276 research outputs found
Effect of preillumination on photomotile responses of the marine ciliate Fabrea salina
No full textFabrea salina is a marine ciliate that shows photomotile responses such as positive phototaxis and a step-down photophobic reaction. We found that preilluminated F. salina cells show a phototactic response significantly greater than that of dark-adapted cells when exposed to the same phototactic light stimulus. In particular, positive phototaxis is strongly enhanced by preillumination. This enhancement effect depends on the preillumination light irradiance, on the total preillumination dose, and on the duration of the dark interval between preillumination and the phototaxis measurement. Our results show that the determining factor is the tot preillumination dose given to the sample. The enhancement effect shows an asymptotic behavior over a certain range of energy values (10-200 W/m(2)). Further, the effect is transient; after 120 s in the dark, the cells lose any memory of the preillumination, independent of the preillumination energy received. These results are tentatively discussed in terms of light-driven membrane potential or membrane channel conductances
Phototactic orientation mechanism in the ciliate Fabrea salina, as inferred from numerical simulations
No full textFailures, exploitations and deceits in communication
No full textIn this paper we sketch the general lines of a model of an elementary interchange in a dialogue, and concentrate on the analysis of the dialogue failures and exploitations the model can account for, as well as on deceitful uses of communication and non-expressive uses of language. We show that our model of standard communication can explain non-standard uses of language without special adaptation. In this way we can account for a variety of linguistic phenomena which are often neglected in formal treatments of dialogue, and provide a first validation of the knowledge structures and inference processes assumed in the model
Conversation and behavior games in the pragmatics of dialogue
No full textIn this article we present the bases for a computational theory of the cognitive processes underlying human communication. The core of the article is devoted to
the analysis of the phases in which the process of comprehension of a communicative act can be logically divided: (1) literal meaning, where the reconstruction
of the mental states literally expressed by the actor takes place; (2) speaker’s meaning. where the partner reconstructs the communicative intentions of the actor; (3) communicative effect, where the partner possibly modifies his own beliefs and intentions; (4) reaction, where the intentions for the generation of the response are produced: and (5) response, where an overt response is constructed. The model appears to be compatible with relevant facts about human behavior. Our hypothesis is that, through communication, on actor tries to exploit the motivational structures of a partner so that the desired goal is generated. A second point is that social behavior requires that cooperation be maintained at some level. In the case of communication, cooperation is, in
general, pursued even when the partner does not adhere to the actor’s goals, and therefore no cooperation occurs at the behavioral level. This important distinction is reflected in the two kinds of games we introduce to account for communication. The main concept implied in communication is that two agents overtly reach a situation of shared mental states. Our model deols with sharedness through two primitives: shared beliefs and communicative intentions
Some metallic spherules in calcareous-marly sediments of the Romanoro Flysch, Sestola-Vidiciatico tectonic unit (Modena district, Northern Apennines, Italy).
No full text
Behavior Analysis and Training: A Methodology for Behavior Engineering
No full textinfo:eu-repo/semantics/publishe
Effects of UV-B Irradiation on a Marine Microecosystem
No full textPurpose of this work was to study the effect of UV irradiation on a microecosystem consisting of several interacting species. The system chosen was of a hypersaline type, where all the species present live at high salt concentration; it comprises different bacteria; a producer, the photosynthetic green alga Dunaliella salina; and a consumer, the ciliated protozoan Fabrea salina, which form a complete food chain. We were able to establish the initial conditions that give rise to a self-sustaining microecosystem, stable for at least 3 weeks. We then determined the effect of UV irradiation on this microecosystem under laboratory-controlled conditions, in particular by measuring the critical UV exposure for the two main components of the microecosystem (algae and protozoa) under UV-B irradiances comparable to those of solar irradiation. In our experiments, we varied irradiance, total dose and spectral composition of the actinic light. The critical doses at irradiances of the order of 56 kJ/m2 (typical average daily irradiance in a sunny summer day in Pisa), measured for each main component of the microecosystem (algae and ciliates), turned out to be around 70 kJ/m2 for ciliates and 50 kJ/m2 for D. salina. By exposing microecosystems to daily UV-B irradiances of the order of 8 kJ/m2 (typical average daily irradiance in a sunny winter day in Pisa), we found no effect at total doses of the order of the critical doses at high irradiances, showing that the reciprocity law does not hold. We have also measured a preliminary spectral-sensitive curve of the UV effects, which shows an exponential decay with wavelength
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