Remarks on stability of the rotating shallow water vortices in the frontal dynamics regime

Stability properties of large-scale strongly nonlinear isolated vortices in the rotating shallow water on the f-plane are analysed. Working first in the framework of the balanced frontal dynamics equations we demonstrate that vortices of arbitrary sign with monotonous profiles of the free-surface elevation are formally stable and establish criteria for nonlinear stability. We then discuss stability in the framework of the full rotating shallow-water equations and obtain a conditional stability criterion

Nonlinear theory of geostrophic adjustment. Part 2. Two-layer and continuously stratified primitive equations.

International audienceThis paper continues the work started in Part 1 (Reznik, Zeitlin & Ben Jelloul 2001) and generalizes it to the case of a stratified environment. Geostrophic adjustment of localized disturbances is considered in the context of the two-layer shallow-water and continuously stratified primitive equations in the vertically bounded and horizontally infinite domain on the $f$-plane. Using multiple-time-scale perturbation expansions in Rossby number $\hbox{\it Ro}$ we show that stratification does not substantially change the adjustment scenario established in Part 1 and any disturbance of well-defined scale is split in a unique way into slow and fast components with characteristic time scales $f_0^{-1}$ and $(f_0 \hbox{\it Ro})^{-1}$ respectively, where $f_0$ is the Coriolis parameter. As in Part 1 we distinguish two basic dynamical regimes: quasi-geostrophic (QG) and frontal geostrophic (FG) with small and large deviations of the isopycnal surfaces, respectively. We show that the dynamics of the FG regime in the two-layer model depends strongly on the ratio of the layer depths. The difference between QG and FG scenarios of adjustment is demonstrated. In the QG case the fast component of the flow essentially does not ‘feel' the slow one and is rapidly dispersed leaving the slow component to evolve according to the standard QG equation (corrections to this equation are found for times $t\,{\gg}\, (f_0 \hbox{\it Ro})^{-1}$). In the FG case the fast component is a packet of inertial oscillations produced by the initial perturbation. The space-time evolution of the envelope of inertial oscillations obeys a Schrödinger-type modulation equation with coefficients depending on the slow component. In both QG and FG cases we show by direct computations that the fast component does not produce any drag terms in the equations for the slow component; the slow component remains close to the geostrophic balance. However, in the continuously stratified FG regime, as well as in the two-layer regime with the layers of comparable thickness, the splitting is incomplete in the sense that the slow vortical component and the inertial oscillations envelope evolve on the same time scale

Collect more, spend better ? Assessing the incidence of fiscal systems and public spending in three Francophone West African countries

The objective of this study is to analyse and compare the incidence of fiscal systems of three western African countries: Côte d’Ivoire, Mali and Senegal. The analysis relies on different data and tools: (1) individual and household level data from three recent household surveys (EMOP2011, ESPS 2011, ENV 2014), (2) a detailed description of the three fiscal systems, (4) the CEQ conceptual framework, and (4) the OpenFisca platform, an open source tax-benefit calculator parameterized to simulate the fiscal systems of each country. Results indicate that fiscal systems in Mali, Senegal and Côte d’Ivoire have a slightly progressive impact on inequality. This stems from the combination of slightly progressive direct taxes, regressive indirect taxes, and progressive public spending on education. Various features are likely to explain these results: (1) Direct taxes are paid by a very small fraction of the population; (2) Indirect taxes such as VAT and import tariffs affect poorest households more since they consume a higher share of their income; (3) Primary schooling rates are high and poorer households tend to have more children. These results point to some recommendations to enhance the redistributive power of existing systems: expand the reach of direct PIT; reexamine the incidence of exemptions to VAT and import taxes; increase transparency on public spending to maintain Willingness-to-Pay taxes at high levels; improve household survey data quality and promote access to fiscal data

Towards rationalization of crystallization screening for small- to medium-sized academic laboratories: the PACT/JCSG+ strategy.

A crystallization screening process is presented that was developed for a small academic laboratory. Its underlying concept is to combine sparse-matrix screening with systematic screening in a minimum number of crystallization conditions. The sparse-matrix screen is the cherry-picked combination of conditions from the Joint Center for Structural Genomics (JCSG) extended using conditions from other screens. Its aim is to maximize the coverage of crystallization parameter space with no redundancy. The systematic screen, a pH-, anion- and cation-testing (PACT) screen, aims to decouple the components of each condition and to provide information about the protein, even in the absence of crystals, rather than cover a wide crystallization space. This screening strategy is combined with nanolitre-volume dispensing hardware and a small but practical experiment-tracking system. The screens have been tested both at the NKI and in other laboratories and it is concluded that they provide a useful minimal screening strategy

SPINE bioinformatics and data-management aspects of high-throughput structural biology.

SPINE (Structural Proteomics In Europe) was established in 2002 as an integrated research project to develop new methods and technologies for high-throughput structural biology. Development areas were broken down into workpackages and this article gives an overview of ongoing activity in the bioinformatics workpackage. Developments cover target selection, target registration, wet and dry laboratory data management and structure annotation as they pertain to high-throughput studies. Some individual projects and developments are discussed in detail, while those that are covered elsewhere in this issue are treated more briefly. In particular, this overview focuses on the infrastructure of the software that allows the experimentalist to move projects through different areas that are crucial to high-throughput studies, leading to the collation of large data sets which are managed and eventually archived and/or deposited