Lutte contre les cercosporioses du bananier aux Antilles françaises Banatrace, un système d'information géographique multi-acteurs pour la gestion et la traçabilité des épandages aériens

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIREBanatrace est un système d'information intégrant les tâches de gestion des épandages aériens qui incombent aux opérateurs dans le cadre de la lutte contre la cercosporiose de la banane en Guadeloupe et en Martinique. Cet outil multi-acteurs est l'aboutissement d'un travail d'analyse-conception réalisé par le Cemagref. En combinant une base de données répartie et des fonctions d'information géographique, il répond aux différents besoins de traçabilité imposée par la réglementation récente sur les épandages aériens. Il assure l'interface entre le gestionnaire, les opérateurs aériens, les planteurs, les groupements de producteurs, et l'administration. Au-delà de l'efficacité obtenue dans les taches de gestion, il contribue à améliorer la sécurité des personnes et la protection des cours d'eau et de l'environnement. / " Banatrace " is an information system integrating the European rules and regulations relative to the aerial spraying of pesticide over the banana plantations. It helps to the fight against the cercosporia contamination in the French West Indies. This tool aims to fulfill the information needed by the different parties involved in this process: user manager, planters, aerial treatment companies, planters' cooperatives and administration. It includes DBMS and GIS functionalities in order to program the treatments and to record all events, leading to a better traceability. Moreover carrying out treatment management, it contributes to improve people security and environment protection

The size-star formation relation of massive galaxies at 1.5<z<2.5

We study the relation between size and star formation activity in a complete sample of 225 massive (M > 5 x 10^10 Msun) galaxies at 1.5<z<2.5, selected from the FIREWORKS UV-IR catalog of the CDFS. Based on stellar population synthesis model fits to the observed restframe UV-NIR SEDs, and independent MIPS 24 micron observations, 65% of galaxies are actively forming stars, while 35% are quiescent. Using sizes derived from 2D surface brightness profile fits to high resolution (FWHM_{PSF}~0.45 arcsec) groundbased ISAAC data, we confirm and improve the significance of the relation between star formation activity and compactness found in previous studies, using a large, complete mass-limited sample. At z~2, massive quiescent galaxies are significantly smaller than massive star forming galaxies, and a median factor of 0.34+/-0.02 smaller than galaxies of similar mass in the local universe. 13% of the quiescent galaxies are unresolved in the ISAAC data, corresponding to sizes <1 kpc, more than 5 times smaller than galaxies of similar mass locally. The quiescent galaxies span a Kormendy relation which, compared to the relation for local early types, is shifted to smaller sizes and brighter surface brightnesses and is incompatible with passive evolution. The progenitors of the quiescent galaxies, were likely dominated by highly concentrated, intense nuclear star bursts at z~3-4, in contrast to star forming galaxies at z~2 which are extended and dominated by distributed star formation.Comment: 6 pages, 4 figures, accepted for publication in Ap

Optical Spectroscopy of Distant Red Galaxies

We present optical spectroscopic follow-up of a sample of Distant Red Galaxies (DRGs) with K 2.3, in the Hubble Deep Field South, the MS 1054-03 field, and the Chandra Deep Field South. Spectroscopic redshifts were obtained for 15 DRGs. Only 2 out of 15 DRGs are located at z < 2, suggesting a high efficiency to select high-redshift sources. From other spectroscopic surveys in the CDFS targeting intermediate to high redshift populations selected with different criteria, we find spectroscopic redshifts for a further 30 DRGs. We use the sample of spectroscopically confirmed DRGs to establish the high quality (scatter in \Delta z/(1+z) of ~ 0.05) of their photometric redshifts in the considered deep fields, as derived with EAZY (Brammer et al. 2008). Combining the spectroscopic and photometric redshifts, we find that 74% of DRGs with K 2. The combined spectroscopic and photometric sample is used to analyze the distinct intrinsic and observed properties of DRGs at z 2. In our photometric sample to K < 22.5, low-redshift DRGs are brighter in K than high-redshift DRGs by 0.7 mag, and more extincted by 1.2 mag in Av. Our analysis shows that the DRG criterion selects galaxies with different properties at different redshifts. Such biases can be largely avoided by selecting galaxies based on their rest-frame properties, which requires very good multi-band photometry and high quality photometric redshifts.Comment: Accepted for publication in the Astrophysical Journal, 13 pages, 8 figures, 5 table

The Dearth of z~10 Galaxies in all HST Legacy Fields -- The Rapid Evolution of the Galaxy Population in the First 500 Myr

We present an analysis of all prime HST legacy fields spanning >800 arcmin^2 for the search of z~10 galaxy candidates and the study of their UV luminosity function (LF). In particular, we present new z~10 candidates selected from the full Hubble Frontier Field (HFF) dataset. Despite the addition of these new fields, we find a low abundance of z~10 candidates with only 9 reliable sources identified in all prime HST datasets that include the HUDF09/12, the HUDF/XDF, all the CANDELS fields, and now the HFF survey. Based on this comprehensive search, we find that the UV luminosity function decreases by one order of magnitude from z~8 to z~10 at all luminosities over a four magnitude range. This also implies a decrease of the cosmic star-formation rate density by an order of magnitude within 170 Myr from z~8 to z~10. We show that this accelerated evolution compared to lower redshift can entirely be explained by the fast build-up of the dark matter halo mass function at z>8. Consequently, the predicted UV LFs from several models of galaxy formation are in good agreement with this observed trend, even though the measured UV LF lies at the low end of model predictions. In particular, the number of only 9 observed candidate galaxies is lower, by ~50%, than predicted by galaxy evolution models. The difference is generally still consistent within the Poisson and cosmic variance uncertainties. However, essentially all models predict larger numbers than observed. We discuss the implications of these results in light of the upcoming James Webb Space Telescope mission, which is poised to find much larger samples of z~10 galaxies as well as their progenitors at less than 400 Myr after the Big Bang.Comment: 13 pages, 6 figures, minor updates to match accepted versio

