Variation around a Pyramid theme: optical recombination and optimal use of photons

We propose a new type of Wave Front Sensor (WFS) derived from the Pyramid WFS (PWFS). This new WFS, called the Flattened Pyramid-WFS (FPWFS), has a reduced Pyramid angle in order to optically overlap the four pupil images into an unique intensity. This map is then used to derive the phase information. In this letter this new WFS is compared to three existing WFSs, namely the PWFS, the Modulated PWFS (MPWFS) and the Zernike WFS (ZWFS) following tests about sensitivity, linearity range and low photon flux behavior. The FPWFS turns out to be more linear than a modulated pyramid for the high-spatial order aberrations but it provides an improved sensitivity compared to the non-modulated pyramid. The noise propagation may even be as low as the ZWFS for some given radial orders. Furthermore, the pixel arrangement being more efficient than for the PWFS, the FPWFS seems particularly well suited for high-contrast applications.Comment: 4 pages, 4 figures, accepted for publication in Optics Letters - Version corrected for affiliation

Is Law an Economic Contest? French Reactions to the Doing Business World Bank Reports and Economic Analysis of the Law

The economic analysis of law has provoked strong reactions among French academics, in particular since 2004 when the first of the Doing Business reports was published. French jurists have joined forces to expose the methodological limits inherent to these reports, which rated France a long way behind other legal systems allegedly more able to facilitate business. In its first part, this article examines the various reactions to these reports, almost all of which were published in French only. In the second part, the focus is on the position of economic analysis in French law, its role, and, in particular, the impact of the Law and Economics school on comparative law in France. It also takes a look at the studies that followed, especially the legal origins thesis. The article shows that the various approaches are complementary and that economic analysis, without supplanting the traditional comparative approach, has considerable use. At a time when the globalization of business relationships is leading more than ever to a competition between the various national laws, comparatists should include more of this dimension into their field of study. Comparatists can also take a cue from economists on how to improve the relevance and the influence of their research in the public debate

Ion exchange membranes based upon crosslinked sulfonated polyethersulfone for electrochemical applications

Synthesis and characterization of new ion exchange membranes made from chlorosulfonated polyethersul- fone (SO2Cl-PES) crosslinked by polyaminated crosslinking reagents have been performed. Two examples are described: one crosslinked by hexane diamine, the other by amino-polyethersulfone (NH2-PES). Sulfonated polyether sulfone (S-PES) and NH2-PES have similar chemical structures that allow compatibility. Surpris- ingly enough, better results were obtained using amino-polyethersulfone. The best results have been obtained using SO2Cl-PES with 1.3 SO2Cl group per monomer unit crosslinked by 0.2 equivalent of NH2-PES. The membranes, less brittle than pristine SPES and insoluble in solvents such as DMAc, were characterized by TGA, DMA, DSC, ionic conductivity, transport numbers, and water swelling. The results showed that these membranes presented very promising performances for use in Proton Exchange Membrane Fuel Cells

Identifying USPs regulating immune signals in Drosophila: USP2 deubiquitinates Imd and promotes its degradation by interacting with the proteasome.

International audienceBACKGROUND: Rapid activation of innate immune defences upon microbial infection depends on the evolutionary conserved NF-κB dependent signals which deregulation is frequently associated with chronic inflammation and oncogenesis. These signals are tightly regulated by the linkage of different kinds of ubiquitin moieties on proteins that modify either their activity or their stability. To investigate how ubiquitin specific proteases (USPs) orchestrate immune signal regulation, we created and screened a focused RNA interference library on Drosophila NF-κB-like pathways Toll and Imd in cultured S2 cells, and further analysed the function of selected genes in vivo. RESULTS: We report here that USP2 and USP34/Puf, in addition to the previously described USP36/Scny, prevent inappropriate activation of Imd-dependent immune signal in unchallenged conditions. Moreover, USP34 is also necessary to prevent constitutive activation of the Toll pathway. However, while USP2 also prevents excessive Imd-dependent signalling in vivo, USP34 shows differential requirement depending on NF-κB target genes, in response to fly infection by either Gram-positive or Gram-negative bacteria. We further show that USP2 prevents the constitutive activation of signalling by promoting Imd proteasomal degradation. Indeed, the homeostasis of the Imd scaffolding molecule is tightly regulated by the linkage of lysine 48-linked ubiquitin chains (K48) acting as a tag for its proteasomal degradation. This process is necessary to prevent constitutive activation of Imd pathway in vivo and is inhibited in response to infection. The control of Imd homeostasis by USP2 is associated with the hydrolysis of Imd linked K48-ubiquitin chains and the synergistic binding of USP2 and Imd to the proteasome, as evidenced by both mass-spectrometry analysis of USP2 partners and by co-immunoprecipitation experiments. CONCLUSION: Our work identified one known (USP36) and two new (USP2, USP34) ubiquitin specific proteases regulating Imd or Toll dependent immune signalling in Drosophila. It further highlights the ubiquitin dependent control of Imd homeostasis and shows a new activity for USP2 at the proteasome allowing for Imd degradation. This study provides original information for the better understanding of the strong implication of USP2 in pathological processes in humans, including cancerogenesis