Paradoxical effects of the topoisomerase inhibitor, ethoxidine, in the cellular processes leading to angiogenesis on EaHy.926 endothelial cells

Topoisomerase I generates transient single-stranded breaks in DNA and have the capacity to fragment the genome. Thus, this enzyme is the target for some of the most successful anticancer drugs. Ethoxidine, a benzo[c]phenanthridines derivative, was identified as a potent inhibitor of topoisomerase I. As angiogenesis is a critical step in tumorigenesis, this study was designed to test the potential effect of ethoxidine on different processes leading to neovascularisation on EaHy endothelial cells including adhesion, migration and proliferation. Ethoxidine was tested at two concentrations, 100 μM and 10 μM . VEGF (20 ng/mL) was used as control. Adherent cells were evaluated using crystal violet staining, migration using a model of wound healing. Proliferation was analyzed using CyQUANT Cell Proliferation Assay Kit. Both O2- and NO productions were assessed using electronic paramagnetic resonance technique. All the effects of ethoxidine were evaluated at 24 h treatment. Low concentration of ethoxidine promoted migration to the same extent as that produced by VEGF whereas high concentration inhibited this process. Ethoxidine significantly enhanced adhesion at similar level than VEGF at low concentration. It was without effect at high concentration. Although ethoxidine had no effect at low concentration, it significantly reduced cell proliferation at high concentration. At any concentration tested, ethoxidine did not modify basal O2- production. Interestingly, ethoxidine significantly increase NO production at low concentration but it was without effect at high concentration. As control experiment, VEGF enhanced Eahy cells NO production under the same experimental conditions. Altogether, the present study highlights paradoxical effects of ethoxidine depending on the concentration used. At low concentration, it promotes both Eahy cells migration and adhesion without any effect on proliferation. Importantly, these effects were associated with an increase of NO production. In contrast at high concentration, ethoxidine reduced Eahy cells migration and proliferation but had no effect neither on adhesion nor NO release. Of note is the fact that ethoxidine did not alter endothelial cells oxidative stress at any concentration tested. Thus, these data underscore the potential anti-tumoral property of ethoxidine at high concentration and endothelial cells in the present study. The property of ethoxidine in inhibiting proliferation in both cell type probably account for its high antitumor activity

Upper bound on the density of Ruelle resonances for Anosov flows

Using a semiclassical approach we show that the spectrum of a smooth Anosov vector field V on a compact manifold is discrete (in suitable anisotropic Sobolev spaces) and then we provide an upper bound for the density of eigenvalues of the operator (-i)V, called Ruelle resonances, close to the real axis and for large real parts.Comment: 57 page

Electron microprobe monazite geochronology : a tool for evaluating magmatic ages with examples from Variscan Massif Central migmatites and granotoids, France.

U–Th–Pb dating of monazite with the electron probe microanalyser (EPMA) is increasingly documented as a reliable geochronological method offering high spatial resolution. This method has been applied on monazite from the Cévennes migmatites and granitoids from the southeast of the French Massif Central. Measurements were performed on separated grains after systematic back-scattered electron (BSE) imaging. Monazites from migmatites record two main ages: (i) a protolith age of about 550–543 Ma obtained on inherited cores, and (ii) a migmatization event between 329 ± 5 and 323 ± 3 Ma recorded by monazite rims and all other monogenetic grains. Monazite from the peraluminous Rocles pluton yields a 318 ± 3 Ma age. Finally, three granite dykes are dated at 333 ± 6, 318 ± 5 and 311 ± 5 Ma; the older dyke is the most deformed of them and is interpreted as linked to the migmatization event; the two other dykes are geochronologically, petrologically and structurally coeval with the Rocles pluton. The data constrain the timing of crustal melting following Variscan thickening in the northern Cévennes area. Migmatization of Ordovician protoliths took place at 329–323 Ma and was shortly followed by intrusion of leucogranite at 318–311 Ma. The study shows that EPMA dating of monazite can be successfully used to resolve a close succession of regional melting events

