WWP2 ubiquitin ligase and its isoforms: New biological insight and promising disease targets

A number of recent papers on the WWP2 E3 ubiquitin ligase and two novel WWP2 isoforms have revealed important biological insight and disease-specific functions, and also impacted on our understanding of ubiquitin ligases in cell cycle regulation, apoptosis and differentiation. Gene knockout studies suggest a developmental role for WWP2 in chondrogenesis via mechanisms involving cartilage-specific transcription factors. Furthermore, WWP2 isoforms have been shown to selectively target oncogenic signaling pathways linked to both the pTEN tumour suppressor and the TGFß/Smad signaling pathway. Here, it is suggested that WWP2 isoforms have now emerged as central physiological regulators as well as promising new disease targets, and that the challenge ahead is to now develop highly selective WWP2 inhibitors with utility in cartilage disease such as osteoarthritis and as new anticancer strategies

Studying edge geometry in transiently turbulent shear flows

In linearly stable shear flows at moderate Re, turbulence spontaneously decays despite the existence of a codimension-one manifold, termed the edge of chaos, which separates decaying perturbations from those triggering turbulence. We statistically analyse the decay in plane Couette flow, quantify the breaking of self-sustaining feedback loops and demonstrate the existence of a whole continuum of possible decay paths. Drawing parallels with low-dimensional models and monitoring the location of the edge relative to decaying trajectories we provide evidence, that the edge of chaos separates state space not globally. It is instead wrapped around the turbulence generating structures and not an independent dynamical structure but part of the chaotic saddle. Thereby, decaying trajectories need not cross the edge, but circumnavigate it while unwrapping from the turbulent saddle.Comment: 11 pages, 6 figure

Universal continuous transition to turbulence in a planar shear flow

We examine the onset of turbulence in Waleffe flow -- the planar shear flow between stress-free boundaries driven by a sinusoidal body force. By truncating the wall-normal representation to four modes, we are able to simulate system sizes an order of magnitude larger than any previously simulated, and thereby to attack the question of universality for a planar shear flow. We demonstrate that the equilibrium turbulence fraction increases continuously from zero above a critical Reynolds number and that statistics of the turbulent structures exhibit the power-law scalings of the (2+1)-D directed percolation universality class

Turbulent-laminar patterns in shear flows without walls

Turbulent-laminar intermittency, typically in the form of bands and spots, is a ubiquitous feature of the route to turbulence in wall-bounded shear flows. Here we study the idealised shear between stress-free boundaries driven by a sinusoidal body force and demonstrate quantitative agreement between turbulence in this flow and that found in the interior of plane Couette flow -- the region excluding the boundary layers. Exploiting the absence of boundary layers, we construct a model flow that uses only four Fourier modes in the shear direction and yet robustly captures the range of spatiotemporal phenomena observed in transition, from spot growth to turbulent bands and uniform turbulence. The model substantially reduces the cost of simulating intermittent turbulent structures while maintaining the essential physics and a direct connection to the Navier-Stokes equations. We demonstrate the generic nature of this process by introducing stress-free equivalent flows for plane Poiseuille and pipe flows which again capture the turbulent-laminar structures seen in transition.Comment: 13 pages, 9 figure

An investigation into the relationships between the geomagnetic field, cosmic rays and trapped particles by means of the earth satellite Ariel 1

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COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses X. Modeling based on high-precision astrometry of a sample of 25 lensed quasars: consequences for ellipticity, shear, and astrometric anomalies

(abridged) Gravitationally lensed quasars can be used as powerful cosmological and astrophysical probes. We can (i) infer the Hubble constant based on the time-delay technique, (ii) unveil substructures along the l.o.s. toward distant galaxies, and (iii) compare the shape and the slope of baryons and dark matter distributions in galaxies. To reach these goals, we need high-accuracy astrometry and morphology measurements of the lens. In this work, we first present new astrometry for 11 lenses with measured time delays. Using MCS deconvolution on NIC2 HST images, we reached an astrometric accuracy of about 1-2.5 mas and an accurate shape measurement of the lens galaxy. Second, we combined these measurements with those of 14 other systems to present new mass models of these lenses. This led to the following results: 1) In 4 double-image quasars, we show that the influence of the lens environment on the time delay can easily be quantified and modeled, hence putting these lenses with high priority for time-delay determination. 2) For quadruple-image quasars, the difficulty often encountered in reproducing the image positions to milli-arcsec accuracy (astrometric anomaly) is overcome by explicitly including the nearest visible galaxy in the model. However, one anomalous system (J1131-1231) does not show any luminous perturber in its vicinity, and three others (WFI2026-4536, WFI2033-4723, and B2045+265) have problematic modeling. These 4 systems are the best candidates for a pertubation by a dark matter substructure. 3) We find a significant correlation between the PA of the light and of the mass distributions in lensing galaxies. In contrast with other studies, we find that the ellipticity of the light and of the mass also correlate well, suggesting that the overall spatial distribution of matter is not very different from the baryon distribution in the inner \sim 5 kpc of lensing galaxies.Comment: Accepted for publication in Astronomy and Astrophysics abridged abstrac

A comparative study of the NCATE Standards and the Virginia Licensure Regulations for School Personnel with the perceptions of elementary principals and teachers

The purpose of this study was to compare the National Council for the Accreditation of Teacher Education (NCATE) 2000 Standards for Elementary Preparation and the Virginia Licensure Regulations for Elementary Personnel (1998) with the perceptions of principals and teachers in the elementary schools in Chesterfield County, Virginia. The methodology incorporated an exploratory design using qualitative data collection and analyses of surveys of school-based personnel, as well as the NCATE standards and Virginia Licensure Regulations. Specifically, themes were identified through a series of reductions of the terms and phrases contained within the documents and surveys.;The results of this study identified similarities and differences between the perceptions of the school-based individuals and the documents analyzed. Among others, some significant themes that emerged were knowledge of content and pedagogy, assessment, personal and professional skills, and authentic experiences