Analyse de la structure des haies dans les vergers pour la définition de paysages mieux adaptés contre les bioagresseurs

National audienceAfin de modéliser la structure des haies de vergers, nous utilisons des méthodes de fouille de données. Ainsi, les chaînes de Markov couplées avec les chemins de Hilbert-Peano et les processus ponctuels servent à déterminer les paramètres propres à la disposition des haies dans le paysage. Ceci permet, par la suite, de simuler des paysages valides afin de créer des scénarios paysagers luttant contre les ravageur

UNDERSTANDING THE IMPLICATION OF AN ENVIRONMENTAL STRATEGY ADOPTION

The objective of this paper is to follow the consequences on the product environmental impact of the industrial strategy through the product development process. Students were observed while designing a bicycle luggage carrier for tracing a cause-effect network that would link the strategy to the designed product and its environmental impact. The results show the strategy's influence through the design process at a macro-level

Motion safety and constraints compatibility for multibody robots

International audienceIn this paper we propose a methodology to ensure safe behaviors of multibody robots in reactive control frameworks. The permanent satisfaction of constraints being insufficient to ensure safety, this approach focuses on the constraints expression: the compatibility between these constraints is studied, and safe alternatives are ensured when compatibility cannot be established. Case studies involving obstacles, joint position, velocity and acceleration limits illustrates the approach. A particular method is developed to take full advantage of a smooth state of the art avoidance techniques (Faverjon and Tournassoud in Proceedings of the 1987 IEEE international conference on robotics and automation, pp. 1152-1159, 1987) while maintaining safety. Experiments involving a 6-DOF manipulator operating in a cluttered environment illustrate the reliability of the approach and validate the expected performances

Structures de haies dans un paysage agricole : une étude par chemin de Hilbert adaptatif et chaînes de Markov

National audienceDans cet article nous présentons une approche couplant une courbe remplissant l'espace et une chaîne de Markov pour analyser des données spa-tiales concernant la localisation de haies. Du fait de l'hétérogénéité spatiale des données, nous utilisons une courbe adaptative de Hilbert qui permet de linéariser l'espace en s'ajustant localement à la densité des données. Pour ensuite exploiter la séquence produite, il est nécessaire de caractériser la distance entre un point et son prédecesseur sur la courbe ainsi que la densité locale. Nous proposons de calculer un temps d'accès à un point à partir du point précédent en utilisant la notion de profondeur de découpe. Cette variable, couplée avec les variables caractérisant les haies est ensuite analysée avec un modèle de Markov. Nous présentons et interprétons les résultats obtenus sur un jeu de données d'environ 10000 segments de haies d'une zone de la Basse vallée de la Durance

Structure Analysis of Hedgerows with Respect to Perennial Landscape Lines in Two Contrasting French Agricultural Landscapes

International audienceCharacterizing the spatial distribution of hedgerows over landscapes is important for understanding the effects of this distribution on the dynamics of plant and animal populations. Because hedgerows are planted or managed, the authors hypothesized that their distribution depends on the presence of other linear landscape elements, namely, roads and channels. Using proximity analyses, the authors thus assessed how the spatial distribution of hedgerows was impacted by the position of these linear landscape elements and the spatial extent of this impact for two contrasting agricultural landscapes. The results indicate that hedgerows were generally associated at short distances with other elements (100-150 m). Hedgerows had different association patterns depending on their orientation in one of the two landscapes. In that same landscape, within-landscape heterogeneity was related to different association patterns. These results indicate that models of the spatial distribution of hedgerows would gain from being based on the location of roads and channels in the studied landscape

Hybrid localized graph kernel for machine learning energy-related properties of molecules and solids

Nowadays, the coupling of electronic structure and machine learning techniques serves as a powerful tool to predict chemical and physical properties of a broad range of systems. With the aim of improving the accuracy of predictions, a large number of representations for molecules and solids for machine learning applications has been developed. In this work we propose a novel descriptor based on the notion of molecular graph. While graphs are largely employed in classification problems in cheminformatics or bioinformatics, they are not often used in regression problem, especially of energy-related properties. Our method is based on a local decomposition of atomic environments and on the hybridization of two kernel functions: a graph kernel contribution that describes the chemical pattern and a Coulomb label contribution that 1encodes finer details of the local geometry. The accuracy of this new kernel method in energy predictions of molecular and condensed phase systems is demonstrated by considering the popular QM7 and BA10 datasets. These examples show that the hybrid localized graph kernel outperforms traditional approaches such as, for example, the smooth overlap of atomic positions (SOAP) and the Coulomb matrices

Regulation of Ca2+ channels by SNAP-25 via recruitment of syntaxin-1 from plasma membrane clusters

