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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
Interventionsstudie zur Rolle von Isoflavonen im Fettstoffwechsel gesunder postmenopausaler Frauen
Get PDFIn postmenopausalen Frauen (PMF) gehen hormonelle Veränderungen mit charakteristischen Wechseljahrsbeschwerden und Veränderungen der Körperfettverteilung sowie der Lipoprotein- und Serumlipidkonzentrationen einher und stehen in Zusammenhang mit einem gesteigerten Risiko für kardiovaskuläre Erkrankungen (KVE). Epidemiologische- und Querschnittsstudien deuten auf ein niedrigeres Risiko für u. a. KVE in PMF aus asiatischen Ländern hin, was mit einem höheren Konsum an Soja und Sojaisoflavonen (IF) in Zusammenhang gebracht wird. IF werden in westlichen Ländern als Nahrungsergänzungsmittel für PMF als Alternative zu einer Hormonersatztherapie postuliert und von vielen Frauen konsumiert. Allerdings sind Studienergebnisse zu Wirkungen der IF z. B. auf die Lipoprotein- oder Serumlipidkonzentrationen oder weitere Risikofaktoren für KVE uneinheitlich. Modulierende Faktoren auf die Wirkungen der IF sind denkbar, welche ursächlich für diese uneinheitlichen Studienergebnisse sein könnten. So erfolgt der Transport der IF zu ca. 50 % an Lipoproteine assoziiert und Lipoproteinprofile können sich in Abhängigkeit des Körperfettgehaltes- bzw. der Körperfettverteilung unterscheiden, sodass ein Zusammenhang zwischen Körperfettgehalt- bzw. Verteilung und IF-Wirkungen angenommen wurde. Ziel der Arbeit war es, einen umfassenden Überblick über die Rolle der IF im Fettstoffwechsel der PMF zu geben. Die 12 wöchige, randomisierte, doppelblinde und Placebo-kontrollierte Studie im Paralleldesign wurde mit 179 gesunden PMF durchgeführt, die 117,4 mg/d IF-Extrakt konsumierten. Untersucht wurde einerseits der Einfluss der Inter-vention auf Serumlipidkonzentrationen und die Expression des LDLR und Scavenger-rezeptors CD36 (CD36) auf den Leukozyten und andererseits, ob modulierende Einflüsse durch den Körperfettgehalt bzw. die Viszeralfettmenge (VAT) oder den Equolbildnerstatus (EBS) auf die Intervention mit IF bestehen. Eine Genexpressionsanalyse in Biopsaten des subkutanen Bauchfettgewebes (SAT) wurde durchgeführt, um differentiell exprimierte Gene des Energie- und Fettstoffwechsels in diesem aufzuzeigen. Zudem wurde untersucht, ob die Intervention sich auf die Körperfettverteilung auswirkt und ob IF und IF-Metabolite im SAT nachgewiesen werden können. Die Intervention erhöhte die LDL-Cholesterolkonzentrationen (LDL-Chol) um ca. 3,4 %. Die weiteren Serumlipidkonzentrationen, die LDLR- und CD36-Expression auf den Leukozyten sowie die Parameter der Körperzusammensetzung wurden durch die Intervention nicht verändert. Ein Effekt des Körperfettanteils- bzw. der Menge an VAT oder des EBS auf die Intervention hinsichtlich der Serumlipidkonzentrationen und der LDLR- und CD36-Expression konnte ebenfalls nicht festgestellt werden. Im SAT waren keine Gene differentiell zwischen der Placebo- und IF-Gruppe exprimiert, auch wenn hier nach der Intervention IF nachzuweisen waren. Interventionsunabhängig kam es durch die Durchführung der Studie in zwei unterschiedlichen Jahreszeiten u. a. zu einem Anstieg der LDL Chol um 3,5 %. Die 12-wöchige Intervention mit IF-Extrakt hatte somit, mit Ausnahme des moderaten Anstiegs der LDL-Chol, keinen Einfluss auf Parameter des Fettstoffwechsels gesunder PMF. Dieser leichte Anstieg kann jedoch dadurch relativiert werden, dass ein Anstieg der LDL-Chol in vergleichbarer Höhe interventionsunabhängig auch allein durch die Durchführung der Studie in einer bestimmten Jahreszeit hätte auftreten können. Auch modulierende Effekte durch den Körperfettgehalt, die Viszeralfettmenge oder den EBS lagen nicht vor. Die Ergebnisse dieser randomisierten, doppelblinden und Placebo-kontrollierten Studie lassen den Schluss zu, dass IF im Fettstoffwechsel PMF eher eine untergeordnete Rolle spielen.The role of isoflavones in lipid metabolism of healthy postmenopausal women - an intervention study Menopause is accompanied by hormonal alterations as well as changes in lipid and lipoprotein metabolism and is furthermore associated with alterations in body fat distribution. These alterations lead to an increased risk of cardiovascular diseases (CVD) in postmenopausal women (PMW). Epidemiological and cross sectional studies indicate lower incidence of CVD and menopausal symptoms in PMW in Asian countries. This is assumed to be associated with a higher amount of soy and soy isoflavones (IF) in Asian diets. In Western countries, IF are over-the–counter supplements and represent a potential alternative to hormone replacement therapies for PMW suffering from menopausal symptoms. However, studies regarding the effects of IF on e.g. lipoprotein or serum lipid concentrations or other risk factors concerning CVD show heterogeneous results. It is conceivable that modulating factors exist, which are responsible for these disparate results. It is known that approx. 50 % of the IF transport is associated with lipoproteins. Lipoprotein profiles can vary due to different body fat contents or body fat compositions. Therefore, a direct interaction between body fat content or the amount of visceral adipose tissue and effects of IF can be assumed. The objective of the presented work was to give a comprehensive overview about the role of IF in the lipid metabolism of PMW. A randomized, double-blind and placebo-controlled study with 179 healthy PMW was conducted over a period of 12 weeks. An over-the-counter IF extract was used as the intervention product with a daily dose of 117.4 mg. Effects of IF on serum lipid concentrations and the expression of LDLR and CD36 receptors on leukocytes were examined. Moreover, a modulating effect of body fat content or rather the amount of visceral adipose tissue (VAT) or the ability to produce equol on effects of IF was investigated. Biopsies of subcutaneous adipose tissue (SAT) were used to perform a gene expression analysis to show differentially expressed genes of lipid and energy metabolism due to the intervention. Furthermore, IF and their metabolites were determined in these samples. Effects of IF on body fat content and body composition were also investigated. An effect of IF on serum lipid concentrations was only shown for LDL-cholesterol concentrations (LDL-chol), which rose around 3.4 % after 12 weeks of IF intervention. No effects were shown for total cholesterol and HDL-cholesterol concentrations. Expression of LDLR and CD36 receptors as well as body composition parameters were not affected through the intervention. The postulated effect of body fat content or rather the amount of VAT on IF effects on serum lipid concentrations and receptor expressions could not be proved. The ability to produce equol did not contribute to potential IF effects in these women compared to women not able to produce equol. In subcutaneous adipose tissue, genes of lipid or energy metabolism were not differentially expressed between the placebo and IF group. However, IF could be found in this tissue after 12 weeks of intervention. As the study was conducted during two different seasons, effects on e. g. LDL-chol occurred independently of the intervention with IF. This seasonal effect increased LDL-chol by 3.5 %. Summarizing the aforementioned results, the intervention with 117.4 mg IF extract per day for 12 weeks did not affect parameters of lipid metabolism in healthy PMW, except for a moderate rise in LDL-chol. A similar increase of LDL-chol can also occur independently of the IF intervention by simply conducting a study in a particular season. Therefore, the moderate effect of IF on LDL-chol can be qualified. A modulating effect of body fat content or rather the amount of VAT regarding IF effects was not observed. It can be concluded that IF only play a minor role in the lipid metabolism of healthy PMW
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
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