1,721,016 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
Farming systems analysis and modelling in the Livestock Systems and Environment group of ILRI
No full textPoster on Farming systems analysis and modelling in the Livestock Systems and Environment group of ILR
Die vielfältigen Dimensionen der Dynamik der Fischvielfalt und der Stabilität der Gemeinschaft
No full textA decrease in global biodiversity has been recently recorded and is attributed to human activities, mainly caused by predation, modification of natural habitats and climate change. Biological diversity, defined as the variability among living organisms, is known to have a positive effect on productivity and stability of ecosystems. The loss of biodiversity can have a cascading effect and lead to drastic changes in the dynamics and functioning of ecosystems, and subsequently to the services they provide to humans. In marine ecosystems, fish are extremely valuable as a source of protein for more than 3 billion people, and a source of income for more than 40 million people. Yet, fish communities are threatened by high fishing pressure and fast changing habitat conditions. Using a collection of fisheries-independent bottom-trawl surveys and advanced statistical analysis, this thesis aims to understand the importance of biodiversity for the resilience of marine fish populations to climate change and fisheries exploitation. More specifically, this complex issue has been divided into three interconnected sub-questions: (i) how to characterize the spatio-temporal dynamics of fish assemblages and identify their external drivers? (ii) how does fish functional diversity respond to changing external pressures? and (iii) what is the importance of biodiversity for the stability of ecosystems?
This dissertation combines case studies demonstrating the benefits of using novel approaches to look at existing datasets and integrating information from multiple sources. Each chapter studies different aspects of the complexity of biodiversity dynamics. For instance, the interaction between spatial and temporal dynamics of fish communities was investigated using multiway multivariate analysis (chapters 2 and 3). Three-matrix multivariate approaches can integrate information about functional traits and disentangle the relation between traits and environmental changes (chapters 3, 4). Additionally, new morphological traits were derived from outline analysis and linked to environmental processes (chapter 5). Finally, the relationship between diversity and stability of communities was explored by combining abundance time series with ecological network analysis (chapter 6) and by considering the intra-specific trait variability (chapter 7). None of these approaches are better than another, but together they highlight the multiple dimensions of fish diversity dynamics and community stability.
A better understanding of the complexity and the multidimensionality of diversity is a first step toward an integrative ecosystem assessment. For example, understanding the link between traits and environment (chapters 3 and 4) is important to understand and predict the impact of changing environmental conditions on the functional diversity of communities. However, these predictions would be incomplete if one fails to consider the network of interactions between species and the possible cascading effects throughout the food web (chapter 6). Additionally, the intra-specific trait variability (chapter 7) might enhance the adaptation of communities to changing conditions. Combining these different approaches into a common framework can provide key information for the management and conservation of ecosystems, as well as relevant advices for marine ecosystem-based management.
Embracing the complexity of ecosystem dynamics is recognizing our limited scientific knowledge and the high unpredictability of community dynamics. Therefore, the safest and the most recommendable management option is the precautionary approach. It is urgent that society as a whole take actions to preserve biodiversity, in all its dimensions, which is the best management strategy to help biotic communities adapt to ongoing and future changes.Kürzlich wurde ein Rückgang der globalen Biodiversität verzeichnet, der auf Aktivitäten des Menschen wie Prädation, Modifikation natürlicher Lebensräume und den Klimawandel zurückzuführen ist. Die biologische Vielfalt, definiert als die Variabilität lebender Organismen, wirkt sich bekanntermaßen positiv auf die Produktivität und Stabilität von Ökosystemen aus. Eine Abnahme von Biodiversität kann kaskadenartig wirken und zu drastischen Veränderungen in der Dynamik und Funktionsweise von Ökosystemen führen, sowie zu Veränderungen in Ökosystem-Dienstleistungen, die sie für den Menschen bereitstellen. In marinen Ökosystemen sind Fische äußerst wertvoll, als Proteinquelle für mehr als 3 Milliarden Menschen und als Einkommensquelle für mehr als 40 Millionen Menschen. Fischgemeinschaften sind jedoch durch den hohen Fischereidruck und die sich schnell ändernden Lebensraumbedingungen bedroht. Anhand einer Sammlung von fischereiunabhängigen Untersuchungen der Grundschleppnetzfischerei und fortschrittlicher statistischer Analysen soll die Bedeutung der Biodiversität für die Widerstandsfähigkeit der Meeresfischbestände gegenüber dem Klimawandel und der Fischereibewirtschaftung verstanden werden. Im Einzelnen wurde dieses komplexe Thema in drei miteinander verbundene Unterfragen unterteilt: (i) wie lässt sich die räumlich-zeitliche Dynamik von Fischbeständen charakterisieren und deren externe Treiber identifizieren? (ii) wie reagiert die funktionale Fisch-Vielfalt auf sich ändernde äußere Einwirkungen? und (iii) welche Bedeutung hat Biodiversität für die Stabilität von Ökosystemen?