SNAP-25 regulates Ca(2+) channels, with potentially important consequences for diseases involving an aberrant SNAP-25 expression level. How this regulation is executed mechanistically remains unknown. We investigated this question in mouse adrenal chromaffin cells and found that SNAP-25 inhibits Ca(2+) currents, with the B-isoform being more potent than the A-isoform, but not when syntaxin-1 is cleaved by botulinum neurotoxin C. In contrast, syntaxin-1 inhibits Ca(2+) currents independently of SNAP-25. Further experiments using immunostaining showed that endogenous or exogenous SNAP-25 expression recruits syntaxin-1 from clusters on the plasma membrane, thereby increasing the immunoavailability of syntaxin-1 and leading indirectly to Ca(2+) current inhibition. Expression of Munc18-1, which recruits syntaxin-1 within the exocytotic pathway, does not modulate Ca(2+) channels, whereas overexpression of the syntaxin-binding protein Doc2B or ubMunc13-2 increases syntaxin-1 immunoavailability and concomitantly down-regulates Ca(2+) currents. Similar findings were obtained upon chemical cholesterol depletion, leading directly to syntaxin-1 cluster dispersal and Ca(2+) current inhibition. We conclude that clustering of syntaxin-1 allows the cell to maintain a high syntaxin-1 expression level without compromising Ca(2+) influx, and recruitment of syntaxin-1 from clusters by SNAP-25 expression makes it available for regulating Ca(2+) channels. This mechanism potentially allows the cell to regulate Ca(2+) influx by expanding or contracting syntaxin-1 clusters

Hylomyrma villemantae sp. nov. (Hymenoptera: Formicidae), a New Ant Species from Mountain Rainforests of the Atlantic Forest Biome

A new species of Myrmicinae, Hylomyrma villemantae Neves and Lacau (Hymenoptera: Formicidae), is described after the morphology of the worker. This species is easily distinguished from any other ones in the genus by a unique combination of characters, including the fourth abdominal tergite wholly smooth and shining. This ant is probably endemic from southern Bahia in Brazil. It was collected in a forest remnant of Tropical Mountain Rainforests in the Atlantic Forest biome

UNDERSTANDING THE IMPLICATION OF AN ENVIRONMENTAL STRATEGY ADOPTION

The objective of this paper is to follow the consequences on the product environmental impact of the industrial strategy through the product development process. Students were observed while designing a bicycle luggage carrier for tracing a cause-effect network that would link the strategy to the designed product and its environmental impact. The results show the strategy's influence through the design process at a macro-level

A Plasmodium falciparum FcB1-schizont-EST collection providing clues to schizont specific gene structure and polymorphism

<p>Abstract</p> <p>Background</p> <p>The <it>Plasmodium falciparum </it>genome (3D7 strain) published in 2002, revealed ~5,400 genes, mostly based on <it>in silico </it>predictions. Experimental data is therefore required for structural and functional assessments of <it>P. falciparum </it>genes and expression, and polymorphic data are further necessary to exploit genomic information to further qualify therapeutic target candidates. Here, we undertook a large scale analysis of a <it>P. falciparum </it>FcB1-schizont-EST library previously constructed by suppression subtractive hybridization (SSH) to study genes expressed during merozoite morphogenesis, with the aim of: 1) obtaining an exhaustive collection of schizont specific ESTs, 2) experimentally validating or correcting <it>P. falciparum </it>gene models and 3) pinpointing genes displaying protein polymorphism between the FcB1 and 3D7 strains.</p> <p>Results</p> <p>A total of 22,125 clones randomly picked from the SSH library were sequenced, yielding 21,805 usable ESTs that were then clustered on the <it>P. falciparum </it>genome. This allowed identification of 243 protein coding genes, including 121 previously annotated as hypothetical. Statistical analysis of GO terms, when available, indicated significant enrichment in genes involved in "entry into host-cells" and "actin cytoskeleton". Although most ESTs do not span full-length gene reading frames, detailed sequence comparison of FcB1-ESTs versus 3D7 genomic sequences allowed the confirmation of exon/intron boundaries in 29 genes, the detection of new boundaries in 14 genes and identification of protein polymorphism for 21 genes. In addition, a large number of non-protein coding ESTs were identified, mainly matching with the two A-type rRNA units (on chromosomes 5 and 7) and to a lower extent, two atypical rRNA loci (on chromosomes 1 and 8), TARE subtelomeric regions (several chromosomes) and the recently described telomerase RNA gene (chromosome 9).</p> <p>Conclusion</p> <p>This FcB1-schizont-EST analysis confirmed the actual expression of 243 protein coding genes, allowing the correction of structural annotations for a quarter of these sequences. In addition, this analysis demonstrated the actual transcription of several remarkable non-protein coding loci: 2 atypical rRNA, TARE region and telomerase RNA gene. Together with other collections of <it>P. falciparum </it>ESTs, usually generated from mixed parasite stages, this collection of FcB1-schizont-ESTs provides valuable data to gain further insight into the <it>P. falciparum </it>gene structure, polymorphism and expression.</p