1,721,592 research outputs found
Refocusing Algorithm for Correlation Plenoptic Imaging
Full text linkCorrelation plenoptic imaging (CPI) is a technique capable of acquiring the light field emerging from a scene of interest, namely, the combined information of intensity and propagation direction of light. This is achieved by evaluating correlations between the photon numbers measured by two high-resolution detectors. Volumetric information about the object of interest is decoded, through data analysis, from the measured four-dimensional correlation function. In this paper, we investigate the relevant aspects of the refocusing algorithm, a post-processing method that isolates the image of a selected transverse plane within the 3D scene, once applied to the correlation function. In particular, we aim at bridging the gap between existing literature, which only deals with refocusing algorithms in case of continuous coordinates, and the experimental reality, in which the correlation function is available as a discrete quantity defined on the sensors pixels
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
3D and hyperspectral imaging through photon correlation and coherence of light
No full textPhoton correlation imaging has emerged as a powerful framework for overcoming the fundamental limitations of conventional optical systems. While initially explored in the quantum domain using entangled photons, similar performance can be achieved with thermal or pseudo-thermal light, thanks to the spatial coherence inherent in such sources. Correlation plenoptic imaging (CPI) leverages this principle to perform high-resolution, scan-free volumetric imaging by measuring second-order correlations between two spatially resolving detectors. Unlike standard light-field imaging, CPI avoids resolution trade-offs imposed by microlens arrays and achieves diffraction-limited performance even with low numerical apertures. Recent theoretical developments have clarified that the imaging capabilities of CPI originate not from photon correlation itself, but from the analytical form of the measured correlation function-essentially a coherent diffraction pattern. This insight has led to the implementation of analogous systems using standard optics illuminated by structured, spatially coherent light, enabling real-time direct 3D imaging through programmable illumination arrays. Building on these results, correlation hyperspectral imaging (CHI) has been introduced as a new technique that couples a conventional imaging system with a spectrometer through intensity correlation measurements. CHI enables diffraction-limited hyperspectral imaging without scanning, offering independent control of spatial and spectral resolution. Ongoing research explores the integration of CHI and CPI into a single device, capable of acquiring fully three-dimensional, spectrally resolved datacubes in a passive and mechanically stable configuration. Such a system promises broad impact across microscopy, materials analysis, and remote sensing
MASSARO G.
No full textNella recensione del libro di Massaro viene presentata la sua concezione sul rapporto fra soggettività e sviluppo del senso critico
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
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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