1,720,976 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
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
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
Analysis of multifractal scaling laws describing satellite observations of continental surfaces
No full textCompte tenu de la forte hétérogénéité spatio-temporelle des surfaces continentales, la télédétection spatiale s’est avérée être un moyen indispensable pour réaliser un suivi à la fois régulier, local et global des processus qui régissent ces surfaces. Les facteurs dont ils dépendent, tels que l’humidité du sol ou la végétation sont variables sur de larges gammes d’échelles auxquelles seuls les satellites peuvent accéder. En raison du nombre grandissant d’observations satellitaires présentes à plusieurs échelles spatiales et fondées sur de multiples technologies, diverses méthodes ont alors été développées pour permettre d’analyser et d’extraire au mieux l’information riche et conséquente acquise par satellite. Les méthodes basées sur l’analyse multi-échelle fournissent un moyen efficace pour décrire l’hétérogénéité de ces observations et ainsi mieux comprendre la complexité des processus de surface. En particulier, une possibilité consiste à s’intéresser à l’existence de lois d’échelles statistiques qui offrent un outil conceptuel générique applicable à la caractérisation de tout type de géométrie. Cela peut contribuer à caractériser les processus de surface selon une approche multi-échelle rarement prise en compte dans les modèles actuels de surface.Dans ce contexte, l’objectif de cette thèse est de montrer le potentiel d’une méthode permettant de caractériser sur plusieurs échelles spatiales les comportements de variables géophysiques de surface. Pour cela, différentes observations satellitaires complémentaires ont été analysées au moyen du modèle des Multifractales Universelles (Schertzer and Lovejoy, 1987). Deux cas d’étude ont permis de répondre à cet objectif. La première application porte sur l’analyse multifractale des produits intervenant dans l’algorithme de désagrégation spatiale d’humidité du sol DisPATCh (Disaggregation based on Physical And Theoretical scale Change; Merlin et al., 2008; Molero et al., 2016), sur la partie Sud-Est de l’Australie. Dans le deuxième cas d’étude, nous avons étudié le comportement multi-échelle de réflectances de surface et indices optiques acquis par le satellite Sentinel-2 sur la région Sud-Ouest de la France, et corrigés des effets atmosphériques par la chaine MAJA (MACCS-ATCOR Joint Algorithm; Hagolle et al., 2010, 2015; Rouquié et al., 2017). Dans ces deux cas d’étude, l’analyse de séries temporelles d’images nous a permis de mettre en relation l’évolution temporelle des propriétés d’échelle avec les variations saisonnières de la région d’étude (conditions météorologiques, cycles de cultures).Ce travail a révélé dans les produits de surface la présence de lois d’échelles qui diffèrent en fonction de la gamme d’échelles considérée. Ces comportements différents mettent en évidence des régimes d’échelles spécifiques qui, selon le produit étudié, peuvent s’expliquer de deux manières. D’une part, les régimes observés peuvent traduire la présence de processus de surface non-linéaires tels que les précipitations, le ruissellement ou l’évapotranspiration, agissant à différentes échelles spatiales et modulés par divers facteurs tels que la composition et la structure du sol (distribution de la végétation, présence de parcelles agricoles, etc.). D’autre part, ces comportements d’échelle peuvent également refléter l’impact sur les variables de surface des méthodes d’acquisition (fonction de transfert des capteurs) ou de traitement (combinaison de produits au sein des modèles) qui sont couramment utilisées en télédétection. De cette manière, cette étude a montré le potentiel de l’analyse multifractale pour décrire l’hétérogénéité des surfaces continentales, mais également pour évaluer la fiabilité de produits ou modèles de surface. Cette méthode pourrait être utile à la préparation de futures missions spatiales afin de déterminer les limites des capteurs en termes de propriétés multi-échelles, et ainsi mieux estimer la résolution effective de différents produits satellitaires.Considering the strong spatial and temporal heterogeneity of continental surfaces, remote sensing has proved to be an indispensable means for conducting regular, local and global monitoring of the physical and biophysical processes governing these surfaces. The factors on which they depend, such as soil moisture, surface temperature, vegetation, or topography, are variable over wide ranges of scales that only satellites can access. Thus, over the last fifty years, we have seen a growing number of satellite observations defined at multiple spatial scales and based on multiple technologies. Various methods were then developed to analyze and extract the rich and consistent information acquired by satellites. Methods based on multi-scale analysis can provide an effective means to describe the heterogeneity of these observations and thus better understand the complexity of surface processes. In particular, one possibility is to focus on the existence of statistical scaling laws offering a generic tool applicable to the characterization of any type of geometry. The