186,724 research outputs found
Authigenic iron sulphides in recent sediments of the Venice Lagoon (northern Italy)
No full textThe data indicate early formation of microcrystalline pyrite, in both the framboids and the grains which are disseminated in the organic matter; it is frequently surrounded by massive pyrite growths and/or mixed Fe sulphides. Authigenic Fe sulphide formation in recent sediments (10-30 years old) in the Venice Lagoon is due to the anoxic conditions which seasonally affect the surface sediments and lead to interactions between reactive iron in solution and H2S. Iron may also be solubilized in a reducing environment from ferric hydroxides adsorbed on clays, from organo-metallic complexes, or directly by reduction of clastic grains of Fe oxides and hydroxides; H2S is produced in the same environment by bacterial reduction of sulfates in the pore-water. -from Author
An haematite slab from Central Europe found at the epigravettian site of Bus de La Lum (Venetian Pre-Alps).
No full textNew data regarding Lithostratigraphy and Metamorphism of the Steinach Nappe (Brenner region, Eastern Alps)
No full textDistribuzione di Fe, Mn, Ti, P, Cr, Zn, Cu, Pb nei suoli delle vulcaniti ladiniche delle alpi Vicentine. Rapporti fra magmatismo medio-triassico e mineralizzazioni piombo-zincifere del Recoarese.
No full textWith the aim of solving the problem of the metallogenesis of the Middle Triassic Pb-Zn deposits of the Alps, an investigation was begun on the distribution of some significant elements in the soils of the Ladinian volcanics of the Recoaro area. Analysis of an initial group of elements indicates: 1) the existence of geochemical correlations between soils and host rocks with, in both cases, increasing Fe, Ti, Cu and Cr contents towards more basic rocks; 2) local anomalies and a large area rich in Pb, Zn + or - Cu, due to disseminated sulphides or vein concentrations in the volcanics or in masses at the contact between these and the Anisian limestones; 3) correspondence between abnormal areas and zones of volcanic propylitization and argillification. S and metals are related to the residual fluids resulting from crystallization of deep magmatic masses which crossed the volcanics, giving rise to intense transformations and sulphide deposition. -J.M.H
The ancient mine of Servette (Saint-Marcel, Val d'Aosta, Western Italy): a mineralogical, metallurgical and charcoal analysis of furnace slags.
No full textThe Cu–Fe mining district of Servette is located in the valley of Saint-Marcel (Val d’Aosta)
at about 1800 m a.s.l. in the western Italian Alps. A large furnace slag deposit occurs near
the Servette mine. Slags are mainly constituted by silicate and oxide in a glassy matrix, with
disseminated sulphides and iron–copper alloys, and they record temperatures of 1380–
1100
°
C. Radiocarbon dating of slag charcoals has shown that metallurgy in this site took
place around
AD
890–980. The charcoal analysis has shown that coniferous wood was
mainly utilized, and intensive exploitation over the centuries led to a change in the
composition of the local woods
Sulphide speciation in surface sediments of the Lagoon of Venice: a geochemical and minerographic study
No full textAuthor-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
- …
