1,720,975 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
TEMPERATURES AND FLOWS IN HORIZONTAL EPI REACTORS
No full textDans les réacteurs d'épitaxie horizontaux, des flux importants de gaz porteurs H 2, N2, He ou argon sont présents pour entraîner les constituants de croissance chimiquement actifs tels que SiHCl3, SiH4 pour la croissance de silicium par CVD ou les espèces de gallium et d'arsenic pour la croissance de GaAs en phase gazeuse. Des flux importants sont nécessaires pour avoir des vitesses de croissance égales sur toute la longueur du tube du réacteur. De cette manière, la dépression de la phase gazeuse est neutralisée. Les flux des quatre gaz porteurs ont été étudiés en détail pour différents types de réacteurs d'épitaxie horizontaux par des techniques de mesures optiques in-situ telles que l'holographie interférentielle. L'analyse des résultats montre clairement l'influence dominante des effets d'entrée, particulièrement importants pour l'argon et l'azote. H2 et He ont dans des conditions normales des lignes de flux laminaires bien développées,alors que N2 et Ar donnent en général un mélange de flux turbulents et convectifs, fortement sous-développés en vitesse et en température. Les figures d'interférence rendent possibles le calcul des profils de température dans le tube du réacteur. Cela a été fait pour plusieurs vitesses de flux et types de cellules de reacteurs. Dans ce cas, l'influence de l'effet d'entrée est vu moins clairement : il se manifeste par la présence d'un doigt froid dans le courant gazeux. D'autre part, dans le cas de CVD à basse pression, sont présents simultanément une plus faible pression et de plus grandes vitesses de flux. L'effet de ces paramètres sur les profils des flux est discuté. En plus, quelques calculs de T. Cherepanova donnent les profils de température en fonction des vitesses de flux des processus d'épitaxie. Dans ce cas aussi, l'échauffement du flux gazeux est le principal phénomène rencontré.In horizontal epitaxial reactors high flows are present of the carrier gases H2, N2, He or argon which carry the chemically active growth components e.g. SiHCl3, SiH4 for silicon growth by CVD or the gallium and arsenic species for the growth of GaAs from the gas phase. High flows are needed in order to achieve equal growth rates along the length of the reactor tube. In this way the depletion of the gas phase is counter acted. For various types of horizontal epitaxial reactors the flow of these four carrier gases has been studied in detail using in situ optical measuring techniques i.c. interference holography. Analysis of the results clearly shows the dominant influence of the so called entrance effects, which, especially are of importance for argon and nitrogen. It appears that H2 and He under normal conditions will have well developed laminar streamlines, whereas N2 and Ar nomally will give a mixture of turbulent and convective streams, which are highly underdeveloped qua velocity and temperature. The interference patterns make it possible to calculate the temperature profiles in the reactor tube. This has been done for several flow velocities and types of reactor cells. Here the influence of the entrance effect is most clearly seen : it demonstrates itself as the presence of a cold finger in the gas stream. In low pressure CVD besides the lower pressure also higher flow velocities are present. The effect of these parameters on the flow profiles is discussed. In addition some calculations made by T. Cherepanova are given on temperature profiles as a function of flow velocity for furnace processes. Also here the heating up of the gas stream is the main phenomenon which is encountered
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
The flash-photolysis of sodium pyrenide in tetrahydrofuran. On the photo-oxidation process and on the existence of sodium atoms NaO
No full textTHE INCORPORATION OF PHOSPHORUS IN SILICON; THE TEMPERATURE DEPENDENCE OF THE SEGREGATION COEFFICIENT
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