Cognitive Interference Alignment for OFDM Two-tiered Networks

In this contribution, we introduce an interference alignment scheme that allows the coexistence of an orthogonal frequency division multiplexing (OFDM) macro-cell and a cognitive small-cell, deployed in a two-tiered structure and transmitting over the same bandwidth. We derive the optimal linear strategy for the single antenna secondary base station, maximizing the spectral efficiency of the opportunistic link, accounting for both signal sub-space structure and power loading strategy. Our analytical and numerical findings prove that the precoder structure proposed is optimal for the considered scenario in the face of Rayleigh and exponential decaying channels.Comment: 5 pages, 4 figures. Accepted and presented at the IEEE 13th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2012. Authors' final version. Copyright transferred to IEE

Cognitive Orthogonal Precoder for Two-tiered Networks Deployment

In this work, the problem of cross-tier interference in a two-tiered (macro-cell and cognitive small-cells) network, under the complete spectrum sharing paradigm, is studied. A new orthogonal precoder transmit scheme for the small base stations, called multi-user Vandermonde-subspace frequency division multiplexing (MU-VFDM), is proposed. MU-VFDM allows several cognitive small base stations to coexist with legacy macro-cell receivers, by nulling the small- to macro-cell cross-tier interference, without any cooperation between the two tiers. This cleverly designed cascaded precoder structure, not only cancels the cross-tier interference, but avoids the co-tier interference for the small-cell network. The achievable sum-rate of the small-cell network, satisfying the interference cancelation requirements, is evaluated for perfect and imperfect channel state information at the transmitter. Simulation results for the cascaded MU-VFDM precoder show a comparable performance to that of state-of-the-art dirty paper coding technique, for the case of a dense cellular layout. Finally, a comparison between MU-VFDM and a standard complete spectrum separation strategy is proposed. Promising gains in terms of achievable sum-rate are shown for the two-tiered network w.r.t. the traditional bandwidth management approach.Comment: 11 pages, 9 figures, accepted and to appear in IEEE Journal on Selected Areas in Communications: Cognitive Radio Series, 2013. Copyright transferred to IEE

Evaluating the impact of Hymenoscyphus fraxineus in Trentino (Alps, Northern Italy): first investigations

The spread of Hymenoscyphus fraxineus has been causing great concern regarding the survival of European ash (Fraxinus excelsior) throughout Europe since the 1990s. The disease was first recorded in Trentino (southern Alps, Italy) in 2012 and has spread throughout the mountain landscape, where ash trees are scattered in small and isolated stands in different valleys. The status of the disease was checked by monitoring the damage to natural regeneration and adult trees in 90 sites spread over the whole region. The survey confirmed the complete colonization by the pathogen of the whole investigated area, with high levels of damage to both young and adult ash trees. Regeneration (both seedlings and saplings) was observed to be affected by the fungus in 88 plots out of 90. Out of 4486 examined young European ashes, 2261 (50.4%) were affected and 789 (17.6%) were already dead. Ten of the 384 assayed flowering ashes (Fraxinus ornus) showed symptoms on branches and apical stems, similar to those observed for European ash. Isolation and molecular analysis proved the presence of the fungus on both symptomatic European and flowering ashes. The examined 386 adult trees showed different levels of damage, sometimes reaching more than 75% of the crown. Some individual trees (42) growing close to severely damaged trees appeared fully healthy, which suggests the possible existence of some resistant/tolerant individuals in the examined populations

Zero-derived forms in the mental lexicon: Experimental evidence from Italian

Our paper investigates how zero-affixed verbal forms (specifically, denominal and deadjectival verbs) are processed by native speakers of Italian during visual word recognition. More specifically, we verify whether, and possibly to what extent, the processing of such forms differs from or resembles the processing of verbs resulting from two other productive word formation schemas in Italian, i. e., suffixation and parasynthesis. The interest of such a comparison lies in the fact that the three considered schemas behave similarly from a functional point of view, i. e.: i) they all change the category of the base, ii) they select the same base category (nouns and adjectives), and iii) they show similar semantic characteristics. However, this shared function is realized by means of different formal exponents (both overt and covert) which might imply different degrees of complexity. Crucially, suffixation and parasynthesis display an overt derivational marking, while zero-affixation obviously does not. On such premises, to verify whether the strength of connections between morphologically complex words and their bases is affected by the nature of the transcategorization marking (overt v s vs covert) or whether other factors play a more determining role, we conducted a psycholinguistic experiment involving a lexical decision task combined with the masked priming paradigm, which allows focusing on such relations in the mental lexicon. Results indicate that the processing of zero-affixed verbs resembles that of suffixed but differs from that of parasynthetic forms. We interpret such results discussing the possibility that the perception of a morphological relationship might depend less on the overtness of the marking, and more on the overall derivational complexity of the morphological process

Paradeigmata voluntatis. All’origine della concezione moderna di volontà

‘Will’ descends, etymologically, from voluntas. However, in the meaning of voluntas it is no longer possible to grasp the terminological plurivocity present in the Greek language. Consequently, the theory of action, which Aristotle and Greek thought in general had extensively dealt with, in the Roman context has adapted to a simplified conceptual framework. The essays collected here have allowed us to focus on a brand new articulated paradigm. Within it, we find a renewed concept of ‘will’: the voluntas which is explained in the modern interpretation of the ‘voluntary act’, and ‘voluntarism’ tout-court

Cicerone 'De fato'. Seminario internazionale, Venezia 10-12 luglio 2006

II edizione dei contributi presentati e discussi nel 'Seminario internazionale' di studio svoltosi a Venezia dal 10 al 12 luglio 2006, organizzato dal dipartimento di "Filosofia e Teoria delle Scienze" dell'Università Ca' Foscari di Venezia e dal dipartimento di "Studi Filosofici ed Epistemologici" dell'Università di Roma la Sapienza. Contributi di Stefano Maso, Carlos Lévy, Hermann Weidemann, Robert Sharples, Carlo Natali, Michele Alessandrelli, Anna Maria Ioppolo, Jean-Baptiste Gourinat, Francesca Masi. Ai contributi pubblicati in prima edizione presso la rivista Lexis 25/2007 è stata aggiunta un'Introduzione di S. Maso (pp. IX-XXX) e gli indici dei nomi e delle cose notevoli

Le regard de la vérité. Cinq études sur Sénèque

Raccolta di cinque studi dedicati alle modalità attraverso cui Seneca si rapporta con la verità. a) La transparence de la vérité, b) Sénèque face aux anciens, c) La question épicurienne, d) 'Sibi fidere'; Sénèque entre ptium et constantia, d) Sénèque et le mécanisme de la vérit