1,720,960 research outputs found
The effect of a cylinder on the velocity field at the outlet of a circular jet measured by PIV and PTV.
No full textIntegration of Two-Dimensional MEMS Ultrasonic Transducer Arrays with Front-End Electronics for Medical Ultrasound Imaging
No full textElectrostatically actuated MEMS ultrasonic transducers, also known as Capacitive Micromachined Ultrasonic Transducers (CMUTs), offer better performance with respect to conventional piezoelectric transducers in terms of bandwidth and efficiency. The enhanced compatibility between MEMS and standard integrated circuit technologies enables the integration of the transducer and the front-end electronics, and is currently leveraged in the development of new-generation diagnostic systems for clinical, emergency and point-of-care uses. This paper reports on the development of an integrated 2-D CMUT array designed for volumetric ultrasound imaging. An acoustically optimized 3-D packaging technology has been applied to the design, fabrication and characterization of a Multi-Chip Module (MCM) obtained by 3-D interconnection of a 256-element CMUT spiral array and a 256-channel analog front-end Application Specific Integrated Circuit (ASIC) with integrated pulsers, low-noise receivers and a programmable TX beamformer
A Low Frequency Broadband Flexural Mode Ultrasonic Transducer for Immersion Applications
No full textPerformance optimization of a high frequency CMUT probe for medical imaging
No full textIn this work we report on the performance optimization of a recently developed high frequency CMUT probe. By leveraging the advantages offered by our proprietary "Reverse Fabrication Process (RFP)" CMUT technology, we have developed an efficient and reliable packaging process, useful for the fabrication of small sized ultrasound probe-heads. We have maximized the performance by connecting the CMUT probe-head to multichannel analog front-end electronic circuits housed into the probe. An experimental comparison with an equivalent piezoelectric probe, the LA435 commercialized by Esaote S.p.A. (Italy), carried out by means of pulse-echo measurements, showed superior performance for the CMUT probe. Real time in-vivo ultrasound imaging capability demonstrates the actual usability of CMUT technology for medical imaging
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
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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