1,721,369 research outputs found
Calorimetric and UV spectroscopic study of the interaction of paraquat with phospholipids
No full textParaquat (PQ) is a popular herbicide and its main effect is the modification of the membrane integrity. The PQ-dipalmitoylphosphatidic acid (DPPA) and PQ-dipalmitoylphosphatydilcholine (DPPC) water suspension systems at pH 7 have been investigated in order to determine the kind of the molecular interaction that exists between PQ and phospholipids (PL) with different charges, and the influence of the presence of Ca++ ions on this interaction. The experimental results demonstrate that the interaction between PQ and PL is mainly electrostatic; PQ strongly binds to DPPA, which bears one negative charge at pH 7, but only weakly to DPPC, which, unlike DPPA, is uncharged. The presence of Ca++, in an amount sufficient to completely bind the lipid (1 M), strongly alters the DPPA-PQ interactions, thus inhibiting the binding of PQ to lipid. On the contrary, the DPPC-PQ interactions are not modified by the presence of calcium ions
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
Optical field reconstruction with digital micromirror interferometry
No full textWe investigate the possibility of interferometric optical field sensor with DMD forming a series of sampling interferometers in the pupil of an optical system. Our preliminary experiment validates the feasibility of our approach for the field reconstruction in the case of coherent field. We believe that this approach can be extended to sensing of speckle patterns and even incoherent fields, by analyzing not only the intensity and phase, but also the amplitude and the visibility of the interference patterns. Such analysis would yield the complete complex amplitude and/or coherence function, making the approach directly applicable to a wide range of inverse source problems in optics.Team Raf Van de Pla
Curvature sensing with a Shack-Hartmann sensor
No full textShack-Hartmann (SH) sensor, based on sampling of wavefront tilts in subapertures, is a simple, reliable, and widely used in adaptive optics wavefront sensor. A wavefront curvature sensor has the advantage of providing the results suitable for direct control of membrane and bimorph deformable mirrors [1], but requires linear registration of intensity in two planes. SH sensor modifications using astigmatic microlens array [2] and three SH sensors [3] provide measurement both in the form of wavefront gradients and Laplacian curvatures. In this work, we consider a simple arrangement that turns a standard SH sensor into a curvature sensor by moving the camera chip of the SH sensor into the optical plane conjugated to a deformable mirror. This establishes a direct geometric correspondence between the coordinates on the DM surface and the sensor chip. Then, change in the local centroid density corresponds to the Laplacian curvature of the mirror, and the phase at the boundary can be found from the centroid displacements along the edge of the pupil. We investigate the feasibility of this approach for direct control of membrane deformable mirror by measuring the dependence of the calculated centroid density on the control signal applied to the mirror actuators. The experimental results demonstrate a good linear dependence.Team Raf Van de Pla
Associazione Biblica Italiana, Quaerere Deum. Scritti di A. Bonora, S. Cipriani, E. Cortese, G. Crocetti, R. Fabris, F. Festorazzi, P. Grech, G. Leonardi, N.M. Loss, B. Maggioni, C. Marcheselli, S. Migliasso, G. Odasso, L. Pacomio, R. Penna, G.L. Prato, B. Prête, G. Segalla, 1980
No full textBogaert Pierre-Maurice. Associazione Biblica Italiana, Quaerere Deum. Scritti di A. Bonora, S. Cipriani, E. Cortese, G. Crocetti, R. Fabris, F. Festorazzi, P. Grech, G. Leonardi, N.M. Loss, B. Maggioni, C. Marcheselli, S. Migliasso, G. Odasso, L. Pacomio, R. Penna, G.L. Prato, B. Prête, G. Segalla, 1980. In: Revue théologique de Louvain, 13ᵉ année, fasc. 1, 1982. pp. 98-99
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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