747 research outputs found
New radiometric age of volcanic rocks in the Central Eritrean Plateau (form Asmara to Adi Quala): consideration on stratigraphy and correlation.
No full textNew radiometric data have recently been acquired on basalt and rhyolite sampled at various levels of the volcanic sequence occurring in the central Eritrean plateau, confirming the stratigraphic reconstruction suggested in a previous paper [Zanettin, B., Bellieni, G., Justin Visentin, E., Haile, T., 1999. The volcanic rocks of the Eritrean plateau: stratigraphy and evolution. Acta Volcanologica 11(1), 183-193]. New considerations indicate the tholeiitic, not alkaline, nature of the Asmara basalt. Doubts about the relative age of the Aiba/Alaji and Asmara basalts have now been clarified: they are, at least partly, coeval (about 30 Ma old). The Serae rhyolite intercalated in the Adi Ugri basalt turns out to be about 24 Ma old, like the more abundant ignimbrite outcropping in the Senafe area, of which it is the westernmost extension. Its age confirms that it does not correspond to the trachyte intercalated in the Oligocene stratoid basalt of the Adwa-Axum area (where the Adi Ugri basalt probably also occurs, intercalated with the Serae trachyte and rhyolite). The upper part of the Adi Ugri basalt is 22 Ma old (an age consistent with the finding of a Deinotherium tooth). The radiometric age of these rocks also confirms already indicated correlations between Eritrean and Ethiopian volcanic formations
La critica dei soggetti collettiva tra l'Ideologia tedesca e il Diciotto Brumaio
No full textThis essay first takes into account a methodological issue, which concerns the relationship between two very different writings such as The German Ideology and The 18 Brumaire of Louis Bonaparte. Starting from the highlighting of their continuity in the construction of the materialist approach to history by Marx and Engels, the essay develops the Marxian critique of bourgeois political concepts (constitution, people, democracy, etc.), which allows the author to show the dichotomous character of capitalist society, as well as the fiction of any attempt to unify it. On the contrary, Marx shows how the class struggle continuously divides any attempt to give life to a unitary collective subject, and how any project of institutionalisation of the conflict is always challenged by the original contradiction, which manifests itself first of all on the imaginative level and on the level of passions, first of all fear
Premessa
No full textSi tratta della Premessa alla monografia di Barbara Visentin su Capua altomedievale, risultato di una tesi di dottorato condotta sotto la guida di F. Panarell
Objective characterization of speech intelligibility under continuous fluctuating masker: Comparing speech transmission index (STI) and speech fluctuation quality index (SFQI)
No full textWhen a listener is exposed to babble noise in a room or space, the reception of speech is influenced by the amount of temporal fluctuations present in the disturbance which in turn is mediated by the sound tail in the room. In order to investigate these conditions a set of simulated signals having different ratios of single talker and babble was prepared for a range of reverberation times. Two regular rooms with volumes equal to 352m3 and 3072m3 respectively were chosen for simulating the sound tails, and the reverberated signals were characterized by means of their "fluctuation strength". It was shown that the overall room dimensions and hence the impulse response details play a minor role whereas the reverberation time drives the behavior of noise fluctuations. Then the objective characterization of speech intelligibility in the rooms was accomplished for a number conditions by means of STI, which is known to behave critically under fluctuating masker conditions. Also the recently proposed speech fluctuation quality index SFQI, which is based on the comparison of fluctuations in the signal with those in the noise, was calculated. This latter indicator effectively separates the different noise fluctuation groups. Finally, recordings in real environments (bar, restaurant, market, bus) were accomplished and a first comparison with simulated conditions was discussed.When a listener is exposed to babble noise in a room or space, the reception of speech is influenced by the amount of temporal fluctuations present in the disturbance which in turn is mediated by the sound tail in the room. In order to investigate these conditions a set of simulated signals having different ratios of single talker and babble was prepared for a range of reverberation times. Two regular rooms with volumes equal to 352m3 and 3072m3 respectively were chosen for simulating the sound tails, and the reverberated signals were characterized by means of their "fluctuation strength". It was shown that the overall room dimensions and hence the impulse response details play a minor role whereas the reverberation time drives the behavior of noise fluctuations. Then the objective characterization of speech intelligibility in the rooms was accomplished for a number conditions by means of STI, which is known to behave critically under fluctuating masker conditions. Also the recently pr..
