Monorail/Foxa2 regulates floorplate differentiation and specification of oligodendrocytes, serotonergic raphe neurones and cranial motoneurones

In this study, we elucidate the roles of the winged-helix transcription factor Foxa2 in ventral CNS development in zebrafish. Through cloning of monorail (mol), which we find encodes the transcription factor Foxa2, and phenotypic analysis of mol(-/-) embryos, we show that floorplate is induced in the absence of Foxa2 function but fails to further differentiate. In mol(-/-) mutants, expression of Foxa and Hh family genes is not maintained in floorplate cells and lateral expansion of the floorplate fails to occur. Our results suggest that this is due to defects both in the regulation of Hh activity in medial floorplate cells as well as cell-autonomous requirements for Foxa2 in the prospective laterally positioned floorplate cells themselves. Foxa2 is also required for induction and/or patterning of several distinct cell types in the ventral CNS. Serotonergic neurones of the raphe nucleus and the trochlear motor nucleus are absent in mol(-/-) embryos, and oculomotor and facial motoneurones ectopically occupy ventral CNS midline positions in the midbrain and hindbrain. There is also a severe reduction of prospective oligodendrocytes in the midbrain and hindbrain. Finally, in the absence of Foxa2, at least two likely Hh pathway target genes are ectopically expressed in more dorsal regions of the midbrain and hindbrain ventricular neuroepithelium, raising the possibility that Foxa2 activity may normally be required to limit the range of action of secreted Hh proteins

Land Use Patterns and the Scale of Adoption of Agroforestry in the Rural Landscapes of Padma Floodplain in Bangladesh

This research was conducted in six typical villages of Northern Bangladesh. A sample of 170 farmers was selected. Research indicates that the farmers practising agroforestry own small farms and the income of agroforestry helps them to reduce their poverty, maintain their socio-economic needs and sustain their livelihoods. Agroforestry is not a new concept in the study area. The people have been practicing agroforestry traditionally in the form of home gardens, hedgerows and alley cropping. Homestead agroforestry is an age old practice. Alley cropping and hedgerow agroforestry systems are comparatively new. Yet alley cropping is now most popular and is widely accepted in the study area because of its socio-economic advantages and environmental sustainability

Plural valuation of nature for equity and sustainability: Insights from the Global South

Plural valuation is about eliciting the diverse values of nature articulated by different stakeholders in order to inform decision making and thus achieve more equitable and sustainable outcomes. We explore what approaches align with plural valuation on the ground, as well as how different social-ecological contexts play a role in translating plural valuation into decisions and outcomes. Based on a co-constructed analytical approach relying on empirical information from ten cases from the Global South, we find that plural valuation contributes to equitable and sustainable outcomes if the valuation process: 1) is based on participatory value elicitation approaches; 2) is framed with a clear action-oriented purpose; 3) provides space for marginalized stakeholders to articulate their values in ways that can be included in decisions; 4) is used as a tool to identify and help reconcile different cognitive models about human-nature relations; and 5) fosters open communication and collaboration among stakeholders. We also find that power asymmetries can hinder plural valuation. As interest and support for undertaking plural valuation grows, a deeper understanding is needed regarding how it can be adapted to different purposes, approaches, and social-ecological contexts in order to contribute to social equity and sustainability

Modelling the Impact of World Bank Policy-Based Lending: The Case of Malawi's Agricultural Sector

This article uses a multi-market agricultural pricing model to analyse the impact of the World Bank's three structural adjustment loans (SALs) to Malawi on the smallholder agricultural sector. Three price policy scenarios are simulated on the model representing zero, partial and full compliance with the Bank's SAL price policy conditionality. These scenarios are analysed in terms of their impact on: the government budget; smallholder real incomes; maize production; exportable cash crop production; and the balance of payments. Critiques of the Bank's programme and the government and Bank bargaining strategies are assessed in the light of the modelling results.

