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Cephalopod behaviour
Full text linkUnderlying all animal behaviors, from the simplest reflexive reactions to the more complex cognitive reasoning and social interaction, are nervous systems uniquely adapted to bodies, environments, and challenges of different animal species. Coleoid cephalopods — octopuses, squid, and cuttlefish — are widely recognized as the most behaviorally complex invertebrates and provide exciting opportunities for studying the neural control of behaviour. These unusual molluscs evolved over 400 million years ago from slow-moving armored forms to active predators of coastal and open ocean ecosystems. In this primer we will discuss how, during cephalopod evolution, the relatively simple ganglion-based molluscan nervous system has been extensively transformed to control the complex bodies and process extensive visual, tactile, and chemical sensory inputs, and summarize some recent findings about their fascinating behaviors
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
Bioinspired locomotion and grasping in water: the soft eight-arm OCTOPUS robot
No full textThe octopus is an interesting model for the development of soft robotics, due to its high deformability, dexterity and rich behavioural repertoire. To investigate the principles of octopus dexterity, we designed an eight-arm soft robot and evaluated its performance with focused experiments. The OCTOPUS robot presented here is a completely soft robot, which integrates eight arms extending in radial direction and a central body which contains the main processing units. The front arms are mainly used for elongation and grasping, while the others are mainly used for locomotion. The robotic octopus works in water and its buoyancy is close to neutral. The experimental results show that the octopus-inspired robot can walk in water using the same strategy as the animal model, with good performance over different surfaces, including walking through physical constraints. It can grasp objects of different sizes and shapes, thanks to its soft arm materials and conical shape
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
Circadian rhythms in Octopus vulgaris
No full textBiological rhythms enable organisms to measure time and to synchronize their endogenous behavior and physiology with the time constraints of their environment. Since the inhabitants of the littoral zone of marine environments are exposed to complex temporal and environmental changes, biological rhythms play an important role in their lives.Timekeeping is especially important for those with short lives like octopuses. Circadian rhythms, which are rhythms of about a day, are one of the most prominent of biological rhythms. They are ubiquitous through all phyla of the animal kingdom, light being one of the most important “Zeitgebers” for almost all of them. To examine the function of light as a synchronizer for their activity, four octopuses were held in a potentially entrained state with a 24-hour L:D(light/dark) cycle. After this phase the animals were placed in constant conditions to document free running activity with circadian components. The results of this study clarify why publications up to now show conflicting results about circadian aspects of Octopus vulgaris activity. While light was used inefficiently as a Zeitgeber for activity the results of our study proved the presence of an endogenous circadian rhythm in O. vulgaris. These generalistic and opportunistic animals may use several different time cues to synchronize their activity and behavior with the time constraints of their environment
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