1,721,002 research outputs found
L’impiego di strumenti acustici ad alta risoluzione nella valutazione, monitoraggio e gestione delle praterie di Posidonia oceanica.
No full textHigh-resolution sonar system (MBS, SSS, Sub Bottom Profiler) was used to map and characterize Posidonia oceanica meadows, dead matte formations and to long-term monitor its progressive lower limit. Hydro-acoustic techniques allows to quickly acquire, at sufficiently low cost, a synoptic coverage of a large area and a high number of data by mean of non-destructive methods. Hence, they are recommended as useful tools for detecting and characterizing submerged aquatic vegetation
Detection and mapping of "blue carbon" reservoir storage in Posidonia oceanica dead matte in front of an extensive industrial area
No full textThe endemic Mediterranean seagrass Posidonia oceanica is the only marine phanerogam able to form matte, a biogenic structure representing important long-term “blue carbon” reservoir. Natural and/or anthropogenic factors can lead to the formation of a regressive structure, called “dead matte”, resulting from the disappearance of living shoots in the upper part of the matte. In the framework of TETIDE project (PON01_03112, www.progettotetide.it) a multiple sensors acoustic survey -multibeam sonar (MBS), side scan sonar (SSS), sub-bottom profiler (SBP) -was carried out in a portion of the Gulf of Augusta (Sicily, Southern Ionian Sea). The aim of investigation was to estimate the extent of dead mattethat are present in this area due to pollution from industrial activities over the last several decades. The investigated area covers a surface of about 141 ha from 3.5 m to 21.5 m of depth. MBS and SSS showed an irregular seabed morphology with rock, sand and dead mattestructures delimited by walls up to 2 m high. Dead mattecovers about 58 ha, corresponding to 41% of seabed. The seismo-acoustic data, recorded by SBP, allowed to estimate the thickness of the matteand then to calculate its volume per unit surface area of seabed. The volume of mattevaries from 0.83 m3/m2to 2.68 m3/m2with a mean value of 1.46 m3/m2. The total seabed surface affected by industrial activities concerns an area of about 3,000 ha. Considering the percentage of dead mattecoverage and its volume per unit surface area, a total volume of 18•106m3was estimated. From literature data, the amount of carbon storage inside the matteis 0.034 tons/m3on average, thus we extrapolated that total carbon accumulated is about 612 tons. These “blue carbon” reservoirs should be put into preserving in order to contrast their erosion and the consequent potentially massive CO2release into the atmosphere
Hydrodynamism and its influence on the reproductive condition of the edible sea urchin Paracentrotus lividus
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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
Performance assessment of Posidonia oceanica (L.) Delile restoration experiment on dead matte twelve years after planting—structural and functional meadow features
Full text linkFollowing the restoration of natural conditions by reducing human pressures, reforestation is currently considered a possible option to accelerate the recovery of seagrass habitats. Long-term monitoring programs theoretically represent an ideal solution to assess whether a reforestation plan has produced the desired results. Here, we report on the performance of a 20 m2 patch of Posidonia oceanica transplanted on dead matte twelve years after transplantation in the Gulf of Palermo, northwestern Sicily. Photo mosaic performed in the area allowed us to detect 23 transplanted patches of both regular and irregular shape, ranging from 0.1 to 2.7 m2 and an overall surface close to 19 m2. Meadow density was 331.6 ± 17.7 shoot m-2 (currently five times higher than the initial value of 66 shoots m-2), and it did not show statistical differences from a close by natural meadow (331.2 ± 14.9). Total primary production, estimated by lepidochronology, varied from 333.0 to 332.7 g dw m2/year, at the transplanted and natural stand, respectively. These results suggest that complete restoration of P. oceanica on dead matte is possible in a relatively short time (a decade), thus representing a good starting point for upscaling the recovery of the degraded meadows in the area
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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