1,720,967 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
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
Développement de l'imagerie de perfusion cérébrale par marquage des spins artériels
No full textThis PhD work, mainly methodological, focused on the techniques of magnetic resonance imaging (MRI) to measure cerebral blood flow (CBF) and more particularly on arterial spin labeling (ASL), which uses water protons from the blood as markers. We implemented the pseudo-continuous ASL labeling sequence (pCASL) and evaluated its response to a hypercapnic stimulus. We evaluated different strategies to maximize the labeling inversion effeciency. For this, we implemented numerical simulation tools of ASL approaches. Our results demonstrated that the inversion efficiency is influenced by the homogeneity of the magnetic field in the labeling region, which becomes a problem at high magnetic field. The optimized pCASL protocol was then evaluated in rats at three magnetic fields (4.7, 7, and 11.7T) and compared with a conventional continuous ASL approach (CASL). This comparison showed excellent inter-animal and inter-field reproducibility of the developed method. In a second part, we evaluated the influence of the longitudinal relaxation time (T1) of brain tissue on the final CBF values. For this, we modified the tissue T1 by an intracerebral injection of manganese. This study demonstrated the difficulty of taking into account the change in T1 of the tissue. In a third part, we evaluated the contribution of a specific labeling coil for the CASL approach by comparing measurements of CBF obtained with that of pCASL. We found a good agreement between these two methods for all slices. Our results also illustrate the significant contribution of magnetization transfer effects in CASL sequence. The tools developed during this thesis were also used in several preclinical studies including brain tumors, stroke and head trauma models.Ce travail de thèse, principalement méthodologique, s'est intéressé aux techniques d'imagerie par résonance magnétique (IRM) permettant de mesurer le flux sanguin cérébral (CBF) et plus particulièrement aux techniques de marquage de spins artériels (ASL), qui utilisent les protons de l'eau du sang comme marqueur. Nous avons mis en place la séquence ASL de marquage pseudo-continu (pCASL) et évalué sa réponse à un stimulus hypercapnique. Nous avons évalué différentes stratégies pour optimiser l'efficacité d'inversion. Pour cela, nous avons également mis en place des outils de simulations numériques des approches ASL. Nos résultats démontrent que l'efficacité d'inversion est influencée par l'homogénéité du champ magnétique dans la région de marquage, ce qui pose un problème à haut champ magnétique. Le protocole pCASL optimisé a ensuite été évalué chez le rat à trois champ magnétiques (4.7, 7, et 11.7T) et comparé avec une approche en ASL continu classique (CASL). Cette comparaison a montré une excellente reproductibilité inter-animal et inter-champ de la méthode développée. Dans une seconde partie, nous nous sommes également intéressés à l'influence du temps de relaxation longitudinal (T1) du tissu cérébral sur les valeurs du CBF calculées. Pour cela, nous avons modifié le T1 du tissu par une injection intra-cérébrale de manganèse. Cette étude a montré la difficulté de prendre en compte le changement de T1 du tissu. Dans une troisième partie, nous avons évalué l'apport d'une antenne de marquage spécifique pour l'approche CASL en comparant les mesures de CBF obtenues avec celles de la pCASL. Nous avons observé une bonne concordance entre ces deux méthodes à travers les coupes. Nos résultats illustrent également l'importante contribution du transfert d'aimantation dans les séquences de CASL. Les outils développés au cours de cette thèse sont en cours d'application dans des protocoles d'étude de modèles de tumeurs cérébrales, d'accident vasculaire cérébral et de traumatisme crânien
Development of brain perfusion imaging using arterial spin labeling
No full textCe travail de thèse, principalement méthodologique, s'est intéressé aux techniques d'imagerie par résonance magnétique (IRM) permettant de mesurer le flux sanguin cérébral (CBF) et plus particulièrement aux techniques de marquage de spins artériels (ASL), qui utilisent les protons de l'eau du sang comme marqueur. Nous avons mis en place la séquence ASL de marquage pseudo-continu (pCASL) et évalué sa réponse à un stimulus hypercapnique. Nous avons évalué différentes stratégies pour optimiser l'efficacité d'inversion. Pour cela, nous avons également mis en place des outils de simulations numériques des approches ASL. Nos résultats démontrent que l'efficacité d'inversion est influencée par l'homogénéité du champ magnétique dans la région de marquage, ce qui pose un problème à haut champ magnétique. Le protocole pCASL optimisé a ensuite été évalué chez le rat à trois champ magnétiques (4.7, 7, et 11.7T) et comparé avec une approche en ASL continu classique (CASL). Cette comparaison a montré une excellente reproductibilité inter-animal et inter-champ de la méthode développée. Dans une seconde partie, nous nous sommes également intéressés à l'influence du temps de relaxation longitudinal (T1) du tissu cérébral sur les valeurs du CBF calculées. Pour cela, nous avons modifié le T1 du tissu par une injection intra-cérébrale de manganèse. Cette étude a montré la difficulté de prendre en compte le changement de T1 du tissu. Dans une troisième partie, nous avons évalué l'apport d'une antenne de marquage spécifique pour l'approche CASL en comparant les mesures de CBF obtenues avec celles de la pCASL. Nous avons observé une bonne concordance entre ces deux méthodes à travers les coupes. Nos résultats illustrent également l'importante contribution du transfert d'aimantation dans les séquences de CASL. Les outils développés au cours de cette thèse sont en cours d'application dans des protocoles d'étude de modèles de tumeurs cérébrales, d'accident vasculaire cérébral et de traumatisme crânien.This PhD work, mainly methodological, focused on the techniques of magnetic resonance imaging (MRI) to measure cerebral blood flow (CBF) and more particularly on arterial spin labeling (ASL), which uses water protons from the blood as markers. We implemented the pseudo-continuous ASL labeling sequence (pCASL) and evaluated its response to a hypercapnic stimulus. We evaluated different strategies to maximize the labeling inversion effeciency. For this, we implemented numerical simulation tools of ASL approaches. Our results demonstrated that the inversion efficiency is influenced by the homogeneity of the magnetic field in the labeling region, which becomes a problem at high magnetic field. The optimized pCASL protocol was then evaluated in rats at three magnetic fields (4.7, 7, and 11.7T) and compared with a conventional continuous ASL approach (CASL). This comparison showed excellent inter-animal and inter-field reproducibility of the developed method. In a second part, we evaluated the influence of the longitudinal relaxation time (T1) of brain tissue on the final CBF values. For this, we modified the tissue T1 by an intracerebral injection of manganese. This study demonstrated the difficulty of taking into account the change in T1 of the tissue. In a third part, we evaluated the contribution of a specific labeling coil for the CASL approach by comparing measurements of CBF obtained with that of pCASL. We found a good agreement between these two methods for all slices. Our results also illustrate the significant contribution of magnetization transfer effects in CASL sequence. The tools developed during this thesis were also used in several preclinical studies including brain tumors, stroke and head trauma models
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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