Search results for "Spatial"
showing 10 items of 2121 documents
Experimental demonstration and numerical study of plasmon-soliton waves
2019
Merging the fields of plasmonics and nonlinear optics authorizes a variety of fascinating and original physical phenomena. In this work, we specifically study the combination of the strong light confinement ability of surface plasmon polaritons (SPP) with the beam self-trapping effect in a nonlinear optical Kerr medium. Although this idea of plasmon-soliton has been the subject of numerous theoretical papers since the eighties [1–4], up to now, no experimental evidence had been revealed yet. In the present study, a proper structure (Fig. 1a) has been designed and fabricated allowing the first experimental demonstration of these hybrid nonlinear waves merging spatial solitons and SPP. To be …
Dynamic spatial abilities and learning from animation
2016
International audience; This paper presents part of a wider project to create, validate and apply a comprehensive dynamic spatial ability test suitable for use with learning from animation. Four types of test item were devised (two race tasks and two intercept tasks) and tested with forty undergraduate participants. Absolute and relative speed of the objects as well as trajectory directions were manipulated. Task performances and the effect of the manipulated factors are reported. Comparison with a conventional static spatial ability test revealed little correlation, suggesting that dynamic spatial ability can be regarded as a distinct capacity.
Inférence de la résistance du paysage au flux de gènes à l'aide de modèles gravitaires intégrant des variables intra-populationnelles
2021
International audience; Modéliser les mouvements de dispersion nécessite d'associer aux éléments paysagers des valeurs de coût caractérisant leur résistance aux déplacements. En landscape genetics, l'inférence de ces valeurs se fait à partir de mesures de différenciation génétique entre populations. Bien que l'hétérogénéité spatiale des tailles de populations puisse aussi influencer de façon significative la différenciation génétique, les variables intra-populationnelles sont rarement prises en compte dans ce type d'inférence. Nous avons étudié à quel point la prise en compte de ces variables pouvait améliorer l'inférence des coûts. Pour cela, nous avons simulé des flux de gènes entre 60 po…
Analyse de sensibilité des modèles de connectivité écologique
2021
Le succès des mesures de conservation de la biodiversité basées sur le maintien de la connectivité écologique dépend de la qualité de la modélisation spatiale des mouvements des espèces. Le calcul de chemins de moindre coût est censé identifier les trajets qui minimisent les coûts de déplacement à travers la matrice paysagère. Il apporte deux types d’information : (i) la localisation spatiale des chemins de moindre coût et (ii) le coût accumulé le long de ces chemins, aussi appelé distance-coût. Cette modélisation spatiale nécessite qu’un coût soit attribué à chaque type d’occupation du sol, constituant alors un scénario de coût. L’influence de ces scénarios sur la localisation des chemins …
Determinants of the distribution of nitrogen-cycling microbial communities at the landscape-scale
2010
Little information is available regarding the landscape-scale distribution of microbial communities and its environmental determinants. However, a landscape perspective is needed to understand the relative importance of local and regional factors and land management for the microbial communities. In this manuscript, we investigated the distribution of functional microbial communities involved in N-cycling and of the total bacterial and crenarchaeal communities over 107 sites using a grid with a 16 km lag distance within Burgundy, a 31 500 km2 region in France. After quantifying the abundances of the total bacterial, crenarchaeal, nitrate-reducing, denitrifying and ammonia-oxidizing communit…
Isoproturon
2010
Frequent use of phenylurea herbicide isoproturon (IPU) in agricultural fields has resulted not only in the contamination of the natural resources including soil and water but also in the adaptation of the soil microflora to its rapid degradation. However, up to now, the mechanisms underlying this microbial adaptation are not well elucidated. The aim of this study was to explore the processes and factors implicated in IPU degradation from the agricultural field to the genes coding for catabolic genes. The study carried out at the experimental field of Epoisses cropped with a winter wheat / barley / rape seed crop rotation indicated that as a result of its periodically repeated use, the soil …
Mapping intra-plot topsoil diversity of Burgundy vineyards (Aloxe- Corton, France) from very high spatial resolution (VHSR) images
2012
International audience; In this work, we present a method based on very high spatial resolution (VHSR) aerial images acquired in the visible domain and that map soil surface diversity at the hillslope scale with a spatial resolution of a few centimeters. This method combines aerial VHSR image classification with local soil sampling. Principal component analysis (PCA) and non-supervised classification was performed on image characteristics to define soil surface characteristic classes (SSC). Then soil surface mapping was combined with soil surface descriptions and soil profiles to define soil types by physical and chemical characteristics.
Mapping spatial patterns of denitrifiers for bridging community ecology and microbial processes along environmental gradients
2009
International audience; While there is ample evidence that microbial processes can exhibit large variations at a field scale, very little is known about the spatial distribution of the communities mediating these processes. The objective of this study was to explore spatial patterns of size and activity of the denitrifying community, a functional guild involved in N-cycling, in a grassland field subjected to different cattle grazing regimes. We used geostatistical modeling to map the distribution of size and activity of the denitrifier community in the pasture. Size of the denitrifier community was estimated by PCR quantification of the denitrification gene copy numbers while its activity w…
Mapping spatial patterns of denitrifiers for bridging community ecology and microbial processes along environmental gradients
2009
While there is ample evidence that microbial processes can exhibit large variations at a field scale, very little is known about the spatial distribution of the communities mediating these processes. The objective of this study was to explore spatial patterns of size and activity of the denitrifying community, a functional guild involved in N-cycling, in a grassland field subjected to different cattle grazing regimes. We used geostatistical modeling to map the distribution of size and activity of the denitrifier community in the pasture. Size of the denitrifier community was estimated by PCR quantification of the denitrification gene copy numbers while its activity was estimated by measurin…
THE FRENCH NATIONAL SOIL QUALITY MONITORING NETWORK (RMQS) AS A SUPPORT FOR MONITORING SOIL BIODIVERSITY: past, present and future programs
2021
Soil biodiversity would represent about 25% of the species on Earth. It is threatened, and although it is essential for human activities, it remains largely unknown. The French National Soil Quality Monitoring Network (RMQS) has a significant impact in removing the grey areas through its programs on soil microorganisms, soil meso and macrofauna, meadow flora, truffles and more recently enzymatic activities. The first distribution maps of bacterial phyla on a national scale and of soil fauna on a regional scale (in Brittany) have been developed. For the white truffle, three new areas of presence have been identified in France. The habitats of the bacteria were also described for the first ti…