Double-resonant fast particle-wave interaction

In future fusion devices fast particles must be well confined in order to transfer their energy to the background plasma. Magnetohydrodynamic instabilities like Toroidal Alfv\'en Eigenmodes or core-localized modes such as Beta Induced Alfv\'en Eigenmodes and Reversed Shear Alfv\'en Eigenmodes, both driven by fast particles, can lead to significant losses. This is observed in many ASDEX Upgrade discharges. The present study applies the drift-kinetic HAGIS code with the aim of understanding the underlying resonance mechanisms, especially in the presence of multiple modes with different frequencies. Of particular interest is the resonant interaction of particles simultaneously with two different modes, referred to as 'double-resonance'. Various mode overlapping scenarios with different q profiles are considered. It is found that, depending on the radial mode distance, double-resonance is able to enhance growth rates as well as mode amplitudes significantly. Surprisingly, no radial mode overlap is necessary for this effect. Quite the contrary is found: small radial mode distances can lead to strong nonlinear mode stabilization of a linearly dominant mode.Comment: 12 pages, 11 figures; Nuclear Fusion 52 (2012

Wnt3a Induces Myofibroblast Differentiation by Upregulating TGF-β Signaling Through SMAD2 in a β-Catenin-Dependent Manner

Growing evidence suggests the Wnt family of secreted glycoproteins and their associated signaling pathways, linked to development, are recapitulated during wound repair and regeneration events. However, the role of the Wnt pathway in such settings remains unclear. In the current study, we treated mouse fibroblasts with 250 ng/mL of recombinant Wnt3a for 72 hours and examined its affect on cell morphology and function. Wnt3a induced a spindle-like morphology in fibroblasts characterized by the increased formation of stress fibres. Wnt3a decreased the proliferation of fibroblasts, but significantly increased cell migration as well as fibroblast-mediated contraction of a collagen lattice. Wnt3a significantly increased the expression of TGF-β and its associated signaling through SMAD2. Consistent with this, we observed significantly increased smooth muscle α-actin expression and incorporation of this contractile protein into stress fibres following Wnt3a treatment. Knockdown of β-catenin using siRNA reversed the Wnt3a-induced smooth muscle α-actin expression, suggesting these changes were dependent on canonical Wnt signaling through β-catenin. Neutralization of TGF-β with a blocking antibody significantly inhibited the Wnt3a-induced smooth muscle α-actin expression, indicating these changes were dependent on the increased TGF-β signaling. Collectively, this data strongly suggests Wnt3a promotes the formation of a myofibroblast-like phenotype in cultured fibroblasts, in part, by upregulating TGF-β signaling through SMAD2 in a β-catenin-dependent mechanism. As myofibroblasts are critical regulators of wound healing responses, these findings may have important implications for our understanding of normal and aberrant injury and repair events

Engineering students\u27 preferred roles: Are they stable, are there gender differences?

Being able to situate oneself in an engineering role is a developmental process. Students may initially have idealized perceptions of a professional role and over time, they make this role more congruent with their own values and goals [1]. In light of this, Higher Education Institutions are being challenged to offer learning experiences and career exploration activities to enable students to clarify their interests, values and competencies in relation to a professional role [2]. This study compared the professional role preferences of more than 700 engineering students at TU Dublin (Ireland) and KU Leuven (Belgium). Professional role preference was measured with PREFER Explore, a personal preference test for engineers. The test aligns students to three professional roles for early career engineers: Product leadership (focus on radical innovation), Operational excellence (focus on process optimization) and Customer intimacy (focus on tailored solutions and customer satisfaction). A comparison was drawn between the role preference of first year students at TU Dublin and KU Leuven to establish if there were significant differences in preference across both universities. The results suggest that the role preference of engineering students does not shift from first to third year. There is also evidence that the PREFER Explore is sensitive to gender differences, with female students showing a greater preference for customer intimacy than males and males showing a greater preference for operational excellence than females at TU Dublin. The data have a number of implications for the labor market in Ireland and Belgium

Dissecting the Red Sequence--II. Star Formation Histories of Early-Type Galaxies Throughout the Fundamental Plane

This analysis uses spectra of ~16,000 nearby SDSS quiescent galaxies to track variations in galaxy star formation histories along and perpendicular to the Fundamental Plane (FP). We sort galaxies by their FP properties (sigma, R_e, and I_e) and construct high S/N mean galaxy spectra that span the breadth and thickness of the FP. From these spectra, we determine mean luminosity-weighted ages, [Fe/H], [Mg/H], and [Mg/Fe] based on single stellar population models using the method described in Graves & Schiavon (2008). In agreement with previous work, the star formation histories of early-type galaxies are found to form a two-parameter family. The major trend is that mean age, [Fe/H], [Mg/H], and [Mg/Fe] all increase with sigma. However, no stellar population property shows any dependence on R_e at fixed sigma, suggesting that sigma and not dynamical mass (M_dyn ~ sigma^2 R_e) is the better predictor of past star formation history. In addition to the main trend with sigma, galaxies also show a range of population properties at fixed sigma that are strongly correlated with surface brightness residuals from the FP, such that higher surface brightness galaxies have younger mean ages, higher [Fe/H], higher [Mg/H], and lower [Mg/Fe] than lower-surface brightness galaxies. These latter trends are a major new constraint on star-formation histories.Comment: 23 pages, 14 figures. Accepted to Ap

Investigation of Intestinal Atresia in a Jersey Sire Family

PEER-REVIEWEDIntestinal atresia is a congenital defect resulting in calf mortality within a few days of birth. This study focuses on two half-sibling Jersey sires who were identified as having a high proportion of their progeny exhibiting atresia from a longitudinal study of 39 dairy herds over an 8 year period. The objective of this study was to investigate the genetic cause of intestinal atresia within this family. Phased high-density genotypes of the two half-sibling sires were used to identify if common haplotypes were inherited by all affected animals. Whether or not the paternal haplotype that was inherited by the affected animal at a given locus deviated from the expectation was tested. A total of 16 SNPs were significantly overrepresented, 14 located in one region on chromosome 14 and the remaining 2 located in one region on chromosome 26