Unsteady Pressure and Velocity Measurements in 5x5 Rods Bundle Using Grids With and Without Mixing Vanes (full text)

International audienc

Arrest of mammalian fibroblasts in G1 in response to actin inhibition is dependent on retinoblastoma pocket proteins but not on p53

p53 and the retinoblastoma (RB) pocket proteins are central to the control of progression through the G1 phase of the cell cycle. The RB pocket protein family is downstream of p53 and controls S-phase entry. Disruption of actin assembly arrests nontransformed mammalian fibroblasts in G1. We show that this arrest requires intact RB pocket protein function, but surprisingly does not require p53. Thus, mammalian fibroblasts with normal pocket protein function reversibly arrest in G1 on exposure to actin inhibitors regardless of their p53 status. By contrast, pocket protein triple knockout mouse embryo fibroblasts and T antigen–transformed rat embryo fibroblasts lacking both p53 and RB pocket protein function do not arrest in G1. Fibroblasts are very sensitive to actin inhibition in G1 and arrest at drug concentrations that do not affect cell adhesion or cell cleavage. Interestingly, G1 arrest is accompanied by inhibition of surface ruffling and by induction of NF2/merlin. The combination of failure of G1 control and of tetraploid checkpoint control can cause RB pocket protein–suppressed cells to rapidly become aneuploid and die after exposure to actin inhibitors, whereas pocket protein–competent cells are spared. Our results thus establish that RB pocket proteins can be uniquely targeted for tumor chemotherapy

Electronic transport through carbon nanotubes -- effects of structural deformation and tube chirality

Atomistic simulations using a combination of classical forcefield and Density-Functional-Theory (DFT) show that carbon atoms remain essentially sp2 coordinated in either bent tubes or tubes pushed by an atomically sharp AFM tip. Subsequent Green's-function-based transport calculations reveal that for armchair tubes there is no significant drop in conductance, while for zigzag tubes the conductance can drop by several orders of magnitude in AFM-pushed tubes. The effect can be attributed to simple stretching of the tube under tip deformation, which opens up an energy gap at the Fermi surface.Comment: To appear in Physical Review Letter

Repeated cleavage failure does not establish centrosome amplification in untransformed human cells

Transient cleavage failure in dividing cells is not sufficient to establish stable populations of cells with extra centrosomes

Attachment of HeLa cells during early G1 phase

Both growth factor directed and integrin dependent signal transduction were shown to take place directly after completion of mitosis. The local activation of these signal transduction cascades was investigated in early G1 cells. Interestingly, various key signal transduction proteins were found in blebs at the cell membrane within 30 min after mitosis. These membrane blebs appeared in round, mitotic-like cells and disappeared rapidly during spreading of the cells in G1 phase. In addition to tyrosine-phosphorylated proteins, the blebs contained also phosphorylated FAK and phosphorylated MAP kinase. The formation of membrane blebs in round, mitotic cells before cell spreading is not specific for mitotic cells, because similar features were observed in trypsinized cells. Just before cell spreading also these cells exhibited membrane blebs containing active signal transduction proteins. Inhibition of signal transduction did not affect membrane bleb formation, suggesting that the membrane blebs were formed independent of signal transduction

Cytosquelette & cycle cellulaire (étude des conséquences de la perturbation du cytosquelette sur les mécanismes de contrôle de G1 et l'intégrité cellulaire)

GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Thermalisme et tourisme : les évolutions récentes en France

Threatened by a possible withdrawal of the french National Health Service support, facing a decline in the number of patients in the 90% spa resorts are evoling towards new forms of thermal therapy combined with the promotion of good wealth and well-being. As spa resorts are trying to promote this renewed kind of health tourism, local tourism itself uses the spa to lure tourist.Menacées par une éventuelle rupture du lien avec la Sécurité Sociale, confrontées pendant les années 90 à une baisse de la fréquentation, les stations thermales évoluent vers un thermalisme nouveau, orienté vers le bien- être. Cette promotion d'un tourisme de santé rénové va de pair avec la récupération du patrimoine thermal par le tourisme local.Lohez Marc. Thermalisme et tourisme : les évolutions récentes en France. In: L'information géographique, volume 64, n°4, 2000. pp. 314-321

Structure électronique des surfaces (110) des semiconducteurs de type zinc-blende par une méthode de liaisons fortes

The electronic structure of the (110) surface of zinc-blende crystals is studied in a simple tight-binding model. By comparison with the results obtained by the Green's function method it is shown that a good approximation to the bound states energy levels can be obtained by diagonalizing the hamiltonian in a few planes near the surface. This process, owing to its simplicity, can easily be extended to more realistic models including further interactions and self-consistency effects. Finally it is shown that, in this model, the results can be interpreted in terms of Phillips' ionicity.On étudie dans un modèle simple de liaisons fortes la structure électronique des surfaces (110) des cristaux du type de la blende. Comparant avec les résultats obtenus par la méthode des fonctions de Green, on montre qu'il est possible de déterminer de façon satisfaisante les énergies des états liés en diagonalisant l'hamiltonien dans les plans les plus voisins de la surface. Ce procédé, par sa simplicité, semble susceptible d'extension à des modèles plus élaborés, incluant des interactions plus lointaines ainsi que les effets de self-consistence. On montre enfin que dans le modèle utilisé, les résultats peuvent s'interpréter simplement en fonction de l'ionicité de Phillips