Apodization in high-contrast long-slit spectroscopy. Closer, deeper, fainter, cooler

The spectroscopy of faint planetary-mass companions to nearby stars is one of the main challenges that new-generation high-contrast spectro-imagers are going to face. In a previous work we presented a long slit coronagraph (LSC), for which the presence of a slit in the coronagraphic focal plane induces a complex distribution of energy in the Lyot pupil-plane that cannot be easily masked with a binary Lyot stop. To alleviate this concern, we propose to use a pupil apodization to suppress diffraction, creating an apodized long slit coronagraph (ALSC). After describing how the apodization is optimized, we demonstrate its advantages with respect to the CLC in the context of SPHERE/IRDIS long slit spectroscopy (LSS) mode at low-resolution with a 0.12" slit and 0.18" coronagraphic mask. We perform different sets of simulations with and without aberrations, and with and without a slit to demonstrate that the apodization is a more appropriate concept for LSS, at the expense of a significantly reduced throughput (37%) compared to the LSC. Then we perform detailed end-to-end simulations of the LSC and the ALSC that include realistic levels of aberrations to obtain datasets representing 1h of integration time on stars of spectral types A0 to M0 located at 10 pc. We insert spectra of planetary companions at different effective temperatures (Teff) and surface gravities (log g) into the data at angular separations of 0.3" to 1.5" and with contrast ratios from 6 to 18 mag. Using the SD method to subtract the speckles, we show that the ALSC brings a gain in sensitivity of up to 3 mag at 0.3" with respect to the LSC, which leads to a much better spectral extraction below 0.5". In terms of Teff, we demonstrate that at small angular separations the limit with the ALSC is always lower by at least 100K, inducing an increase of sensitivity of a factor up to 1.8 in objects' masses at young ages. [Abridged]Comment: 15 pages, 17 figures. Accepted for publication in A&

Calibration of quasi-static aberrations in exoplanet direct-imaging instruments with a Zernike phase-mask sensor

Context. Several exoplanet direct imaging instruments will soon be in operation. They use an extreme adaptive optics (XAO) system to correct the atmospheric turbulence and provide a highly-corrected beam to a near-infrared (NIR) coronagraph for starlight suppression. The performance of the coronagraph is however limited by the non-common path aberrations (NCPA) due to the differential wavefront errors existing between the visible XAO sensing path and the NIR science path, leading to residual speckles in the coronagraphic image. Aims. Several approaches have been developed in the past few years to accurately calibrate the NCPA, correct the quasi-static speckles and allow the observation of exoplanets at least 1e6 fainter than their host star. We propose an approach based on the Zernike phase-contrast method for the measurements of the NCPA between the optical path seen by the visible XAO wavefront sensor and that seen by the near-IR coronagraph. Methods. This approach uses a focal plane phase mask of size {\lambda}/D, where {\lambda} and D denote the wavelength and the telescope aperture diameter, respectively, to measure the quasi-static aberrations in the upstream pupil plane by encoding them into intensity variations in the downstream pupil image. We develop a rigorous formalism, leading to highly accurate measurement of the NCPA, in a quasi-linear way during the observation. Results. For a static phase map of standard deviation 44 nm rms at {\lambda} = 1.625 {\mu}m (0.026 {\lambda}), we estimate a possible reduction of the chromatic NCPA by a factor ranging from 3 to 10 in the presence of AO residuals compared with the expected performance of a typical current-generation system. This would allow a reduction of the level of quasi-static speckles in the detected images by a factor 10 to 100 hence, correspondingly improving the capacity to observe exoplanets.Comment: 11 pages, 14 figures, A&A accepted, 2nd version after language-editor correction

Micro-Algues De La Mare Et Des Bassins D’arrosage a Port-Bouët (Abidjan, Côte D’ivoire)

