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Frequenza dell'attività oculare rapida e sonno a onde lente (SWS) in seguito a deprivazione selettiva di SWS
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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
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
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
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
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
Ruolo dei parametri ambientali nella scelta del sito di foraggiamento in femmine adulte di tartaruga comune (Caretta caretta)
No full textLa tartaruga comune (Caretta caretta) è la specie di tartaruga marina più diffusa nel Mar
Mediterraneo. Gli individui adulti vivono per la maggior parte del tempo in aree di
foraggiamento in ambiente neritico da cui si spostano verso le aree di nidificazione al momento
della stagione riproduttiva, mostrando una spiccata fedeltà sia ai siti di riproduzione che a quelli
di alimentazione. Solo raramente è stato studiato il comportamento spaziale delle tartarughe
durante questi prolungati soggiorni nelle zone di alimentazione tra periodi riproduttivi
successivi.
Nel presente studio sono stati rilevati gli spostamenti a breve scala compiuti nel periodo inter-
riproduttivo da parte di 4 femmine adulte di tartaruga comune, definendo gli home range
occupati in stagioni successive e cercando di interpretare la scelte comportamentali esibite dagli
animali attraverso l’analisi di parametri ambientali presenti nell’area.
Le tartarughe avevano nidificato in Calabria negli anni 2010-2014 e sono state seguite nei loro
movimenti per periodi compresi tra 12 e 36 mesi tramite la telemetria satellitare Argos, grazie
ad apposite trasmittenti applicate al loro carapace. Per ricostruire i movimenti degli animali, i
dati ottenuti da Argos sono stati filtrati per eliminare localizzazioni erronee e poco plausibili e
gli home range occupati nelle aree di foraggiamento sono stati calcolati impiegando tecniche
basate sul metodo Kernel con fattore di smussamento h ad hoc.
I risultati mostrano che le tartarughe hanno frequentato siti di foraggiamento individualmente
specifici, localizzati in ambiente neritico lungo le coste tunisine vicino al golfo di Gabés.
Durante l’anno, tutte le tartarughe monitorate hanno occupato due siti distanti 60-100 km tra
loro, tra i quali si sono spostate sempre nello stesso periodo dell’anno. L’ampiezza degli home
range è risultata differente tra i diversi individui studiati e il sito invernale è risultato
generalmente più grande di quello estivo.
Per identificare i fattori che contribuiscono alla scelta del sito di foraggiamento stagionale, sono
state confrontate alcune variabili ambientali (temperatura superficiale dell’acqua, batimetria e
concentrazione di clorofilla) rilevate nei due siti occupati dallo stesso individuo con tecniche di
remote sensing satellitare. Questa analisi ha indicato che la scelta del sito è dipesa soprattutto
dalla temperatura dell’acqua e che le tartarughe selezionano il sito in cui essa è più elevata
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