Search results for "Function"
showing 10 items of 14432 documents
Micron-precision in cleaving glass using ultrafast bessel beams with engineered transverse beam shapes
2017
International audience; Ultrafast lasers in association to beam shaping have shown to be excellent candidates for transparent material processing. Non-diffractive solutions such as Bessel beams allows for precise energy deposition since they are robust to undesired non-linear effects and as they do not distort along the propagation. This offers important opportunities in laser-assisted cleaving, i.e. mechanical medium separation after single-pass laser illumination. Here we break the Bessel beam cylindrical symmetry using a novel anisotropic and non-diffractive solutions to investigate both lateral intensity contributions on material response and induced processing effect for non-cylindrica…
Design rules for nonlinear spectral compression in optical fibers
2016
International audience; We present comprehensive design rules to optimize the process of spectral compression arising from nonlinear pulse propagation in an optical fiber. Extensive numerical simulations are used to predict the performance characteristics of the process as well as to identify the optimal operational conditions within the space of system parameters. It is shown that the group-velocity dispersion of the fiber is not detrimental and, in fact, helps achieve optimum compression. We also demonstrate that near-transform-limited rectangular and parabolic pulses can be generated in the region of optimum compression.
Symmetry breakings in a metal organic framework with a confined guest
2020
The MOF $[{\text{Fe(tvp)}}_{2}{(\text{NCS})}_{2}]\ifmmode\cdot\else\textperiodcentered\fi{}2\text{BzCHO}$ is demonstrated to undergo a complex sequence of phase transitions and spin-crossover behavior of its constitutive ${\text{Fe}}^{\text{II}}$ ions upon adsorption of benzaldehyde guest molecules. Our study, combining Raman and synchrotron x-ray diffraction measurements on a single crystal, reveals that the conversion from the pure high-spin to the pure low-spin phases implies a rich sequence of intermediate phases, with symmetry breaking forming at least three different space groups. These different symmetries involve spin-state ordering, ligand ordering, and guest ordering, interpreted …
Quantizations from reproducing kernel spaces
2012
Abstract The purpose of this work is to explore the existence and properties of reproducing kernel Hilbert subspaces of L 2 ( C , d 2 z / π ) based on subsets of complex Hermite polynomials. The resulting coherent states (CS) form a family depending on a nonnegative parameter s . We examine some interesting issues, mainly related to CS quantization, like the existence of the usual harmonic oscillator spectrum despite the absence of canonical commutation rules. The question of mathematical and physical equivalences between the s -dependent quantizations is also considered.
18 parameter deformations of the Peregrine breather of order 10 solutions of the NLS equation
2015
We present here new solutions of the focusing one-dimensional nonlinear Schrödinger (NLS) equation which appear as deformations of the Peregrine breather of order 10 with 18 real parameters. With this method, we obtain new families of quasi-rational solutions of the NLS equation, and we obtain explicit quotients of polynomial of degree 110 in x and t by a product of an exponential depending on t. We construct new patterns of different types of rogue waves and recover the triangular configurations as well as rings and concentric rings as found for the lower-orders.
Generalizing novel names in comparison settings: Role of conceptual distance during learning and at test
2017
International audience; In a comparison setting (two stimuli), we tested 4- and 6-year-old children’s generalization of novel names for objects. We manipulated the semantic distance between the two learning items (e.g., two bracelets versus a bracelet and a watch), and the semantic distance between the learning items and the test items (e.g., a pendant versus a bow tie). We tested whether smaller semantic distance between learning items would lead to more taxonomic (vs. perceptual) choices at test, than broader semantic distance during learning, especially in the case of distant test stimuli. Results revealed main effects of learning distance, of generalization distance and that only childr…
Diversité fonctionnelle au sein des communautés de plantes adventices : effet de la rotation et du type de culture
2012
During this internship I investigated the effects of habitats i.e. field margin or the core of the field, and of crop sequences weed taxonomic and functional diversity in arable fields. We selected 75 fields from a database of flora surveys that have been conducted since 2005 in the area of Fénay. In the 75 fieds, the flora was sampled four consecutive years. The indices of Shannon-Weaver, Simpson and Pielou and species richness were selected for taxonomic study, while Rao's quadratic entropy and the community weighted mean (CWM) of the traits in the community were used for the functional study. Four functional traits were selected for the analyses. Our results showed that all studied facto…
Multifunctionality: refocusing a spreading, loose and fashionable concept for looking at sustainability?
2008
International audience; The notion of agriculture's Multifunctionality (MF) emerged in the 1980s. It then followed two trajectories since the 1990s: a conflicting period linked to its use in the international trade negotiations on the one hand, a spreading in terms of meaning, use and geographically on the other hand. Specific meanings appeared in connection with policy making, at national or international levels, or through the involvement of new disciplines. Yet, very few authors discuss the implication of the chosen meaning on their findings. To explore and take advantage of using this word and to deliver it from its controversial use in international trade negotiations, it is absolutely…
Land use functions — a multifunctionality approach to assess the impact of land use changes on land use sustainability
2008
Part 5. Regional and local evaluation - 17; International audience; The dramatic changes in land use observed in Europe in the last fifty years have generally resulted in improvement of human welfare and economic development. On the other hand, they have caused serious environmental problems. There is therefore a need for approaches that help to understand in an integrative way the economic, environmental and societal impacts that land use changes have on sustainability. Sustainability Impact Assessment(SIA), which assesses the impact of policies on sustainability, addresses this challenge. SIA partly builds on the concept of the multifunctionality of land which helps to deal with the compl…
Biodiversity and characterization of arbuscular mycorrhizal fungi at the molecular level
1994
Biodiversity within a biological group provides the basis for distinguishing members into genera and species according to taxonomic criteria, and between individuals within a species depending on more detailed differences at the genetic level. Diversity between species occurs after a genetic barrier has been created either by a geographic or genetic impedance of gene flow. Divergence can continue by nucleotide substitutions and by mutations in a broader sense (deletions, translocations, duplications), and resulting diversity can be evaluated at the molecular level and used as a phylogenetic character. Diversity at the subspecies level is a function of both mutation rates and gene flow betwe…