1,720,971 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
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
The Role of Plant Growth-Promoting Rhizobacteria (PGPR) in Mitigating Plant’s Environmental Stresses
No full textPhytoremediation is a cost-effective and sustainable technology used to clean up pollutants from soils and waters through the use of plant species. Indeed, plants are naturally capable of absorbing metals and degrading organic molecules. However, in several cases, the presence of contaminants causes plant suffering and limited growth. In such situations, thanks to the production of specific root exudates, plants can engage the most suitable bacteria able to support their growth according to the particular environmental stress. These plant growth-promoting rhizobacteria (PGPR) may facilitate plant growth and development with several beneficial effects, even more evident when plants are grown in critical environmental conditions, such as the presence of toxic contaminants. For instance, PGPR may alleviate metal phytotoxicity by altering metal bioavailability in soil and increasing metal translocation within the plant. Since many of the PGPR are also hydrocarbon oxidizers, they are also able to support and enhance plant biodegradation activity. Besides, PGPR in agriculture can be an excellent support to counter the devastating effects of abiotic stress, such as excessive salinity and drought, replacing expensive inorganic fertilizers that hurt the environment. A better and in-depth understanding of the function and interactions of plants and associated microorganisms directly in the matrix of interest, especially in the presence of persistent contamination, could provide new opportunities for phytoremediation
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
Dealing with complex contamination: A novel approach with a combined bio-phytoremediation strategy and effective analytical techniques
No full textPhytoremediation is a sustainable technology capable of efficiently removing low or moderate contamination. However, complex pollution conditions can drastically reduce efficiency, as plants can show themselves sensitive to organic contaminants, growing slowly and thus impairing metals' absorption. In cases where the action of indigenous bacteria degrading hydrocarbons and promoting plant growth is not sufficient, more sophisticated strategies are necessary.
This investigation aims to evaluate the effectiveness of a train of technologies that sees advanced phytoremediation in combination with other biological approaches to remediate soil from a disused industrial area contaminated by N-containing compounds, alkyl aromatic hydrocarbons, copper, and nickel. In particular, a stepwise procedure was used with a pre-treatment (landfarming and bioaugmentation), significantly affecting the soil's fertility, increasing germinability up to 85%, and allowing the plants to extract the metals adequately. Furthermore, with EDTA as a mobilizing agent, nickel absorption has increased up to 36% in Helianthus annuus and up to 88% in Zea mays. For copper, an increase of up to 262% in Helianthus annuus and up to 202% in Zea Mays was obtained. Analysis through Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry highlighted the biodegradation of some of the N-containing compounds recording, after phytoremediation, a decrease of up to almost 90%. Metagenomic analysis of the soil showed a typical microbial population of oxidizing hydrocarbon strains with a prevalence of the Nocardiaceae family (43%). The results obtained appear to confirm the usefulness of the approach developed, and the employed cutting-edge analytical techniques allowed a top-notch characterization of the remediation scenario
Improved arsenic phytoextraction by combined use of mobilizing chemicals and autochthonous soil bacteria
No full textProper plant selection and application of suitable strategies are key factors to ensure the effectiveness of a reclamation via phytoremediation approach. In this study, micro- and meso-cosm scale experimentation has been realized to address a persistent contamination by arsenic on a disused industrial site through an assisted phytoremediation intervention. Three crop species, namely Brassica juncea, Helianthus annuus and Zea mays, have been considered and the addition of K2HPO4, a common mobilizing agent for As, or (NH4)S2O3, a promising additive for As mobilization in case of mercury co-presence, evaluated. The use of these additives significantly enhanced the bioavailability of the target contaminant and therefore its phytoextraction up to 80%. Furthermore, in order to maximize the extraction efficiency of the plants, the influence of five indigenous Plant Growth Promoting Bacteria (PGPB), in combination with the mobilizing agents, was measured. The addition of the microbial consortium led to a further increase in the total uptake of arsenic, especially in B. juncea (up to 140%). The combined strategy supports and enhances the arsenic phytoextraction together with an improvement of the soil quality, as shown by phytotoxicity tests
CO2 footprint analysis of consolidated and innovative technologies in remediation activities
No full textEffective remediation of contaminated soil requires selecting appropriate technology and adequate strategies. However, activities aimed at the remediation of contaminated sites or the treatment of effluents also have an environmental impact, since they make significant use of chemical products or processes.
In the present work, the potential application of different remediation approaches to a real problem of heavy metal contamination was studied by examining the consequences of their environmental impact through a Life Cycle Assessment (CO2 footprint analysis) procedure, with the aim of identifying the least impacting option from an environmental point of view. Phytoremediation (with various options for the disposal of the biomass generated) and the electrokinetic approach (powered by renewable and non-renewable sources) were compared with soil washing (off-site, or ex-situ on-site) and excavation and landfill disposal (commercial or municipal waste). In all cases, the environmental impacts were reported in terms of global warming potential over a period of 100 years and normalized to the cubic meter of soil to be remediated. The analyses considered each process in its entireness (from cradle to grave) and an application on the whole area of the site to be reclaimed (an area of about 700 m2 located in an abandoned industrial district in Tuscany, Italy, and considered a “site of national interest”).
The results obtained for each technology were then compared, highlighting those phases, activities and materials that present the greatest impacts for each approach (both in relative and absolute terms) and thus revealing aspects that would otherwise have been difficult to notice, such as the weight of chelating agents in phytoremediation or the use of energy from renewable sources for the electrokinetic approach. The resulting increase in knowledge on the technologies considered opens the way for further “eco-compatible” changes and improvements
Green Remediation for the Sustainable Management of Oil Spills in Agricultural Areas
No full textSpills of petroleum products resulting from illegal pipeline extraction also affect agricultural areas. These areas
must be subject to remediation interventions to bring the concentrations of contaminants below the alarm levels
and avoid further damage to the environment and living beings. In these cases, green technologies such as
bioremediation and phytoremediation are an excellent approach to reduce impacts on agriculture. This
contribution evaluates the effectiveness of combining some green techniques in managing soil contaminated by
oil spills. A feasibility test of phytoremediation at a microcosm scale with three plant species (corn, lupine and
alfalfa) was conducted, combining the approach with plant growth-promoting rhizobacteria (PGPR). Particular
attention was given to the reclamation from polycyclic aromatic hydrocarbons (PAHs). At the end of the
experiments, biomass production and PAHs concentration in the soil and plants (roots and aerial parts) were
determined. The remediation strategy was aimed at two concurrent objectives: the need to remove the maximum
amount of contaminants from the soils affected by oil spills and the restoration of the agricultural activity to be
carried out in absolute safety. The results show a decrease in the concentration of hydrocarbons in the soil
favored by the presence of tested plants, which manage to grow satisfactorily on the soil under examination,
albeit with an inevitable decrease in yield compared to uncontaminated soil. Looking at the concentration of
pyrene, which is usually considered as indicator of PAHs contamination, the removal reaches values higher
than 50 % in vegetated soils. The addition of the selected PGPR counteract the negative effect of contamination,
favoring the growth of plants and allowing the production of fresh biomass comparable to that obtained on the
uncontaminated control soil. This results in a further reduction of the contaminant in question up to an additional
20 %. Therefore, the presence of organic contaminants can be concretely reduced in a sustainable and cost-
effective way by the joint action of plants and microorganisms that promote the processes of rizodegradation
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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