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Oculomotor responses to active head movements in darkness: formulation and testing of a mathematical model
No full textEye-head coordination in darkness: formulation and testing of a mathematical model
No full textPassive head rotation in darkness produces vestibular nystagmus, consisting of slow and quick phases. The vestibulo-ocular reflex produces the slow phases, in the compensatory direction, while the fast phases, in the same direction as head rotation, are of saccadic origin. We have investigated how the saccadic components of the ocular motor responses evoked by active head rotation in darkness are generated, assuming the only available sensory information is that provided by the vestibular system. We recorded the eye and head movements of nine normal subjects during active head rotation in darkness. Subjects were instructed to rotate their heads in a sinusoidal-like manner and to focus their attention on producing a smooth head rotation. We found that the desired eye position signal provided to the saccadic mechanism by the vestibular system may be modeled as a linear combination of head velocity and head displacement information. Here we present a mathematical model for the generation of both the slow and quick phases of vestibular nystagmus based on our findings. Simulations of this model accurately fit experimental data recorded from subjects
Modelli del sistema oculomotore
No full textViene tracciata una breve storia dello sviluppo dei modelli matematici del sistema oculomotore, sottolineando la progressiva evoluzione dai primi modelli qualitativi a modelli quantitativi via via più elaborati e il corrispondente crescente contributo al miglioramento delle conoscenze nel settore
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
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
Nouvaux supports informatisés à l'exploration de la fonction vestibulaire: I. Les systèmes experts et leur applications cliniques
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