1,721,284 research outputs found
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
Copper(II) complexation of humic acids from the first generation of EUROSOILS by total luminescence spectroscopy
No full textVariations 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
Microbial taxa distribution in soil organic matter fractions with ecologically different functions
No full textIn a previous study (Zaccone et al., 2018), a preliminary evaluation of potential ecological partition of total, bacterial and plant DNA across soil organic matter (SOM) fractions linked to conceptual stabilization mechanisms was provided. Here, we investigated if different ecologically meaningful SOM fractions share the same microbial communities. To test this hypothesis, DNA was recovered from SOM pools that differ in quality and level of physical and chemical protection from decomposition: free SOM located between aggregates (FR), SOM occluded within macro (MA) and microagreggates (MI), and mineral-associated SOM (MIN) (Plaza et al., 2012). Bacterial communities were then assessed by amplification of V3-V4 region of 16S rDNA while fungal communities by amplification of ITS region. NGS was performed by Illumina Miseq platform and the sequences analysis carried out using QIIME2 v2018.6.0. Bacterial communities show a clear separation among the different SOM fractions, independently from the soil amendment (i.e., biochar, municipal compost). In particular, FR fractions were dominated by Firmicutes (70-80%), followed by Actinobacteria (10-20%) and Proteobacteria (5%). On the opposite, MA had a lower level of Firmicutes (ca. 40%) and higher level of Actinobacteria (30%) and Proteobacteria (20%). The dominance of spore forming taxa in all fractions is of interest and might be due to the better preservation of microbial DNA in the spore structure. Interestingly, the anaerobic spore-forming Clostridium spp. were mainly found in MA and MI and less in the MIN, whereas the most abundant taxa in FR were aerobic spore-formers (Bacillus spp., Brevibacillus spp.). These data clearly depose for a selection of the microbial taxa according to the level of physical and chemical protection of SOM, with O2 availability as one of the main possible drivers. Although at a less extent, also fungal population was related to the SOM pool, with MIN and FR differing from MA and MI. In conclusion, different microbial taxa (mostly bacterial) seem to be specifically associated to SOM fractions linked to conceptual stabilization mechanisms
Does physical fractionation of SOM pools preserve information about microbial taxa distribution and ecological functions?
No full textIn a previous study (Zaccone et al., Appl. Soil Ecol., 2018), a preliminary evaluation of potential ecological partition of total, bacterial and plant DNA across soil organic matter (SOM) fractions linked to conceptual stabilization mechanisms was provided. Here, we investigated if different ecologically meaningful SOM fractions share the same microbial communities. To test this hypothesis, DNA was recovered from SOM pools that differ in quality and level of physical and chemical protection from decomposition: free SOM located between aggregates (FR), SOM occluded within macro (MA) and microagreggates (MI), and mineral-associated SOM (MIN) (Plaza et al., Soil Biol. Biochem., 2013). Bacterial communities were then assessed by amplification of V3-V4 region of 16S rDNA while fungal communities by amplification of ITS region. NGS was performed by Illumina Miseq platform and the sequences analysis carried out using QIIME2 v2018.6.0. Bacterial communities showed a clear separation among the different SOM fractions, independently from the kind of the amendment applied to the soil (i.e., biochar, municipal compost). In particular, FR and MIN fractions were dominated by Firmicutes (65-75%), followed by Actinobacteria (~13%). On the opposite, MA and MI had a lower level of Firmicutes (~50%) and higher level of Actinobacteria (20-30%). Interestingly, among Bacillales, Bacillus and Brevibacillus spp. (aerobic) were largely dominant in FR and MIN, whereas the facultative anaerobic Limnochordaceae were more represented in MA and MI, and the anaerobic sporeforming Clostridium spp. Mainly in MI. These data clearly depose for a ‘selection’ of the microbial taxa according to the level of physical and chemical protection of SOM, with O2 availability as one of the main drivers. Although at a less extent, also fungal population was related to the SOM pools rather than to the amendment, with MIN and FR differing from MA and MI. In particular, Sordariomycetes are a fungal class that can represent a proxy of SOM evolution. In conclusion, (i) the physical fractionation method caused no mixing over of bacterial DNA through all SOM pools, and (ii) different microbial taxa seem to be specifically associated to SOM fractions linked to conceptual stabilization mechanisms
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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