1,721,067 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
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
Genesis and biological activity of cerebral cavernomas in adult and pediatric patients: an immunohistochemical study of 87 patients
No full textDie vorliegende Arbeit soll zur Kärung der Genese und der biologischen Aktivität cerebraler Kavernome in adulten und pädiatrischen Patienten beitragen. Es wurden die Operationspräparate von 87 Kavernompatienten mittels immunhistochemischer Technik auf das Vorhandensein relevanter Antigene im Gewebe untersucht. Sowohl die Kavernome von Patientengruppen mit unterschiedlicher klinischer Symptomatik, als auch die Kavernome von adulten Patienten verglichen mit denen pädiatrischer Patienten, weisen eine unterschiedliche biologische Aktivität auf. Dabei kommt den Antigenen VEGF und Endoglin, sowie den mit diesen Antigenen assoziierten Pathways besondere Bedeutung zu.The thesis contributes to the illucidation of the genesis and the biological activity of cerebral cavernomas in adult and pediatric patients. The specimens of 87 patients suffering from cerebral cavernomas, who underwent surgery, were investigatet with immunohistochemical technique to give proof of the existance of relevant antigenes in the tissue. The cavernomas of patient groups with different clinical symptoms, as well as the cavernomas of adult patients compared to those of pediatric patients, had a different biological activity. Herewith the antigenes VEGF and Endoglin and the associated pathways play keyroles
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
Qualitative detection of CCM1, CCM2 and CCM3 and analysis of morphological and proliferative changes after downregulation of expression of CCM1 in HUV endothelialcells
No full textKavernome sind vaskuläre Neubildungen im zentralen Nervensystem, welche aus dilatierten, dünnwandigen, sinusoidalen Blutgefäßen bestehen. Histologisch zeigen sich nur anormal vorhandene oder gänzlich fehlende Tight Junctions der Endothelzellen und teilweise fehlende astrozytische Fortsätze, was zu einer Vergrößerung der Zwischenräume der Zellen führt. Klinisch weisen die Patienten zerebrale Blutungen, Krampfleiden oder fokale neurologische Defizite auf. Die Prävalenz des Kavernoms beträgt 0,5%, von diesen weisen jedoch nur 20 bis 30% klinische Symptome auf. Das Kavernom tritt sowohl sporadisch als auch autosomal dominant vererbt auf. Die familiären Fälle stehen im Zusammenhang mit drei Genen und deren, zu einem Funktionsverlust führenden, Mutationen. Mutationen in CCM1 sind für 40 bis 50% der familiären Fälle verantwortlich, in CCM2 für 10 bis 20% und in CCM3 für etwa 40%. Das Modell der Entstehung des Kavernoms gründet sich auf dem von Knudson erstellten two-hit Mechanismus und wird von murinen Forschungsergebnissen mit Ccm1+/- Trp53-/- doppelt mutierten Mäusen unterstützt. Sowohl CCM1 (KRIT1) als auch CCM2 (Malcavernin) sind in den β1 Integrin Signalweg eingebunden, welcher unter anderem Zelladhäsion, Zellmigration und Zellproliferation reguliert. Außerdem sind beide Gene an der Aktivierung der p38MAPK beteiligt, von welcher murine Forschungsergebnisse zeigen konnten, dass Mäuse ohne p38αMapk signifikante Defekte in der plazentalen Angiogenese und in der Entwicklung der Blutgefäße, besonders im Bereich des Kopfes, aufwiesen. Außerdem konnte nachgewiesen werden, dass CCM3 (PDCD10) mit dem ERK Signalweg, welcher ebenfalls Einfluss auf Zellproliferation und Transformation hat, interagiert.
Ziel der Arbeit war es, die Expression der CCM Gene nachzuweisen und dadurch die Theorie, dass Endothelzellen in der Pathogenese des Kavernoms eine Hauptrolle spielen, zu unterstützen. Außerdem sollte ein Zellkultursystem erstellt werden, welches uns die Möglichkeit gibt, funktionelle Veränderungen der Endothelzellen nach Runterregulation von CCM1 festzustellen.
Mittels Echtzeit RT-PCR konnte nachgewiesen werden, dass HUV Endothelzellen alle drei CCM Gene exprimieren. Außerdem war es möglich, ein Zellkultursystem in HUV Endothelzellen zu etablieren, in welchem CCM1 erfolgreich runterreguliert werden konnte. Validiert wurde dieses System ebenfalls mittels Echtzeit RT-PCR. Nachfolgend wurden Veränderungen der Morphologie und der Proliferation erfasst. Morphologisch zeigten sich die Zellen nach Transfektion größer und spindelförmiger als die Kontrollen, und sie bildeten vermehrt strangförmige Strukturen. Diese Beobachtungen ähnelten Zellen isoliert aus Kavernomen in Angiogenese-Assays. Die Ergebnisse dieser Arbeit unterstützen die Vermutung, dass der Verlust der Funktion von CCM1 in Endothelzellen die Hauptrolle in der zum Kavernom führenden Veränderung spielt. Im Proliferationsassay ließ sich eine Verringerung der Proliferationsrate feststellen, welche zeigt, dass ein Funktionsverlust von CCM1 einen direkten Einfluss auf die Zellproliferation hat.Cerebral cavernous malformations are vascular neoplasms in the central nervous system. They consist of dilated, thinwalled, sinusoidal bloodvessels. Histologically the tight junctions of these endothelial cells forming the cerebral cavernous malformation are abnormal or totaly missing, also the appendages of the astrozytes can be partly missing, which results wider gaps between the cells.
Main Symptoms are cerebral bleeding, convulsion or focal neurological deficencies.
The prevalence of cerebral cavernous malformation averages at about 0,5%, of these only 20 to 30% present with clinical symptoms. Cerebral cavernous malformations can occur sporadic or can be autosomal dominant inherited. The familial cases are associated with loss of function mutations within three genes. Mutations of CCM1 are responsible for 40 to 50%, of CCM2 for 10 to 20% and mutations of CCM3 for about 40% of the familial cases.
The model of genesis of the cerebral cavernous malformation builds on the two-hit mechanisms established by Knudson, and is supported by Ccm1+/- Trp53-/- mice. CCM1 (KRIT1) as well as CCM2 (Malcavernin) are integrated in β1 integrine signaling, which among other factors regulates adhesion, migration and proliferation of cells. Also both genes are involved in activation of p38MAPK. P38Mapk-/- mice have significant defects in plazental angiogenesis and development of bloodvessels, especially in brain vessels. Moreover CCM3 (PDCD10) interacts with ERK signaling, which also affects proliferation and transformation of cells.
Aim of the present work was to detect the expression of all three CCM genes and to test the hypothesis that endothelial cells play a major role in the pathogenesis of cerebral cavernous malformations. Moreover we wanted to created a tissue culture system, to detect functional changes in endothelial cells after downregulation of CCM1.
Using real-time RT-PCR we found the expression of all three CCM genes in HUV endothelial cells. A tissue culture system was established also in HUV endothelial cells, where we were able to downregulate CCM1 by transient transfection with short interfering RNA.
Morphologically knock down cells were bigger and more fusiform compared to the control cells. The cells also formed more restiform structures. Similar observations were made in cells isolated from cerebral cavernous malformations in angiogenesis assays. The results of this thesis confirm, that the loss of function of CCM1 in endothelial cells plays a major role in changes leading to the pathogenesis of cerebral cavernous malformations.
The accomplished proliferationassay showed a reduction of proliferation, which demonstrates that the loss of function of CCM1 has a direct effect on cellproliferation
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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