Measurement of the polarization parameter in π−p\pi^{-}p backward elastic scattering at 6 GeV/c

The polarization parameter in pi /sup -/p elastic scattering has been measured in the backward angular region at an incident momentum of 6 GeV/c. The measurements cover the range of four momentum transfer u=0 to -1(GeV/c)/sup 2/, and were obtained with a high intensity pion beam, a butanol polarized proton target, and arrays of scintillation counter hodoscopes. The polarization is different from zero, in contradiction to the prediction of the naive one trajectory Regge- exchange model. It increases positively with the four-momentum transfer u, reaching a maximum of about 0.4 at u approximately=-0.3(Ge V/c)/sup 2/. It then decreases and becomes slightly negative beyond u approximately=-0.5(GeV/c)/sup 2/. A variety of baryon exchange models are briefly reviewed and none are found to be in complete agreement with all the experimental data

Influence of single and binary doping of strontium and lithium on in vivo biological properties of bioactive glass scaffolds

Effects of strontium and lithium ion doping on the biological properties of bioactive glass (BAG) porous scaffolds have been checked in vitro and in vivo. BAG scaffolds were prepared by conventional glass melting route and subsequently, scaffolds were produced by evaporation of fugitive pore formers. After thorough physico-chemical and in vitro cell characterization, scaffolds were used for pre-clinical study. Soft and hard tissue formation in a rabbit femoral defect model after 2 and 4 months, were assessed using different tools. Histological observations showed excellent osseous tissue formation in Sr and Li + Sr scaffolds and moderate bone regeneration in Li scaffolds. Fluorochrome labeling studies showed wide regions of new bone formation in Sr and Li + Sr doped samples as compared to Li doped samples. SEM revealed abundant collagenous network and minimal or no interfacial gap between bone and implant in Sr and Li + Sr doped samples compared to Li doped samples. Micro CT of Li + Sr samples showed highest degree of peripheral cancellous tissue formation on periphery and cortical tissues inside implanted samples and vascularity among four compositions. Our findings suggest that addition of Sr and/or Li alters physico-chemical properties of BAG and promotes early stage in vivo osseointegration and bone remodeling that may offer new insight in bone tissue engineering

Diffusion protons-protons à 155 MeV. Section efficace différentielle entre 30° et 110° C. M.

The differential cross-section in p-p scattering at 155 MeV has been measured in a preliminary experiment between 30° and 110° C. M., using three methods : CH2-C difference ; detection of both scattered and recoil protons ; analyses of pulse height spectra of scattered particles. The results are about 10 % lower than those of Harwell and Harvard groups.La section efficace différentielle de diffusion p-p à 155 MeV a été mesurée préliminairement entre 30° et 110° dans le système du centre de masse, en utilisant trois méthodes : différence polythène-carbone ; détection simultanée des protons diffusés et des protons de recul ; analyse des spectres d'énergie des protons diffusés sur le polythène et le carbone. Les valeurs obtenues sont d'environ 10 % inférieures à celles données par les groupes de Harwell et Harvard

Diffusion protons-protons à 155 Mev

Measurements of the proton-proton differential scattering cross-section at 155 MeV have been made within the angular range 8°-90° C. M., using a liquid hydrogen target ; results are consistant with our previous measurements made with a CH2 target between 30°-110° C. M.La section efficace différentielle de diffusion p-p à 155 MeV a été mesurée en utilisant une cible à hydrogène liquide, entre 8° et 90° CM. Nos résultats se recoupent.avec ceux que nous avons obtenus précédemment entre 30° et 110° CM en utilisant une cible de polythène

Crosstalk between tyrosine kinase receptors, GSK3 and BMP2 signaling during osteoblastic differentiation of human mesenchymal stem cells

International audienceBone morphogenic proteins (BMPs) promote mesenchymal stem cell (MSC) osteogenic differentiation, whereas platelet derived growth factor (PDGF) and fibroblast growth factor (FGF) activate their proliferation through receptors tyrosine kinase (RTK). The effects of PDGF or FGF receptor signaling pathway on BMP2-induced osteoblastic differentiation was investigated in human MSC (HMSC). Inhibition of PDGF or/and FGF receptors enhanced BMP2-induced alkaline phosphatase (ALP) activity, expression of Osterix, ALP and Bone sialoprotein, and matrix calcification. These effects were associated with increased Smad-1 activity, indicating that mitogenic factors interfere with Smad signaling in HMSC differentiation. RTK activate MAPK and inhibit GSK3 through the PI3K/Akt pathway. Biochemical analysis indicated that MAPK JNK and GSK3 especially are potential signaling molecules regulating BMP-induced osteoblastic HMSC differentiation. These observations highlight that the osteogenic effects of BMP2 are modulated by mitogenic factors acting through RTK

Mesure des paramètres P et D dans la diffusion p.p à 138 MeV

Polarized protons from the Orsay S. C. (E = 138 MeV; P 1= 0.44) have been scattere don a liquid hydrogen target in the angular range θ2 = 12° —100° (CM) and the value of P2 deduced from experimental asymmetries. The polarization component 2.n normal to the second scattering plane is then observed by horizontal subsequent scattering on a plastic scintillator, the left-right asymmetries giving the depolarisation parameters D at four angles. Results at large angles are in agreement with YLAM solution of the Yale group.Le faisceau de protons polarisés du Synchrocyclotron d'Orsay (E = 138 MeV ; P1 = 0,44) a été diffusé sur une cible d'hydrogène liquide. L'asymétrie gauche-droite des protons diffusés a été mesurée dans l'intervalle 12° — 100° (CM) et la valeur de P2 déduite. La composante des spin 2.n du faisceau diffusé a été mesurée grâce à une troisième diffusion sur cible CH, les asymétries observées permettent le calcul de D. Les valeurs expérimentales aux grands angles confirment les prédictions de la solution YLAM du groupe de Yale