAFLD on CVD risk deserves particular attention in view of
the implications for screening and surveillance strategies in
the growing number of patients with NAFLD
NASH/NAFLD e insulino-resistenza
No full textPer molto tempo la malattia epatica ad origine metabolica è stata sottovalutata come condizione di scarsa rilevanza clinica. Solo oggi si sta prendendo coscienza dell’importanza della patologia, in termini epidemiologici e clinici, anche in rapporto all’epidemia di obesità e diabete del mondo occidentale. L’importanza della NAFLD rimane comunque sottovalutata, se si considera come la presenza di una patologia epatica complichi spesso anche le malattie epatiche di altra eziologia (virus B e C, emocromatosi, malattie autoimmuni ed alcoliche), peggiorandone significativamente la prognosi e riducendo le prospettive terapeutiche. Vi è l’esigenza di trasferire percorsi strutturati di terapia cognitivo-comportamentale, specifici per il diabete e l’obesità, verso il trattamento multidisciplinare dei soggetti NAFLD (68). Vi è l’esigenza di attivare protocolli di sorveglianza epatologica in soggetti con NAFLD evoluta a fibrosi avanzata, per ridurre il rischio di giungere troppo tardivamente alla diagnosi delle complicanze più severe della malattia
Increased risk of cardiovascular disease in NAFLD: causal effect or epiphenomenon?
No full textNonalcoholic fatty liver disease (NAFLD), in its whole spectrum ranging from pure steatosis to steatohepatitis and cirrhosis, has reached epidemic proportions and represents the commonest cause of chronic liver disease in the community. NAFLD prevalence has been estimated between 20% and 30% in the general population, but a much higher prevalence (~70-80%) is observed in type 2 diabetic patients, who are also at higher risk of developing advanced fibrosis and cirrhosis. The importance of NAFLD and its strong relationship to the metabolic syndrome is increasingly recognized, and this has stimulated an interest in the possible role of NAFLD in the development of cardiovascular disease (CVD). Several epidemiological studies indicate that NAFLD, especially in its more progressive forms, is linked to an increased risk of CVD, independently of underlying cardiometabolic risk factors. This suggests that NAFLD is not simply a marker of CVD, but may also be actively involved in its pathogenesis. The possible molecular mediators linking NAFLD and CVD include the release of pro-atherogenic factors from the liver (C-reactive protein, fibrinogen, plasminogen activator inhibitor-1 and other inflammatory cytokines) as well as the contribution of NAFLD per se to whole-body insulin resistance and atherogenic dyslipidemia, in turn favouring CVD progression. The clinical impact of NAFLD on CVD risk deserves particular attention in view of the implications for screening and surveillance strategies in the growing number of patients with NAFLD
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
A large K-foiditic hydromagmatic eruption from the early activity of the Alban Hills Volcanic District, Italy
No full textIn this paper we discuss the uncommon case of an energetic, pyroclastic-flow-forming eruption with a SiO2-poor (42-45 wt.%), K-foiditic magma composition. The Trigoria-Tor de' Cenci Tuff (TTC; 561 ka) is the product of the first large-scale explosive event (of the order of 1-10 km(3) of erupted products) in the Alban Hills Volcanic District, near the city of Rome, Italy. After an initial Plinian phase that produced a scoria fall horizon, pyroclastic current activity emplaced ash deposits with leucite-bearing juvenile scoria lapilli. The abundance of accretionary lapilli, the most distinctive feature of these deposits, together with the high degree of fragmentation, the abundance of minute lithic inclusions and the morphology of ash particles, indicates a hydromagmatic character for the most part of the eruption. The absence of vent-derived carbonate lithic clasts from the deep regional aquifer and the abundance of cognate lithic fragments suggest that the interaction with external water involved a surficial aquifer in the older Alban Hills volcanic terrains. Perhaps the most striking aspect of the TTC is the K-foiditic composition of the pre-eruptive melt, which, to our knowledge, is unique among explosive events of comparable size elsewhere in the world. The pre-eruptive magma system feeding the TTC was controlled mainly by leucite+clinopyroxene fractionation under a(H2O)<1 conditions. The low SiO2 activity prevented plagioclase and K-feldspar crystallization. The depth of the magma chamber can be estimated at 3-6 km within the carbonate substrate. In contrast to the other major pyroclastic-flow-forming eruptions of the Alban Hills, the juvenile volatile exsolution due to magma crystallization is not seen as the main mechanism driving the TTC eruption. We suggest that the explosive behaviour of the TTC magma in the early magmatic phase resulted from a rapid decompression due to a regional seismic event and from magma-water interaction in the succeeding phase
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
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