1,721,046 research outputs found
Molecular characterization of harmful algal species
No full textThe main purpose of the research activities carried out in this thesis was to give contributions to ecological studies on potentially harmful algal species (HAS) present in
Sardinia’s aquatic environments through the application of biomolecular techniques. In Sardinia, as well as globally in the world, the reports of blooms caused by HAS
(Harmful Algal Blooms, HABs) have increased in recent decades, requiring specific studies and investigations.
The identification of the species involved is particularly important. Microalgae species identification based on cell morphology with the traditional microscopic methods is not a simple task. A valid support is represented by the recently developed biomolecular tecniques which can help in resolving species identification and detection problems.
In this thesis, several cases of study were investigated, regarding different types of environments, algal classes, genera, species within a same class and, therefore,
different linked problems. Analyses were carried out on natural samples fresh or fixed and cell cultures obtained from isolated vegetative cells and/or cysts of resistance. The identification of HAS was carried out using molecular techniques, with nucleotide sequences of the LSU (or 28S rDNA) and 5.8S rDNA-ITS (internal transcribed spacer)
regions such as genetic markers.
The confirm of taxonomic attribution was achieved for new isolates of the Alexandrium Halim genus, analysing cell cultures obtained by the germination of cysts isolated from sediments and the growth of vegetative cells isolated from the water column from different areas of Sardinia (Chapter Ia, Ib).
The presence of Chattonella subsalsa Biecheler was assessed in samples collected from the Santa Giusta Lagoon during events of fish kills in the summers of 1994, 1998, 1999 and 2010 by analyzing samples fixed with Lugol and conserved in the Department's collection (Chapter II).
It was possible obtain a preliminary framework of the HAS’s presence in beach environments, including Alexandrium taylorii Balech, Ostreopsis cf. ovata Fukuyo,Barrufeta bravensis Sampedro et Fraga and Gymnodinium instriatum Freudenthal et Lee (Chapter III).
Finally, the first study on dinoflagellates species involved in blooms in reservoirs of Sardinia, was carried out (Chapter IV)
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
Ecological surveys for the valorization of spring environments of Sardinia: implications for their fruition and environmental protection.
Full text linkSprings are ecosystems with unique features and great ecological value. In the Mediterranean area they are more exposed to the risks of alteration of their structure and natural functioning because of direct and indirect human pressures and climate change. Despite this, springs remain poorly studied and specific approaches of management and protection are still missing. The main purpose of this PhD was to acquire knowledge on ecology of karst and thermo-mineral springs of Sardinia, traditionally neglected. The research activities focused on diatom microflora from different substrates in 17 springs of the Island. The results indicated a high diatom biodiversity, also highlighted by the presence of Sellaphora gologonica sp. nov. and Chamaepinnularia thermophila, the latter observed only in very few sites in the world so far. The analysis of the relationships between species and environmental variables, confirmed that diatoms can reflect the effects of important factors related to the vulnerability of these ecosystems, such as hydrological stability (flow permanence), discharge, climate change (extreme flash floods) and nutrient enrichment. This thesis offer food for thought on the importance of enhancing and preserving these environments so important from an ecological point of view and of so large interests for human uses. The information collected may represent a starting point for the development of strategies aimed at their proper management
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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