1,720,966 research outputs found
Chironomid (Diptera, Chironomidae) species assemblages in northeastern Algerian hydrosystems
Get PDFThe aim of this paper was to analyze the distribution of chironomids (Diptera, Chironomidae), and determine their substrate preferences, from two hydrosystems located in northeastern Algeria: the Kebir-East and the Seybouse wadis. Sixty-five species were recorded in 49 sampling sites distributed along the main courses of the two hydrographic nets and their tributaries. The majority of taxa comprised cosmopolitan species widely distributed along these two hydrosystems. Cricotopus (Cricotopus) bicinctus showed the highest abundance and frequency of occurrence (29.52%) and was widespread in almost all the sampling sites. Species richness ranged from 4 to 23, Shannon diversity between 0.15 and 0.90, Evenness from 0.23 to 1. A cluster analysis was carried out to represent the different groups of sites sharing similar species composition. Agglomerative cluster analysis grouped the sampling sites into four clusters according to the community data. An Indval analysis was then carried out to detect indicator species for each group of the sampling sites. Cricotopus (Isocladius) sylvestris was indicator of the first group of the sampling sites. Orthocladius pedestris, Rheocricotopus chalybeatus and C. bicinctus were indicators of the second group, and Polypedilum cultellatum of the third group. The fourth group was not characterized by any species. Indval analysis allowed also to determine species preferences for substrate size: Corynoneura scutellata and Dicrotendipes nervosus emphasized a preference to fine gravel, and Glyptotendipes pallens to fine sand
Chironomid taxocenosis in a South Mediterranean wadi, the Kebir-East (Algeria)
Get PDFSUMMARY - Chironomid taxocenosis in a South Mediterranean wadi, the Kebir-East (Algeria) - A total of 37 chironomid species were
recorded during a survey of the catchment of the Kebir-East wadi, northeast Algeria. Chironomids spatial and temporal distributions were
investigated based on 23 sampling sites, situated mainly within the El Kala National Park, across 4 seasons. Chironomid assemblages in
the Kebir-East were similar to the ones known from other Mediterranean areas and were composed mostly of tolerant species (Chironomus
riparius, Cricotopus (Isocladius) sylvestris), but some intolerant species (Paratrissocladius excerptus, Parakiefferiella gracillima, Thienemanniella
partita) were present in some samples. A coinertia analysis was carried out to match 21 environmental variables at different
spatial scales with the 37 chironomid species recorded in 90 samples: A longitudinal gradient was found along the first axis, which accounted
for 42 % of the total variance; the samples ordered along the second axis, which accounted for 13 % of the total variance, were
separated according to water temperature, water chemistry and site’s morphometry. The influence of anthropogenic pressures was evaluated
with different benthic quality indices based on species diversity and on species optima (i.e. mean value of environmental variables
weighted for species abundance). Results showed that the trophic status index was influenced by water quality and habitat type (krenal,
rhithral, potamal), while the biotic indices were more influenced by season. To improve knowledge on the response of intolerant species,
we suggest the implementation of a regular, more intensive sampling program
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
Environmental factors affecting the distribution of Chironomid larvae of the Seybouse wadi, Northeastern Algeria
Get PDFA survey of the Seybouse wadi (North-Eastern Algeria) between 2008 and 2011 was conducted in 26 sampling sites located on the main river and its tributaries using chironomids. From 3264 collected larvae, forty-five chironomid species were identified, and were correlated to 13 environmental variables to predict determinant factors affecting their distribution. Indicator value (IndVal) analysis was first performed to determine indicator chironomid species according to several factors (sites, seasons, source distance, granulometry, conductivity, water temperature, dissolved oxygen, water velocity, pollution and the abundance of filamentous algae). Co-inertia analysis
(CoIA) supported the IndVal results, emphasising an upstream/downstream gradient in the first axis, while a granulometry gradient was emphasised by the second axis. A pollution gradient was also highlighted in the plane of the first two axes, separating tolerant Chironomus sp. 1, Cricotopus bicinctus and Cricotopus (Isocladius) sylvestris from intolerant species as Phaenopsectra flavipes, Rheotanytarsus sp.1 and Cladotanytarsus sp. 1
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
- …
