1,720,987 research outputs found
Late Holocene environmental dynamics, vegetation history, human impact, and climate change in the ancient Literna Palus (Lago Patria; Campania, Italy)
No full textA new late-Holocene high-resolution pollen record is presented from Lago Patria with the aim of investigating past vegetation and environmental dynamics in a still under-investigated coastal sector of the Campania region (Italy). Our results showthe evolution of amixed deciduous and evergreen oak-dominated lowland forest, rich in both xeric and mesicwoody taxa, under the influence of climate, human impact, geomorphic processes and their interplay. Between 4800 and 2800 cal BP, the pollen record highlights only slight vegetation changes, featured by amodest forest decline around 4200 cal BP, consistent with the deforestation pattern produced by the 4.2 ka arid climate event in southern and central Italy. This event was followed, between 3900 and 3300 cal BP, by a forest recovery with a remarkable development of mesic trees, notably Fagus, influenced by wet climate conditions. While Bronze Age and Iron Age settlements are missing from this coastal area, which suggests a marginal role of human activity in the environmental changes of this period, the continuous presence of anthropogenic pollen indicators in the pollen record stimulates new archeological investigations. Between 2800 and 2200 cal BP, the area experienced successive domination by Greek, Etruscan, Italic and Roman populations, culminating with the foundation and expansion of cities like Cumae, Capua, and Dicearchia/Puteoli, which determined major impact on the natural forest through intense agricultural practices. After a sedimentation hiatus between 2200 and 180 BP, the pollen record documents a few tens of years, during the Bourbon domination, when the vegetational landscape, characterized by cultivations and pasturelands, appears almost completely treeless. Pollen and other palynomorphs of aquatic taxa evidence a change from freshwater to brackish conditions, consistent with the transition from cat's eye freshwater ponds to open lagoon
Post-fire erosion response in a watershed mantled by volcaniclastic deposits, Sarno Mountains, Southern Italy
No full textIn this study we document a post-fire erosion response to a short-lived, intense rainstorm occurred on 6 September 2012 in the Sant'Angelo creek watershed, Sarno Mountains, Southern Italy. The rainstorm occurred one month after a wildfire that burned about 11 ha of the steep watershed (55 ha), almost entirely mantled by volcaniclastic deposits. The research was based on fieldwork and laboratory analysis addressed to the understanding of the geomorphic effects of the wildfire and their impact on erosional and depositional processes triggered by subsequent rainstorms. Field evidence indicates that a series of overland flows caused significant runoff and sediment yields along the hillslope and accumulation of hyperconcentrated flow deposits in a concrete channel occluded by a sealed culvert at the outlet of the watershed. The results of geomorphological and sedimentological analysis suggest that the occurrence of volcaniclastic covers mantling the slopes likely favored accelerated soil erosion, especially where vegetation and litter had been removed by the fire. Chemical analysis on sediment samples, revealed the occurrence of iron oxides that enhanced soil water repellency conditions over wide areas of the burned watershed compared to the unburned areas. Quantitative analysis of sediment budgets showed that the rainfall-induced erosion response at Sant'Angelo creek watershed resulted in a soil loss of 19.8–33.1 tons ha− 1 over burned areas. Post-fire erosion response following severe rainstorms needs to be considered in the spectrum of natural hazards associated with the geomorphological evolution of mountainous landscapes mantled by volcaniclastic deposits
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
Elaborazione delle analisi granulometriche: metodologie e tecniche. Il Granulometro Laser
No full textAppropriate 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
Interplay between sea level rise and tectonics in the Holocene evolution of the Sant'Eufemia Plain (Calabria, Italy)
No full textA multi-proxy approach has been adopted to reconstruct the Holocene history of the St. Eufemia Plain (western Calabria, Italy) and to discern the influence that sea level rise and tectonics exerted in its evolution. Sedimentological, paleoecological and palynological data have been obtained from a 24-m long core, mostly made of pelitic back-barrier sediments, chronologically constrained by twelve AMS 14C dates. Radiocarbon ages of lagoon samples have been corrected by taking into account the influence of both the marine and hardwater effect on the reservoir age. The new data have been integrated with those of pre-existing stratigraphies in order to better characterize the overall sedimentary architecture of the plain. In the early Holocene (from ca. 8300 to ca. 6900 yr cal BP), eustasy largely prevailed on the tectonic uplift, causing coastline ingression and aggradation. From ca. 6900 to ca. 2800 yr cal BP, coastline progradation and aggradation were driven by high detrital inputs and slowdown of sea level rise, during a phase characterized by a general weak subsidence. From ca. 2800 to ca. 1400 yr cal BP, higher rates of subsidence favored the establishment of marsh and flooded alluvial plain environments in the back-barrier domain. After ca. 1400 yr cal BP, a substantial stability characterized the St. Eufemia Plain
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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