New tool for late stage visualization of Oskar protein in Drosophila melanogaster oocytes

My goal was to look for new factors involved in osk translational control by monitoring Osk::GFP expression and ‘knocking down’ the expression of candidate genes by using RNA interference (RNAi). An expansive collection of transgenic RNAi (TRiP) lines target a large fraction of all Drosophila genes. Knockdown is achieved by crossing a chosen TRiP line to a GAL4 driver (MAT3), which directs TRiP expression in the germline cells of the ovary. To simplify the screen I recombined the MAT3 driver and osk::GFP transgene on to the same chromosome. This allowed me to test each TRiP line with a single cross, with the TRiP transgene from one parent and osk::GFP and MAT3 from the other parent. To make the recombinant I crossed MAT3 and osk::GFP flies, and used a PCR assay to test the progeny of individual candidates for presence of MAT3 and Osk::GFP. To validate the knockdown approach, I crossed the osk::GFP MAT3 recombinant TRiP lines of known regulators of osk mRNA to see if I obtained the same phenotypes as previously observed for mutants of these genes. It was found that these knockdowns show no change in expression of Oskar::GFP protein in TRiP lines of activators and increased expression in TRiP lines of repressors, except for that of hephaestus, which exhibited decreased expression. vasa, which should not have exhibited any change in Osk expression, also appears to have decreased expression. In the future, we plan to use this recombinant in crosses with other TRiP lines of known genes used in osk translational control such as tudor, orb, and bruno. The knockdown of hephaestus, vasa, and aubergine should be reperformed in order to ensure that the results are accurate. In addition, this recombinant can be used in screens to find genes involved in osk expression during late stage oogenesis so that more detailed mechanisms of control in posterior development can be described.Cellular and Molecular Biolog

L'appropriation de la liaison variable en français: quelles différences en perception et en production chez les enfants L1 et les adultes L2?

This article reports on a comparative study of the acquisition of the variable liaison in French as a first (L1) and second – or more – language (L2). Although such a comparison encounters a number of difficulties (e.g. matching learners in terms of language exposure, age and cognitive skills), it allows some differences and similarities between L1 and L2 learners to emerge. This study is based on the analysis of experimental tasks performed by native French-speaking children aged 2 to 6, and by adult Korean learners of French as a Foreign Language. Results show that, for both L1 and L2 learners, the acquisition of categorical liaison precedes variable liaison. However, concerning variable liaison, L2 learners increase the realised variant by decreasing the non-realised variant, while L1 learners augment the production of both variants. Moreover, when L2 learners are matched individually to L1 learners based on the results of a production task, they differ in their perception of variable liaison in a judgment task. We conclude with a discussion in terms of pedagogical implications to L2 learners

Les réactions de directions d’écoles de milieux défavorisés aux caractéristiques des écoles performantes de milieux défavorisés

La littérature scientifique sur la direction d'écoles de milieux défavorisés est peu abondante. Cependant, elle identifie des caractéristiques observées de façon récurrente dans les écoles performantes de milieux défavorisés. Dans le cadre d'un programme de recherche plus vaste visant à comprendre le travail de direction d'école de milieu défavorisé, nous avons utilisé ces caractéristiques afin de connaître les réactions de 45 directions d'écoles primaires de l'île de Montréal à leur égard. Bien que connaissant ces caractéristiques, plusieurs directions ont manifesté leurs réticences à l'effet que, dans les écoles performantes, l'apprentissage constitue la priorité. Nous présentons ici cette recherche effectuée en collaboration avec le Programme de soutien à l'école montréalaise (MELS) et nous discutons les résultats, qui nous surprennent.Scientific literature on the administration of schools in disadvantaged environments is scarce. Nonetheless, it identifies recurrent characteristics observed in schools that perform well in disadvantaged environments. In a broader research program studying the work of school administrators in disadvantaged environments, we used these characteristics to identify the reactions of 45 elementary school directors on the Island of Montréal. Although they knew the characteristics, several directors expressed their reluctance to the fact that leaming is the priority in schools that performed. The research presented here was conducted in collaboration with the Supporting Montréal Schools Program (MELS). We discuss the results, which are of concem to us