Les algues jouent un rôle important dans les chaines trophiques des écosystèmes aquatiques. L'étude a eu pour but, à la fois d'inventorier des peuplements algaux et de déterminer les paramètres physicochimiques du milieu influençant la répartition de ces algues en zone marécageuse à Port-Bouët (Abidjansud, Côte d'Ivoire). Des échantillons d'eau ont été prélevés, mensuellement au niveau de 5 stations, entre septembre 2004 et janvier 2005. L'analyse physico-chimique a montré que ces eaux ont eu des teneurs importantes en silice (SiO2), nutriments (NO3-, NO2-, NH4+, PO43-) et ont recelé d'importantes formes de microalgues. Au total, 105 espèces algales ont été identifiées. Celles-ci ont été réparties en 4 embranchements comme suit : 42, 39, 15 et 4 % Chlorophyta, Euglenophyta, Chrysophyta et de Cyanophyta, respectivement. L'analyse combinée des peuplements phytoplanctoniques, en relation avec les données physico-chimiques de chaque station, a permis d'obtenir 4 groupements phytoplanctoniques.Algae play an important role in trophic chains of aquatic systems. This survey aims to determine both algae community and the physico-chemical characteristics of the media of their distribution. Five water samples were collected monthly from stations located in the swampy areas of Port-Bouët (south of Abidjan, Côte d'Ivoire) between September 2004 and January 2005). The samples were analyzed for physico-chemical and biological characteristics. Results showed that the waters had high silicium (SiO2) and nutrient (NO3-, NO2-, NH4+, PO43-) contents, which resulted in significant algae population, with 105 individuals identified in these media. The taxa were divided into 4 groups as follows : 42, 39, 15 and 4 % of the Chlorophyta, Euglenophyta, Chrysophyta and Cyanophyta, respectively. Canonical Correspondence Analysis of the data revealed 4 main phytoplanktonic groups.Keywords: Micro algae, freshwater algae, swampy area, Port-Bouët, Côte d'Ivoir

Effet du système de production sur l'âge au premier vêlage chez la vache Borgou au Bénin. – Etude rétrospective

Effect of Production Systems on Age at First Calving on Borgou Cow in Benin. -Retrospective Study. Data collected from "Monastère de l'Etoile" in department of Borgou in Benin, were used to evaluate the age at first calving of Borgou cow under two different production systems, i.e., extensive and semi-intensive. Production systems significantly affect age at first calving (p< 0.01): cow represented in the extensive system had a higher age at first calving than those presented in the semi-intensive system

Complications des otites moyennes chroniques

Objectif de l’étude : Rapporter la fréquence des complications des otites moyennes chroniques et présenter notre expérience dans leur prise en charge.Matériel et méthodes : Etude rétrospective concernant la période allant du 1er janvier 2000 au 31 décembre 2009. Les complications ont été réparties en 2 grands groupes : extracrâniennes et intracrâ-niennes.Résultats : 57 patients sur 350 reçus pour OMC ont présenté une complication, soit une fréquence de 18,38 %. Le cholestéatome était le plus grand pourvoyeur de ces complications (84,2%). Dix-neuf patients présentaient plus d’une complication, soit au total 76 cas. Les complications extracrâniennes ont été les plus fréquentes, 63 cas (83%), dominées par la mastoïdite extériorisée profuse (68,3%). Les complications intracrâniennes au nombre de 13 (17%) étaient dominées par la méningite purulente otogène (46,2%). La mastoïdectomie associée à une antibiothérapie à large spectre, occupait une place im-portante dans la prise en charge de ces complications. Elle a été réalisée chez 45 patients (79%). La mortalité a été estimée à 3,5% (2 cas de décès). Un drainage neurochirurgical a été effectué dans 4 cas (8,6 %).Conclusion : Cette étude se caractérise par un taux de complications d’OMC plus élevé que ceux rappor-tés dans la littérature, ainsi que par la prédominance des formes étendues et des associa-tions de complications chez un même patient.Mots clés : Otite moyenne chronique, Complications, Cholestéatome.The objective of this study : was to report the frequency and our experience of management of complications of chronic otitsmedia.Methods : We conducted a retrospective study covering 10 years period (from 1st January 2000 to 31 December 2009). Complications were divided into 2 groups: extracranial and intracranial.Results : Among 350 patients received for chronic otitis media, 57 presented complications, such as a rate of 18.38%. Cholesteatoma was the largest provider of these complications in order of 84.2%. Nineteen (19) patients had more than one complication. So, a total of 76 cases of complications were listed. Subperiostal mastoiditis was the most common findings, 68.3% of the extracranial complications. The intracranial complications, (17%), were domi-nated by otogenic purulent meningitis (46.2%). Radical mastoïdectomy with broad spectrum antibiotics occupied an important place in the management of these complications, performed in 45 patients (79%). Neurosurgical drainage was performed in 4 cases (8.6%). Mortality was estimated at 3.5% (2 deaths).Conclusion : COCM are characterized, in this study, by an elevated rate compared to that reported in the literature, the prevalence of extended forms and associations of complications in the same patient.Keys words : Chronic otitis media, Complications, Cholesteatoma

