3,285 research outputs found
Asymptotic solvers for ordinary differential equations with multiple frequencies
We construct asymptotic expansions for ordinary differential equations with highly oscillatory forcing terms, focusing on the case of multiple, non-commensurate frequencies. We derive an asymptotic expansion in inverse powers of the oscillatory parameter and use its truncation as an exceedingly effective means to discretize the differential equation in question. Numerical examples illustrate the effectiveness of the method
Thick films of YSZ electrolytes by dip-coating process
Yttria stabilized zirconia (YSZ, 8% Y2O3) thick films were coated on porous Ni-YSZ substrates using the dip-coating process and a suspension with a new formulation. The
suspension was obtained by addition of a polymeric matrix in a stable suspension of a commercial YSZ (Tosoh) powders dispersed in an azeotropic MEK-EtOH mixture. The green layers were densified after an optimization of the suspension composition. YSZ Tosoh particles encapsulated by a zirconium alkoxide sol and added with colloidal alkoxide
precursor are used to load the suspension. The in situ growth of these colloids increases significantly the layers density after an appropriated heat treatment. The obtained films are continuous, homogeneous and 20 ÎŒm thick. Different microstructures are obtained depending on the synthesis parameters of the suspension
piRNAs and Aubergine cooperate with Wispy poly(A) polymerase to stabilize mRNAs in the germ plasm
Piwi-interacting RNAs (piRNAs) and PIWI proteins play a crucial role in germ cells by repressing transposable elements and regulating gene expression. In Drosophila, maternal piRNAs are loaded into the embryo mostly bound to the PIWI protein Aubergine (Aub). Aub targets maternal mRNAs through incomplete base-pairing with piRNAs and can induce their destabilization in the somatic part of the embryo. Paradoxically, these Aub-dependent unstable mRNAs encode germ cell determinants that are selectively stabilized in the germ plasm. Here we show that piRNAs and Aub actively protect germ cell mRNAs in the germ plasm. Aub directly interacts with the germline-specific poly(A) polymerase Wispy, thus leading to mRNA polyadenylation and stabilization in the germ plasm. These results reveal a role for piRNAs in mRNA stabilization and identify Aub as an interactor of Wispy for mRNA polyadenylation. They further highlight the role of Aub and piRNAs in embryonic patterning through two opposite functions
On phenomenon of scattering on resonances associated with discretisation of systems with fast rotating phase
Numerical integration of ODEs by standard numerical methods reduces a
continuous time problems to discrete time problems. Discrete time problems have
intrinsic properties that are absent in continuous time problems. As a result,
numerical solution of an ODE may demonstrate dynamical phenomena that are
absent in the original ODE. We show that numerical integration of system with
one fast rotating phase lead to a situation of such kind: numerical solution
demonstrate phenomenon of scattering on resonances that is absent in the
original system.Comment: 10 pages, 5 figure
A micropillar for cavity optomechanics
We present a new micromechanical resonator designed for cavity optomechanics.
We have used a micropillar geometry to obtain a high-frequency mechanical
resonance with a low effective mass and a very high quality factor. We have
coated a 60-m diameter low-loss dielectric mirror on top of the pillar and
are planning to use this micromirror as part of a high-finesse Fabry-Perot
cavity, to laser cool the resonator down to its quantum ground state and to
monitor its quantum position fluctuations by quantum-limited optical
interferometry
Evidence of Brillouin scattering in an ytterbium-doped double-clad fiber laser
We have designed and performed an experiment that permitted direct observation of Brillouin backscattering in an Yb-doped double-clad fiber laser. Fifteen Brillouin-shifted frequencies were observed for the first time to our knowledge. We clearly demonstrate that stimulated Brillouin scattering is directly responsible for both fast transient dynamics of the laser and reduction of the laserâs pulse width
First observation of 55,56Zn
In an experiment at the SISSI/LISE3 facility of GANIL, the most proton-rich
zinc isotopes 55,56Zn have been observed for the first time. The experiment was
performed using a high-intensity 58Ni beam at 74.5 MeV/nucleon impinging on a
nickel target. The identification of 55,56Zn opens the way to 54Zn, a good
candidate for two-proton radioactivity according to theoretical predictions.Comment: 2 pages, 1 figure, accepted for publication in Eur. Phys. J.
- âŠ