1,720,979 research outputs found
Integration on a microchip: A glimpse into the future of optical coherence tomography
Full text linkOptical coherence tomography (OCT) is a noninvasive, three-dimensional imaging technique that offers close-to-histology-level image quality. Based on broadband spectral interferometry, OCT has enabled clinical applications ranging from ophthalmology to cardiology that revolutionized in vivo medical diagnostics. Considering the size and cost of a commercial OCT system, it is essential to investigate different approaches for realizing a compact and low-cost OCT system in order to make it accessible to a significantly larger group of applications and users. Exploiting integrated optics, several central components of an OCT system have been assembled on a microchip so far. Silicon based designs have the advantage of complementary metal-oxide-semiconductor (CMOS) compatible high-volume production while indium phosphate (InP) based designs have the possibility of monolithic integration of the light source and the detector with other components. In this chapter, the design considerations, theoretical analysis and experimental results of the passive integrated optical components of an on-chip OCT system including interferometer, spectrometer, reference arm, and sample arm will be presented. Active components (light source and detectors) are beyond the scope of this chapter
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
Non-moving scanner design for OCT systems
No full textIn this work, a novel beam scanner design based on non-moving parts is introduced which will eliminate the phase and inaccuracy problems of the mechanical scanners while providing two times imaging speed improvement for optical coherence tomography systems. The design is comprised of electro-optically activated switches that are placed on the sample arm. For the example considered here, lateral resolution of 20 µm, and lateral scanning range of 1 mm are aimed at which resulted in a scanner size of 1 mm × 9 mm. Due to its compact size, proposed design can also be implemented in forward-looking endoscopic probe
Design of a high-speed multiple-reference optical coherence tomography system
No full textThe imaging speed of a time domain optical coherence tomography (OCT) system is limited by the speed of the moving mirror. As a solution to this problem an integrated-optics-based multiple-reference TD-OCT system is presented in this work. The reference and sample lights will be sequentially tapped out at multiple locations using electro-optically controlled switches. For the design considered here an axial resolution of 20 µm and a depth range of 1 mm at the central wavelength of 800 nm were aimed at. With this design the mechanical scanner will be completely eliminated and, thereby imaging speed will be significantly improve
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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