Laboratory validation of the dual-zone phase mask coronagraph in broadband light at the high-contrast imaging THD-testbed

Specific high contrast imaging instruments are mandatory to characterize circumstellar disks and exoplanets around nearby stars. Coronagraphs are commonly used in these facilities to reject the diffracted light of an observed star and enable the direct imaging and spectroscopy of its circumstellar environment. One important property of the coronagraph is to be able to work in broadband light. Among several proposed coronagraphs, the dual-zone phase mask coronagraph is a promising solution for starlight rejection in broadband light. In this paper, we perform the first validation of this concept in laboratory. First, we recall the principle of the dual-zone phase mask coronagraph. Then, we describe the high-contrast imaging THD testbed, the manufacturing of the components and the quality-control procedures. Finally, we study the sensitivity of our coronagraph to low-order aberrations (inner working angle and defocus) and estimate its contrast performance. Our experimental broadband light results are compared with numerical simulations to check agreement with the performance predictions. With the manufactured prototype and using a dark hole technique based on the self-coherent camera, we obtain contrast levels down to $2\,10^{-8}$ between 5 and 17$\,\lambda_0/D$ in monochromatic light (640 nm). We also reach contrast levels of $4\,10^{-8}$ between 7 and 17$\lambda_0/D$ in broadband ($\lambda_0=675$ nm, $\Delta\lambda=250$ nm and $\Delta\lambda / \lambda_0 = 40$ %), which demonstrates the excellent chromatic performance of the dual-zone phase mask coronagraph. The performance reached by the dual-zone phase mask coronagraph is promising for future high-contrast imaging instruments that aim at detecting and spectrally characterizing old or light gaseous planets.Comment: 9 pages, 16 figure

Influence d’une co-construction de rationnement amélioré sur les performances d’embouche ovine paysanne dans la commune rurale de Korsimoro au Burkina Faso

L’étude vise l’amélioration des performances d’embouche ovine dans la commune rurale de Korsimoro. Quatre vingt douze (92) béliers de 22 femmes et de 24 hommes de cette commune ont été étudiés. L’équipe de recherche a défini quatre (4) formules de ration sur la base d’un seul profil nutritionnel apportant 98 g MAD (matières azotées digestibles) et 0,80 UF/kg MS. Les producteurs ont analysé ces formules et ont porté leur choix sur celle composée de 15% de tourteau de coton, 6% de son de blé, 31% de graines de coton et 48% de gousses de Piliostigma reticulatum. Cette ration a été distribuée à deux lots d’animaux en comparaison avec les pratiques locales : lot1=aliment composé introduit+fourrages locaux et lot2=aliment composé introduit+fourrages locaux+bloc multinutritionnel. Les GMQ des animaux du lot 2 ont été significativement (P< 0,05) plus élevés que ceux des animaux du lot 1. La croissance des animaux soumis sous rationnement amélioré (75 g/j) a été très significativement (P< 0,01) plus élevée que celle enregistrée des pratiques paysannes (environ 46 g/j). Une marge bénéficiaire moyenne de 9 173 F CFA a été dégagée par ovin embouché. Les résultats de l’étude suggèrent la nécessité d’améliorer le dispositif organisationnel des emboucheurs.Mots clés : Embouche ovine, gain moyen quotidien, Burkina Faso, bloc multinutritionnel, plateforme d’innovation

Periodically modulated geometric and electronic structure of graphene on Ru(0001)

We report here on a method to fabricate and characterize highly perfect, periodically rippled graphene monolayers and islands, epitaxially grown on single crystal metallic substrates under controlled UHV conditions. The periodicity of the ripples is dictated by the difference in lattice parameters of graphene and substrate, and, thus, it is adjustable. We characterize its perfection at the atomic scale by means of STM and determine its electronic structure in the real space by local tunnelling spectroscopy. There are periodic variations in the geometric and electronic structure of the graphene monolayer. We observe inhomogeneities in the charge distribution, i.e a larger occupied Density Of States at the higher parts of the ripples. Periodically rippled graphene might represent the physical realization of an ordered array of coupled graphene quantum dots. The data show, however, that for rippled graphene on Ru(0001) both the low and the high parts of the ripples are metallic. The fabrication of periodically rippled graphene layers with controllable characteristic length and different bonding interactions with the substrate will allow a systematic experimental test of this fundamental problem.Comment: 12 pages. Contribution to the topical issue on graphene of Semiconductor Science and Technolog

