1,720,962 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
Percutaneous metals absorption following exposure to road dust powder
Full text linkThe skin constitutes a protective barrier to external physical and chemical aggressions. Although it is constantly exposed to various xenobiotics, it is generally considered poorly permeable to them, as for example metal ions, becoming unfortunately an entry route of such substances. Metals may penetrate inside the skin inducing more or less local effects such as skin sensitization and potential metals diffusion into the bloodstream. The objective of the study was to investigate the percutaneous penetration of metals in vitro - ex vivo in Franz cell with intact as well damaged skin applying a road dust powder. Moreover, porcine and human skins were compared. This study demonstrated that, after the application of a road dust powder on the skin, metals can penetrate and permeate this cutaneous membrane. From this experimental analysis, in intact skin lead (Pb) achieved the highest skin absorption in both human and porcine skin, while skin absorption profile of cobalt (Co) was the lowest in human skin than the one in porcine model. The concentrations of Ni present in receiving solution were higher compared to other metals in all experiments performed. The present work, definitely shows that metals permeation through damaged skin is accelerated than intact skin, as a result of the weaker cutaneous barrier function. According to published data, pig skin appeared as a suitable model for human skin. Our results confirmed that skin absorption of metals can be relevant in environmental exposures
May biochar be a suitable amendment to mitigate mercury availability from contaminated sediments? Preliminary evidences from leaching and incubation experiments
No full textMercury (Hg) methylation and methylmercury (MeHg) production in sediments represent an environmental issue of concern due to potential bioaccumulation of MeHg along the trophic chain. These processes are especially enhanced in semi-confined aquatic systems where scarce water circulation, high organic matter production and frequent hypoxia/anoxia events may promote Hg mobility and methylation. In this context, the application of sustainable sorbent amendments may be an affordable and low impact remediation approach to mitigate Hg bioavailability.
This study is focused on the Marano and Grado Lagoon (northern Adriatic Sea, Italy), which is known to be contaminated with Hg from the second largest Hg mine worldwide (Idrija, Slovenia) and from a decommissioned chlor-alkali plant. Although the biogeochemical behaviour of Hg has been intensively investigated in this area, key information is lacking to understand if in situ sustainable remediation may be successfully employed to mitigate Hg mobility in porewaters and potential MeHg production.
The aim of this study is to preliminary evaluate the application of vineyard pruning residues biochar on Hg contaminated sediments at a selected fish farm, one of the most productive sites devoted to aquaculture in the lagoon. Leaching tests were performed on biochar to evaluate the potential release of major and potentially toxic elements (PTEs) in solution. For porewater and sediment characterisation, two short sediment cores were collected and the surface sediment layers (0-5 cm) were extruded under an inert atmosphere: one was amended with biochar (3 % w/w) and one was untreated (control sample). Both samples were divided into different aliquots and incubated until 6 months. Porewaters were periodically extracted from both untreated and amended sediment samples and chemical analyses were performed on solid and dissolved fractions to evaluate the effect of biochar on the mobility of Hg, MeHg and other PTEs
Combining synchrotron radiation techniques for the analysis of gold coins from the Roman Empire
Full text linkFour gold coins minted in the V century have been studied with non-destructive synchrotron radiation techniques, namely X-Ray Fluorescence (XRF) and X-ray Absorption Near Edge Spectroscopy (XANES). XRF data analyzed coupling standard and statistical methods were used to distinguish the composition of the alloy constituting the coins from that of successive deposits processes. Our analysis presents a quantification of the trace elements present in the metallic alloy providing interesting details for historical insight. Furthermore, on the basis of the XRF maps, some regions of interest were selected for XANES at the K-edge of Fe. Our analysis of the Fe spectra points out two main phases which can be related to Fe oxides naturally present in soil. From the relative abundance of these oxides, information on the site where the coins were found can be obtained, providing additional information on their fate across the centuries
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
Skin absorption of metals following exposure to road dust powder
Full text linkHuman skin forms a unique interface between the body and the external environment. Its main role is to protect the internal organs from external factors. Notably, the outermost skin layer, stratum corneum, forms a remarkable barrier for permeation of xenobiotics in general, but unfortunately it may become an entry route of hazardous substances. Metals can penetrate and permeate the skin inducing local effects such as skin sensitization with allergic contact dermatitis and potential metals diffusion into the bloodstream with systemic intoxication[1] [2].
Metals in nano dimensions penetrate and permeate the skin in higher amount[3] [4] compared to bulk materials due to their smaller dimensions[5].Therefore, if the stratum corneum is damaged to various factors such as inflammation, desquamation, defects in lipid distribution or epidermal thickening, the transcutaneous passage of a molecule is expected to be drastically enhanced[6] [7]. In this study, we investigate the percutaneous penetration of metals from the road dust powder in intact as well damaged skin to mimic the effect of skin lesions. In addition, porcine and human skin were compared as skin models. The certified reference material BCR®-723 provided by the European Institute for Reference Materials and Measurements was used as road dust formulation. To evaluate the extent of
ionization of metals from BCR®-723, the dissolution of powder in synthetic sweat solutions at two different pH (pH 4.5, 6.5) was carried out. Periodic quantification of metals concentration was monitored and analyzed via inductively coupled plasma - optical emission spectroscopy (ICP-OES). The choice of synthetic sweat solution at pH 4.5 was dictated to reproduce the workplace conditions.
Dermal absorption from donor compartment containing metals was monitored for 24 hours. The amounts of metals retained in skin were quantified post-exposure by inductively coupled plasma - mass spectrometer (ICP-MS). Percutaneous absorption of lead (Pb) was higher in both intact skin models (549 ng/cm2 in porcine skin vs 68.80 ng/cm2 in human model). Moreover, cobalt (Co) accumulation was higher in porcine skin reaching a value of 518 ng/cm2 than those found in human skin (1.85 ng/cm2). In contrast with the observations reported in human skin model, chromium (Cr) achieved the lowest skin absorption in porcine model (183 ng/cm2). As expected, metals permeation on damaged skin was enhanced due to the removal of the barrier function. These consequence differences may be due to the skin tissues, but pig skin appeared as the most suitable replacement for human skin
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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