1,720,969 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Dinamiche post-incendio in rimboschimenti di conifere dell'Appennino centrale L'importanza della necromassa nel processo di ricostituzione naturale
No full textLate frosts effects on Mediterranean beech forests: insights from tree rings
No full textBeech is one of the most important European broadleaved trees. It is a mesic species tolerant to very cold winters, but sensitive to late spring frost and to summer drought. Phenological observations show that beech unfolding is occurring up to 3.5 days earlier per decade, increasing sensitivity to spring frost events. We aimed to assess i) how frequent and spatially extended are severe late-frost events at some Mediterranean beech forests during the last decades; ii) how their effects are recorded in tree-ring width series. Upon literature and satellite image analysis we selected a few sites that experienced recent frost events in the Central and Southern Apennines, Eastern Italian Pre-Alps and central Spanish Pyrenees. At each site, we sampled 60 dominant beech trees within 3 plots located along an altitudinal gradient to detect different frost damage intensity. We extracted cores for dendrochronological analyses searching for specific markers to identify late frost damages. Our first results, compared with other beech chronologies, show that in central and southern Apennines two documented late frost events (in 1957 and 2016) caused tree-ring different growth responses along the elevation gradient. In some sites frost caused tree-ring reduction only at mid and high altitudes whereas in others high altitudes trees were not affected. This can be explained with a thermal inversion or with a delay of the leaf unfolding at higher altitudes. Finally, beech forests sensitivity to late frosts seems locally controlled by stand altitude and aspect that modulate tree phenology, leaf damage intensity and xylogenesis
Variations on the Author
Get PDF“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
Dinamiche post-incendio in rimboschimenti di conifere dell'Appennino centrale L'importanza della necromassa nel processo di ricostituzione naturale
No full textBurn Severity Drivers in Italian Large Wildfires
Get PDFThe increase of wildfire incidence in highly populated areas significantly enhances the risk for ecosystems and human lives, activities and infrastructures. In central and southern Italy, recent decades' fire records indicate that 2007 and 2017 were extreme years in terms of the number of fires and total burned area. Among them, we selected large fire events and explored their features and drivers of burn severity. We used a standardized extraction procedure to identify large wildfires (>100 ha) from the MODIS burned areas database and Landsat multi-spectral images. We mapped burn severity with the Relative Difference Normalized Burn Ratio index and explored the main drivers of severity using topographic, land-cover and anthropogenic predictors. We selected 113 wildfires for a collective total burned area of over 100,000 ha. Large fires were more frequent in the southern than in the central and northern regions, especially in July and August. The average fire size was about 900 ha and occurred mainly in shrublands (30.4%) and broadleaf forests (19.5%). With a random forest model, we observed that the highest severity occurred in conifer plantations and shrublands, in highly populated areas and at lower elevations. Burn severity models, at the landscape or regional scales, can be very useful tools for pre- and post-fire forest management planning
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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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