1,720,964 research outputs found
Trace elements in daily collected aerosol: levels characterization and source identification in a four-year study
No full textAtmospheric particulate concentrations were measured at an industrial site in southern Italy from September 2001 to December 2004. In this period, we collected 741 daily samples of PM2.5 by means of a low-volume gravimetric automatic sequential sampler. The 24-h PM2.5 samples were analysed for heavy metal content (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn). We also measured temperature, relative humidity, wind speed and wind direction. Data analysis was performed with univariate and multivariate statistical methods. Principal component analysis and cluster analysis were applied in order to point out the correlation structure among particulate concentrations and heavy metal content and to highlight source profile characterization. In order to discriminate between natural and anthropogenic origin of the trace elements, we also applied the enrichment factor method. In the investigated period, PM2.5 concentrations ranged from 0.04 μg m− 3 to 117 μg m− 3, with a mean value of 13 μg m− 3 and a median value of 10 μg m− 3. A mix of different source emissions and different meteorological conditions may determine this large variation in PM2.5 values. Regarding heavy metal levels, we observed that they decreased during the four years assuming the lowest values in 2004. All the measured elements, except Mn, showed high values of the enrichment factor, suggesting a prevailing anthropogenic origin. The analysis of the relationships among pollutant concentrations and meteorological parameters showed that they were influenced by wind speed and relative humidity. The multivariate analysis allowed us to identify two source profiles for heavy metals. The first profile was characterized both by elements typical of soil dust and crustal material (Fe, Mn) and by elements typical of industrial processes (Ni, Cr and Cu). The second profile was characterized by Pb, Zn and Cd and it may be mainly related to exhaust emissions from both gasoline and diesel fuelled road vehicles
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
Lidar and punctual observations for the characterization of the Saharan dust impact on PM10 levels
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The contribution of the scientific research for a less vulnerable and more resilient community: the Val d’Agri (Southern Italy) case
No full textThe increasingly intensive use of natural resources with consequent environmental impacts has generated numerous social conflicts over the years, for whose solution it is necessary to build up an innovative territorial governance model based on sustainable and resilience thinking. At the international level, the problems associated with oil and gas extraction activities have been tackled by recognizing scientific research as a strategic role aimed at guaranteeing a more in-depth knowledge of environmental issues, the creation of collaboration networks between the various stakeholders and the whole usability of environmental data. This article presents the commitment made by the National Research Council of Italy–Institute of Methodologies for Environmental Analysis–CNR-IMAA to make the Val d’Agri community, an area affected by mining activities, less vulnerable and more resilient. Through the combined use of different scientific research methodologies, a multidisciplinary approach was developed which contributed to increasing the overall knowledge of the environmental problems of Val d’Agri as well as providing concrete indications for the development of more effective territorial management tools. Other activities, complementary to those of research, were aimed at ensuring correct and detailed environmental data information and communication and a broaden participation and involvement of citizens
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