Search results for "Signal"
showing 10 items of 6924 documents
A Study on the Impact of Spectral Characteristics of Filters on Multispectral Image Acquisition
2013
International audience; In every aspect, filter design plays an important role in an image acquisition system based on a single image sensor and a colour filter array (CFA) mounted onto the sensor. Complementary CFAs are used by some colour cameras in the interest of higher sensitivity, which motivated us to employ filters of wide pass bands in the effort to adapt CFA for multispectral image acquisition. In this context, filter design has an effect on the accuracy of spectrum reconstruction in addition to other aspects. The results show that wider bandwidths in general result in more faithful spectrum reconstruction and higher signal-to-noise performance.
Intérêt de l’analyse multispectrale des images endoscopiques de la muqueuse gastrique pour reconnaitre la gastrite inflammatoire et ses différents…
2014
International audience
Exploiter une plateforme de recherche en télécommunications optiques pour souligner la dualité temps/fréquence
2015
National audience; L’analyse de Fourier [1] tient une place majeure dans l’analyse et la compréhension de nombreux phénomènes de la physique et de l’ingénierie contemporaines. Pourtant les étudiants, qui ont souvent découvert cette notion à travers des travaux numériques ou en cours de mathématiques, ne cernent pas forcément toute la richesse qui peut être tirée de l’analyse conjointe dans les domaines temporels et spectraux, notamment dans le domaine de l’optique [2, 3]. De plus, si une grande attention est souvent accordée aux profils temporels ou spectraux en intensité, la notion de phase est souvent balayée beaucoup rapidement.Nous avons mis en place dans le cadre de la seconde année du…
Manipulation expérimentale de la cohérence temporelle d'ondes partiellement cohérentes
2019
National audience; Nous décrivons deux expériences nous permettant de manipuler les propriétés de cohérence d'ondes partiellement cohérentes. Les montages expérimentaux développés reposent sur la manipulation de la phase spectrale du champ initial, assistée éventuellement d'une modulation sinusoïdale préalable de sa phase temporelle. Les signaux d'autocorrélation en intensité mesurés soulignent le changement significatif des caractéristiques temporelles des signaux incohérents obtenus.
Wavelength conversion and temporal compression of a pulse train using a dispersion oscillating fiber
2014
International audience; We demonstrate the generation of a picosecond pulse train taking advantage of the cross gain occurring in a dispersion oscillating fibre. The resulting frequency-converted signal is detuned by more than 20 nm from the pump and can be temporally compressed by a factor 2 compared to the input sinusoidal pump wave.
Pulse transition to similaritons in normally dispersive fibre amplifiers
2013
selected by the editors of Journal of Optics as a Highlight of 2013a video linked to the experiments can be seen at : http://youtu.be/thbXaW91D5g; International audience; A detailed experimental characterization of the transition process of an initially Gaussian pulse to the asymptotic self-similar parabolic solution in optical fibre amplifiers operating in the normal dispersion regime is performed.
Modal and wavelength conversions in plasmonic nanowires
2021
We show that plasmonic nanowire-nanoparticle systems can perform nonlinear wavelength and modal conversions and potentially serve as building blocks for signal multiplexing and novel trafficking modalities. When a surface plasmon excited by a pulsed laser beam propagates in a nanowire, it generates a localized broadband nonlinear continuum at the nanowire surface as well as at active locations defined by sites where nanoparticles are absorbed (enhancement sites). The local response may couple to new sets of propagating modes enabling a complex routing of optical signals through modal and spectral conversions. Different aspects influencing the optical signal conversions are presented, includ…
The evolution of nitric oxide signalling diverges between the animal and the green lineages
2019
AbstractNitric oxide (NO) is a ubiquitous signalling molecule with widespread distribution in prokaryotes and eukaryotes where it is involved in countless physiological processes. While the mechanisms governing nitric oxide (NO) synthesis and signalling are well established in animals, the situation is less clear in the green lineage. Recent investigations have shown that NO synthase, the major enzymatic source for NO in animals, is absent in land plants but present in a limited number of algae. The first detailed analysis highlighted that these new NO synthases are functional but display specific structural features and probably original catalytic activities. Completing this picture, analy…
Are the xyloglucans new elicitors of plant immunity ?
2017
Damaged-Associated Molecular Patterns (DAMPs) are endogenous molecules released from the plant cell wall after wounding by pathogens. DAMPs are recognized by Pattern- Recognition Receptors (PRRs) that play a key role in plant immunity by mediating defense responses. The plant cell wall-derived oligogalacturonides (OG) are well characterized DAMPs that elicit plant immune responses such as MAPK activation, [Ca2+]cyt variations, H2O2 production, defense-related gene expression and enhanced resistance against Botrytis cinerea. Our study focused on a new polysaccharide component of the plant cell wall called xyloglucans (Xh) and compared the immune events triggered by OG and Xh in Arabidopsis t…
Mixed Driven Refinement Design of Multidimensional Models based on Agglomerative Hierarchical Clustering
2015
20 pages; International audience; Data warehouses (DW) and OLAP systems are business intelligence technologies allowing the on-line analysis of huge volume of data according to users' needs. The success of DW projects essentially depends on the design phase where functional requirements meet data sources (mixed design methodology) (Phipps and Davis, 2002). However, when dealing with complex applications existing design methodologies seem inefficient since decision-makers define functional requirements that cannot be deduced from data sources (data driven approach) and/or they have not sufficient application domain knowledge (user driven approach) (Sautot et al., 2014b). Therefore, in this p…