1,720,985 research outputs found
Mineral composition of organic and conventional white wines from Italy
No full textDespite of the increased interest of consumers for organic agro-food products and of the growing demand for organic wines, scientific literature reports a limited number of studies aimed to evaluate the chemical composition of organic wine with respect to conventional wine in terms of major and trace metals. In the present study the concentrations of 19 elements (Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, V, and Zn) were determined in samples of white wines from Italy, conventionally and organically produced. No significant difference in the mineral composition was found between the two groups, except for Ni, which showed a higher concentration in organic wines. By comparing our data with data from literature it can be pointed out that there is no agreement among the results presented in the different studies referring to comparisons between organically and conventionally produced wines, concluding that the mineral composition of wines depends on factors different from organic/conventional production method
Tree bark as a bioindicator of the presence of scandium, yttrium and lanthanum in urban environments
No full textAlthough rare earth elements (REEs) are important in modern industry, few processes use them, so the
possibility of these elements being dispersed in the environment is small. For this reason, there are few
studies on their presence in urban environments. REEs exhibit similar chemical properties, and Group 3
elements may be used as indicators of the presence of other REEs in the environment. Tree bark is a
suitable collector of airborne trace elements and has been successfully used as a bioindicator. In this
study, samples of holm oak bark were collected from three sampling sites subjected to different anthropic
pressures (one area is far from human influence, while the other two sites are urban areas
characterized by different types of human impact). The reference area is significantly different from
urban areas where the concentrations measured are up to 5 times higher (Y) than the reference area. The
differences between the two urban areas are also significant. The presence of industrial activities causes a
50% higher exposition of the population with respect to an urban area where only residential activities
are present. In the case of La, there is no significant difference between the reference and the residential
areas, while the industries are responsible for higher La concentrations (0.9 mg g-1 vs. 0.4-0.6 mg g-1).
The availability of samples, due to the wide distribution of trees in urban environments, makes possible
the production of maps indicating the sources of these elements and highlighting areas which are critical
for certain atmospheric pollutants
Annual variations in trace element levels in the atmosphere as detected in holm oak bark of branch segments
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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
Arbuscular mycorrhizae increase the arsenic tranlocation factor in the As hyperaccumulating fern Pteris vittata L
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Introduzione alla Chemiometria: La Componenti Principali, la Classificazione, la Regressione, le Reti Neurali
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