1,721,071 research outputs found
Development of new analytical methods based on ICP-MS for the determination of rare earth elements in geological samples
No full textDevelopment of new analytical methods based on ICP-MS for the determination of rare earth elements in geological samples
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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
Chemical characterisation of a volcanic event (about AD 1500) at Styx Glacier plateau, northern Victoria Land, Antarctica
No full textA dark layer (similar to 1 cm thick, 93.41 m deep) was identified in an ice core (116 m deep, covering the period similar to 1350-1995) drilled at Styx Glacier plateau, northern Victoria Land, Antarctica. The ice-core section was dated around AD 1500 +/- 20 by a firn-densification model. A chemical characterisation was performed on ten subsamples (resolution 3 cm) located around the dark layer by ion chromatography. The concentration/depth profiles of anions (Cl(-), Br(-), NO(3)(-), H(2)PO(4)(-), SO(4)(2-)), cations (Na(+), NH(4)(+), K(+), Mg(2+), Ca(2+)) and some organic anions (acetate, formate, propionate and methanesulphonate (MSA)) indicate very high concentration peaks for all the components. However, non-sea-salt sulphate (nssSO(4)(2-)) and F(-) show the greatest increase with respect to background values (370 and 860 times, respectively). A crustal contribution is attributed to Ca(2+) and MSA. The profiles of gas-phase emitted substances (HF, HBr, HNO(3) and carboxylic acid) suggest gas emission just before the volcanic eruption. Chloride depletion is evident in the dark layer with respect to Na(+)/Cl(-) sea-water ratio. At present, it is not possible to attribute an unambiguous source to the volcanic event, but several pieces of evidence lead us to believe that this may be a time-limited local event
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
Identification of sources of Antarctic aerosol in Victoria Land by means of Principal components analysis of chemical data.
No full textAppropriate 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
Formaldehyde determination in seawater. Preliminary applicationto coastal samples at Terra Nova Bay (Antarctica)
Get PDFA sensitive spectrofluorimetric-FIA (flow injection analysis) method for formaldehyde (HCHO)
determination was improved with the aim of analysing seawater samples.The fluorescence emission versus
HCHO concentration shows a linear pattern from sub mg L1 to about 1000 mg L1. The reproducibility at
15 ppb level is about 2%. Interferences from other aldehydes were checked; only glyoxal shows a
significative interference, but only when its concentration is about 6000 times higher than that of
formaldehyde. Superficial (microlayer, just sub-pack or sea-ice free sea surface) and deep (along the water
column, sub-pack or in sea-ice free areas) seawater samples were collected near the coast at Terra Nova Bay
(Ross Sea, Antarctica) during the 1998/1999 and 2001/2002 Italian Antarctic Expedition. We report here the
preliminary results of the spectrofluorimetric-FIA determination of the HCHO content. The mean seawater
superficial formaldehyde concentration was 15 mg L1; the concentration along the water column ranged
between 4.5 to over 40 mg L1 (20 mg L1 mean concentration), usually with a maximum value for the 30 m
depth, corresponding to a fluorescence maximum. The sampling was repeated 7 times in the austral summer
in order to evaluate seasonal changes in the formaldehyde concentration/seawater depth profiles. The results
show changes in the formaldehyde concentration at different depths
Sources of Antarctic aerosol in Victoria Land identified by means of principal component analysis of chemical data
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