Orbitally-driven Peierls state in spinels

We consider the superstructures, which can be formed in spinels containing on B-sites the transition-metal ions with partially filled t2g levels. We show that, when such systems are close to itinerant state (e.g. have an insulator-metal transition), there may appear in them an orbitally-driven Peierls state. We explain by this mechanism the very unusual superstructures observed in CuIr2S4 (octamers) and MgTi2O4 (chiral superstructures) and suggest that similar phenomenon should be observed in NaTiO2 and possibly in some other systems.Comment: 4 pages, 3 figure

FIREWORKS U38-to-24 micron photometry of the GOODS-CDFS: multi-wavelength catalog and total IR properties of distant Ks-selected galaxies

We present a Ks-selected catalog, dubbed FIREWORKS, for the Chandra Deep Field South (CDFS) containing photometry in U_38, B_435, B, V, V_606, R, i_775, I, z_850, J, H, Ks, [3.6 um], [4.5 um], [5.8 um], [8.0 um], and the MIPS [24 um] band. The imaging has a typical Ks limit of 24.3 mag (5 sigma, AB) and coverage over 113 arcmin^2 in all bands and 138 arcmin^2 in all bands but H. We cross-correlate our catalog with the 1 Ms X-ray catalog by Giacconi et al. (2002) and with all available spectroscopic redshifts to date. We find and explain systematic differences in a comparison with the 'z_850 + Ks'-selected GOODS-MUSIC catalog that covers ~90% of the field. We exploit the U38-to-24 micron photometry to determine which Ks-selected galaxies at 1.5<z<2.5 have the brightest total IR luminosities and which galaxies contribute most to the integrated total IR emission. The answer to both questions is that red galaxies are dominating in the IR. This is true no matter whether color is defined in the rest-frame UV, optical, or optical-to-NIR. We do find however that among the reddest galaxies in the rest-frame optical, there is a population of sources with only little mid-IR emission, suggesting a quiescent nature.Comment: Accepted for publication in the Astrophysical Journal, 20 pages, 10 figures, reference to website correcte

Probing the Dawn of Galaxies at z~9-12: New Constraints from HUDF12/XDF and CANDELS Data

We present a comprehensive analysis of z>8 galaxies based on ultra-deep WFC3/IR data. We constrain the evolution of the UV luminosity function (LF) and luminosity densities from z~11 to z~8 by exploiting all the WFC3/IR data over the Hubble Ultra-Deep Field from the HUDF09 and the new HUDF12 program, in addition to the HUDF09 parallel field data, as well as wider area WFC3/IR imaging over GOODS-South. Galaxies are selected based on the Lyman Break Technique in three samples centered around z~9, z~10 and z~11, with seven z~9 galaxy candidates, and one each at z~10 and z~11. We confirm a new z~10 candidate (with z=9.8+-0.6) that was not convincingly identified in our first z~10 sample. The deeper data over the HUDF confirms all our previous z>~7.5 candidates as genuine high-redshift candidates, and extends our samples to higher redshift and fainter limits (H_160~29.8 mag). We perform one of the first estimates of the z~9 UV LF and improve our previous constraints at z~10. Extrapolating the lower redshift UV LF evolution should have revealed 17 z~9 and 9 z~10 sources, i.e., a factor ~3x and 9x larger than observed. The inferred star-formation rate density (SFRD) in galaxies above 0.7 M_sun/yr decreases by 0.6+-0.2 dex from z~8 to z~9, in good agreement with previous estimates. The low number of sources found at z>8 is consistent with a very rapid build-up of galaxies across z~10 to z~8. From a combination of all current measurements, we find a best estimate of a factor 10x decrease in the SFRD from z~8 to z~10, following (1+z)^(-11.4+-3.1). Our measurements thus confirm our previous finding of an accelerated evolution beyond z~8, and signify a rapid build-up of galaxies with M_UV<-17.7 within only ~200 Myr from z~10 to z~8, in the heart of cosmic reionization.Comment: 21 pages, 13 figures, 6 tables; submitted to Ap

SiNx:Tb3+--Yb3+, an efficient down-conversion layer compatible with a silicon solar cell process

SiN x : Tb 3+-Yb 3+, an efficient down-conversion layer compatible with silicon solar cell process Abstract Tb 3+-Yb 3+ co-doped SiN x down-conversion layers compatible with silicon Photovoltaic Technology were prepared by reactive magnetron co-sputtering. Efficient sensitization of Tb 3+ ions through a SiN x host matrix and cooperative energy transfer between Tb 3+ and Yb 3+ ions were evidenced as driving mechanisms of the down-conversion process. In this paper, the film composition and microstructure are investigated alongside their optical properties, with the aim of maximizing the rare earth ions incorporation and emission efficiency. An optimized layer achieving the highest Yb 3+ emission intensity was obtained by reactive magnetron co-sputtering in a nitride rich atmosphere for 1.2 W/cm${}^2$ and 0.15 W/cm${}^2$ power density applied on the Tb and Yb targets, respectively. It was determined that depositing at 200 {\textdegree}C and annealing at 850 {\textdegree}C leads to comparable Yb 3+ emission intensity than depositing at 500 {\textdegree}C and annealing at 600 {\textdegree}C, which is promising for applications toward silicon solar cells.Comment: Solar Energy Materials and Solar Cells, Elsevier, 201