1,720,990 research outputs found
The relationship between loggerhead turtle (Caretta caretta) movement patterns and Mediterranean currents
No full textPrevious studies have shown that loggerhead sea turtles (Caretta caretta), monitored by satellite telemetry, complete long-distance migration between the western and eastern Mediterranean basins following a seasonal pattern. This study investigated if these migration routes may be influenced by surface currents by superimposing the tracks of three loggerhead turtles (curved carapace length >55 cm), migrating from the western to the eastern Mediterranean basin, on Lagrangian data of current developed into pseudo-eulerian speed fields. The average travel speed of the turtles was 1.6 km h-1 and did not depend on the current speed or direction. We observed a connection between surface currents and the turtles' migration routes, although not a conclusive one. These observations show that neritic stage loggerhead turtles conduct migration in two distinct alternate phases: the first characterized by high and constant speed of travel both when swimming with or against currents and the second typified by low travel speeds and a good concurrence between the trailed routes and the course of the currents. These two phases corresponded to two types of movements, one where the turtle migrates actively to reach a specific destination (either neritic foraging, wintering or nesting ground) and the other, where the turtle drifts with the mesoscale current and forages pelagically. It seemed thus, that the influence of currents on a turtle's movements depends on the turtle's momentary behaviour and location of residenc
Normal ultrasonographic features of loggerhead (Caretta caretta) eyes
Full text linkThe Loggerhead sea turtle (Caretta caretta) is widely distributed in the Mediterranean Sea but, like other sea turtles, it is considered a threatened species. Improving anatomical knowledge on normal aspects of the species is important for correct diagnosis and proper therapy and, therefore, for improving the chances of a complete recovery and a fast reintroduction into the wild for a greater number of sea turtle bycatch and other mishaps. For this reason, 15 Loggerhead turtles, with clinically healthy eyes, were submitted to ocular ultrasonographic (US) examinations. The US exam was quick, non-invasive, and simple to perform and permitted researchers to assess all the ocular features. © 2020, Croatian Natural History Museum. All rights reserved
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
The relationship between loggerhead turtle (Caretta caretta) movement patterns and Mediterranean currents
No full textPrevious studies have shown that loggerhead sea turtles (Caretta caretta), monitored by satellite telemetry, complete long-distance migration between the western and eastern Mediterranean basins following a seasonal pattern. This study investigated if these migration routes may be influenced by surface currents by superimposing the tracks of three loggerhead turtles (curved carapace length >55 cm), migrating from the western to the eastern Mediterranean basin, on Lagrangian data of current developed into pseudo-eulerian speed fields. The average travel speed of the turtles was 1.6 km h-1 and did not depend on the current speed or direction. We observed a connection between surface currents and the turtles' migration routes, although not a conclusive one. These observations show that neritic stage loggerhead turtles conduct migration in two distinct alternate phases: the first characterized by high and constant speed of travel both when swimming with or against currents and the second typified by low travel speeds and a good concurrence between the trailed routes and the course of the currents. These two phases corresponded to two types of movements, one where the turtle migrates actively to reach a specific destination (either neritic foraging, wintering or nesting ground) and the other, where the turtle drifts with the mesoscale current and forages pelagically. It seemed thus, that the influence of currents on a turtle's movements depends on the turtle's momentary behaviour and location of residenc
Gastrointestinal investigation of parasites and Enterobacteriaceae in loggerhead sea turtles from Italian coasts
Full text linkBACKGROUND: Caretta caretta is the most abundant sea turtle species in the Mediterranean, and studies on this species have vastly expanded during recent years, including those investigating gut bacterial and parasitic communities. Members of these communities have been reported with variable prevalence and pathogenicity, mainly depending on their host and environment (e.g. lifespan, distribution, habitat, diet, health status and stressors). Indeed, many species commonly inhabiting the sea turtle gastrointestinal tract exhibit an opportunistic behaviour. This study aimed to provide baseline data on enterobacterial and parasitic composition, through bacteriological culture-based methods and the FLOTAC parasitological technique, in cloacal and faecal samples of 30 live Caretta caretta, examined upon their arrival at the Marine Turtle Research Centre (Portici, Italy). RESULTS: Enterobacteriaceae were isolated in 18/23 cloacal samples (78.3%), with Citrobacter and Morganella as the most common genera, followed by Proteus, Enterobacter, Providencia, and Hafnia. Parasitic elements were detected in 11/30 faecal samples (36.7%), with Enodiotrema, Rhytidodes, and Eimeria as most common genera, followed by Pachypsolus and Cymatocarpus. Additionally, Angiodyctium is reported for the first time in this host. The majority (47.8%) of sea turtles hosted exclusively Enterobacteriaceae, whereas 30.4% hosted both parasites and Enterobacteriaceae; the remaining 21.8% hosted neither of the agents. CONCLUSIONS: Bacteria and parasites evaluated in the present study are common in Mediterranean loggerhead sea turtles, with slight differences between the western and eastern basin. Although naturally present in the gastrointestinal system of free-living sea turtles, their relationship with these hosts might range from mutualism to parasitism. Indeed, members of the gut community might express their pathogenic potential in immune-compromised animals, such as those in rehabilitation facilities. Therefore, it is advisable to include in the standard work-up of rescued sea turtles a screening procedure for such opportunistic agents, in order to better evaluate the animal's health status and achieve timely intervention with appropriate treatment, thus improving rehabilitation. Furthermore, data collected from free-living sea turtles represent a starting point for investigating wild populations. However, further studies are needed to clarify the differences between sea turtle's normal gut microbiome and pathobiome
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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