56 research outputs found
Generalized Stable Multivariate Distribution and Anisotropic Dilations
After having closely re-examined the notion of a L\'evy's stable vector, it
is shown that the notion of a stable multivariate distribution is more general
than previously defined. Indeed, a more intrinsic vector definition is obtained
with the help of non isotropic dilations and a related notion of generalized
scale. In this framework, the components of a stable vector may not only have
distinct Levy's stability indices 's, but the latter may depend on its
norm. Indeed, we demonstrate that the Levy's stability index of a vector rather
correspond to a linear application than to a scalar, and we show that the
former should satisfy a simple spectral property
Anomalous Scaling of Structure Functions and Dynamic Constraints on Turbulence Simulations
The connection between anomalous scaling of structure functions
(intermittency) and numerical methods for turbulence simulations is discussed.
It is argued that the computational work for direct numerical simulations (DNS)
of fully developed turbulence increases as , and not as
expected from Kolmogorov's theory, where is a large-scale Reynolds number.
Various relations for the moments of acceleration and velocity derivatives are
derived. An infinite set of exact constraints on dynamically consistent subgrid
models for Large Eddy Simulations (LES) is derived from the Navier-Stokes
equations, and some problems of principle associated with existing LES models
are highlighted.Comment: 18 page
Non-additive effects of mixing hybrid poplar and white spruce on aboveground and soil carbon storage in boreal plantations
International audienc
RMI1 and TOP3 alpha limit meiotic CO formation through their C-terminal domains
At meiosis, hundreds of programmed DNA doublestrand breaks (DSBs) form and are repaired by homologous recombination. From this large number of DSBs, only a subset yields crossovers (COs), with a minimum of one CO per chromosome pair. All DSBs must be repaired and every recombination intermediate must be resolved to avoid subsequent entanglement and chromosome breakage. The conserved BLM-TOP3 alpha-RMI1 (BTR) complex acts on early and late meiotic recombination intermediates to both limit CO outcome and promote chromosome integrity. In Arabidopsis, the BLM homologues RECQ4A and RECQ4B act redundantly to prevent meiotic extra COs, but recombination intermediates are fully resolved in their absence. In contrast, TOP3 alpha is needed for both processes. Here we show through the characterization of specific mutants that RMI1 is a major anti-CO factor, in addition to being essential to prevent chromosome breakage and entanglement. Further, our findings suggest a specific role of the C-terminal domains of RMI1 and TOP3 alpha, that respectively contain an Oligo Binding domain (OB2) and ZINC finger motifs, in preventing extraCO. We propose that these domains of TOP3 alpha and RMI1 define a sub-domain of the BTR complex which is dispensable for the resolution of recombination intermediates but crucial to limit extra-COs
The synthesis of hydroxy-pyrrolizidines and indolizidines from cyclopropenones: towards hyacinthacines, australines and jenamidines
The reaction of cyclic imines (1-pyrrolines and piperideines) with a cyclopropenone leads to pyrrolizidines and indolizidines, respectively, each with a hydroxy group on the carbon atom of the bridgehead. The cyclopropenone functions as an all-carbon 1,3-dipole equivalent towards the cyclic imine in this reaction, and the cyclic imines used include polyhydroxylated systems, thus allowing access to australine, alexine and hyacinthacine type compounds. The pyrrolizidine products contain the core of the jenamidine and bohemamine natural products which are of interest as cell-proliferation inhibitors and cell-cell adhesion inhibitor
Turbulent Inflow Conditions for Large-Eddy-Simulation of Compressible Wall-Bounded Flows
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