Una generalizzazione di alcuni teoremi di stabilità asintotica.
No full textTramite l’uso di due funzioni di Lyapunov (una scalare e una vettoriale) si perviene alla dimostrazione di due teoremi concernenti la stabilità asintotica ed equiasintotica rispettivamente, richiedendo solo la limitatezza inferiore e non la definitezza in segno della funzione scalare. I risultati vengono applicati al caso di un sistema olonomo ad n gradi di libertà
Volcanic cycles and magmatic evolution in the territory surrounding the Turkana Lake (Northern Kenya).
No full textStratigraphy and evolution og the trachy-rhyolitic volcanism of the Senafe Area (Eastern Eritrean Plateau).
No full textThe Senafe area reveals a pile of stratoid volcanic rocks ("Senafe" ignimbrite), of considerable extent and thickness, which are the products of the first volcanic event which took place in this sector, close to the upper margin of the Afar escarpment. The Senafe ignimbrite is composed prevalently of trachyte with differing degrees of alkalinity: trachy-dacite of transitional series, and trachyte s.s. of mildly alkaline series. K/Ar radiometric measurements carried out on three samples give ages ranging between 21 and 23 Ma (Lower Miocene) and show that the Senafe ignimbrite with transitional character is an extension of the Serae rhyolite of the Central Eritrean Plateau, and may also be correlated with the Miocene Alaji rhyolite of the Central Ethiopian Plateau. In contrast, the more alkaline ignimbrite shows good correlations with the trachyte emitted by the Miocene Termaber alkaline central volcanoes of Ethiopia. It is noted that, in the course of the Miocene volcanism in Eritrea, the volumetric ratio between associated basalt and ignimbrite diminishes from west to east, i.e., approaching the Afar escarpment. The stratoid volcanic rocks are injected by thick trachytic and rhyolitic dykes. As radiometric measurements on them could not be performed, their age is unknown, but it is probably more recent than that of the injected ignimbrite, according to Merla and Minucci [Merla, G., Minucci, E., 1938. Missione geologica nel Tigrai. In: La serie dei terreni, vol. 1. Regia Accademia d'Italia, Centro Studi per l'Africa Orientale Italiana, Rome, Italy, pp. 1-362] for similar dykes and domes occurring in the Adwa-Axum area (Tigrai, Ethiopia), not far from Senafe. A section is devoted to the dyke feeders of the Eritrean and Adwa-Axum volcanism
Aumentare l’effetto della paura: stimolo pubblicitario e livello di astrazione del comportamento
No full textAcutissimus o prudentissimus? Intorno alla presenza di Machiavelli nel Trattato politico di Spinoza
No full textThe article focuses on par.7, chapter V, of the Political Treatise, one of the two paragraphs in which
Machiavelli’s name can be read. This is the starting point for a synthetic analysis of Machiavelli’s
presence in some topoi of the Dutch thought of the XVIIth century; finally, thus returning to
Spinoza, the author tries to comprehend the meaning of this presence within the a. m. tradition, in
order to evaluate the role played by the Florentine secretary in Spinoza’s political reflection.
Machiavelli’s presence actually goes deeper than the famous two passages may lead to believe, and
a careful analysis of the a. m. paragraph reveals a fundamental aspect of the strong link between
the two philosophers: the centrality – both theoretical and practical – that both thinkers tribute to
the political role of multitude, in contrast with any reductio ad unum of the processes of constitution
and justification of power
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