1,720,963 research outputs found
Branchlets abscission in Quercus cerris L. related to oak decline: anatomical studies
No full textThe basic anatomy of lateral twig insertion onto the main branch in both healthy and damaged Quercus cerris L. trees was studied. An abscission zone is always present: in healthy trees it is formed by a smaller number of cell layers than in damaged ones, where it is more evident with many layers of cells. Cells of the abscission zone are roundish, with many intercellular spaces between them; cell walls are thin, non-lignified and without secondary walls. No starch was found in cells of the abscission zone, where, instead, a few scattered calcium oxalate druses are seen. © 1995 Springer-Verlag
Vascular flora of "Scodella" Nature Reserve (Arezzo, Eastern Tuscany) [Flora vascolare della Riserva Naturale Biogenetica "Scodella" (Arezzo, Toscana orientale)]
No full textWe report the results of floristic research carried out in the "Scodella" Nature Reserve. Firstly, a brief description of the geomorphological, climatical and vegetational features of the area is given. Secondly, the list of the vascular flora is given, which was made out through floristic field researches, bibliography and herbarium specimens. This list includes 286 species belonging to 72 families and to 186 genera; 6 of them are introduced species. The biological spectrum shows that hemicryptophytes outnumber therophytes here - 54,1% against 8,5% - suggesting the dominance of subcontinental subclimate. This is also confirmed by the chorological analysis, which reveals the abundance of Eurosiberian elements and numerous connections with the oroipsophylous subdominion. There are 6 endemic species and a number of interesting species from a phytogeographical and conservational viewpoint: Aconitum lycoctonum, Arisarum proboscideum, Lilium martagon, Paris quadrifolia, Sedum monregalense, Senecio brachychaetus. The presence of rare or noteworthy plants underscores the role of the Reserve as a local hotspot for the conservation of plant diversity into the "Foreste Casentinesi" National Park. © 2009, Informatore Botanico Italiano
Contribution to the knowledge of aquatic vegetation of montane and submontane areas of Northern Apennines (Italy)
No full textThe importance of wetlands for biodiversity conservation is widely recognized. Their relevance is crucial in the identification of habitat types included in the Habitats Directive 92/43/EEC and in the application of the following conservation measures. Yet, several montane and submontane areas are poorly investigated from the phytosociological point of view. Here we studied aquatic communities of the Tuscan-Romagna Apennines in Italy using 52 vegetation plots dominated by hydrophytes collected in wetlands of natural and artificial origin. We analysed our data using a cluster analysis and identified 12 vegetation types that we classified as three vegetation classes Charetea intermediae, Lemnetea and Potamogetonetea, and two habitat types of conservation importance, as the hard oligo-mesotrophic waters with benthic vegetation of Chara spp. (Natura 2000 code 3140) and the natural eutrophic lakes with Magnopotamion or Hydrocharition (Natura 2000 code 3150). Our study highlights the diversity of aquatic habitats in montane and submontane areas of the Northern Apennines where water bodies are generally small and scattered. This study further highlights the important role of natural freshwater ecosystems for vegetation, but also the notable role of partly or entirely artificial water bodies in maintaining aquatic communities
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
Effect of cold treatment on germination of Saxifraga aizoides and S. paniculata: a comparison of central (eastern Alps) and southern populations (northern Apennines)
No full textThe best duration of cold treatment for germination of Saxifraga aizoides and S. paniculata was investigated comparing seeds collected from Alpine and Apennine populations. For S. aizoides seeds of both provenances, the highest germination was obtained after 12 weeks of cold treatment, and Apennine seeds showed the best performance. For S. paniculata, the effect of cold treatment differed greatly in relation to provenance: Alpine seeds showed theirs highest germination after 20 weeks, while Apennine seeds showed their best, albeit low, germination percentage after 8-16 weeks. For both species, a maximum germination plateau was reached 20 days after sowing. Thus, for ex situ conservation and restoration projects in the Apennines, we suppose that S. aizoides seeds should be collected from the location closest to the restoration site and S. paniculata seeds from the Alps. These results also suggest that specific responses to cold treatment exist within the genus Saxifraga in relation to provenance
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
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