The cosmological information of shear peaks: beyond the abundance

We study the cosmological information of weak lensing (WL) peaks, focusing on two other statistics besides their abundance: the stacked tangential-shear profiles and the peak-peak correlation function. We use a large ensemble of simulated WL maps with survey specifications relevant to future missions like Euclid and LSST, to explore the three peak probes. We find that the correlation function of peaks with high signal-to-noise (S/N) measured from fields of size 144 sq. deg. has a maximum of ~0.3 at an angular scale ~10 arcmin. For peaks with smaller S/N, the amplitude of the correlation function decreases, and its maximum occurs on smaller angular scales. We compare the peak observables measured with and without shape noise and find that for S/N~3 only ~5% of the peaks are due to large-scale structures, the rest being generated by shape noise. The covariance matrix of the probes is examined: the correlation function is only weakly covariant on scales < 30 arcmin, and slightly more on larger scales; the shear profiles are very correlated for theta > 2 arcmin, with a correlation coefficient as high as 0.7. Using the Fisher-matrix formalism, we compute the cosmological constraints for {Om_m, sig_8, w, n_s} considering each probe separately, as well as in combination. We find that the correlation function of peaks and shear profiles yield marginalized errors which are larger by a factor of 2-4 for {Om_m, sig_8} than the errors yielded by the peak abundance alone, while the errors for {w, n_s} are similar. By combining the three probes, the marginalized constraints are tightened by a factor of ~2 compared to the peak abundance alone, the least contributor to the error reduction being the correlation function. This work therefore recommends that future WL surveys use shear peaks beyond their abundance in order to constrain the cosmological model.Comment: 15 pages, 10 figures, submitted to MNRA

Cacao agroforestry systems do not increase pest and disease incidence compared with monocultures under good cultural management practices

Pests and diseases threaten cacao production worldwide. Agroforestry systems are traditionally seen by farmers as one of the causes of increased pest and disease incidence, in contrast with full-sun monocultures. Cultural management practices - e.g. regular tree pruning, frequent pod harvest, regular removal of infested pods, weed management - have been reported to be crucial for pest and disease management. We performed two experiments for the purpose of assessing the effect of (i) different cacao production systems, and (ii) the frequency of harvest and removal of infested pods on the incidence of pests and diseases and on the cacao yield. The first experiment was performed in a long-term system comparison trial in Bolivia, where data on pest and disease incidence were recorded for three years in five production systems: two monocultures and two agroforestry system under organic and conventional farming, and one successional agroforestry system, i.e. a high tree density multi-strata system. Pest and disease management did not differ between systems and relied on cultural management practices. Overall, the incidence of pests and diseases did not differ between production systems, which indicated they were not the driver of yield differences between them. Across production systems, only 14% of the pods were affected by pests and diseases; 70% of these were affected by frosty pod rot. More than 80% of the pods infected by frosty pod rot were removed before the sporulation phase. In the second experiment, the effects of the frequency of harvest and removal of infected pods - every 15 days versus every 25 days - on pest and disease incidence and yield were tested in four farmers’ fields. Fortnightly harvest and diseased pod removal significantly decreased disease incidence and increased cacao yield, by 25% and 46% respectively. Our results show that cacao agroforestry systems do not increase pest and disease incidence compared with monocultures when good cultural management practices are implemented, which, in turn, can increase the productivity of the cacao plantations

Tests comparatifs d'oculométrie des plateformes Swissbib.ch et Data.bnf.fr

Ce travail consiste à réaliser une comparaison des interfaces de Swissbib.ch et de Data.bnf.fr en utilisant la méthode de l’oculométrie en vue d’améliorer le design de l’interface de Swissbib.ch. Ce dernier est un métacatalogue suisse financé par la Conférence universitaire suisse et swissuniversities. Il est maintenu à la bibliothèque universitaire de Bâle. Data.bnf.fr est une nouvelle plateforme en Linked open data qui a été développée par la Bibliothèque nationale de France. La méthode d’évaluation de ces deux sites est l’oculométrie : les utilisateurs observent des captures d’écran des deux sites web et la machine enregistre le parcours de leurs yeux sur l’écran. Pour réaliser ce travail, j’ai sélectionné 24 utilisateurs qui ont participé à ces tests. Les résultats ont déterminé que l’interface de Swissbib.ch est bien appréciée par les utilisateurs. Cependant, j’ai pu relever certains problèmes sur l’interface, comme un menu sur deux lignes. Les recommandations d’améliorations sont présentées à la fin de ce document et offrent des solutions concrètes que mon mandant pourra utiliser lors du développement futur de Swissbib.ch. La méthodologie de conception et de réalisation de mon test est décrite étape par étape dans ce travail. J’ai également effectué une comparaison entre les deux eye-trackers que j’ai utilisés pour réaliser ce travail