demonstration of specific scaling behaviors can help to characterize surface processes using a multi-scale approach that is rarely taken into account in current surface models.In this context, the objective of this thesis is to demonstrate the potential of a method dedicated to the characterization of the behaviors of surface geophysical variables on several spatial scales. For this, different complementary satellite observations were analyzed using the Universal Multifractal model (Schertzer and Lovejoy, 1987). Two case studies helped to meet this objective. The first application concerns the multifractal analysis of the products involved in the soil moisture disaggregation algorithm called DisPATCh (Disaggregation based on Physical And Theoretical scale Change; Merlin et al., 2008; Molero et al., 2016), on the southeastern part of Australia. In the second case study, we studied the multi-scale behavior of surface reflectances and optical indices acquired by Sentinel-2 satellite over the South-West region of France, and corrected from atmosphere effects by the processing chain MAJA (MACCS-ATCOR Joint Algorithm; Hagolle et al., 2010, 2015; Rouquié et al., 2017). In both case studies, time series of images were analyzed. Thus, for each variable studied, we were able to relate the temporal evolution of scaling properties to the seasonal variations specific to the study area (meteorological conditions, crop cycles).During this work, different scaling laws were observed on different scale ranges. Two arguments were given to explain these different scaling behaviors, depending on the case study and the product. On the one hand, the observed regimes can reflect the presence of non-linear surface processes such as precipitation, runoff or evapotranspiration, acting at different spatial scales and modulated by various factors such as soil composition and structure (distribution of vegetation, presence of agricultural parcels, etc.). On the other hand, these scaling behaviors may also reflect the impact on surface variables of acquisition techniques (sensor transfer function) or processing methods (combination of products within surface models) that are commonly used in remote sensing. In this way, this study showed the potential of multifractal analysis to describe the heterogeneity of continental surfaces, but also to evaluate the reliability of geophysical products and surface models. This method could be useful for the preparation of future space missions in order to determine the limits of satellite sensors in terms of multi-scale properties, and thus to better estimate the effective resolution of different products derived from satellite acquisitions
Etude des lois d'échelle multifractales caractérisant les observations satellitaires des surfaces continentales
Full text linkCompte tenu de la forte hétérogénéité spatio-temporelle des surfaces continentales, la télédétection spatiale s'est avérée être un moyen indispensable pour réaliser un suivi à la fois régulier, local et global des processus qui régissent ces surfaces. Les facteurs dont ils dépendent, tels que l'humidité du sol ou la végétation sont variables sur de larges gammes d'échelles auxquelles seuls les satellites peuvent accéder. En raison du nombre grandissant d'observations satellitaires présentes à plusieurs échelles spatiales et fondées sur de multiples technologies, diverses méthodes ont alors été développées pour permettre d'analyser et d'extraire au mieux l'information riche et conséquente acquise par satellite. Les méthodes basées sur l'analyse multi-échelle fournissent un moyen efficace pour décrire l'hétérogénéité de ces observations et ainsi mieux comprendre la complexité des processus de surface. En particulier, une possibilité consiste à s'intéresser à l'existence de lois d'échelles statistiques qui offrent un outil conceptuel générique applicable à la caractérisation de tout type de géométrie. Cela peut contribuer à caractériser les processus de surface selon une approche multi-échelle rarement prise en compte dans les modèles actuels de surface. Dans ce contexte, l'objectif de cette thèse est de montrer le potentiel d'une méthode permettant de caractériser sur plusieurs échelles spatiales les comportements de variables géophysiques de surface. Pour cela, différentes observations satellitaires complémentaires ont été analysées au moyen du modèle des Multifractales Universelles (Schertzer and Lovejoy, 1987). Deux cas d'étude ont permis de répondre à cet objectif. La première application porte sur l'analyse multifractale des produits intervenant dans l'algorithme de désagrégation spatiale d'humidité du sol DisPATCh (Disaggregation based on Physical And Theoretical scale Change; Merlin et al., 2008; Molero et al., 2016), sur la partie Sud-Est de l'Australie. Dans le deuxième cas d'étude, nous avons étudié le comportement multi-échelle de réflectances de surface et indices optiques acquis par le satellite Sentinel-2 sur la région Sud-Ouest de la France, et corrigés des effets atmosphériques par la chaine MAJA (MACCS-ATCOR Joint Algorithm; Hagolle et al., 2010, 2015; Rouquié et al., 2017). Dans ces deux cas d'étude, l'analyse de séries temporelles d'images nous a permis de mettre en relation l'évolution temporelle des propriétés d'échelle avec les variations saisonnières de la