1,721,011 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
Liposomes in cosmetics: which kind of phospholipid? Which loading method?
No full textPhospholipids of different origin (egg and soya) and purity were used to prepare liposomes by sonication. Loading of these vesicles was performed by means of two different techniques using a fluorescent lipophilic model molecule. The stability of the aggregated structures was checked by addition of increasing amounts of a surfactant to the liposome dispersion. No remarkable differences were observed in either the stability in regard to surfactant-induced breakage or the loading capacity of liposomes respectively prepared with 99% pure egg phosphatidylcholine or with the vegetable phospholipid, a commercial product that had a much lower purity. The comparison of the two loading methods indicated that incorporation of the model molecule within the vesicle structure was higher when the fluorescent marker was added before sonication
Liposomes in cosmetics (II): entrapment of a hydrophylic probe
No full textPhospholipids of different origin (egg and soya) and purity were used to prepare liposomes by sonication. Loading of these vesicles with a fluorescent hydrophilic model molecule (calcein) was carried out by means of two different methods. No appreciable differences were observed in the loading capacities of liposomes prepared with the two products. Obtained results indicated that the fraction of incorporated or absorbed calcein was always very small with respect to the total amount of this substance used for the preparation of the vesicles; furthermore, the quantity of hydrophilic probe in the vesicle structure was remarkably affected by the loading method.
The results of this investigation allowed us to consider the possible incorporation, inion the vesicles, of additives that can be present in a formulation containing liposomes
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
Egg and soya phospholipids, sonication and dialysis: a study onliposome characterization
No full textLiposome-Triton X-100 interactions were studied by turbidity measurements and two detergent concentrations, corresponding to the maximum (i.e., detergent-saturated vesicles; Rsat) and minimum (i.e., completely disruped liposomes; Rsat) turbidity values, were identified. The tested liposomes (SUV) were prepared with phospholipids of different origin (egg and soya) and according to different methods (sonication and dialysis). The data obtained, together with size measurements carried out by electron microscopy, were related to the stability of the vesicles. © 1995
Lipid peroxidation of L-alpha-phosphatidylcholine from fresh egg yolk and from soybean during liposome preparation andstorage
No full textOxidative processes that may occur when susceptible materials like phospholipids are processed and stored should be avoided because they can lead to undesired byproducts. Our attention was focused on the formation of hydroperoxides of conjugated dienes of the esterified polyunsaturated fatty acids that are present in phospholipids. The method used for the evaluation of lipid peroxidation was based on the determination of the "oxidation index" calculated from UV absorbance. The investigated products were phospholipids of different origin and purity, with and without antioxidants; their autooxidation process was evaluated in the presence of air and under nitrogen. A comparison of the behavior of the various tested products, under the different experimental conditions, indicate how important it is to acquire informations on the autooxidation process for a correct preparation of cosmetic, dermatological or other formulations containing liposomes. © 1993 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted
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
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