1,720,972 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
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Impact of Eisenia fetida earthworms and biochar on potentially toxic element mobility and health of a contaminated soil
Full text linkThis study aimed to evaluate the influence of Eisenia fetida (Savigny), added to an acidic soil contaminated with potentially toxic elements (PTEs; As, Sb, Cd, Pb, Zn) and amended with a softwood-derived biochar (2 and 5% w/w), on the mobility of PTEs and soil health (i.e. nutrient availability, enzyme activity and soil basal respiration). The PTEs bioaccumulation by E. fetida and the acute ecotoxicity effects of the amended soils were also evaluated. The interaction between earthworms and biochar led to a significant increase in soil pH, organic matter, dissolved organic carbon content, cation exchange capacity, and exchangeable Ca compared to the untreated soil. Moreover, the water-soluble and readily exchangeable PTE fraction decreased (with the exception of Sb) between 1.2- and 3.0-fold in the presence of biochar and earthworms. Earthworms, biochar, and their combination, led to a reduction of phosphomonoesterase activity which in soils amended with biochar and earthworms decreased between 2.2- and 2.5-fold with respect to the untreated soil. On the other hand, biochar and earthworms also enhanced soil basal respiration and protease activity. Although the survival rate and the weight loss of E. fetida did not change significantly with the addition of 2% biochar, adding the highest biochar percentage (5%) resulted in a survival rate that was ~2-fold lower and a weight loss that was 2.5-fold higher than the other treatments. The PTE bioaccumulation factors for E. fetida, which were less than 1 for all elements (except Cd), followed the order Cd>As>Zn>Cu>Pb>Sb and were further decreased by biochar addition. Overall, these results highlight that E. fetida and biochar, especially at 2% rate, could be used for the restoration of soil functionality in PTE-polluted environments, reducing at the same time the environmental risks posed by PTEs, at least in the short time
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
Mobility, bioaccessibility and toxicity of potentially toxic elements in a contaminated soil treated with municipal solid waste compost
No full textThe aim of this study was to assess the influence of a municipal solid waste compost (MSWC) on the mobility,bioaccessibility and toxicity of several potentially toxic elements (PTE), i.e. Pb (15,383 mg kg−1), Zn(4076 mg kg−1), Cu (181 mg kg−1), Sb (109 mg kg−1), Cd (67 mg kg−1) and As (49 mg kg−1), present in acontaminated sub-acidic soil (pH = 5.93).The addition of MSWC at 2 and 4% rates significantly decreased the labile fractions of PTE (with the ex-ception of Cu and As) and at the same time increased the residual fractions of Zn and Sb. In-vitro tests alsoshowed that compost amendment was able to decrease Cd and Cu gastric bioaccessibility, with respect to un-treated soil (−19 and 13% of Cd and Cu in MSWC-4% respectively), while a significant increase of As intestinalbioaccessibility was recorded. This increment was attributed to the pH rise (up to 7.0) during the in-vitro in-testinal phase, which likely favoured a release of the arsenic non-specifically bonded to MSWC. Soil enzymeactivities, i.e. dehydrogenase andβ-glucosidase, were significantly enhanced in MSWC-amended soils (i.e. up to~6.0 and 1.4 times higher in MSWC-4% than in control soil, respectively), as well as soil basal respiration, andthe potential metabolic activity and catabolic versatility of soil microbial communities (as assessed by the Biologecoplate community level physiological profile).Overall, the results obtained suggested that MSWC, particularly at 4% rate, could be useful to stabilise PTE insub-acidic contaminated soils and to increase the microbial activity and functionality in these latter soils
Germination and seedling development of selected Mediterranean aromatic plants in heavy metal contaminated soils: A preliminary study for the recovery of mining sites in Sardinia