Diese Dissertation kombiniert Fallstudien, in denen die Vorteile der Verwendung neuer Ansätze zur Untersuchung vorhandener Datensätze und der Integration von Informationen aus mehreren Quellen demonstriert werden. In jedem Kapitel werden verschiedene Aspekte der Komplexität der Biodiversitätsdynamik untersucht. Zum Beispiel wurde die Wechselwirkung zwischen räumlicher und zeitlicher Dynamik von Fischgemeinschaften mithilfe einer multivariaten Mehrweg-Analyse untersucht (Kapitel 2 und 3). Multivariate Drei-Matrix-Ansätze können Informationen über funktionale Merkmale integrieren und die Beziehung zwischen Merkmalen und Umweltveränderungen aufdecken (Kapitel 3, 4). Darüber hinaus wurden neue morphologische Merkmale aus der Umrissanalyse abgeleitet und mit Umweltprozessen verknüpft (Kapitel 5). Schließlich wurde der Zusammenhang zwischen Diversität und Stabilität von Gemeinschaften untersucht, indem Abundanz-Zeitreihen mit einer ökologischen Netzwerkanalyse (Kapitel 6) kombiniert wurden und die intraspezifische Merkmalsvariabilität (Kapitel 7) betrachtet wurde. Keiner dieser Ansätze ist besser als der andere, aber gemeinsam betonen sie die vielfältigen Dimensionen der Dynamik der Fischvielfalt und der Stabilität der Gemeinschaft.
Ein besseres Verständnis der Komplexität und der Multidimensionalität von Diversität ist ein erster Schritt hin zu einer integrativen Ökosystembewertung. Das Verständnis der Verbindung zwischen Merkmalen und der Umgebung (Kapitel 3 und 4) ist wichtig, um die Auswirkungen sich ändernder Umweltbedingungen auf die funktionale Vielfalt von Gemeinschaften zu verstehen und vorherzusagen. Diese Vorhersagen wären jedoch unvollständig, wenn man das Netzwerk aus Interaktionen zwischen den Arten und die möglichen Kaskadeneffekte im gesamten Nahrungsnetz nicht berücksichtigt (Kapitel 6). Darüber hinaus kann die intraspezifische Merkmalsvariabilität (Kapitel 7) die Anpassung von Gemeinschaften an sich ändernde Bedingungen verstärken. Die Kombination dieser unterschiedlichen Ansätze in einem gemeinsamen Rahmen kann wichtige Informationen für das Management und die Erhaltung von Ökosystemen, sowie relevante Ratschläge für das Management von marinen Ökosystemen liefern.
Um die Komplexität der Ökosystemdynamik zu erfassen, müssen wir unser begrenztes wissenschaftliches Wissen und die hohe Unvorhersagbarkeit von Gemeinschaftsdynamik erkennen. Daher stellt ein vorsorglicher Ansatz die sicherste und empfehlenswerteste Managementoption dar. Es ist dringend geboten, dass die Gesellschaft als Ganzes Maßnahmen zum Erhalt der Biodiversität in all ihren Dimensionen ergreift. Dies ist die beste Managementstrategie, um Ökosysteme dabei zu unterstützen, sich an die fortlaufenden Veränderungen anzupassen
Development of an open source tool to analyze Vegetation Index from Remote Sensing data: Internship report
Full text linkThis report concludes my six-months internship within the Consultative Group on International Agricultural Research (CGIAR)'s Systemwide Livestock Programme. I was involved in the project \Optimizing livelihood and environmental benefits from crop residues n smallholders crop-livestock systems in sub-Saharan Africa and South Asia". During my internship, I have been involved in a large scale agricultural survey focused on crop residues uses. I have also developed a tool to conduct automated analysis of Normalized Diference Vegetation Index (NDVI) from diferent optical satellite instruments AVHRR, Spot Vegetation). Land Surface Phenology metrics can be computed for every season as well as vegetation anomaly maps to study agricultural landscapes. Finally, my internship has been concluded by the development of a package and the submission of scientific article. The aim of this documents is to explain and present the package ndvits. First, I will detail the specificity of the NDVI dataset and the methods used for its analysis. Then, I will comment some examples of applications of the package
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
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