1,720,981 research outputs found
Characterisation of airborne particles in London by computer-controlled scanning electron microscopy
No full textThis study assessed the personal exposure of cyclists and Underground train users in London to particulate matter below 5 ?m in diameter (PM5) and provides evidence of the number, shape, size distribution and elemental composition of collected particles. Samples were analysed using computer-controlled scanning electron microscopy (CCSEM) and energy dispersive X-ray detection (EDX), including analysis of samples for low energy elements (carbon) by open window detection. Results were processed and classified using a custom written software package (MIDAS). A total of 33 938 particles were analysed for size and 12 568 particles were classified for size and elemental composition. Samples were also collected for gravimetric analysis. Thirty volunteers cycling commuter routes into central London were selected and monitored according to particulate matter for 1 week during November 1995–February 1996. Samples were also collected by three commuters using London Underground during their daily commuter journeys as a comparison. Cassella personal sampling pumps fitted with cyclone heads incorporating filters were used to collect particles. Carbon particles are clearly the dominant particle type in the road traffic samples with mean particle fractions of 66% carbon. The size distribution of the aerosol sampled by cyclists — high numbers of the smallest sized particles — is typical of vehicle emissions. Samples from the Underground show a distinctly different size distribution and elemental composition. Samples exhibited a higher loading of coarse mode particles with a more even distribution across the particle sizes collected. The most abundant particles in the Underground are Fe/Si-rich particles with 53% (56% in the 20-kV range) of the total number of particles. The average Fe concentration in this particle class was 22.8% and the Si concentration 17.4% together with C, Ca and K. The particle mass concentration in the London Underground trains proved to be almost 10 times higher than those measured by cyclists in traffic generated aerosol.<br/
Analysis of silicon germanium standards for the quantification of SiGe microelectronic devices using AES
No full textFour samples of well-defined silicon-germanium alloys were used as standards for calibration purposes to allow accurate quantification of silicon-germanium-on-insulator (SGOI) microelectronic devices using Auger electron spectroscopy. Narrow Si KLL and the Ge LMM, high resolution Si KL2,3L2,3 and Ge L3M4,5M4,5 together with survey spectra were collected and are presented from each sample. A matrix effect was observed for silicon in germanium and calculated as 0.85 and 0.95 for the Ge77.5Si22.5 and Ge52.4Si47.6 alloys respectively
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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