1,721,008 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Open Ocean Reorientation and Challenges of Island Finding by Sea Turtles during Long-Distance Migration
Get PDFIn 1873, Charles Darwin marveled at the ability of sea turtles to find isolated island breeding sites [1], but the
details of how sea turtles and other taxa navigate during these migrations remains an open question [2].
Exploring this question using free-living individuals is difficult because, despite thousands of sea turtles being
satellite tracked across hundreds of studies [3], most are tracked to mainland coasts where the navigational
challenges are easiest.We overcame this problem by recording unique tracks of green turtles (Chelonia
mydas)migrating long distances in the Indian Ocean to small oceanic islands. Our work provides some of the
best evidence to date, from naturally migrating sea turtles, for an ability to reorient in the open ocean, but only
at a crude level. Using individual-based models that incorporated ocean currents, we compared actual
migration tracks against candidate navigational models to show that turtles do not reorient at fine scales
(e.g., daily), but rather can travel several 100 km off the direct routes to their goal before reorienting, often
in the open ocean. Frequently, turtles did not home to small islands with pinpoint accuracy, but rather overshot
and/or searched for the target in the final stages of migration. These results from naturally migrating individuals
support the suggestion from previous laboratory work [4–6] that turtles use a true navigation system
in the open ocean, but their map sense is coarse scale
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
First tracking data on Eurasian teals (Anas crecca) provides new information their spring migration phenology
No full textAbstract non disponibil
A biphasic navigational strategy in loggerhead sea turtles
Get PDFThe homing journeys of nine loggerhead turtles translocated from their nesting beach to offshore release sites, were reconstructed through Argos and GPS telemetry while their water-related orientation was simultaneously recorded at high temporal resolution by multi-sensor data loggers featuring a three-axis magnetic sensor. All turtles managed to return to the nesting beach area, although with indirect routes encompassing an initial straight leg not precisely oriented towards home, and a successive homebound segment carried out along the coast. Logger data revealed that, after an initial period of disorientation, turtles were able to precisely maintain a consistent direction for several hours while moving in the open sea, even during night-time. Their water-related headings were in accordance with the orientation of the resulting route, showing little or no effect of current drift. This study reveals a biphasic homing strategy of displaced turtles involving an initial orientation weakly related to home and a successive shift to coastal navigation, which is in line with the modern conceptual framework of animal migratory navigation as deriving from sequential mechanisms acting at different spatial scales
Effect of weather conditions on spring migrating Eurasian teals (Anas crecca)
No full textWeather conditions experienced during migration are expected to influence bird movements and their timing of arrival. We analysed satellite-tracking data from Eurasian teals (Anas crecca) fitted with Argos tags in three wintering Italian sites in order to define the migratory strategies of the species. We determined the course, speed and duration of spring migratory movements, together with the number and length of stopovers made along the route. Most of the tracked teals left the wintering grounds in FebruaryMarch and reached the breeding sites located in North-Eastern Europe in May. Along their migratory route most birds stopped for several weeks at stopover sites, especially at the very beginning of migration, and this led to a slow overall migratory speed. We then focused on investigating the effect of a series of environmental cues on teal’s migratory strategies. The analysis mainly aimed at assessing if temperature and winds experienced during teal’s sojourn in an area could have had an effect on its decision to leave their wintering grounds and the stopover sites. Given that teal are small ducks and not diving ones, they need shallow water areas to feed which may freeze quite easily when temperatures decrease, so it can be hypothesized that temperatures may be a relevant cue for this species. We tried different models using different time windows, aggregate statistics and response functions, running distinct analysis for wintering and stopover sites. As expected, our data indicate that weather conditions, and especially temperature, affect migration movements, but, as already noted for other Anseriformes, this effect was mostly evident once the migration had started. Under the observed conditions, wind, on the other hand, did not seem to play a major role in teal’s decision to leave or not an area
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