1,721,012 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
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
Visualization of arteriovenous malformations using color-coded transcranial duplex ultrasonography
No full textThe aim: Arteriovenous malformations (AVM) may be visualized using transcranial color-coded duplex ultrasonography (TCCS). The research presented aimed at examining typical sonographic characteristics and visualization of AVM in relation to their location. Methods: In the course of 6 years ultrasonographic prospective examination was used in 54 patients with AVM demonstrated by means of angiography. The arteries of circulus arterious Willisi were identified on the base of location, anatomical course and flow direction. During the first 3 years, investigations were realized using ultrasonographic system Acuson 128 XP 10 with 7.0 MHz linear probe for the extracranial vascular system, and with 2 MHz sector probe for transcranial visualization. Acuson Seqouia TM 512 apparatus was applied in the latter half of the trial. Results: In accordance with digital subtraction angiography (DSA) 42 AVMs were visualized by means of sonography (sensitivity 77.8 %). The blood-vessels supplying an angioma were identified on the base of typical hemodynamic parameters (increased systolic and diastolic flow velocity, decreased index of pulsatility). AVMs located subcortically could be visualized with difficulties. On the contrary, AVMs situated in the axial plane in basal regions of the brain were visualized best (sensitivity 88.9 %). TCCS showed to be most helpful in assessing the post-operative course or the course after embolizing interventions. Conclusion: TCCS is a valuable diagnostic method for visualizing AVM as well as for evaluating the course after interventions on AVMs. However, this method should not be applied as a screening examination
Physical-based model for exposure coefficient and its validation towards the second generation of Eurocode EN 1991-1-3 for roof snow loads
No full textIn standards for structural design, models for snow loads on flat roofs generally provide the basis for determination of snow loads on any roof shapes. They are typically derived from ground snow loads and the predicted effects of exposure of flat roofs primarily due to wind, often conveyed through the exposure coefficient. The paper provides background information on the revision of the model for exposure coefficient in the second generation of the Eurocode on snow loads on structures, prEN 1991-1-3:2020. With the aim to provide an easy-to-use procedure with a minimum amount of input data, but to cover the main physical phenomena, a new formulation is proposed in prEN reflecting up-to-date scientific findings and the model provided in ISO 4355:2013. The prEN model corrects the main deficiency of the model in EN 1991-1-3:2003 where no account for wind velocities expected at the site during a snow season is taken. The prEN formulation additionally requires information on mean wind velocity for the coldest month at the site, that is commonly easily accessible. The contribution starts off by introducing the prEN model. To validate the new model, a parametric study is presented, considering plausible ranges of the main parameters influencing the determination of exposure coefficient in Europe. The outcomes of the new simplified prEN formulation are then compared with an advanced theoretical model. The prEN model is further applied considering detailed meteorological data representative for various climates. The results obtained by the prEN provisions are critically compared with those based on the advanced theoretical model and meteorological data, and with the estimates of the models in ISO 4355:2013 and in the JCSS Probabilistic Model Code. The presented validation demonstrates that the prEN model reflects well typical European snow and wind climates. The model captures a clear decreasing tendency of exposure coefficient with an increasing mean wind velocity. Mean wind velocity in the coldest month of 4.5 m/s appears to provide a reasonable threshold to make distinction between normal and exposed conditions
Visualization of arteriovenous malformations using color-coded transcranial duplex ultrasonography
No full textThe aim: Arteriovenous malformations (AVM) may be visualized using transcranial color-coded duplex ultrasonography (TCCS). The research presented aimed at examining typical sonographic characteristics and visualization of AVM in relation to their location. Methods: In the course of 6 years ultrasonographic prospective examination was used in 54 patients with AVM demonstrated by means of angiography. The arteries of circulus arterious Willisi were identified on the base of location, anatomical course and flow direction. During the first 3 years, investigations were realized using ultrasonographic system Acuson 128 XP 10 with 7.0 MHz linear probe for the extracranial vascular system, and with 2 MHz sector probe for transcranial visualization. Acuson Seqouia TM 512 apparatus was applied in the latter half of the trial. Results: In accordance with digital subtraction angiography (DSA) 42 AVMs were visualized by means of sonography (sensitivity 77.8 %). The blood-vessels supplying an angioma were identified on the base of typical hemodynamic parameters (increased systolic and diastolic flow velocity, decreased index of pulsatility). AVMs located subcortically could be visualized with difficulties. On the contrary, AVMs situated in the axial plane in basal regions of the brain were visualized best (sensitivity 88.9 %). TCCS showed to be most helpful in assessing the post-operative course or the course after embolizing interventions. Conclusion: TCCS is a valuable diagnostic method for visualizing AVM as well as for evaluating the course after interventions on AVMs. However, this method should not be applied as a screening examination
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
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
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