Structures de Poisson sur une intersection complète à singularités isoléesPoisson structures over a complete intersection with isolated singularities

We study Poisson structures over singular varieties. For this purpose, we consider the Koszul complex associated to the equations of a complete intersection. This complex forms a differential graded algebra which is equivalent to the algebra of the variety. We show that a Poisson structure is equivalent to a sequence of multiderivations over the Koszul complex. If the variety has isolated singularities, then we can construct a sequence of multiderivations of reduced form. To cite this article: B. Fresse, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 5–10.     

Abnormal viscosimetric behavior of homopolymers in mixed solvents and preferential solvation

It is shown that the applicability of the Stockmayer–Fixman–Burchard plot is much more limited in the case of solvent–precipitant mixtures than in the case of pure solvents. The observed deviations can be explained by taking into account the variation of preferential solvation as a function of the molecular weight of the polymer. More precisely the average density of the segments in the region occupied by the coiled molecule seems to be the parameter governing both changes in viscosity and in preferential solvation.     

Études en série indolique—XI : Synthèses dans la série de la dihydro-18, 19-dl antirhine

Three methods for the synthesis of (dl) 18, 19-dihydroantirhine and its epimers at C-15 and C-20 have been compared; a modified Polonovski reaction, mercuric acetate oxidation of the appropriate N-alkylpiperidine, and hydrogenation according to Wenkert of the appropriate pyridinium salt.     

Scattering from copolymer solutions at finite concentration

We consider the variation of the coherent elastic scattering structure factor S(q) with momentum transfer q for a solution of block copolymers at finite concentration. We introduce the effect of concentration using a generalization of Zimm's model to copolymers which enables us to express intermolecular scattering functions in terms of intramolecular form factors only. We show that the shape of the scattering curve is very sensitive to the polymer concentration as well as to the contrast factors, the relative composition of co units, and the second virial coefficients characterizing constituents of the copolymer. In particular, we show that the scattering curve develops a maximum at low q for certain values of these parameters. We also discuss the variation of the apparent radius of gyration with polymer concentration.     

The decay of 187Pt: Comparison of the levels of 187Ir with those of heavier odd mass iridium isotopes

The decay scheme of 2.35 h ¹⁸⁷Pt has been investigated using isotopically separated samples produced by the ISOLDE facility at CERN. A total of 20 excited levels in ¹⁸⁷Ir have been established. For many of these levels, spin, parity and absolute probabilities of depopulating transitions have been determined. The results indicate that the ¹⁸⁷Ir nucleus can be described in terms of a single particle Nilsson model including Coriolis coupling between bands ($\text{3}\text{2}{}^{\mathrm{+}}\text{[402],}\text{1}\text{2}{}^{\mathrm{+}}\text{[400]}$).     

Viskosimetrische Untersuchung des tern?ren Systems Polystyrol/Polymethylmethacrylat/p-Xylol

Ohne Zusammenfassung     

Nuclear orientation experiemnts on Al2LaCe alloys

Nuclear orientation experiments on ^137mCe impurities in Al₂La show directly at almost 0 K that these alloys correspond to the magnetic conditions assumed by Müller-Hartmann and Zittartz.     

The benzoyl cation: The participation of isolated electronic excited states in the dissociation of molecular ions of the form [C6H5COX]+˙

The heat of formation of the benzoyl cation generated from [C₆H₅COX]⁺˙ is found to depend on X, while the heat of formation of the phenyl ion produced therefrom is, with one exception, independent of X. The excess energy of the benzoyl cation can be accounted for by an electronic excited state of the ion in the mass spectra of benzoic acid, benzaldehyde, benzamide, methyl benzoate and possibly benzophenone; the benzoyl cation is not excited in the mass spectra of acetophenone and benzoyl chloride.