1,720,960 research outputs found
Risultati di un'indagine limnologica: le comunità algali del lago "la Stua" (Parco Nazionale Dolomiti Bellunesi
No full textDiatoms in very-shallow pools of the site of community importance danta di cadore mires (South-Eastern Alps), and the potential contribution of these habitats to diatom biodiversity conservation
No full textMires are very selective habitats, and the colonisation by specifically adapted organisms makes them very important both for nature conservation and environmental education. They have, however, been threatened by different types of impacts. Our objective was to study diatoms in stations representative of the main typologies in the Site of Community Importance IT3230060 "Danta Mires", also to produce data for a management plan in the frame of a Life Project. Five shallow pools within different mountain mires were sampled in summer 2005 and morphologically and physicochemically characterized. The sampled sites cover a rather wide pH and TDS content gradient with very low nitrate and silica values. Diatoms were found to dominate in terms of numbers of taxa, followed by desmids, cyanoprokaryotes and filamentous green algae. In total, 86 diatom taxa, belonging to 35 genera, were found. As expected for acidic, low-mineralization waters the genera with the highest number of taxa were Eunotia and Pinnularia, followed by Encyonema, Cymbopleura, Gomphonema, and Nitzschia. The most frequent and abundant taxa were: Frustulia crassinervia, Nitzschia acidoclinata, Kobayasiella micropunctata, Encyonema neogracile, Brachysira brebissonii, Nitzschia perminuta, and Encyonema lunatum. Taxa abundant only in one or few sites were: Eunotia paludosa, Staurosira spinarum, Encyonopsis cesatii, and Achnanthidium minutissimum. Several rare taxa of special interest for their distribution and/or rarity could be found (e.g. Chamaepinnularia schauppiana, Cymbopleura incertiformis var. linearis, C. subapiculata, Eunotia lapponica, Microfissurata paludosa). On average, 17 taxa per site were found. The highest number (26) was found in a sediment sample taken in a site with special hydrochemical characteristics, and the minimum (11 taxa) in the sediment sample of the demolition materials dump mire. Diatom communities allowed characterising the mire pools studied as oligotrophic, acidic environments often affected by desiccation. On the basis of the autecology and distribution of the most frequent and abundant taxa, pH and hydroperiod appeared to be the most relevant environmental determinants. A striking result, also in view of eventual management consequences, was the very high proportion (72%) of rare and Red List taxa (including also species of the categories "Threatened with extinction", "Severely endangered", and "Endangered"). To preserve diatom biodiversity, these mires must be sheltered from uses other than recreational ones, and abrupt changes in hydrological regime and increases in nutrient input must be prevented. © 2011 J. Cramer in Gebr
Occurrence of PAH in the seasonal snowpack of the Eastern Italian Alps
No full textPAH concentrations have been determined in 47 seasonal snowpack samples collected in the Valbelluna
valley and in the Bellunesi Dolomites National Park, in the Italian North-Eastern Alps, during the winter
of 2005. The sum of PAH concentration in high-altitude alpine sites (above 1700 m) was 32 +- 20 ng/kg while in
valley bottom urban areas it was 165 +- 54 ng/kg with maximum values of 290 ng/kg. The GIS mapping
technique was employed to produce a PAH spatial distribution. The urbanized Valbelluna valley, and in
particular the SW part, had the highest accumulation of all PAH, with values an order of magnitude more
than those in rural and alpine areas. This behaviour is consistent with urban air quality data, and is due to
geo-morphological and meteorological factors such as the deeper shape of the valley at the position of
the town of Feltre and the low altitude of the boundary layer during the winter season
Evoluzione a lungo termine delle caratteristiche chimiche e del fitoplancton nel Lago di Garda
No full text
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
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
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