1,720,993 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
The dark-PMT: A novel directional light dark matter detector based on vertically-aligned carbon nanotubes
No full textThe ANDROMeDa project, recently funded by the italian ministry of research with a 1Me grant, has the objective of developing, over the course of the next three years, a novel dark matter (DM) detector based on carbon nanotubes: the ‘dark-PMT’. Such a detector would be sensitive to DM-electron recoils in the eV energy range, and could have world-leading sensitivity for DM masses below 30 MeV with an exposure of only 1 g ⋅ year. Significant R&D is needed to produce carbon nanotubes with ideal properties for a DM target. In particular two by-products of synthesis (non-aligned crust layer and the sub-μm ‘waviness’) are expected to reduce electron transmission probability, and therefore need to be minimized. This will be done via a precise tuning of the evaporation and growth parameters, and of post-growth plasma etching
Absolute efficiency of a two-stage microchannel plate for electrons in the 30-900 eV energy range
No full textWe report on an apparatus able to measure the absolute detection efficiency of a detector for electrons in the 30-900 eV range. In particular, we discuss the characterisation of a two-stage chevron microchannel plate (MCP). The measurements have been performed in the LASEC laboratory at Roma Tre University, whit a custom-made electron gun. The very good stability of the beam current in the fA range, together with the picoammeter nominal resolution of 0.01 fA, allowed the measurement of the MCP absolute efficiency ?. We found an ? = (0.489 ± 0.003) with no evident energy dependence. We fully characterised the MCP pulse shape distribution, which is quasi-Gaussian with a well visible peak above the noise level. We measured a 68% variation of the average pulse height between 30 and 500 eV. Furthermore, with a deeper analysis of the pulse shape, and in particular of the correlation between pulse height, area and width, we found a method to discriminate single- and multi- electron events occurring within a 10 ns time window
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Response of windowless silicon avalanche photo-diodes to electrons in the 90–900 eV range
Get PDFWe report on the characterization of the response of windowless silicon avalanche photodiodes to electrons in the 90-900 eV energy range. The electrons were provided by a monoenergetic electron gun present in the LASEC laboratories of University of Roma Tre. We find that the avalanche photo-diode generates a current proportional to the current of electrons hitting its active surface. The gain is found to depend on the electron energy , and varies from 2.147+-0.027 (for = 90 eV) to 385.8+-3.3 (for = 900 eV), when operating the diode at a bias of apd = 350V. This is the first time silicon avalanche photo-diodes are employed to measure electrons with <1 keV
Searching for dark matter with vertically-aligned carbon nanotubes:The ANDROMeDa project
No full textThe ANDROMeDa project, recently funded by the Italian ministry of research with a 1Me grant, aims to
develop a novel light dark matter (DM) detector sensitive to DM-electron recoil in a target of vertically-aligned
carbon nanotubes: the ‘‘dark-PMT’’. Thanks to their vanishing density in the direction of the tube axis, carbon
nanotubes allow a scattered electron to leave the target without being re-absorbed only if it travels parallel
to the tubes. Therefore the detector is expected to have directional sensitivity, a key feature in DM searches.
With only 1 g of exposure per year and a careful suppression of the backgrounds, such detector might achieve
world-leading sensitivity for DM masses below 30 MeV
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