Current Issues and Regulations in Tendon Regeneration and Musculoskeletal Repair with Mesenchymal Stem Cells

Mesenchymal stem cells are multipotent stromal cells residing within the connective tissue of most organs. Their surface phenotype has been well described. Most commonly, mesenchymal stem cells demonstrate the ability to differentiate into mesenchymal tissues (bone, catailge, fat, etc...), however, under the proper conditions these cells can differentiate into epithelial cells and neuroectoderm derived lineages. Their developmental plasticity also depends on the ability of mesenchymal stem cells to alter the tissue microenvironment by secreting soluble factors, as well as their capacity for differentiation in tissue repair. It is the cell-matrix interaction which defines the tissue characteristics. The molecular and functional heterogeneity of this cell population may confound interpretation of their differentiation potential, but it is this heterogeneity that is believed to provide for their therapeutic efficacy. Stem cell therapies are an attractive therapeutic approach for soft tissues as they offer a vehicle for repair and regeneration at the end of a needle. The early introduction of stem cell treatments into the therapeutic armamentarium involves both commercial and non-commercial multidisciplinary partnerships and has occurred in a climate of regulatory reform, so not all the relevant information resides in the public domain, but early clinical studies have shown promising results. Against this backdrop, novel techniques and early results of a small series of tendon and musculotendinous junction interventions are being published and other ongoing studies are yet to report their results. The issue of ensuring governance of these novel technologies falls upon both the scientific community and the established licensing authorities

Electron transport in quantum wire superlattices

Electronic transport is theoretically investigated in laterally confined semiconductor superlattices using the formalism of non-equilibrium Green's functions. The transport properties are calculated for nanowire superlattices of varying diameters, from the quantum dot superlattice regime to the quantum well superlattice regime. Scattering processes due to electron-phonon couplings, phonon anharmonicity, charged impurities, surface and interface roughness and alloy disorder are included on a microscopic basis. Elastic scattering mechanisms are treated in a partial coherent way beyond the self-consistent Born approximation. The nature of transport along the superlattice is shown to depend dramatically on the lateral dimensionality. In the quantum wire regime, the electron velocity-field characteristics are predicted to deviate strongly from the standard Esaki-Tsu form, with pronounced current peaks due to integer and fractional resonances with optical phonons

New Results from MiniBooNE Charged-Current Quasi-Elastic Anti-Neutrino Data

MiniBooNE anti-neutrino charged-current quasi-elastic (CCQE) data is compared to model predictions. The main background of neutrino-induced events is examined first, where three independent techniques are employed. Results indicate the neutrino flux is consistent with a uniform reduction of $\sim$ 20% relative to the largely uncertain prediction. After background subtraction, the $Q^{2}$ shape of \numub CCQE events is consistent with the model parameter $M_{A}$ = 1.35 GeV determined from MiniBooNE \numu CCQE data, while the normalization is $\sim$ 20% high compared to the same prediction.Comment: 6 pages, 4 figures. Proceedings for the NuInt 2011 conferenc

Contrasting influence of charged impurities on transport and gain in terahertz quantum cascade lasers

Transport and gain properties of a resonant-phonon terahertz quantum cascade laser are calculated using nonequilibrium Green's functions. Impurity scattering is shown to be responsible for contrasting nonlinear effects in the transport and the gain properties. For typical doping concentrations, the current density is found to be weakly sensitive to the impurity scattering strength. In contrast, the calculated gain is found to be very sensitive to the impurity scattering strength. This difference is attributed to the strong momentum dependence of the long-range coupling to charged impurities. Small-momentum impurity scattering is shown to be responsible for an incoherent regime of resonant tunneling processes. These new insights into the crucial role of impurity scattering open a new route of improvement of terahertz quantum cascade lasers by engineering of the doping profile.Comment: 4 pages, 4 figure