The configuration of β-halogenoenamines. The use of a new procedure for NOE measurements

The configurations of 16 different β-halogenoenamines have been determined using the proton NOE effect, and the same results were obtained as when the ²J(CH) coupling constants were used. A new procedure called the ‘repetitive shift frequency’ is presented for the NOE determinations which allows better reproducibility and improves the precision.     

On the Onsager-Yang-Value of the spontaneous magnetization

We show that the value of the spontaneous magnetization for the two-dimensional Ising model computed by Onsager is indeed, the appropriate derivative of the free energy with respect to the magnetic field. The argument is based on a simple application of the duality transformation.Lavoro eseguito nell'ambito del G.N.F.M.     

Fundamental optical properties of In halides

Reflectance and thermoreflectance spectra between 2 and 9 eV have been measured for InBr and InI crystals. A correlation between optical structures and electronic levels is proposed taking into account of the X-ray photoelectron spectroscopy data and of the expected similarity of In and Tl halides band scheme.     

Vorticity—velocity formulation in the computation of flows in multiconnected domains

The thermofluid dynamic fields in two-dimensional multiconnected domains are analysed by solving the Navier–Stokes equations with the Boussinesq approximation in the vorticity–velocity formulation. The need of an integral condition for the pressure to be single-valued on each independent irreducible loop, in analogy with the ω–Ψ formulation, is demonstrated. The field equations are discretized by a finite difference technique and solved at the steady state via an alternating direction implicit method of a scalar type. Two test cases at low Reynolds and Rayleigh numbers are considered: the multiconnected driven cavity and an annulus with isothermal walls and stationary or rotating inner cylinder.     

Infrared thermoreflectance of VχTi1-χSe2

Thermoreflectance data in V_χTi_1-χSe₂ show that an interband optical structure, present both below and above the transition temperature, is relatively unaffected by the vanadium content (for χ ? 1.5%).     

Renormalization and scaling of a two-dimensional Ising system in a transverse field at Tc>0

A quantum generalization of the Niemeijer and van Leeuwen (N-vL) renormalization group transformation is constructed which allows to study the critical properties (at T_c>0) of a two-dimensional Ising system with a transverse field on a triangular lattice. Explicit calculations are performed in a second order cumulant expansion. Only one fixed point is found corresponding to the same Ising-like hamiltonian given by N-vl. The linearized transformation has a zero eigenvalue associated with Γ, the transverse field strength. The critical properties of the system are briefly discussed; in particular we show that the singular behaviour of the transverse susceptibility at Γ = 0, which turns out to be of the same kind as that of the energy density, is explained by the existence of such a zero eigenvalue. Our arguments suggest a natural extension of this result to three dimensions.     

Argue to agree: A case-based argumentation approach

The capability of reaching agreements is a necessary feature that large computer systems where agents interoperate must include. In these systems, agents represent self-motivated entities that have a social context, including dependency relations among them, and different preferences and beliefs. Without agreement there is no cooperation and thus, complex tasks which require the interaction of agents with different points of view cannot be performed. In this work, we propose a case-based argumentation approach for Multi-Agent Systems where agents reach agreements by arguing and improve their argumentation skills from experience. A set of knowledge resources and a reasoning process that agents can use to manage their positions and arguments are presented. These elements are implemented and validated in a customer support application.     

Associativity, Commutativity and Symmetry in Residuated Structures

In this paper we develop the study of extended-order algebras, recently introduced by C. Guido and P. Toto, which are implicative algebras that generalize all the widely considered integral residuated structures. Particular care is devoted to the requirement of completeness that can be obtained by the MacNeille completion process. Associativity, commutativity and symmetry assumptions are characterized and their role is discussed toward the structure of the algebra and of its completion. As an application, further operations corresponding to the logical connectives of conjunction negation and disjunction are considered and their properties are investigated, either assuming or excluding the additional conditions of associativity, commutativity and symmetry. An overlook is also devoted to the relationship with other similar structures already considered such as implication algebras (in particular Heyting algebras), BCK algebras, quantales, residuated lattices and closed categories.