Etude de l’effet de la date de semis et de l’age des plantules au repiquage sur le rendement de trois varietes de riz adoptees dans les perimetres irrigues villageois des regions de Tombouctou et de Gao

Les périmètres irrigués villageois (PIV) sont utilisés pour atténuer les effets néfastes des changements climatiques. Les variétés cultivées dans les PIV sont d’origine asiatique et souffrent des conditions agro climatiques des régions nord du Mali. Les expérimentations ont été conduites en milieu paysan dans les PIV de Tombouctou et de Gao afin de sélectionner des variétés ayant les caractéristiques désirables des producteurs. Sept paysans ont été sélectionnés par site pour la conduite des tests. Trois variétés de riz WARDA Sahel (WAS) et la variété Nionoka (témoin) ont été testées. Le dispositif expérimental utilisé était le factoriel en blocs dispersés avec comme facteur principal variétés et facteurs secondaires date de semis et l’âge des plantules au repiquage. La collecte des données a porté sur la variable rendement. Le logiciel GENSTAT version 4.0 a été utilisé pour l’analyse des données. Le test de Student-Newman-Keuls au seuil de 5% a été utilisé pour la séparation des moyennes à l’aide du logiciel SPSS version 17.0. Sur l’ensemble des sites, la variété SUTURA a enregistré le bon rendement. La période propice de semis des pépinières des trois variétés est la première quinzaine du mois de juillet. L’âge limite de repiquage des plantules est de 30 jours.Mots clés : Périmètre Irrigué Villageois (PIV), Variétés de riz, Rendement, Date de semis et Age des plantules au repiquag

Comportement des dromadaires adultes sur paturages sahelien et subhumide en station au Mali: 1. Description des principales activites

No Abstrac

Review of high-contrast imaging systems for current and future ground- and space-based telescopes I. Coronagraph design methods and optical performance metrics

The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this first installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of design methods and optical performance metrics developed for coronagraph instruments. The design and optimization of coronagraphs for future telescopes has progressed rapidly over the past several years in the context of space mission studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based telescopes. Design tools have been developed at several institutions to optimize a variety of coronagraph mask types. We aim to give a broad overview of the approaches used, examples of their utility, and provide the optimization tools to the community. Though it is clear that the basic function of coronagraphs is to suppress starlight while maintaining light from off-axis sources, our community lacks a general set of standard performance metrics that apply to both detecting and characterizing exoplanets. The attendees of the OOC workshop agreed that it would benefit our community to clearly define quantities for comparing the performance of coronagraph designs and systems. Therefore, we also present a set of metrics that may be applied to theoretical designs, testbeds, and deployed instruments. We show how these quantities may be used to easily relate the basic properties of the optical instrument to the detection significance of the given point source in the presence of realistic noise.Comment: To appear in Proceedings of the SPIE, vol. 1069

From Fe3O4/NiO bilayers to NiFe2O4-like thin films through Ni interdiffusion

Ferrites with (inverse) spinel structure display a large variety of electronic and magnetic properties, making some of them interesting for potential applications in spintronics. We investigate the thermally induced interdiffusion of Ni$^{2+}$ ions out of NiO into Fe$_3$O$_4$ ultrathin films, resulting in off-stoichiometric nickel ferrite–like thin layers. We synthesized epitaxial Fe$_3$O$_4$ bilayers on Nb-doped SrTiO$_3$(001) substrates by means of reactive molecular beam epitaxy. Subsequently, we performed an annealing cycle comprising three steps at temperatures of 400$^\circ$C, 600$^\circ$C, and 800$^\circ$C under an oxygen background atmosphere. We studied the changes of the chemical and electronic properties as result of each annealing step with help of hard x-ray photoelectron spectroscopy and found a rather homogeneous distribution of Ni and Fe cations throughout the entire film after the overall annealing cycle. For one sample we observed a cationic distribution close to that of the spinel ferrite NiFe$_2$O$_4$. Further evidence comes from low-energy electron diffraction patterns indicating a spinel-type structure at the surface after annealing. Site- and element-specific hysteresis loops performed by x-ray magnetic circular dichroism uncovered the antiferrimagnetic alignment between the octahedral coordinated Ni$^{2+}$ and Fe$^{3+}$ ions and the Fe$^{3+}$ ion in tetrahedral coordination. We find a quite low coercive field of 0.02 T, indicating a rather low defect concentration within the thin ferrite films

