Mean Field Dynamos with Algebraic and Dynamic alpha-Quenchings

Calculations for mean field dynamo models (in both full spheres and spherical shells), with both algebraic and dynamic $\alpha$--quenchings, show qualitative as well as quantitative differences and similarities in the dynamical behaviour of these models. We summarise and enhance recent results with extra examples. Overall, the effect of using a dynamic $\alpha$ appears to be complicated and is affected by the region of parameter space examined.Comment: 6 pages, 2 postscript figures, also available at http://www.maths.qmw.ac.uk/~eo

Dynamo models and differential rotation in late-type rapidly rotating stars

Increasing evidence is becoming available about not only the surface differential rotation of rapidly rotating cool stars but, in a small number of cases, also about temporal variations, which possibly are analogous to the solar torsional oscillations. Given the present difficulties in resolving the precise nature of such variations, due to both the short length and poor resolution of the available data, theoretical input is vital to help assess the modes of behaviour that might be expected, and will facilitate interpretation of the observations. Here we take a first step in this direction by studying the variations in the convection zones of such stars, using a two dimensional axisymmetric mean field dynamo model operating in a spherical shell in which the only nonlinearity is the action of the azimuthal component of the Lorentz force of the dynamo generated magnetic field on the stellar angular velocity. We consider three families of models with different depths of dynamo-active regions. For moderately supercritical dynamo numbers we find torsional oscillations that penetrate all the way down to the bottom of the convection zones, similar to the case of the Sun. For larger dynamo numbers we find fragmentation in some cases and sometimes there are other dynamical modes of behaviour, including quasi-periodicity and chaos. We find that the largest deviations in the angular velocity distribution caused by the Lorentz force are of the order of few percent, implying that the original assumed `background' rotation field is not strongly distorted.Comment: Astronomy and Astrophysics, in pres

Erratum to: Mechano-Transduction Signals Derived from Self-Assembling Peptide Nanofibers Containing Long Motif of Laminin Influence Neurogenesis in In-Vitro and In-Vivo (Mol Neurobiol, 10.1007/s12035-016-9836-z)

Astroglial scaring and limited neurogenesis are two problematic issues in recovery of spinal cord injury (SCI). In the meantime, it seems that mechanical manipulations of scaffold to inhibit astroglial scarring and improve neurogenesis is worthy of value. In the present investigation, the effect of nanofiber (gel) concentration as a mechanical-stimuli in neurogenesis was investigated. Cell viability, membrane damage, and neural differentiation derived from endometrial stem cells encapsulated into self-assembling peptide nanofiber containing long motif of laminin were assessed. Then, two of their concentrations that had no significant difference of neural differentiation potential were selected for motor neuron investigation in SCI model of rat. MTT assay data showed that nanofibers at the concentrations of 0.125 and 0.25 % w/v induced higher and less cell viability than others, respectively, while cell viability derived from higher concentrations of 0.25 % w/v had ascending trend. Gene expression results showed that noggin along with laminin motif over-expressed TH gene and the absence of noggin or laminin motif did not in all concentrations. Bcl2 over-expression is concomitant with the decrease of nanofiber stiffness, NF+ cells increment, and astrogenesis inhibition and dark neuron decrement in SCI model. It seems that stiffness affects on Bcl2 gene expression and may through β-Catenin/Wnt signaling pathway and BMP-4 inhibition decreases astrogenesis and improves neurogenesis. However, stiffness had a significant effect on upregulation of GFAP+ cells and motor neuron recovery in in vivo. It might be concluded that eventually there is a critical definitive point concentration that at less or higher than of it changes cell behavior and neural differentiation through different molecular pathways

Angiotensin-converting enzyme inhibitors and cytokines in heart failure: dose and effect?∗∗Editorials published in the Journal of the American College of Cardiologyreflect the views of the authors and do not necessarily represent the views of JACCor the American College of Cardiology.

Tyrosine hydroxylase (TH), a rate-limiting step in catecholamine synthesis in which its activity influences Alzheimer disease, Parkinson disease, and IQ of schizophrenia patients, has been studied for a long time. In the meantime, the present investigation assessed the effect of noggin and type of self-assembling nanofibers in TH gene over-expression by neuron-like cells derived from human endometrial-derived stromal cells (hEnSCs). Neuroblastoma cells and hEnSCs encapsulated into nanofibers including Matrigel, (RADA)4, laminin, and BMHP-1 motif bounded to (RADA)4 and their cell viability were studied for 48 h and 18 days in basal and neurogenic media, respectively, in noggin-rich media. Then, expression of neural genes and proteins has been investigated by immunocytochemistry (ICC) and real-time PCR methods, respectively. The results indicated that neuroblastoma cell and hEnSC viability is in good agreement with the level of Bcl2 and β-tubulin III gene expression; however, -BMHP-1 and -laminin nanofibers exhibited significantly higher cell viability eventually through Wnt/β-catenin signaling pathway as compared to others, respectively. The gene expression analysis of nanofibers showed that none of them induced gamma-aminobutyric acid (GABA) gene expression while glial fibrillary acidic protein (GFAP) gene just over-expressed in cells encapsulated into Matrigel with a low level of Bcl2 gene expression. However, the TH gene just had been over-expressed in cells encapsulated into -laminin nanofiber and 2D cell culture. In the absence of noggin with -laminin nanofibers, TH gene expression was suppressed. It might be concluded that although noggin through anti-BMP pathways resulted in GFAP decrement and TH gene increment, the type of scaffold that defined the final fate of cells and -laminin accompaniment might be useful for the recovery of Alzheimer and Parkinson disease patients. © 2016 Springer Science+Business Media New Yor