1,720,976 research outputs found
Evolutionary genetics of the catfish Clarias gariepinus (Burchell, 1822) in the Congo basin
No full textEvolutionary genetics of the catfish Clarias gariepinus in the Congo Basin
No full textThe Congo Basin features among the oldest, largest and biologically richest on earth
after the Amazon and before the Mekong. Sadly enough it is the least known. It offers
opportunities to study evolution given its treasure of global biodiversity and high
aquaculture potential (large hydrographic network and suitable climate). It is within
this framework that phylogeographical research has been initiated to understand the
origin of the ichthyological fauna and to identify potential strains for the development
of aquaculture. The model chosen is the catfish Clarias gariepinus (Burchell, 1822), a
species with great aquaculture potential. This fish lives in the Congo River from
source to mouth, as well over a large part of the African continent. The results show
the presence of four clades and several groups which represent a large genetic
differentiation. Evolution is ancestral in the south and north of the Congo Basin (relict
population) and represents a Pleistocene colonisation in the Central Basin. Even in a
contemporary context, evolution seems to follow these two models. Two hypotheses
have been retained to support the causes for the accumulation of diversity: the
hypothesis of long-distance dispersal in the Central Basin and the refuge hypothesis in
the peripheral zones of the Central Basin. Moreover, the four major clades have been
identified to match with four major ichthyological provinces of Africa: Nilo-Sudan,
Zambezi, East Coast and Congo. This confirms an ancient connection between the
various basins. Hence, the evolution of C. gariepinus in the Congo basin corresponds
with that of the fishes and mammals with a high dispersal capacity, which is found in
several African basins. Ideally the evolution of the endemic fauna of the Congo basin
should be studied in order to compare it with the higher mentioned high dispersal
group. It would facilitate our understanding of the evolution of the fish fauna of this
large African basin for sustainable management.Le bassin du Congo est l’un des plus vieux, vastes et biologiquement riches au monde
après celui de l’Amazone et avant celui du Mekong. Malheureusement ce bassin est le
moins connu. En tant que réserve de la biodiversité mondiale et ayant un potentiel
aquacole élevé (grand réseau hydrographique et bon climat), ce bassin offre des
opportunités d’études d’évolution. C’est dans ce cadre que des études phylogéographiques
ont été initiées afin de connaître l’origine de la faune ichthyologique.
Le modèle retenu était celui du poisson chat Clarias gariepinus (Burchell, 1822). Ce
poisson est signalé dans le fleuve Congo de la source à l’embouchure, ainsi que dans la
plus grande partie du continent africain. Les résultats obtenus ont révélé l’existence de
cinq clades (groupements historiques de populations) dont quatre rencontré dans le
bassin du Congo et plusieurs groupes présentant une grande différentiation génétique.
Une évolution ancestrale (relique) caractérise le sud et le nord du bassin congolais; par
contre dans la Cuvette Centrale on observe une colonisation récente. Même dans un
contexte contemporain, l’évolution semble suivre les deux modèles. Deux hypothèses
ont été retenues pour soutenir les causes de l’accumulation de la diversité. Il s’agit de
l’hypothèse sur la longue distance de dispersion dans la Cuvette Centrale et celle des
refuges dans les régions périphériques de la Cuvette Centrale. En plus, les quatre
clades principaux ont été identifiés comme couvrant les quatre principales provinces
ichthyologiques d’Afrique: Nilo-Soudanique, Zambèze, Côte Est et Congo. Ceci
confirme l’ancienne connexion entre les différents bassins. Ainsi, l’évolution du C.
gariepinus dans le bassin du Congo correspond à celle des poissons et mammifères à
grande dispersion rencontrés dans plusieurs bassins africains. L’idéal serait d’étudier
aussi l’évolution de la faune endémique du bassin congolais afin de la comparer avec
celle appartenant au premier groupe (grande dispersion). Cla facilitera la compréhension
de l’évolution de la faune ichtyologique de ce grand bassin d’Afrique pour un
but de gestion durable.(DOCSC03) -- FUNDP, 201
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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