1,721,011 research outputs found
Optical profiles with 180 micron resolution of objects hidden in scattering media
No full textWe measure the time-of-flight distributions of near-infrared photons emerging from thick scattering media within a collection angle of 0.6 mrad about the incident light direction by means of a time-correlated single-photon counting apparatus endowed with <35 ps resolution. These measurements, which are performed with a picosecond laser beam, allow us to isolate the weakly scattered (ballisticsnake) photons from the multiply scattered ones. By scanning the incidence position across a target we find variations in the fraction of detected unscattered photons that are significative of local changes in the optical parameters of the target. In particular, if either opaque, light diffusing, or transparent objects are embedded in the scattering medium, their profiles can be reconstructed and their nature can be assessed. Opaque objects embedded in realistic tissue phantoms are detected with <180 μm spatial resolution. © 2007 American Institute of Physics
Distribuzione della popolazione microbica nella biomassa di un reattore biologico a letto fluidizzato per la depurazione di acque reflue
No full textInhibition of Rous sarcoma virus-induced transformation by proteins involved in blood coagulation
No full textDifference-frequency-generated holograms of two-dimensional objects
No full textWe demonstrate both analytically and experimentally that second-order nonlinear interaction in a uniaxial crystal produces a holographic replica of one of the incident fields. In particular, we consider difference-frequency generation and directly calculate the field transformation that is produced by the nonlinear interaction for some simple but nontrivial two-dimensional objects, such as a long wire, a circular hole, and a regular net. Finally we show experimental results for such objects that validate the theoretical calculations. (C) 2004 Optical Society of America
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
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