1,720,991 research outputs found
Escape rooms: behavioural response of two invasive crayfish species under water decline scenarios
Get PDFClimate change and invasive alien species pose a significant threat to biodiversity and the survival of native species. This study considered the impact of drought conditions on the escape behaviour through terrestrial dispersal ability of two invasive freshwater crayfish species, the red swamp crayfish (Procambarus clarkii) and signal crayfish (Pacifastacus leniusculus). Using an experimental design simulating drought conditions and Mediterranean summer temperatures, we tested the hypothesis that P. clarkii exhibits a greater tendency to terrestrial migration and a higher land-walking speed than the P. leniusculus. The results indicated that both species demonstrated strong escape behaviour, with P. clarkii showing escape success higher than P. leniusculus, and increasing with decreasing mean night temperature and crayfish weight. Although drought conditions did not trigger escape, invasive species showed increased resistance and the ability to move to more favourable environments, suggesting that drought is not an effective geographic barrier against the spread of these species. These results underline the importance of considering invasive species' ability to escape and climb as part of management and control strategies
A new alternative technique for sterilising invasive crayfish: removing female pleopods did not alter courtship pheromone release in signal crayfish
No full textInvasive species require effective management, especially when population density is still low. Autocidal methods for controlling invasive species offer the advantages of being species-specific and inversely density dependent, without causing environmental changes. An ideal control technique should decrease numbers of juveniles, and, therefore, progressive population ageing. In crayfish, female pleopods can be removed to eliminate support for the attachment of newly fertilised eggs. The aim of this study was to investigate if pleopod removal affects the release of female sexual pheromones. An experiment was performed by exposing signal crayfish males to four waters conditioned by (1) mature females after cutting pleopods (treated), (2) untreated mature females, (3) sexually inactive females, and (4) control water. Males exposed to both treated and untreated mature female waters showed behavioural similarities and increased mating activity compared to males exposed to sexually inactive female or control waters. Removing female pleopods did not affect the release of courtship pheromones, so treated females were still able to attract males by misleading them into mating activity. When females spawn their eggs, they will be lost due to the missing pleopods. Therefore, this method might be considered to control invasive crayfish in management programmes
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
DIET AND TROPHIC NICHE OF THE INVASIVE SIGNAL CRAYFISH IN THE FIRST INVADED ITALIAN STREAM ECOSYSTEM
No full textWe evaluated the seasonality of diet and trophic niche of invasive signal crayfish (Pacifastacus leniusculus) in order to estimate the ecological role and effects on native communities of the first Italian stream ecosystem invaded by this species. We studied the differences in food source use between sexes, life stages and seasons using carbon and nitrogen stable isotope analysis. Results indicated that signal crayfish adults and juveniles diets mainly rely on macroinvertebrates and periphyton using mostly same food sources and occupying an equivalent trophic niche. However, males diet seems to differ between adults and juveniles, indicating diet shift during their life stages. Moreover, any significant differences were found in adults and juveniles diets between summer and autumn seasons. Our findings suggest that signal crayfish juveniles and adults exhibited similar feeding habits regardless of seasonality and that both are likely to pose negative effects on macroinvertebrate communities of this Italian stream ecosyste
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
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
- …
