1,721,000 research outputs found
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
Micro ion beam used to optimize the quality of microstructures based on polydimethylsiloxane
No full textIon micro beam was employed to fabricate microstructures based on poly(dimethylsiloxane) (PDMS). Carbon ions with energy of 6.0 MeV were used. The ion treatment induces modifications in PDMS surface and on the optical properties as a function of the ion current and fluence. PDMS foils were produced from commercially available two component addition materials. The selective modifications of the polymer were studied for applications in micro-fluids, micro-optics and micro-electronics. The comparison between the unirradiated and irradiated PDMS was investigated in morphology and compactness using the atomic force microscopy. The wetting ability of the PDMS surface was also analyzed as a function of the ion microbeam irradiation. The compositional and optical changes in PDMS were monitored by Rutherford backscattering spectrometry, elastic recoil detection analysis and optical spectroscopy measurements
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
Polydimethylsiloxane–graphene oxide composite improving performance by ion beam irradiation
No full textA hybrid film consisting of graphene oxide covered with poly(dimethylsiloxane) was prepared via spin coater and followed by thermal annealing to improve the bond strength of the polymerized systems. Direct patterning on both graphene oxide and hybrid graphene oxide–poly(dimethylsiloxane) foils by ion microbeam was performed to induce localized reduction in the ion irradiated material. It is well established that the ion irradiation of graphene oxide induces modifications in its electrical, mechanical, and optical properties and disorder in the carbon crystal structure and defect production. The presence of poly(dimethylsiloxane) can be useful as it confers flexibility to the produced pattern and oxygen permeability from the graphene oxide surface. Rutherford backscattered spectroscopy and elastic recoil detection analysis were performed to evaluate the compositional changes in the composite. Atomic force microscopy studied the pattern fidelity. The electrical conductivity of the hybrid material was used to evaluate the changes induced during the proton irradiation of the material
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
SiC detector for high helium energy spectroscopy
No full textSiC Schottky detectors, having a superficial active zone up to 80 micron depths and a thin surface metallization, are adapt to detect high energetic ions. In order to demonstrate their detection ability with high-energy resolution, a helium Rutherford backscattering spectroscopy (RBS) was employed to evaluate their detection efficiency, energy resolution in the region 1.0 – 6.0 MeV alpha ions, depth resolution and dependence on the ion beam current. The detector parameters dependencies on the surface passivation layers, ion energy and current are presented. The comparison of RBS analysis using a traditional barrier silicon detector is investigated, and the differences with SiC detector is presented and discussed
Characterization of reduced Graphene oxide films used as stripper foils in a 3.0-Mv Tandetron
No full textReduced graphene oxide (rGO) films can be employed as thin ion strippers in an accelerator. They show some advantages with respect to the graphite foils, due to their high thermal and electrical conductivities, low density, high mechanical resistance and high stability. The preparation method of the graphene-based films and their physical characterization are presented and discussed. Thin graphene oxide (GO) films with a thickness of from 0.5 up to 2.0 μm have been synthesized and studied to be used as an ion extractor (stripper) in the 3.0 MV Tandetron of the CANAM Laboratory at the Nuclear Physics Institute in Rez, Czech Republic. GO is transformed to rGO also by low ion beam doses. Measurements of stripper efficiency, as the ion transmission factor of films, have been carried out by accelerating different ions, from helium to carbon, having energies from 1.0 up to 16 MeV, and by using different charge states and a current density ranging between about 10 nA/cm2 and 2 μA/cm2. The ion fluence at which the so-obtained graphene oxide films can be undergone exceeds a dose of 1 × 1016 particles/cm2. Furthermore, these stripper films have demonstrated a significantly high charge production, comparable to that of the graphite films. However, the higher mechanical resistance represents an undiscussed advantage with respect to the graphite films
Selective modification of electrical insulator material by ion micro beam for the fabrication of circuit elements
No full textDispelling 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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