1,721,185 research outputs found
La biodiversité est-elle vraiment importante pour bénéficier des services fournis par les écosystèmes forestiers tropicaux ?
Full text linkDeforestation and degradation constitute the main threats to biodiversity in tropical forest ecosystems. Understanding the impacts of these changes on the services provided to human populations is essential to implement a sustainable management of tropical forest resources. The objective of this PhD thesis is to analyze the interactions between biodiversity and ecosystem services of tropical moist forests for three contrasted land allocation types. The study area is located in South-East Cameroon, and is divided into three zones: a protected area (the Dja Wildlife Reserve), a FSC-certified logging concession (Pallisco) and community forests managed by local communities. The impacts of the three land allocation types are quantified according to several state (biodiversity) and impact (ecosystem services) indicators. The integrated analysis of the relations between biodiversity and ecosystem services allow to identify the synergies and trade-offs between them, while identifying the adequacy of management practices implemented in the way to chase their main aim
Estimation de la biomasse aérienne des forêts sempervirentes et semi-décidues du sud-Cameroun : importance de l’allométrie hauteur – diamètre
No full textQuantifier les stocks de biomasse et de carbone dans les forêts denses humides tropicales est une priorité mondiale dans le cadre de la mise en oeuvre de la politique de mitigation, d’atténuation du changement climatique et du mécanisme REDD+. A cette fin, il est indispensable de disposer d’équations allométriques robustes permettant d’estimer les stocks de biomasse et de carbone contenus dans les forêts tropicales. L’objectif de cette étude est de mieux comprendre les relations allométriques entre la hauteur et le diamètre des arbres pour les forêts denses humides tropicales du Cameroun et ses conséquences sur les estimations de la biomasse et des stocks de carbone.
Cette étude a été réalisée au Cameroun dans deux types de forêts denses humides (sempervirentes et semi-décidues). Un total de 521 arbres appartenant à 12 espèces repartis sur toute la gamme de diamètre à partir de 10 cm a été mesuré (diamètre, hauteur totale et hauteur fût). Les résultats montrent que les modèles traduisant la saturation de la hauteur totale avec le diamètre (Weibull et polynomial non linéaire), ajustent mieux l’allométrie hauteur totale – diamètre à l’échelle des deux types de forêts. Toutefois, cette relation diffère entre les types de forêts. Pour un même diamètre, les arbres sont plus grands en forêt dense humide semi-décidue. Des différences entre types de forêts ont également été observées pour les trois espèces communes. Elles s’expliquent surtout par l’allométrie du houppier. Des variabilités interspécifiques ont été mises en évidence au sein d’un même type de forêt.
En termes de biomasse aérienne, l’inclusion de la hauteur totale dans les équations allométriques par rapport à la seule utilisation du diamètre, permet d’améliorer considérablement la précision de l’estimation de la biomasse aérienne. Cette dernière est plus élevée en forêt dense humide semi-décidue qu’en forêt dense humide sempervirente. Cette différence est due aux différences d’allométrie hauteur totale – diamètre observées entre les deux types de forêts
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
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