Stability analysis of agegraphic dark energy in Brans-Dicke cosmology

Stability analysis of agegraphic dark energy in Brans-Dicke theory is presented in this paper. We constrain the model parameters with the observational data and thus the results become broadly consistent with those expected from experiment. Stability analysis of the model without best fitting shows that universe may begin from an unstable state passing a saddle point and finally become stable in future. However, with the best fitted model, There is no saddle intermediate state. The agegraphic dark energy in the model by itself exhibits a phantom behavior. However, contribution of cold dark matter on the effective energy density modifies the state of teh universe from phantom phase to quintessence one. The statefinder diagnosis also indicates that the universe leaves an unstable state in the past, passes the LCDM state and finally approaches the sable state in future.Comment: 15 pages, 12 figure

On the anomalous large-scale flows in the Universe

Recent combined analyses of the CMB and galaxy cluster data reveal unexpectedly large and anisotropic peculiar velocity fields at large scales. We study cosmic models with included vorticity, acceleration and total angular momentum of the Universe in order to understand the phenomenon. The Zeldovich model is used to mimic the low redshift evolution of the angular momentum. Solving coupled evolution equations of the second kind for density-contrast in corrected Ellis-Bruni covariant and gauge-invariant formalism one can properly normalize and evaluate integrated Sachs-Wolfe effect and peculiar velocity field. The theoretical results compared to the observations favor a much larger matter content of the Universe than that of the concordance model. Large-scale flows appear anisotropic with dominant components placed in the plane perpendicular to the axis of vorticity(rotation). The integrated Sachs-Wolfe term has negative contribution to the CMB fluctuations for the negative cosmological constant and it can explain the observed small power of the CMB TT spectrum at large scales. The rate of the expansion of the Universe can be substantially affected by the angular momentum if its magnitude is large enough.Comment: 13 pages, 6 tables, 4 figures, 36 references; version to appear in Eur. Phys. J.

shRNA-Mediated Decreases in c-Met Levels Affect the Differentiation Potential of Human Mesenchymal Stem Cells and Reduce Their Capacity for Tissue Repair

Mesenchymal stem cells/marrow stromal cells (MSC) are adult multipotent cells that can augment tissue repair. We previously demonstrated that culturing MSC in hypoxic conditions causes upregulation of the hepatocyte growth factor (HGF) receptor c-Met, allowing them to respond more robustly to HGF. MSC preconditioned in hypoxic environments contributed to restoration of blood flow after an ischemic injury more rapidly than MSC cultured in normoxic conditions. We now investigated the specific role of HGF/c-Met signaling in MSC function. An shRNA-mediated knockdown (KD) of c-Met in MSC did not alter their phenotypic profile, proliferation, or viability in vitro. However, we determined that while HGF/c-Met signaling does not play a role in the adipogenic differentiation of the cells, the disruption of this signaling pathway inhibited the ability of MSC to differentiate into the osteogenic and chondrogenic lineages. We next assessed the impact of c-Met KD on human MSC function in a xenogeneic hindlimb ischemia injury model. A 70% KD of c-Met in MSC resulted in a significant decrease in their capacity to regenerate blood flow to the ischemic limb, as compared to the MSC transduced with control shRNA. MSC with only a 60% KD of c-Met exhibited an intermediate capacity to restore blood flow, suggesting that MSC function is sensitive to the dosage of c-Met signaling. The current study highlights the significance of HGF/c-Met signaling in the capacity of MSC to restore blood flow after an ischemic injury and in their ability to differentiate into the osteogenic and chondrogenic lineages