1,721,039 research outputs found
Tecniche di procreazione medicalmente assistita nelle coppie sierodiscordanti per il virus HIV
No full text
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
Analyse expérimentale de l'écoulement dans la zone axiale des canaux adducteurs des turbines-Hélices
No full textThe paper presents sorne results of the measurements carried out, in water, in the axial region of a propeller turbine admission duct (Hy), without runner, and, in air, in an annular section cylindrical duct fed by a radial distributor (1MB) (see Fig. 2). The measurements have been performed with different wicket-gate openings a and the attention has been drawn on the small openings where different phenomena have been observed (see Fig. 1) : a variation of the radial distribution of the tangential velocity near the hub, associated with the arising of a quite forced vortex ; the decrease and sometimes the inversion of the axial velocity; the presence of radial flows directed towards the hub; the drop of the total pressure, due to the viscous dissipation, These phenomena mainly develop in the axial region of the two ducts, rapidly extend their influence and finally settle on a practically constant area (see Fig. II). The distribution of axial and tangential velocity components change almost similarly in the two ducts according to the decrease of the wicket-gate opening, as it can be observed in figures 3 and 4. These figures show the distribution of axial and tangential velocity components divided by the average axial velocity, as a function of the ratio between the radius of the measurement points and the external one in the closest sections of the two ducts (1MB 2 and HyG). The similarity of the flow evolution in the two ducts is even more underlined by the comparison (see Fig. 5-8) of the velocity distributions for comparable values of the m parameter, called swirl rate, defined by the equation (1) and usually utilized in technical literature for the evaluation of the flow vortex intensity. In the diagram of figure 9 the radius limiting the central core, which is characterized by the decrease of axial velocity (ri) and the radius of the core characterized by the quite forced vortex distribution of tangential velocities (rf) have been associated to mparameter values, calculated by means of the geometric data of the duct according to the equation (2). The mand m values have been compared in the diagram of figure 10 versus a. Some experimental tests carried out on the Hy model with runner showed that, at small openings, a central core similar to the one previously described in the case without runner is developed (see Fig. 12). In axial turbines this phenomenon causes efficiency drop and cavitating vortexes which, as it happens without the runner (see Fig. 14), detach near the hub and pass through the runner (see Fig. 15) in a helix spiral form, thus causing vibrations and noise at low operation loads. The operation areas concerned by this phenomenon are indicated in figure 13 on the hill diagrams of a propeller and a Kaplan turbine with medium specific speed
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
- …
