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Effect of Wettability on the Agglomeration of Silicon Nanowire Arrays Fabricated by Metal-Assisted Chemical Etching
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A meta-approach for improving the prediction and the functional annotation of ortholog groups
No full textInternational audienceBackground: In comparative genomics, orthologs are used to transfer annotation from genes already characterized to newly sequenced genomes. Many methods have been developed for finding orthologs in sets of genomes. However, the application of different methods on the same proteome set can lead to distinct orthology predictions. Methods: We developed a method based on a meta-approach that is able to combine the results of several methods for orthologous group prediction. The purpose of this method is to produce better quality results by using the overlapping results obtained from several individual orthologous gene prediction procedures. Our method proceeds in two steps. The first aims to construct seeds for groups of orthologous genes; these seeds correspond to the exact overlaps between the results of all or several methods. In the second step, these seed groups are expanded by using HMM profiles. Results: We evaluated our method on two standard reference benchmarks, OrthoBench and Orthology Benchmark Service. Our method presents a higher level of accurately predicted groups than the individual input methods of orthologous group prediction. Moreover, our method increases the number of annotated orthologous pairs without decreasing the annotation quality compared to twelve state-of-the-art methods. Conclusions: The meta-approach based method appears to be a reliable procedure for predicting orthologous groups. Since a large number of methods for predicting groups of orthologous genes exist, it is quite conceivable to apply this meta-approach to several combinations of different methods
High repetition rate Yb:CaF2 multipass amplifiers operating in the 100 mJ range
No full textInternational audience— We present the research advances on the development of 50-200 mJ energy range diode-pumped Yb:CaF 2-based multipass amplifiers operating at relatively high repetition rates. These laser amplifiers are based on diverse innovative geometries. All these innovations aim to design compact, stable and reliable amplifiers adapted to our application that consists in pumping ultrashort-pulse OPCPA (optical parametric chirped pulse amplifier) systems in the frame of the Apollon 10 PW laser project. The targeted repetition rate is in the range of 20-100 Hz with energies of few tens of mJ for the first stages up to 1 J for the final stage. An analysis of the specificities of Yb:CaF 2 is done to explain the different options we chose to fulfil these specifications. The critical points and limitations of the multipass Yb:CaF 2-based amplifiers are subsequently discussed. To overcome the encountered problems, different issues are investigated such as crystal optimisation, laser head geometry, thermo-optical dynamics or coherent combining techniques. Experimental results for different multipass configurations are demonstrated and discussed
Improved numerical integration for locking treatment in isogeometric structural elements, Part I: Beams
No full textInternational audienceA general mathematical framework is proposed, in this paper, to define new quadrature rules in the context of BB-spline/NURBS-based isogeometric analysis. High order continuity across the elements within a patch turned out to have higher accuracy than C0C0 finite elements, as well as a better time efficiency. Unfortunately, a maximum regularity accentuates the shear and membrane locking in thick structural elements. The improved selective reduced integration schemes are given for uni-dimensional beam problems, with basis functions of order two and three, and can be easily extended to higher orders. The resulting BB-spline/NURBS finite elements are free from membrane and transverse shear locking. Moreover, no zero energy modes are generated. The performance of the approach is evaluated on the classical test of a cantilever beam subjected to a distributed moment, and compared to Lagrange under-integrated finite elements
Signed tree associahedra
No full textInternational audienceAn associahedron is a polytope whose vertices correspond to the triangulations of a convex polygon and whose edges correspond to flips between them. J.-L. Loday gave a particularly elegant realization of the associahedron, which was then generalized in two directions: on the one hand to obtain realizations of graph associahedra, and on the other hand to obtain multiple realizations of the associahedron parametrized by a sequence of signs. The goal of this paper is to unify and extend these two constructions to signed tree associahedra.Un associaèdre est un polytope dont les sommets correspondent aux triangulations d’un polygone convexe et dont les arêtes correspondent aux flips entre ces triangulations. J.-L. Loday a donné une construction particulièrement élégante de l’associaèdre qui a été généralisée dans deux directions : d’une part pour obtenir des réalisations des associaèdres de graphes, et d’autre part pour obtenir de multiples réalisations de l’associaèdre paramétrées par une suite de signes. L’objectif de ce travail est d’unifier et d’étendre ces constructions aux associaèdres d’arbres signés
Femtosecond laser ablation with high angle Bessel and Bessel vortex beams
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Laser wakefield accelerator based light sources: potential applications and requirements
No full textInternational audienceIn this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, x-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser–plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications
Physics of landau resonances, cyclotron resonances and current generation
No full textInternational audienceIrreversible energy and momentum transfer from waves to particles for tokamak confinement, heating, and control is based on Landau and cyclotron resonances. Above a stochasticity threshold, these interactions can be viewed as a random walk in energy (action) space within the random phase approximation. We present and discuss the quasi-linear theory describing this random walk with a particular emphasis on the interplay between the dynamical picture (electromagnetic forces) and the statistical description (photons emission/absorption). Landau and cyclotron absorptions in tokamaks are thus derived, and the classical theory of current generation in tokamaks is presented in local and nonlocal regimes