1,720,977 research outputs found
Pilot study of genetic relatedness in a solitary small carnivore, the weasel: implications for kinship and dispersal
No full textFew researches have been carried out on wild populations of small carnivores involving animals live trapping. Problems in field data collection make spatial and reproductive dynamics of these species still not understood. This research used data about only 14 live trapped individuals, because of the quoted problems, nevertheless results showed important and preliminary considerations on this topic. In the study, genetic microsatellite methodology applied to natural weasel population produced data on kinship and dispersal patterns. All the 11 microsatellite analyzed loci were found polymorphic, with an average number of alleles per locus of 5.36 ; estimated expected heterozygosity He (0.62) is at the highest end of the range of other Mustela species. No significant deviations from Hardy-Weinberg equilibrium were found (p≥ 0.05). The analysis of genetic kinship showed no full siblings and only one parent-offspring pair : so only 1.09% of the total possible pair wise comparisons (91) showed close genetic kinship. The proportion of related animals from the sampled population was 14,2%.Magrini Caterina, Cento Michele, Manzo Emiliano, Pierpaoli Massimo, Zapponi Livia, Cozzolino Roberto. Pilot study of genetic relatedness in a solitary small carnivore, the weasel: implications for kinship and dispersal. In: Ecologia mediterranea, tome 38 n°2, 2012. pp. 23-27
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
Effetto dell’eterogeneità del paesaggio su comunità di vertebrati in frammenti boschivi
No full textEnvironmental fragmentation leads to the transformation of continuous habitats in several patches, separated from each other by a habitat ifferent from the original that is generally efined matrix. To study its effect on the iodiversity of the residual patches, this process
has initially being assimilated to the theories developed on insular fauna dynamics (e.g. acArthur & Wilson). However, the reductionist
approach of describing patches as islands, in a sea of non-habitat, does not allow the inclusion of the complexity of real landscapes. The aim of the present study is therefore the investigation of the relationship existing between animal species distribution and landscape heterogeneity, to examine the influence of matrix composition and
configuration, and patch structure on the vertebrate assemblages of
residual woods. The field part of the study took place in the Marche Region, in an area of 100,000 ha approximately, which encompasses the Chienti and Potenza River catchments. This area was selected since it offered the opportunity of comparing woodland fragments included in landscapes that have suffered a diverse human impact. In the area, 24 sample sites were selected, characterised by the presence of Turkey oak (Quercus cerris) and downy oak (Q. rubescens). In each site, the bird
communities composition was described using 66 point counts. The
presence and absence of two arboreal mammals was assessed, with 115
hair tubes for the European red squirrel (Sciurus vulgaris), and 132
nestboxes for what concerns the hazel dormouse (Muscardinus
avellanarius). Each site spatial structure was also studied, through
circular sample plots in which the vertical organization and
composition of the herbaceous, shub and arboreal layers was described.
Aerial photographs were used to describe and quantify landscape
patterns. Four classes of land cover were identified (woodland,
cropland, hedges, shrubs, grassland and anthropic areas) and mapped
with GIS. Two software were employed to describe the landscape
configuration according to the developed map, Patch Analyst and
Image Analyzer. The extracted metrics were both structural and
functional, and for every land cover class, percentage of occurrence,
nearest neighbor, edge density, spatial aggregation and several more
parameters were calculated.
To avoid multicollinearity a principal components analysis (PCA)
was performed on the variables, divided in three subsets describing respectively patch characteristics, landscape composition and
landscape configuration. Six factors were extracted from the PCA and
used as explanatory variables for the analysis of the target species
distributions.
The most abundant species present in the bird communities were
also the most widespread. The consideration of the existing
relationship between single species and environmental variables
stressed how the whole community is influenced only by factors
describing matrix composition and configuration, and in particular the
lack of isolation of the patches, their connectivity and the presence of
woods, grasslands and anthropic areas in the landscape. The factors
associated to the patch features did not influence the observed pattern.
The only feature of the patches that had an effect on the observed
abundances was the size of the wood (R2 =0.435, p<0.001).
Considering species diversity, the smaller and poorer sites tended to contain subsets of the species present in bigger and richer woods, showing a significant nested pattern that mostly involved generalist species.
Using the species’ life history traits, the communities were subdivided in several different guilds, considering their breeding period diet, feeding technique, nest location, average laying date, clutch size and body mass. For each subgroup, the percentage of species and individuals present in each site was calculated, and included in multiple regression models. The fact that patch related factors, as the extent of the canopy cover, the canopy height and the average tree diameter, could not be disregarded in any of the models indicates the importance of the available internal components for species persistence. The contemporaneous consideration of landscape and patch analysis scales led to the emergence of different patterns, highlighting the presence of different driving forces, belonging to the two scales, contemporaneously shaping community structure.
The effect of landscape heterogeneity on the two considered mammal species was studied using logistic regressions. The resulting models were ranked using second order Aikaike Information Criterion (AICc and AICc) and the importance of the included parameters was evaluated with Akaike weights (wi).
The use of three different sets of variables confirmed the importance of the amount of hedgerows in the landscapes surrounding the patches for the occurrence of both species. The convergence of the two arboreal mammals towards landscapes that offered a higher amount of hedges proved the critical role of this element to ensure species persistence through landscape structural connectivity. The relevance of other elements, as the amount of shrublands and grasslands in the matrix, suggests that since the local forest management impoverished the woods available resources, species occurrence is may be linked to the contemporaneous exploitation of sub-optimal habitats, through a process defined “habitat compensation”.
The inclusion of species belonging to different taxa emphasised the matrix essential role, both in terms of composition and configuration, in determining the actual use of residual patches. In a heterogeneous landscape, structure heterogeneity matters in terms of connectivity and lack of isolation, and the presence and position of hedgerows and woods in the landscape were key determinants of species distribution. The contemporaneous consideration of parameters describing landscape and patch features showed how these two
elements and their associated scales affect species in a different degree, and their lack of simultaneous consideration may lead to misleading conclusions.
The matrix therefore holds the capability to at least mitigate the effects of isolation and habitat loss, if its management, and hence its permeability, allows animal movement
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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