1,720,995 research outputs found
Morpho-functional defences of Mediterranean sea urchin, Paracentrotus lividus and Arbacia lixula, against fish predator
No full textMorpho-functional features potentially involved in defence mechanisms against fish predators (i.e. attachment tenacity, spine length, and test robustness and thickness) have been assessed in two Mediterranean sea urchins, Paracentrotus lividus and Arbacia lixula. All four morpho-functional features were significantly and positively related to individual size for both species of sea urchins. Test robustness (i.e. static load needed to break sea urchin tests) was significantly greater for A. lixula (from 3,450 to 15,000 g depending on size) than for P. lividus (1,180–11,180 g). Attachment tenacity (i.e. force needed to dislodge sea urchins from the rocky substrate) was greater in A. lixula (280–3,300 g) than in P. lividus (110–1,450 g), and the difference tended to decrease in relation to smaller sea urchin size. Spine length was greater in A. lixula (1.5–2.9 cm) than in P. lividus (0.5–2.3 cm), but the difference decreased for larger sea urchin size. Test thickness was slightly greater (but not significantly) in A. lixula (0.35–1.10 mm) than in P. lividus (0.12–0.90 mm). These results provide evidence that morpho-functional features of sea urchins could be involved in affecting predation rates by fishes upon P. lividus and A. lixula, with potential implications for the population structure and distribution patterns of the two sea urchins in shallow rocky reefs
On a new occurrence of the alien flat crab, Percnon gibbesi (H. Milne Edwards) (Crustacea, Brachyura, Grapsidae), in the southern Sicily (Central Mediterranean Sea)
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Allosquilla africana (Manning) (Crustacea, Stomatopoda), a new record from southern Tuscan Archipelago (western Mediterranean)
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The occurrence of Thelohania contejeani Henneguy, a microsporidian parasite of the crayfish Austropotamobius pallipes (Lereboullet), in Liguria Region (NW Italy)
No full textThe presence of the microsporidian parasite Thelohania contejeani Henneguy, responsible for porcelain disease (thelohaniasis), is reported in several crayfish populations inhabiting the Liguria Region. The infestation rate of this parasite was low, ranging from 0.17 to 3.7 per cent, and in two water courses it remained constant through years. However, we recommend performing periodically sanitary controls on the infected populations of Liguria and extending such controls to other populations not yet monitored. In fact, the virulence of the pathogens could increase owing to environmental stresses such as pollution, increase in crayfish density, paucity of food etc. We underline the importance, already suggested by other authors, of creating a central disease register to check the diffusion of the pathogens and facilitate the adoption of countermeasures
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
Fecundity and egg volume in Norway lobster (Nephrops norvegicus) from different depths in the northern Tyrrhenian Sea
Full text linkThe relationships between fecundity and egg volume of Norway lobster (Nephrops norvegicus) inhabiting three different depth ranges (200-300, 350-450, and 500-550 m) in the North Tyrrhenian Sea (western Mediterranean) were compared. Fecundity was not dependent on depth and egg volume did not vary with female size. The egg volume of females collected in the shallowest areas (200-450 m) was instead significantly larger than that collected in deeper waters (500-550 m). Possible explanations for this fact are examined.No disponibl
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
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