1,721,138 research outputs found
Calcium and polyphosphoinositides: their distribution in relation to the membrane changes occurring in the head of boar spermatozoa
No full textEjaculated boar spermatozoa, previously incubated in a rigorously Ca++-free medium, were exposed to Ca++ for different incubation times and processed for the detection of Ca++ localization by a pyroantimonate technique. The distribution of polyphosphoinositides, anionic phospholipids natural constituents of membrane known to bind Ca++, was investigated using a specific cytochemical probe, i.e., neomycin conjugated with horseradish peroxidase. The in situ localizations thus obtained revealed: short exposure to Ca++ ions (10 min) evocated a Ca++-induced release of calcium from the nonmitochondrial intracellular store, i.e., the outer acrosomal membrane; a more prolonged exposure (20 min) triggered the occurrence of fusional and exocytotic events, that appeared to be morphologically related to the acrosome reaction; the outer acrosomal membrane, which is the fusigenic sperm membrane, was the elective site of the neomycin/peroxidase labeling. When assayed for the presence of a phospholipase C-like activity, the detergent extract obtained from boar spermatozoa exhibited substantial amount of p-nitrophenyl-phosphorylcholine hydrolyzing activity. The results, on the whole, allow us to suggest a relationship between Ca++ and polyphosphoinositides turnover in the events triggering the acrosome reaction, the exocytotic process peculiar to mammalian spermatozoa
Frisoni e Franchi a Roma nell'età carolingia
No full textLe colonie germaniche nella Roma carolingia, cioè Franchi, Longobardi, Frisoni, e Sassoni, si concentravano nelle vicinanze di San Pietro, nella città Leonina. Questa circostanza e il fatto che questi stranieri furono chiamati « peregrini » hanno dato origine a una interpretazione storiografica in cui i motivi religiosi sono centrali. Non mancano tuttavia argomenti per sostenere che questo tipo di pellegrinaggio aveva il carattere di una migrazione vera e propria, da collocare nel quadro di una apposita politica economica e sociale del papato e nell'insieme delle migrazioni germaniche dell'epoca. Una tale interpretazione non è in contrasto con il significato della parola « peregrinus » a quell'epoca ancora senza la connotazione religiosa del periodo posteriore.Van Kessel Peter J. Frisoni e Franchi a Roma nell'età carolingia. In: Les fondations nationales dans la Rome pontificale. Actes du colloque de Rome (16-19 mai 1978) Rome : École Française de Rome, 1981. pp. 37-46. (Publications de l'École française de Rome, 52
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
Chromotropic guaiazulene-derived radical scavengers for the detection of oxygen-centred radicals in micellar media
No full textSimulazione termica analitica per dispositivi elettronici di potenza
No full textUna nuova tecnica di simulazione termica dedicata
ai dispositivi elettronici di potenza e alle loro strutture
di assemblaggio basata sulla risoluzione analitica
delle equazioni di trasmissione del calor
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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