1,721,008 research outputs found
Dal monitoraggio delle specie della Direttiva Habitat alla conservazione in situ: il caso di Kosteletzkya pentacarpos (L.) Ledeb
No full textDal monitoraggio delle specie della Direttiva Habitat alla conservazione in situ. Questa presentazione dimostra la complessità degli interventi di traslocazione di specie vegetali. Tali interventi, al fine di risultare efficaci e sostenibili nel tempo, necessitano di approfonditi studi preliminari che consentano di acquisire informazioni sulla biologia, l'ecologia e la genetica della specie oggetto di intervento al fine di aumentare le probabilità di successo sul lungo periodo
Il rischio di estinzione oltre i confini amministrativi: l’approccio biogeografico applicato al protocollo IUCN di red listing
No full textDensity as an important parameter for the success of the summer snowflake reintroduction in northern Italy
No full textChallenges and risks of conservation of an aquatic macrophyte extinct in the wild
No full textThe reintroduction of a plant species regionally extinct in the wild poses a stimulating conservation challenge. However, when the issue concerns an aquatic dioecious macrophyte, with vigorous asexual reproduction forming very dense floating mats that can alter aquatic communities (through competition and allelopathy), each step must be very well planned. This is the case of Stratiotes aloides L. (water soldier), a keystone species that is declining in Europe, but is recognized as invasive in North America. The species, once abundant in the wetlands of North-Eastern Italy, is currently extinct in the wild in Italy. Only female Italian plants have been saved from extinction and are cultivated ex situ. To assess the feasibility of the de-extinction of Stratiotes aloides in Italy we investigated the water quality, the genetic diversity, and the potential spread of the species in its European range.
The high concentrations of surface water inorganic nitrogen (especially nitrates) were identified as the likely cause of decline and extinction of S. aloides. The analyses of genetic diversity revealed the presence of different genetic patterns across Eurasia, that could be explained through long-distance bird-mediated dispersal events. Moreover, chromosome counts revealed the presence of diploid (2n =24) and tetraploid (2n =48) populations.
According to our results the reintroduction of vital populations of Stratiotes aloides in Italy could be carried out using male individuals from the same genetic cluster of the Italian females, to avoid outbreeding depression. High-density stands must be reintroduced to permit self-facilitation of S. aloides under high nitrogen loads.
However, considering the presence of high nitrogen loads in historical growing sites of S. aloides, there is a high risk of failure. Though in case of successful reintroduction, the risk to spread vegetatively downstream and the long-distance bird-mediated dispersal of seeds with unknown consequences on already threatened freshwater ecosystems cannot be ruled out.
Therefore, considering the risks and benefits of the de-extinction of Stratiotes aloides, chaperoned managed relocation of female individuals in isolated water bodies basin (like gravel pits) could be the best solution
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
Drought tolerance in germination of Aegilops geniculata (Poaceae) populations along a latitudinal gradient: implications for crop improvement
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