The Ubiquitin-Like Protein PLIC-1 or Ubiquilin 1 Inhibits TLR3-Trif Signaling

Background: The innate immune responses to virus infection are initiated by either Toll-like receptors (TLR3/7/8/9) or cytoplasmic double-stranded RNA (dsRNA)-recognizing RNA helicases RIG-I and MDA5. To avoid causing injury to the host, these signaling pathways must be switched off in time by negative regulators. Methodology/Principal Findings: Through yeast-two hybrid screening, we found that an ubiquitin-like protein named protein linking integrin-associated protein to cytoskeleton 1(PLIC-1 or Ubiquilin 1) interacted with the Toll/interleukin-1 receptor (TIR) domain of TLR4. Interestingly, PLIC-1 had modest effect on TLR4-mediated signaling, but strongly suppressed the transcriptional activation of IFN-β promoter through the TLR3-Trif-dependent pathway. Concomitantly, reduction of endogenous PLIC-1 by short-hairpin interfering RNA (shRNA) enhanced TLR3 activation both in luciferase reporter assays as well as in new castle disease virus (NDV) infected cells. An interaction between PLIC-1 and Trif was confirmed in co-immunoprecipitation (Co-IP) and GST-pull-down assays. Subsequent confocal microscopic analysis revealed that PLIC-1 and Trif colocalized with the autophagosome marker LC3 in punctate subcellular structures. Finally, overexpression of PLIC-1 decreased Trif protein abundance in a Nocodazole-sensitive manner. Conclusions: Our results suggest that PLIC-1 is a novel inhibitor of the TLR3-Trif antiviral pathway by reducing the abundance of Trif. © 2011 Biswas et al

Acceptability and efficacy of intra-rectal quinine alkaloids as a pre-transfer treatment of non-per os malaria in peripheral health care facilities in Mopti, Mali

<p>Abstract</p> <p>Background</p> <p>The acceptability and efficacy of a new kit with a new formulation of quinine alkaloids designed for the intra-rectal administration in the treatment of non-per os malaria was assessed in the peripheral health care system of Mopti, Mali.</p> <p>Methods</p> <p>A single-arm trial was conducted from August 2003 to January 2004. An initial dose of diluted quinine alkaloids (20 mg/kg Quinimax^®) was administered by the intra-rectal route to children with presumptive non per-os malaria at six peripheral heath care centres. The children were then referred to two referral hospitals where standard inpatient care including intravenous route were routinely provided. A malaria thick smear was done at inclusion and a second malaria thick smear after arrival at the referral facility, where a more complete clinical examination and laboratory testing was done to confirm diagnosis. Confirmed cases of severe malaria or others diseases were treated according to national treatment guidelines. Cases of non per-os malaria received a second dose of intra rectal quinine alkaloids. Primary outcome was acceptability of the intra rectal route by children and their parents as well as the ease to handle the kit by health care workers.</p> <p>Results</p> <p>The study included 134 children with a median age of 33 months and 53.7% were male. Most of the children (67%) and 92% of parents or guardians readily accepted the intra-rectal route; 84% of health care workers found the kit easy to use. At the peripheral health care centres, 32% of children had a coma score ≤ 3 and this was reduced to 10% at the referral hospital, following one dose of intra-rectal quinine alkaloids (IRQA). The mean time to availability of oral route treatment was 1.8 ± 1.1 days. Overall, 73% of cases were confirmed severe malaria and for those the case fatality rate was 7.2%.</p> <p>Conclusion</p> <p>IRQA was well accepted by children, their parents/guardians and by the health workers at peripheral health facilities in Mopti, Mali. There was also a quick recovery from deep coma and a reduced case fatality rate in severe malaria.</p