60 resultados para Pseudoconvessità curvatura di Levi pseudoconvexity curvature


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Encyclopedia entry for "idioms" and "idiomatic expressions" in Italian

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The article – which is co-authored with Irene Zagrebelsky – focuses on the work of the Italian playwright and actor Beppe Rosso, and it is the most detailed critical account on Rosso’s production so far. Based on original material and interviews, it not only analyses Rosso’s widely acclaimed “Trilogy of invisibility” in the light of recent political events in Italy, but it also – in its first two sections – introduces the so called “teatro di narrazione” to Italian scholars in the UK, and in its two last sections opens up new perspectives on the relationship between contemporary theatre, citizenship and political participation.

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The book is part of a multi-year investigation on the historical construction and representation of ethnic otherness through the use of language, and focuses on the history of the tópos expressed by the proverb Lavare/sbiancare un etiope (‘to wash an Ethiop white’), a tópos which is traceable in different languages across many centuries (and since II c. A.D.), which stays for either ‘to attempt the impossible’ or ‘to do something useless’. The research also tries to shine a light upon the cultural and social contexts in which ‘Ethiopian’ otherness have generated. Its final goal is to find out how the washing-the-Ethiopian tópos (in its verbal and iconographical forms) has become long-lasting, ductile and semantically productive key expression whose heterogeneous use not only document but also produce and fix otherness in time.

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The analytical model proposed by Teixeira, Miranda, and Valente is modified to calculate the gravity wave drag exerted by a stratified flow over a 2D mountain ridge. The drag is found to be more strongly affected by the vertical variation of the background velocity than for an axisymmetric mountain. In the hydrostatic approximation, the corrections to the drag due to this effect do not depend on the detailed shape of the ridge as long as this is exactly 2D. Besides the drag, all the perturbed quantities of the flow at the surface, including the pressure, may be calculated analytically.

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An analytical model is developed to predict the surface drag exerted by internal gravity waves on an isolated axisymmetric mountain over which there is a stratified flow with a velocity profile that varies relatively slowly with height. The model is linear with respect to the perturbations induced by the mountain, and solves the Taylor–Goldstein equation with variable coefficients using a Wentzel–Kramers–Brillouin (WKB) approximation, formally valid for high Richardson numbers, Ri. The WKB solution is extended to a higher order than in previous studies, enabling a rigorous treatment of the effects of shear and curvature of the wind profile on the surface drag. In the hydrostatic approximation, closed formulas for the drag are derived for generic wind profiles, where the relative magnitude of the corrections to the leading-order drag (valid for a constant wind profile) does not depend on the detailed shape of the orography. The drag is found to vary proportionally to Ri21, decreasing as Ri decreases for a wind that varies linearly with height, and increasing as Ri decreases for a wind that rotates with height maintaining its magnitude. In these two cases the surface drag is predicted to be aligned with the surface wind. When one of the wind components varies linearly with height and the other is constant, the surface drag is misaligned with the surface wind, especially for relatively small Ri. All these results are shown to be in fairly good agreement with numerical simulations of mesoscale nonhydrostatic models, for high and even moderate values of Ri.

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During the reaction of di-2-pyridyl ketone (dpk) with Na(2)[PdCl(4)] in alcoholic media, the C=O fragment of dpk undergoes facile solvolysis and the transformed di-2-pyridyl ketone (dpk(ROH), R = Me or H) binds to palladium as NN-donor. When the reaction is carried out in refluxing methanol, a mono-complex of type [Pd(dpk(MeOH))Cl(2)] is obtained. A similar reaction in ethanol affords a bis-complex of type [Pd(dpk(ROH))(2)]Cl(2). Structure of both the complexes have been determined by X-ray crystallography. In acetonitrile solution the [pd(dpk(MeOH))Cl(2)] and [pd(dpk(ROH))(2)]Cl(2) complexes show intense absorptions in the visible and ultraviolet region, origin of which has been probed through uvr calculations. These two palladium complexes are found to be efficient catalysts for Suzuki cross-coupling reactions.

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Reaction of a potential NCN-pincer ligand, viz. 1,3-di(phenylazo)benzene (L), with [Rh(PPh3)(3)Cl] affords, via a C-H bond activation, an interesting dinuclear Rh(II) complex (1), and with RhCl3 center dot 3H(2)O affords a mononuclear Rh(III) complex (2) containing a catalytically useful Rh-OH2 fragment.

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La poesia di Amelia Rosselli costituisce uno dei fenomeni linguistico-espressivi più complessi della poesia italiana del secondo Novecento. Percorsa da tensioni stilistiche ed espressive peculiari che l'hanno resa uno dei vertici dello sperimentalismo plurilingue novecentesco, l'opera rosselliana costituisce, nel suo insieme, una poderosa meditazione sull'alienazione e sulle possibilità di esprimere a pieno il proprio disagio esistenziale se non attraverso la creazione di una lingua che sfida, al medesimo tempo, convenzioni sintattiche, grammaticali, e grafiche di ben tre sistemi linguistici, e che impone al lettore, in virtù di un trilinguismo biograficamente motivato, la flessuosità di una logica del senso plurima e simultanea. Scopo del volume è offrire un contributo sistematico alla comprensione di un'opera poetica sulla quale ancora gravano radicati fraintendimenti e pervicaci clichés critici.

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Viral replication occurs within cells, with release (and onward infection) primarily achieved through two alternative mechanisms: lysis, in which virions emerge as the infected cell dies and bursts open; or budding, in which virions emerge gradually from a still living cell by appropriating a small part of the cell membrane. Virus budding is a poorly understood process that challenges current models of vesicle formation. Here, a plausible mechanism for arenavirus budding is presented, building on recent evidence that viral proteins embed in the inner lipid layer of the cell membrane. Experimental results confirm that viral protein is associated with increased membrane curvature, whereas a mathematical model is used to show that localized increases in curvature alone are sufficient to generate viral buds. The magnitude of the protein-induced curvature is calculated from the size of the amphipathic region hypothetically removed from the inner membrane as a result of translation, with a change in membrane stiffness estimated from observed differences in virion deformation as a result of protein depletion. Numerical results are based on experimental data and estimates for three arenaviruses, but the mechanisms described are more broadly applicable. The hypothesized mechanism is shown to be sufficient to generate spontaneous budding that matches well both qualitatively and quantitatively with experimental observations.

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We describe herein preliminary studies on the Intramolecular Diels-Alder Furan-Mediated Synthesis of 8-Aryl-3, 4-di-hydroisoquinolin-1(2H)-ones that constitutes a new, formal synthesis of Indeno[1,2,3-ij]isoquinolines.

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Libraries as centres of culture in the Roman world - illustrated essay in the catalogue of the exhibition at the Colosseum, Rome, March - October 2014.