1,720,970 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
Presynaptic enzymatic neurotoxins
No full textBotulinum neurotoxins produced by anaerobic bacteria of the genus Clostridium are
the most toxic proteins known, with mouse LD50 values in the 1-5 ng/kg range, and
are solely responsible for the pathophysiology of botulism. These
metalloproteinases enter peripheral cholinergic nerve terminals and cleave
proteins of the neuroexocytosis apparatus, causing a persistent, but reversible,
inhibition of neurotransmitter release. They are used in the therapy of many
human syndromes caused by hyperactive nerve terminals. Snake presynaptic PLA2
neurotoxins block nerve terminals by binding to the nerve membrane and catalyzing
phospholipid hydrolysis with production of lysophospholipids and fatty acids.
These compounds change the membrane conformation, causing enhanced fusion of
synaptic vesicle via hemifusion intermediate with release of neurotransmitter
and, at the same time, inhibition of vesicle fission and recycling. It is
possible to envisage clinical applications of the lysophospholipid/fatty acid
mixture to inhibit hyperactive superficial nerve terminals
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
Analogs of a natural peptaibol exert anticancer activity in both cisplatin-and doxorubicin-resistant cells and in multicellular tumor spheroids
Full text linkPeptaibols, by disturbing the permeability of phospholipid membranes, can overcome anticancer drug resistance, but their natural hydrophobicity hampers their administration. By a green peptide synthesis protocol, we produced two water-soluble analogs of the peptaibol trichogin GA IV, termed K6-Lol and K6-NH2. To reduce production costs, we successfully explored the possibility of changing the naturally occurring 1,2-aminoalcohol leucinol to a C-terminal amide. Peptaibol activity was evaluated in ovarian cancer (OvCa) and Hodgkin lymphoma (HL) cell lines. Peptaibols exerted comparable cytotoxic effects in cancer cell lines that were sensitive—and had acquired resistance—to cisplatin and doxorubicin, as well as in the extrinsic-drug-resistant OvCa 3-dimensional spheroids. Peptaibols, rapidly taken up by tumor cells, deeply penetrated and killed OvCa-spheroids. They led to cell membrane permeabilization and phosphatidylserine exposure and were taken up faster by cancer cells than normal cells. They were resistant to proteolysis and maintained a stable helical structure in the presence of cancer cells. In conclusion, these promising results strongly point out the need for further preclinical evaluation of our peptaibols as new anticancer agents
Role of dystrophin and dystrophin-associated proteins in the pathogenesis of muscular dystrophies.
No full textShining Light on Carbon Dots: New Opportunities in Photocatalysis
Full text linkPhotocatalysis is an emerging field that exploits light-absorbing catalysts to yield transformations not even achievable in the dark. Considering the drawbacks of metal-based photocatalysts, Carbon Dots (CDs) recently emerged as suitable green alternatives for different photocatalytic reactions. These carbon nanoparticles are easy to prepare, non-toxic and potentially recyclable. Moreover, CDs usually display core-shell structures which are highly tunable via synthetic and post-synthetic strategies. This Concept Article focuses on the recent advancements in the CD-based photocatalysis, highlighting the link between their superficial and core composition and their resulting photo-redox abilities, and giving future perspectives on their application in cutting-edge area
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
Different mechanisms of inhibition of nerve terminals by botulinum and snake presynaptic neurotoxins
No full textThe different mode of action on peripheral nerve terminals of the botulinum
neurotoxins and of the snake presynaptic phospholipase A2 neurotoxins is reviewed
here. These two groups of toxins are highly toxic because they are neurospecific
and at the same time are enzymes that can modify many substrate molecules before
being inactivated. The similarity of symptoms they cause in humans derives from
the fact that both botulinum neurotoxins (seven serotypes named A-G) and snake
presynaptic PLA2 neurotoxins block the nerve terminals and that peripheral
cholinergic terminals are major targets. Given this general similarity of targets
and clinical symptoms, the specific molecular and cellular mechanisms at the
basis of their action are very different. This difference appears evident from
the beginning of intoxication, i.e. neurotoxins binding to peripheral nerve
terminals and proceeds with the different site of actions and molecular targets
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