1,721,160 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
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
Iron-induced damage in cardiomyopathy: oxidative-dependent and independent mechanisms
Full text linkThe high incidence of cardiomyopathy in patients with hemosiderosis, particularly in transfusional iron overload, strongly indicates that iron accumulation in the heart plays a major role in the process leading to heart failure. In this context, iron-mediated generation of noxious reactive oxygen species is believed to be the most important pathogenetic mechanism determining cardiomyocyte damage, the initiating event of a pathologic progression involving apoptosis, fibrosis, and ultimately cardiac dysfunction. However, recent findings suggest that additional mechanisms involving subcellular organelles and inflammatory mediators are important factors in the development of this disease. Moreover, excess iron can amplify the cardiotoxic effect of other agents or events. Finally, subcellular misdistribution of iron within cardiomyocytes may represent an additional pathway leading to cardiac injury. Recent advances in imaging techniques and chelators development remarkably improved cardiac iron overload detection and treatment, respectively. However, increased understanding of the pathogenic mechanisms of iron overload cardiomyopathy is needed to pave the way for the development of improved therapeutic strategies
Lack of macrophage ferroportin affects wound healing
No full textOBJECTIVE Alternatively activated (M2) macrophages, which are associated with inflammation resolution and tissue repair, are major players in wound healing. Since we showed that ferroportin (Fpn) expression is elevated in M2 macrophages, we investigated the role of macrophage iron in wound repair using a mouse model with macrophage-specific Fpn inactivation.
MATERIALS AND METHODS Full-thickness excisional skin wounds on the back of mice lacking Fpn in macrophages (FpnLys/Lys) and Fpnflox/flox littermates was evaluated at 2, 7, 12 days.
RESULTS Macroscopical analysis showed that wound closure was delayed in FpnLys/Lys mice compared to littermates at all time points. Histological analysis showed reduced reepithelization, predominance of immature granulation tissue, less fibroblasts and an inflammatory
infiltrate characterized by granulocytes. Moreover, in FpnLys/Lys mice, increased iron content was evident in macrophages localized in healing wounds. FACS analysis of mesenchymal (CD 45-) cells showed that at 7 and 12 days after skin excision endothelial (CD31+) cells were less in Fpn Lys/Lys mice than in Fpnflox/flox littermates, whereas no differences were found in leukocytes (CD 45+). Confocal analysis of CD31 and lyve-1 showed a defect of both blood and lymphatic vessel formation, and decreased number of myofibroblasts (α-
SMA+) cells at 7 days. Cytokine and growth factors production, evaluated by RT-PCR in 14FACS-sorted macrophages, and by ELISA in wound tissue did not differ significantly in the two mice lines.
CONCLUSION Fpn deficiency, with consequent disruption of iron export from macrophages, does not seem to change macrophage polarization but affects wound healing, possibly by impairing growth/differentiation of mesenchymal cells
Macrophages : central regulators of iron balance
Full text linkMacrophages are important to immune function and also actively participate in iron homeostasis. The involvement of splenic and liver macrophages in the processing of effete erythrocytes and the subsequent return of iron to the circulation is well established, and the molecular details of iron recycling have been characterized recently. Another important aspect regarding iron handling by macrophages is their capacity to act as immune cells, which involves the inflammatory response, as well as other pathological conditions in which macrophages are central. This review discusses the latest advances in macrophage iron trafficking and the pathophysiological consequences of altered iron homeostasis in these cells
Recent advances in iron metabolism : relevance for health, exercise, and performance
No full textABSTRACT: Iron is necessary for physiological processes essential for athletic performance, such as oxygen transport, energy production and cell division. However, an excess of “free” iron is toxic, because it produces reactive hydroxyl radicals that damage biological molecules, thus leading to cell and tissue injury. Therefore, iron homeostasis is strictly regulated, and in recent years there have been important advancements in our knowledge of the underlying processes. Hepcidin is the central regulator of systemic iron homeostasis and exerts its function by controlling the presence of the iron exporter ferroportin on the cell membrane. Hepcidin binding induces ferroportin degradation, thus leading to cellular iron retention and decreased levels of circulating iron. As iron is required for hemoglobin synthesis, the tight link between erythropoiesis and iron metabolism is particularly relevant to sports physiology. The iron needed for hemoglobin synthesis is ensured by inhibiting hepcidin, in order to increase ferroportin activity and iron availability, and hence to make certain that efficient blood oxygen transport occurs for aerobic exercise. However, hepcidin expression is also affected by exercise-associated conditions, such as iron deficiency, anemia or hypoxia, and, particularly, inflammation, which can play a role in the pathogenesis of sports anemia.Low body iron levels can cause anemia and thus limit the delivery of oxygen to exercising muscle; but tissue iron deficiency may also affect performance by, for example, hampering muscle oxidative metabolism. Accordingly, a hemoglobin-independent effect of iron on exercise capacity has been demonstrated in animal models and humans. Here we review recent advances showing the relevance of iron for physical exercise and athletic performance
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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