Subharmonic resonant optical excitation of confined acoustic modes in a free-standing semiconductor membrane at GHz frequencies with a high-repetition-rate femtosecond laser.

We propose subharmonic resonant optical excitation with femtosecond lasers as a new method for the characterization of phononic and nanomechanical systems in the gigahertz to terahertz frequency range. This method is applied for the investigation of confined acoustic modes in a free-standing semiconductor membrane. By tuning the repetition rate of a femtosecond laser through a subharmonic of a mechanical resonance we amplify the mechanical amplitude, directly measure the linewidth with megahertz resolution, infer the lifetime of the coherently excited vibrational states, accurately determine the system's quality factor, and determine the amplitude of the mechanical motion with femtometer resolution.

[Myelosclerosis : pseudo-tumors forms (author's transl)]. / Formes pseudo-tumorales des myéloscléroses.

Signs of pseudo-tumor growth may be seen in myelosclerosis. Eight personal cases and a review of the literature are discussed in this article. The observations here reported cover pseudo-tumors occurring in ganglia, liver, suprarenals (3), abdomen and pancreas. They are classified as sclerotic haemopoietic tumors. This category has particular characteristics when compared to extra-medullary haemopoiesis, extra-medullary haemopoietic growths, and a fourth category, sarcoma-type malignant tumors in myelosclerosis. The identity of these last three entities is widely discussed in the literature. The main histological and cytological characteristics for pseudo-tumor diagnosis in myelosclerosis are reported here.

[Comparative study of A, B, and H substances in stromas with and without lipid removal. Studies of the erythrocyte membrane]. / Recherche comparative des substances de groups A, B, H, dans les stromas délipidés et non délipidés. Etudes de la membrane érythrocytaire

Human erythrocyte membranes were prepared by hypotonic hemolysis and extracted with water pH 7, EDTA and mercapto-ethanol solutions pH 8. The complex residue which contains lipids, proteins and the A, B, H antigens was dissolved in SDS and analysed by preparative acrylamide gel electrophoresis in the presence of SDS. Each fraction was assayed for A, B or H blood-group activity by hemagglutination inhibition tests. Two experiments were done for each blood-group A, B, O. One with entire ghosts, another after extraction of the ghosts residue with a mixture of chloroform-methanol. The comparison of results showed that the distribution of proteins and blood-group antigen activity among the different fractions is not modified and that, in the two experiments, the elution of H substance is delayed by comparison with elution of A and B substances. The blood-group A, B and H antigens are known to be glycosphingolipids and are not entirely eliminated by treatment of the ghosts with cloroform and methanol. It has recently been reported [7] that these antigens are complex glycosphingolipids with hydrophilic character and remain in the aqueous phase after extraction of the erythrocyte membrane with organic solvents.