On the Resolution of Critical Flow Regions in Inviscid Linear And Nonlinear Instability Calculations

Numerical methods for tackling the inviscid instability problem are discussed. Convergence is demon- strated to be a necessary, but not a sufficient condition for accuracy. Inviscid flow physics set requirements regarding grid-point distribution in order for physically accurate results to be obtained. These requirements are relevant to the viscous problem also and are shown to be related to the resolution of the critical layers. In this respect, high-resolution nonlinear calculations based on the inviscid initial-boundary-value problem are presented for a model shear-layer flow, aiming at identification of the regions that require attention in the course of high-Reynolds-number viscous calculations. The results bear a remarkable resemblance with those pertinent to viscous flow, with a cascade of high-shear regions being shed towards the vortex-core centre as time progresses. In parallel, numerical instability related to the finite-time singularity of the nonlinear equations solved globally contaminates and eventually destroys the simulations, irrespective of resolution

A multi-level spectral deferred correction method

The spectral deferred correction (SDC) method is an iterative scheme for computing a higher-order collocation solution to an ODE by performing a series of correction sweeps using a low-order timestepping method. This paper examines a variation of SDC for the temporal integration of PDEs called multi-level spectral deferred corrections (MLSDC), where sweeps are performed on a hierarchy of levels and an FAS correction term, as in nonlinear multigrid methods, couples solutions on different levels. Three different strategies to reduce the computational cost of correction sweeps on the coarser levels are examined: reducing the degrees of freedom, reducing the order of the spatial discretization, and reducing the accuracy when solving linear systems arising in implicit temporal integration. Several numerical examples demonstrate the effect of multi-level coarsening on the convergence and cost of SDC integration. In particular, MLSDC can provide significant savings in compute time compared to SDC for a three-dimensional problem

A Very High-Order Accurate Staggered Finite Volume Scheme for the Stationary Incompressible Navier–Stokes and Euler Equations on Unstructured Meshes

International audienceWe propose a sixth-order staggered finite volume scheme based on polynomial reconstructions to achieve high accurate numerical solutions for the incompressible Navier-Stokes and Euler equations. The scheme is equipped with a fixed-point algorithm with solution relaxation to speed-up the convergence and reduce the computation time. Numerical tests are provided to assess the effectiveness of the method to achieve up to sixth-order con-2 Ricardo Costa et al. vergence rates. Simulations for the benchmark lid-driven cavity problem are also provided to highlight the benefit of the proposed high-order scheme

Contribution of Germline Mutations in the RAD51B, RAD51C, and RAD51D Genes to Ovarian Cancer in the Population

PURPOSE: The aim of this study was to estimate the contribution of deleterious mutations in the RAD51B, RAD51C, and RAD51D genes to invasive epithelial ovarian cancer (EOC) in the population and in a screening trial of individuals at high risk of ovarian cancer. PATIENTS AND METHODS: The coding sequence and splice site boundaries of the three RAD51 genes were sequenced and analyzed in germline DNA from a case-control study of 3,429 patients with invasive EOC and 2,772 controls as well as in 2,000 unaffected women who were BRCA1/BRCA2 negative from the United Kingdom Familial Ovarian Cancer Screening Study (UK_FOCSS) after quality-control analysis. RESULTS: In the case-control study, we identified predicted deleterious mutations in 28 EOC cases (0.82%) compared with three controls (0.11%; P < .001). Mutations in EOC cases were more frequent in RAD51C (14 occurrences, 0.41%) and RAD51D (12 occurrences, 0.35%) than in RAD51B (two occurrences, 0.06%). RAD51C mutations were associated with an odds ratio of 5.2 (95% CI, 1.1 to 24; P = .035), and RAD51D mutations conferred an odds ratio of 12 (95% CI, 1.5 to 90; P = .019). We identified 13 RAD51 mutations (0.65%) in unaffected UK_FOCSS participants (RAD51C, n = 7; RAD51D, n = 5; and RAD51B, n = 1), which was a significantly greater rate than in controls (P < .001); furthermore, RAD51 mutation carriers were more likely than noncarriers to have a family history of ovarian cancer (P < .001). CONCLUSION: These results confirm that RAD51C and RAD51D are moderate ovarian cancer susceptibility genes and suggest that they confer levels of risk of EOC that may warrant their use alongside BRCA1 and BRCA2 in routine clinical genetic testing

Impact of improved maize varieties on food security in Eastern Zambia : A doubly robust analysis

This study investigates the impact of improved maize varieties on household food security in eastern Zambia using household survey data from a sample of over 800 rural households. Since treatment effect estimates are often prone to misspecification in either the treatment or outcome equation, we use the doubly robust inverse probability weighted regression adjustment method, complemented with propensity score matching on six different food security measures to obtain reliable impact estimates. Generally, we find a positive impact of improved maize adoption on food security across the two econometric approaches. Maize being the most important food staple in Zambia has a great bearing on the food security status of farm households. It is therefore imperative that a conducive environment is created that promotes the adoption of maize yield improving technologies.</p