U.S. Domestic Barter : an Empirical Investigation

This paper studies the barter industry developed in North America during he 1950s, pointing ut some of its main characteristics. Thus, it examines its two main sectors : (i) Corporate Barter and (ii) Commercial Barter. Contrary to expectations, the analysis of official data shows that this phenomenon is essentially pro-cyclical for the Commercial Barter component. Moreover, commecial barter activity turns out to be complementary to the cash economy. While the two sectors display some differences in their pattern, they both help firms to increase their profits.E-Barter; Corporate Barter; Economic Cycle

Quantum Hall effect in polycrystalline graphene: The role of grain boundaries

We use numerical simulations to predict peculiar magnetotransport fingerprints in polycrystalline graphene, driven by the presence of grain boundaries of varying size and orientation. The formation of Landau levels is shown to be restricted by the polycrystalline morphology, requiring the magnetic length to be smaller than the average grain radius. The nature of localization is also found to be unusual, with strongly localized states at the center of Landau levels (including the usually highly robust zero-energy state) and extended electronic states lying between Landau levels. These extended states percolate along the network of grain boundaries, resulting in a finite value for the bulk dissipative conductivity and suppression of the quantized Hall conductance. Such breakdown of the quantum Hall regime provoked by extended structural defects is also illustrated through two-terminal Landauer-B\"uttiker conductance calculations, indicating how a single grain boundary induces cross-linking between edge states lying at opposite sides of a ribbon geometry

Unconventional Features in the Quantum Hall Regime of Disordered Graphene: Percolating Impurity States and Hall Conductance Quantization

We report on the formation of critical states in disordered graphene, at the origin of variable and unconventional transport properties in the quantum Hall regime, such as a zero-energy Hall conductance plateau in the absence of an energy bandgap and Landau level degeneracy breaking. By using efficient real-space transport methodologies, we compute both the dissipative and Hall conductivities of large size graphene sheets with random distribution of model single and double vacancies. By analyzing the scaling of transport coefficients with defect density, system size and magnetic length, we elucidate the origin of anomalous quantum Hall features as magnetic-field dependent impurity states, which percolate at some critical energies. These findings shed light on unidentified states and quantum transport anomalies reported experimentally.Comment: 7 pages, 7 figures. Accepted in PR

The illocution-prosody relationship and the Information Pattern in spontaneous speech according to the Language into Act Theory (L-AcT)

This paper introduces the question of the definition of reference units for speech, correlating with the necessary condition that they must be an adequate and useful means for analyzing large spoken corpora. According to Language into Act Theory (L-AcT), the utterance is the proper reference unit and the counterpart of the speech act (Austin 1962), being demarcated by prosody within the flow of speech. The pragmatic foundations of the utterance and its information structure will be described and are closely connected to the role of prosody in their identification. The pragmatic and information analysis of English and Romance examples are presented, which are taken from representative spoken corpora (C-ORAL-ROM, C-ORAL-BRAZIL, S. Barbara Corpus). Regarding the information structure, the Comment unit is considered the core of the Information Pattern and since its role is the expression of the illocution it automatically conveys the new information. The Comment may be accompanied and supported by other optional information units which are functionally differentiated. The Information Pattern is systematically demarcated by a Prosodic Pattern within an isomorphic correlation

Joseph Beuys: la parola e la rosa

Il saggio ripercorre la vita e la parabola artistica di Joseph Beyus, mettendole in relazione con le teorie antroposofiche di Rudolf Steiner, le quali ispirano diverse sue opere e, soprattutto, la presenza di due simboli in esse ricorrenti: la rosa e la croce. Pur non essendo immune da influenze esoteriche e gnostiche, Beuys prende le mosse da alcuni capisaldi dell\u2019antroposofia: l\u2019"et\ue0 del Dio-figlio\u201d, i caratteri dell\u2019Io in questa et\ue0, il mutamento della luce in calore e la nascita delle comunit\ue0 tramite la parola