1,720,977 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
Combining Fast Scanning Chip Calorimetry with Structural and Morphological Characterization Techniques
No full textThanks to the development of fast-scanning (chip-based) calorimeters (FSC) it is nowadays possible to achieve very high cooling rates, which enabled the study of polymer crystallization at large supercoolings, in conditions similar to what is experienced in real industrial processes. In such extreme conditions formation of structures very different from those commonly obtained under relatively slow cooling can occur. Albeit important, the information about thermal events gained by FSC might not be sufficient for a proper understanding of polymer structuring. In this chapter, new exciting developments on the coupling between FSC/fast cooling devices and structural or morphological probes are reported. For example, atomic force and polarized optical microscopy can be applied ex situ to polymer samples which have been submitted to a chosen FSC thermal protocol. Moreover, ballasting cooling and FSC-based devices have been realized, to allow fast Wide Angle X-ray Diffraction measurements at synchrotron facilities. Some recent examples of real-time detection of polymer structuring during fast cooling are presented
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
Gefractioneerde kristallatie van isotactisch polypropylene in dispersies op water-basis.
No full textThough polymers exist for many years, crystallization by homogeneous nucleation has seldom been studied. To explore this kind of nucleation, polyolefin-water matrix systems have been developed. Low-viscosity, not-vitrified water is not expected to influence the crystallization of the polyolefin; it is safer to work with than with any organic solvent; it is completely inert from an environmental point of view, and therefore potentially of interest for industrial applications.Usually, polymer crystallization occurs by way of heterogeneous nucleation because in a polymer a large number of heterogeneous nuclei is present, facilitating the crystallization process. However, in case these nuclei are absent or when somehow they are removed, homogeneous crystallization can occur. Hence, if the polymer is dispersed into a large enough number of particles the vast majority of them will not contain any heterogeneous nucleus and thus they must undergo homogenous crystallization.In this work water-borne dispersions of a maleic anhydride-grafted, isotactic polypropylene (MA-g-PP) covering a very wide range of particle size distributions were successfully prepared. The dispersions proved to be stable over very long periods of time and over a broad range of temperatures. Thus, by varying the nucleation density in droplets by changing their dimensions, the different modes of crystallization sought - heterogeneous, fractionated and homogenous crystallization - have indeed been found, enabling the study of the various modes.The particle size distributions of these waterborne MA-g-PP dispersions have been determined and compared to the crystallization (from the melt) and subsequent melting behavior. The larger-particle dispersions showed crystallization at the usual (bulk) crystallization temperatures; dispersions having intermediate-size particles showed several ways of fractionated crystallization, and the smaller-particle dispersions showed crystallization exclusively at a very high, extra supercooling resulting from homogeneous nucleation. The obtained lowest crystallization temperature - 34 ºC - was the lowest ever reported for isotactic polypropylene (iPP), and has only recently been realized by two other groups. The obtained particle size distributions cover approximately three orders of magnitude, with size averages ranging from less than 100 nm up to a few tens of micrometers. Such a complete set of samples is seldom available and it constitutes a solid base for the research work carried out.Next, a deeper analysis of the process of crystal formation was undertaken. Self-nucleation was successfully used in order to confirm that fractionated and homogenous crystallization were due to the increased number of droplets as compared to the number of active impurities. However, due to the vast number of droplets in the dispersions having the smallest particles it was necessary to use extremely low self-nucleation temperatures in order to change all different crystallization modes into crystallization in the bulk, heterogeneous crystallization temperature range. Most remarkably, in this case the self-nucleation regimes II and III - as defined and used in literature - overlap.Concerning the density of nucleating seeds, a novel procedure that takes into account the entire size distribution was proposed for the estimation of that density. The results show that the nucleation density in the dispersions is always larger than in bulk, even when polymer dispersions that crystallize exclusively in the bulk crystallization temperature range are considered. Besides, the number of less active nucleating seeds was also estimated, as well as the required particle size in order not to observe any crystallization until the homogenous crystallization temperature has been reached. It turns out that the size of the dispersed droplets has to be drastically reduced to sub-micrometer dimensions in order to obtain homogenous crystallization exclusively.Then, an analysis of the kinetics of the crystallization process was performed in order to establish which type of primary nucleation takes place at each crystallization temperature. The originality of the proposed and performed analysis consists in taking into consideration the particle size distribution of the samples, and not just an average particle size, as it is commonly done. It was possible to conclude that no impurity is involved in the primary nucleation observed at the maximum supercooling. Moreover, the results of the analysis favor the possibility of volume nucleation over surface nucleation.Finally, the mesomorphic phase of isotactic polypropylene has been studied. The enthalpy of the mesophase was determined over a wide temperature range, on the basis of a number of reasonable assumptions. Next, the enthalpy of crystallization/fusion obtained has been used to fully characterize the samples regarding the crystallinity and polymorph evolution as function of temperature. The morphology of the different crystal phases observed was analyzed too, showing interesting but sometimes contradicting results.status: Publishe
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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