The structure of a collineation group preserving an oval in a projective plane of odd order

We investigate the structure of a collineation groupG preserving an oval in a finite projective plane of odd order and we obtain several results aboutG, whenG is a2-group. These results are then used to investigate the structure ofG/O(G) in the general case and, in particular, that ofF*(G/O(G)).This research was supported in part by a grant from the M.U.R.S.T.     

Conformational effects on circular dichroism in the photoelectron angular distribution.

The B-spline density-functional method has been applied to the conformers of the (1R, 2R)-1,2-dibromo-1,2-dichloro-1,2-difluoroethane molecule. The cross section, asymmetry, and dichroic parameters relative to core and valence orbitals, which do not change their nature along the conformational curve, have been systematically studied. While the cross section and the asymmetry parameter are weakly affected, the dichroic parameter appears to be rather sensitive to the particular conformer of the molecule, suggesting that this dynamical property could be a useful tool for conformational analysis. The computational method has also been applied to methyl rotation in methyloxirane. Unexpected and dramatic sensitivity of the dichroic-parameter profile to the methyl rotation, both in the core and valence states, has been found. Boltzmann averaging over the conformers reproduces quite closely the profiles previously obtained for the minimum-energy conformation, which is in good agreement with the experimental results.     

Sul primo principio della termodinamica per I materiali semplici

It is known that the correct formulation of rational thermodynamics for mixtures requires an inequality more general than the Clausius-Duhem principle. On the other hand, in a recent paper on the thermodynamics of “interstitial working”[2] it was pointed out the need to correct the classical balance law of internal energy. There is no good reason for modifying both, however. It is worth to derive, hence, the most general expression of the Second Law by keeping the First in its classical form, as shown in a previous paper [4], or, what is the object of this article, to look for the most general formulation of the First Law assuming the Clausius-Duhem inequality as the Second. As a consequence of results obtained here, the statement of the First Principle needs not to be changed in the class of “simple material”. Thus, it is worth noting that a generalized expression of the First Law applies only non-simple materials, like as Korteweg fluids.

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Lavoro eseguito nell'ambito delle attività del G.N.F.M. del C.N.R. e dei progetti di ricerca ministeriali 40% e 60%.     

Nouve determinazioni concernenti l’equazione integrale non lineare di Volterra

Sunto Nella Nota dal titolo ?Sull’equazione integrale di Volterra ? apparsa nel volume di questi Annali, precedente a quello che accoglie la presente, applicando un nuovo metodo d’approssimazioni successive, sono stati conseguiti nuovi teoremi d’esistenza e d’unicità, nonché talune limitazioni, per la soluzione dell equazione considerata. Con la presente si fanno conoscere ulteriori risultati esistenziali e quantitativi, per la soluzione dell equazione stessa, dovuti all’applicazione aello stesso metodo di approssimazioni successive.

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Summary In the paper entitled ?On the Volterra integral equation ? and published in the immediately preceding volume of these Annali, new existence and uniqueness theorems were given, by means of a successive approximation procedure. The present note shows further results concerning existence and uniqueness of the solution of that equations, which follow from the application of the same method.

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Ad Antonio Signorini nel suo 70^mo compleanno.     

A theory of the dielectric loss in the aligned nematic mesophase

A theory of dielectric absorption and dispersion in the nematic phase is developed which does not rely on the use of a nematic “director”. The major features of the spectrum are reproduced by using the fact that the autocorrelation functions 〈μ(0) · υ(t)〉 and 〈υ(t) · μ(0)〉 are no longer symmetry disallowed when the overall sample is anisotropic, as in the aligned nematic. Here μ is the dipole vector of the diffusing molecule and υ the centre of mass linear velocity.