High Performance P3M N-body code: CUBEP3M

This paper presents CUBEP3M, a publicly-available high performance cosmological N-body code and describes many utilities and extensions that have been added to the standard package. These include a memory-light runtime SO halo finder, a non-Gaussian initial conditions generator, and a system of unique particle identification. CUBEP3M is fast, its accuracy is tuneable to optimize speed or memory, and has been run on more than 27,000 cores, achieving within a factor of two of ideal weak scaling even at this problem size. The code can be run in an extra-lean mode where the peak memory imprint for large runs is as low as 37 bytes per particles, which is almost two times leaner than other widely used N-body codes. However, load imbalances can increase this requirement by a factor of two, such that fast configurations with all the utilities enabled and load imbalances factored in require between 70 and 120 bytes per particles. CUBEP3M is well designed to study large scales cosmological systems, where imbalances are not too large and adaptive time-stepping not essential. It has already been used for a broad number of science applications that require either large samples of non-linear realizations or very large dark matter N-body simulations, including cosmological reionization, halo formation, baryonic acoustic oscillations, weak lensing or non-Gaussian statistics. We discuss the structure, the accuracy, known systematic effects and the scaling performance of the code and its utilities, when applicable.Comment: 20 pages, 17 figures, added halo profiles, updated to match MNRAS accepted versio

The influence of twin boundaries on the Flux Line Lattice structure in YBaCuO: a study by Small Angle Neutron Scattering

The influence of Twin Boundaries (TB) on the Flux Line Lattice(FLL) structure was investigated by Small Angle Neutron Scattering (SANS). YBaCuO single crystals possessing different TB densities were studied. The SANS experiments show that the TB strongly modify the structure of the FLL. The flux lines meander as soon as the magnetic field makes an angle with the TB direction. According to the value of this angle but also to the ratio of the flux lines density over the TB density, one observes that the FLL exhibits two different unit cells in the plane perpendicular to the magnetic field. One is the classical hexagonal and anisotropic cell while the other is affected by an additional deformation induced by the TB. We discuss a possible relation between this deformation and the increase of the critical current usually observed in heavily twinned samples.Comment: accepted for publication in Phys Rev

Physical measurement of a slow drag of a drag embedment anchor during sea trials

Anchor drag during operation of offshore structures could significantly alter the initial load design characteristics of a mooring system. Hence an estimation of anchor positions during operation is essential to identify whether slow or abrupt anchor motion occurs and might require the redeployment of an anchor. During storm conditions, monitoring of mooring tensions and structure motions at the South West Mooring Test Facility (SWMTF) revealed the slow drift motion of one anchor. This facility is a surface buoy with a three-legged, compliant mooring system designed to investigate mooring system behaviour for Marine Renewable Energy (MRE) devices. This paper presents i) some methods to identify the deployment anchor positions: numerical model, acoustics diver survey, and towed sonar ii) the analyses procedure, and estimations of slow drift anchor motion. The findings indicate that one drag embedment anchor moved slowly during a moderate but prolonged and isolated storm, before embedding again. The work demonstrates that anchor position can be accurately monitored and that anchor motion is not necessarily due to excessive peak loads

On peak mooring loads and the influence of environmental conditions for marine energy converters

Mooring systems are among the most critical sub-systems for floating marine energy converters (MEC). In particular, the occurrence of peak mooring loads on MEC mooring systems must be carefully evaluated in order to ensure a robust and efficient mooring design. This understanding can be gained through long-term field test measurement campaigns, providing mooring and environmental data for a wide range of conditions. This paper draws on mooring tensions and environmental conditions that have been recorded (1) for several months during the demonstration of an MEC device and (2) over a period of 18 months at a mooring test facility. Both systems were installed in a shallow water depth (45 m and 30 m, respectively) using compliant multi-leg catenary mooring systems. A methodology has been developed to detect peak mooring loads and to relate them to the associated sea states for further investigation. Results indicate that peak mooring loads did not occur for the sea states on the external contour line of the measured sea states, but for the sea states inside the scatter diagram. This result is attributed to the short-term variability associated with the maximum mooring load for the given sea state parameters. During the identified sea states, MEC devices may not be in survival mode, and thus, the power take-off (PTO) and ancillary systems may be prone to damage. In addition, repeated high peak loads will significantly contribute to mooring line fatigue. Consequently, considering sea states inside the scatter diagram during the MEC mooring design potentially yields a more cost-effective mooring system. As such, the presented methodology contributes to the continuous development of specific MEC mooring systems.The work described in this publication has received funding from the Technology Strategy Board (TSB), Project Number 100855. The authors would like to acknowledge the support of the South West Regional Development Agency for its support through the Partnership for Research in Marine Renewable Energy (PRIMaRE) institution. They also gratefully acknowledge Fred Olsen for supplying the measurements of mooring loads