In situ observation of stress relaxation in epitaxial graphene

Upon cooling, branched line defects develop in epitaxial graphene grown at high temperature on Pt(111) and Ir(111). Using atomically resolved scanning tunneling microscopy we demonstrate that these defects are wrinkles in the graphene layer, i.e. stripes of partially delaminated graphene. With low energy electron microscopy (LEEM) we investigate the wrinkling phenomenon in situ. Upon temperature cycling we observe hysteresis in the appearance and disappearance of the wrinkles. Simultaneously with wrinkle formation a change in bright field imaging intensity of adjacent areas and a shift in the moire spot positions for micro diffraction of such areas takes place. The stress relieved by wrinkle formation results from the mismatch in thermal expansion coefficients of graphene and the substrate. A simple one-dimensional model taking into account the energies related to strain, delamination and bending of graphene is in qualitative agreement with our observations.Comment: Supplementary information: S1: Photo electron emission microscopy and LEEM measurements of rotational domains, STM data of a delaminated bulge around a dislocation. S2: Movie with increasing brightness upon wrinkle formation as in figure 4. v2: Major revision including new experimental dat

Etude des comportements rheologiques des melanges de farine ble/sorgho sans tanins issue de trois nouvelles varietes cultivees au Senegal et mise au point de pains a base de farines composees (ble/sorgho)

Cette étude a été réalisée à partir de différents mélanges de farine sans tannin issus de trois variétés de sorgho (621A, 621B, 622B) et de blé. Ces trois variétés de sorgho ont été homologuées par l’Institut Sénégalais de Recherche Agricole (ISRA). Les paramètres tels que l’indice de Zeleny, le temps de chute de Hagberg et la force boulangère des différents mélanges de farine de blé avec 20 % et 30 % d’incorporation de farine de sorgho ont été déterminées au niveau de l’Unité de Biochimie Industrielle de la faculté Universitaire des Sciences Agronomiques de Gembloux (Belgique). L’étude a montré qu’une substitution de la farine de blé par de la farine de sorgho entraine une diminution de l’indice de Zeleny, de l’activité amylasique, de la force de la farine, de l’extensibilité et une augmentation du temps de chute et de l’équilibre entre la ténacité et l’extensibilité. Des tests de panification à base de farines composées incorporant 20 % des farines issues des différentes variétés de sorgho ont été effectués aussi au niveau de la boulangerie pilote de l’Institut de Technologie Alimentaire de Dakar. Les pains obtenus ont présenté un bon volume, une bonne texture de la mie, de la croute et un bon goût comparable au pain 100 % blé.Mots clés : Sorgho, tannin, variétés, farines composée

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

Construction of an integrated consensus map of the Apple genome based on four mapping populations

An integrated consensus genetic map for apple was constructed on the basis of segregation data from four genetically connected crosses (C1¿=¿Discovery × TN10-8, C2¿=¿Fiesta × Discovery, C3¿=¿Discovery × Prima, C4¿=¿Durello di Forli × Fiesta) with a total of 676 individuals using CarthaGene® software. First, integrated female¿male maps were built for each population using common female¿male simple sequence repeat markers (SSRs). Then, common SSRs over populations were used for the consensus map integration. The integrated consensus map consists of 1,046 markers, of which 159 are SSR markers, distributed over 17 linkage groups reflecting the basic chromosome number of apple. The total length of the integrated consensus map was 1,032 cM with a mean distance between adjacent loci of 1.1 cM. Markers were proportionally distributed over the 17 linkage groups (¿ 2¿=¿16.53, df¿=¿16, p¿=¿0.41). A non-uniform marker distribution was observed within all of the linkage groups (LGs). Clustering of markers at the same position (within a 1-cM window) was observed throughout LGs and consisted predominantly of only two to three linked markers. The four integrated female¿male maps showed a very good colinearity in marker order for their common markers, except for only two (CH01h01, CH05g03) and three (CH05a02z, NZ02b01, Lap-1) markers on LG17 and LG15, respectively. This integrated consensus map provides a framework for performing quantitative trait locus (QTL) detection in a multi-population design and evaluating the genetic background effect on QTL expression