Norme composée et norme associée généralisée d'une matrice

Sans résumé     

Studies related to the synthesis of maytansinoids.

Two approaches to the partial synthesis of C₁–C₅ of a bis-nor maytansinoid $\text{1}$ have been investigated starting on the one hand with (S)-(?)-malic acid and on the other, with D-(+)-ribonolactone.     

Density of states of crystalline chlorine and bromine

The interpolation method for calculation of the density of states g(ν) of Gilat and Raubenheimer has been extended to monoclinic crystals. Numerical results are given for Cl₂ at 118 K and Br₂ at 130 and 250 K.     

Ein Gitterpunktproblem im dreidimensionalen hyperbolischen Raum

Ohne Zusammenfassung     

Pinning of an interface by a weak potential

We prove that in a two-dimensional Gaussian SOS model with a small attractive potential the height of the interface remains bounded no matter how small the potential is; this is in sharp contrast with the free situation in which the interface height diverges logarithmically in the thermodynamic limit.     

DNA liquid crystalline blue phases. Electron microscopy evidence and biological implications

The isotropic-liquid crystalline transition of concentrated DNA solutions is investigated using freeze-fracture electron microscopy in order to understand the first steps of the DNA condensation process. Between the isotropic liquid and the cholesteric mesophase, we report the existence of double twist DNA bundles and describe their long range ordering into 3D networks. This organization corresponds to the formation of 'blue phases' already observed in thermotropic liquid crystals, but never reported in lyotropic systems. In addition, the size of the DNA molecule, about ten times that of most thermotropic materials, allows here the molecular resolution imaging of blue phase structures. Since such structures recall chromatin organization of some Procaryotes and lower Eucaryotes, we suspect that they may be widespread and of potential interest in the regulation of chromatin functions.