887 research outputs found

    Geometric expansion of the log-partition function of the anisotropic Heisenberg model

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    We study the asymptotic expansion of the log-partition function of the anisotropic Heisenberg model in a bounded domain as this domain is dilated to infinity. Using the Ginibre's representation of the anisotropic Heisenberg model as a gas of interacting trajectories of a compound Poisson process we find all the non-decreasing terms of this expansion. They are given explicitly in terms of functional integrals. As the main technical tool we use the cluster expansion method.Comment: 38 page

    Molecular Conformation of Pyridinic Aromatic Esters. II. Electronic Absorption Spectra and Dipole Moments by Semiempirical Methods

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    The semiempirical MIM method was applied to calculate the UV spectra of nine pyridine-aromatic-ester derivatives (having the general formula R1-COO-R2) assuming a planar geometry. Benzene, pyridine and formic acid were adopted as component systems. The dipole moments of the same compounds were evaluated at the MIM and INDO levels and the equilibrium percentage of the conformers was deduced from experimental and theoretical values. Comparable results were generally obtained. On the whole the results are satisfactory but not sufficient to affirm with certainty if the molecular skeleton is or is not planar

    Molecular Conformation of Aza-substituted Benzanilides by Electronic Absorption Spectra and Dipole Moments

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    The electronic absorption spectra of thirteen pyridine aromatic amides of general formula R1-CO-NH- R2 (Ri, R2 = pyridil or phenyl) were obtained in methanol and dioxane solution. The band assignment is briefly discussed. The dipole moments were measured in dioxane at 25 ± 0.1 °c and compared with values calculated by both the S. H. M. 0. method and vectorial model. The comparison suggests the most probable conformation of derivatives which have the nitrogen either in the ortho or meta position in one or both rings of the molecule

    Identità e relazioni sociali. Dai popoli migranti alla cultura del Web 2.0

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    Nel saggio è una riflessione preliminare su cos'è da intendere per identità prima di individuare il ruolo che svolge la comunicazione non solo nel mantenere ma anche e soprattutto nel costruire identità e nel gestire relazioni, nel senso di crearle, mutarle o annullarle.The essay is a reflection about identity and role of communication on creating, mantaining and destroying social relations

    Presence of Candida zemplinina in Sicilian Musts and Selection of a Strain for Wine Mixed Fermentations

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    The purpose of this work was to investigate the presence of C. zemplinina yeasts in Sicilian musts andgrapes and to identify strains of oenological interest. We report on the taxonomical reclassificationof Candida yeast isolates from Sicilian musts and on the selection of one strain of oenological interest(Cz3), based on mixed micro-fermentation experiments in sterile Nero d’Avola musts. Our results showthat Candida zemplinina is abundant in Sicilian grapes and musts, and that the Cz3 strain is suitablefor Candida zemplinina/Saccharomyces cerevisiae mixed fermentations. The higher glycerol content andthe lower ethanol level stood out as the most promising features of the wines obtained upon sequentialinoculation of the Cz3 and (S. cerevisiae) NDA21 yeast starters. We therefore have isolated a Sicilian Czstrain endowed with very promising features for the future development of mixed fermentation protocols
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