No full textMining has caused serious contamination issues worldwide. Abandoned mines release toxic elements into the environment and generate pollution, with potential consequences for plant and human health. The aim of this research was to explore the influence of heavy metal contaminated soils from former mining sites in Sardinia (Italy) on the germination and seedling development of six aromatic plant species common to the Mediterranean area. Contaminated soils were retrieved from two sites in Sardinia (Italy): site 1 (Montevecchio, MV) was polluted by As, Cd, Cu, Pb, Sb and Zn, while site 2 (Su Suergiu, SS) by As, Pb, Sb and Zn. A significant impact was observed on most of the germination and seedling parameters between species and treatment. Su Suergiu soil had a dramatic effect on Achillea millefolium, Artemisia dracunculus and Thymus vulgaris, showing > 85 % rate of seedling death after germination. Based on germination and biomass parameters, Salvia officinalis emerged as the most tolerant species in both contaminated soils, as evidenced by the lowest seedling death rate (<5 %) and the highest vigor. Labile As, Sb and Zn in SS soils had a clear negative impact on the seed germination and seedling development. Overall, Ocimum basilicum and Salvia officinalis were identified as potential candidates for the remediation and agricultural redevelopment of heavy-metal contaminated soils
Sb(V) adsorption and desorption onto ferrihydrite: influence of pH and competing organic and inorganic anions
No full textIn this study, we investigated the Sb(V) adsorption on ferrihydrite (Fh) at different pH values, in the presence and absence of common competing anions in soil such as phosphate (P(V)) and arsenate (As(V)). Batch adsorption experiments, carried out at pH 4.5, 6.0, and 7.0, showed a greater affinity of Fh towards P(V) and As(V) with respect to Sb(V), especially at higher pH values, while the opposite was true at acidic pH. The capacity of Fh to accumulate greater amounts of phosphate and arsenate in the 6.0–7.0 pH range was mainly linked to the different acid properties of P(V), As(V), and Sb(V) oxyanions. The Sb(V) adsorption on Fh was highly pH-dependent and followed the following order: pH 4.5 (0.957 mmol·g−1 Fh) > pH 6.0 (0.701 mmol·g−1 Fh) > pH 7.0 (0.583 mmol·g−1 Fh). Desorption of antimonate from Sb(V)-saturated Fh, treated with citric and malic acid solutions, was ~equal to 55, 68, and 76% of that sorbed at pH 4.5, 6.0, and 7.0, respectively, while phosphate, arsenate, and sulfate were able to release significantly lower Sb(V) amounts. The FT-IR spectra revealed substantial absorbance shifts related to the surface hydroxyl groups of Fh, which were attributed to the formation of Fe-O-Sb(V) bonds and supported the formation of inner-sphere bonding between Sb(V) and Fh
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Biochar and Eisenia fetida (Savigny) promote sorghum growth and the immobilization of potentially toxic elements in contaminated soils
Full text linkBiochar is a soil amendment capable of influencing plant growth and potentially toxic elements (PTEs) bioavailability in soils. At the same time Eisenia fetida (Savigny) is able to interact with biochar influencing its performance. As such they could constitute a resource for assisted phytostabilisation of PTE-polluted soils. To this end, a softwood-derived biochar was added at 2 and 5% (w/w) rate, with and without E. fetida, to a soil contaminated with Cd, Pb, Zn, As, and Sb, to evaluate the PTE phytostabilisation potentials when combined with Sorghum vulgare. The combination of sorghum, 5% biochar, and earthworms reduced the mobility of most PTEs in soil (e.g., up to 65% and 60% for Pb and Zn), while sorghum biomass was greatly increased (i.e., ~ 3- and 2-fold for roots and shoots, respectively).
Biochar addition alone reduced the PTE uptake by plants, while the presence of earthworms slightly increased it. Overall, the joint action of biochar and earthworms increased the PTE removal efficiency by S. vulgare compared to control plants (e.g., the amount of root As, Pb and Sb was ~ 5-, 4- and 3-fold higher, respectively). Although 2% biochar didn’t affect E. fetida fitness, the highest biochar rate (5%) exhibited toxic effects (the survival rate reduced by ~2-fold; weight loss increased by ~3-fold). Taken together, these results indicated that S. vulgare, in combination with softwood biochar and E. fetida, could be used for the assisted phytostabilisation of PTEs contaminated soils
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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