région d'étude (conditions météorologiques, cycles de cultures). Ce travail a révélé dans les produits de surface la présence de lois d'échelles qui diffèrent en fonction de la gamme d'échelles considérée. Ces comportements différents mettent en évidence des régimes d'échelles spécifiques qui, selon le produit étudié, peuvent s'expliquer de deux manières. D'une part, les régimes observés peuvent traduire la présence de processus de surface non-linéaires tels que les précipitations, le ruissellement ou l'évapotranspiration, agissant à différentes échelles spatiales et modulés par divers facteurs tels que la composition et la structure du sol (distribution de la végétation, présence de parcelles agricoles, etc.). D'autre part, ces comportements d'échelle peuvent également refléter l'impact sur les variables de surface des méthodes d'acquisition (fonction de transfert des capteurs) ou de traitement (combinaison de produits au sein des modèles) qui sont couramment utilisées en télédétection. De cette manière, cette étude a montré le potentiel de l'analyse multifractale pour décrire l'hétérogénéité des surfaces continentales, mais également pour évaluer la fiabilité de produits ou modèles de surface. Cette méthode pourrait être utile à la préparation de futures missions spatiales afin de déterminer les limites des capteurs en termes de propriétés multi-échelles, et ainsi mieux estimer la résolution effective de différents produits satellitaires.Considering the strong spatial and temporal heterogeneity of continental surfaces, remote sensing has proved to be an indispensable means for conducting regular, local and global monitoring of the physical and biophysical processes governing these surfaces. The factors on which they depend, such as soil moisture, surface temperature, vegetation, or topography, are variable over wide ranges of scales that only satellites can access. Thus, over the last fifty years, we have seen a growing number of satellite observations defined at multiple spatial scales and based on multiple technologies. Various methods were then developed to analyze and extract the rich and consistent information acquired by satellites. Methods based on multi-scale analysis can provide an effective means to describe the heterogeneity of these observations and thus better understand the complexity of surface processes. In particular, one possibility is to focus on the existence of statistical scaling laws offering a generic tool applicable to the characterization of any type of geometry. The demonstration of specific scaling behaviors can help to characterize surface processes using a multi-scale approach that is rarely taken into account in current surface models. In this context, the objective of this thesis is to demonstrate the potential of a method dedicated to the characterization of the behaviors of surface geophysical variables on several spatial scales. For this, different complementary satellite observations were analyzed using the Universal Multifractal model (Schertzer and Lovejoy, 1987). Two case studies helped to meet this objective. The first application concerns the multifractal analysis of the products involved in the soil moisture disaggregation algorithm called DisPATCh (Disaggregation based on Physical And Theoretical scale Change; Merlin et al., 2008; Molero et al., 2016), on the southeastern part of Australia. In the second case study, we studied the multi-scale behavior of surface reflectances and optical indices acquired by Sentinel-2 satellite over the South-West region of France, and corrected from atmosphere effects by the processing chain MAJA (MACCS-ATCOR Joint Algorithm; Hagolle et al., 2010, 2015; Rouquié et al., 2017). In both case studies, time series of images were analyzed. Thus, for each variable studied, we were able to relate the temporal evolution of scaling properties to the seasonal variations specific to the study area (meteorological conditions, crop cycles). During this work, different scaling laws were observed on different scale ranges. Two arguments were given to explain these different scaling behaviors, depending on the case study and the product. On the one hand, the observed regimes can reflect the presence of non-linear surface processes such as precipitation, runoff or evapotranspiration, acting at different spatial scales and modulated by various factors such as soil composition and structure (distribution of vegetation, presence of agricultural parcels, etc.). On the other hand, these scaling behaviors may also reflect the impact on surface variables of acquisition techniques (sensor transfer function) or processing methods (combination of products within surface models) that are commonly used in remote sensing. In this way, this study showed the potential of multifractal analysis to describe the heterogeneity of continental surfaces, but also to evaluate the reliability of geophysical products and surface models. This method could be useful for the preparation of future space missions in order to determine the limits of satellite sensors in terms of multi-scale properties, and thus to better estimate the effective resolution of different products derived from satellite acquisitions
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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