Betatron emission as a diagnostic for injection and acceleration mechanisms in laser-plasma accelerators

Betatron x-ray emission in laser-plasma accelerators is a promising compact source that may be an alternative to conventional x-ray sources, based on large scale machines. In addition to its potential as a source, precise measurements of betatron emission can reveal crucial information about relativistic laser-plasma interaction. We show that the emission length and the position of the x-ray emission can be obtained by placing an aperture mask close to the source, and by measuring the beam profile of the betatron x-ray radiation far from the aperture mask. The position of the x-ray emission gives information on plasma wave breaking and hence on the laser non-linear propagation. Moreover, the measurement of the longitudinal extension helps one to determine whether the acceleration is limited by pump depletion or dephasing effects. In the case of multiple injections, it is used to retrieve unambiguously the position in the plasma of each injection. This technique is also used to study how, in a capillary discharge, the variations of the delay between the discharge and the laser pulse affect the interaction. The study reveals that, for a delay appropriate for laser guiding, the x-ray emission only occurs in the second half of the capillary: no electrons are injected and accelerated in the first half.Comment: 8 pages, 6 figures. arXiv admin note: text overlap with arXiv:1104.245

Toward 3D reconstruction of outdoor scenes using an MMW radar and a monocular vision sensor

International audienceIn this paper, we introduce a geometric method for 3D reconstruction of the exterior environment using a panoramic microwave radar and a camera. We rely on the complementarity of these two sensors considering the robustness to the environmental conditions and depth detection ability of the radar, on the one hand, and the high spatial resolution of a vision sensor, on the other. Firstly, geometric modeling of each sensor and of the entire system is presented. Secondly, we address the global calibration problem, which consists of finding the exact transformation between the sensors' coordinate systems. Two implementation methods are proposed and compared, based on the optimization of a non-linear criterion obtained from a set of radar-to-image target correspondences. Unlike existing methods, no special configuration of the 3D points is required for calibration. This makes the methods flexible and easy to use by a non-expert operator. Finally, we present a very simple, yet robust 3D reconstruction method based on the sensors' geometry. This method enables one to reconstruct observed features in 3D using one acquisition (static sensor), which is not always met in the state of the art for outdoor scene reconstruction.The proposed methods have been validated with synthetic and real data

Zeeman slowers made simple with permanent magnets in a Halbach configuration

We describe a simple Zeeman slower design using permanent magnets. Contrary to common wire-wound setups no electric power and water cooling are required. In addition, the whole system can be assembled and disassembled at will. The magnetic field is however transverse to the atomic motion and an extra repumper laser is necessary. A Halbach configuration of the magnets produces a high quality magnetic field and no further adjustment is needed. After optimization of the laser parameters, the apparatus produces an intense beam of slow and cold 87Rb atoms. With a typical flux of 1 - 5 \times 10^10 atoms/s at 30 ms^-1, our apparatus efficiently loads a large magneto-optical trap with more than 10^10 atoms in one second, which is an ideal starting point for degenerate quantum gases experiments.Comment: 8+6 pages (article + appendices: calculation details, probe and oven description, pictures), 18 figures, supplementary material (movie, Mathematica programs and technical drawings

Quantisations of piecewise affine maps on the torus and their quantum limits

For general quantum systems the semiclassical behaviour of eigenfunctions in relation to the ergodic properties of the underlying classical system is quite difficult to understand. The Wignerfunctions of eigenstates converge weakly to invariant measures of the classical system, the so called quantum limits, and one would like to understand which invariant measures can occur that way, thereby classifying the semiclassical behaviour of eigenfunctions. We introduce a class of maps on the torus for whose quantisations we can understand the set of quantum limits in great detail. In particular we can construct examples of ergodic maps which have singular ergodic measures as quantum limits, and examples of non-ergodic maps where arbitrary convex combinations of absolutely continuous ergodic measures can occur as quantum limits. The maps we quantise are obtained by cutting and stacking