Micro-lentilles à large gamme de diamètres de mode et de distances de travail pour couplage optique

Thème 8 « packaging, interconnexions et connectique » [JNOG8_1], http://www.univ-savoie.fr/labos/lahc/horizonsjnog/download/Actes_Horizons_JNOG_2005.pdfNational audienceLe présent article traite de micro-lentilles à base de fibre à gradient d'indice réalisées directement sur fibre optique monomode pour télécommunications optiques. La nouveauté consiste à utiliser une fibre à gradient d' indice parabolique latéral qui s' étend sur la totalité des 125 μm de diamètre de la fibre au lieu des 85μm du coeur de la fibre précédemment utilisée. Les diamètres de mode peuvent atteindre 90 μm au lieu de 55 μm et la distance de travail 2100 μm au lieu de 900 μm

UTILISATION DES PRINCIPAUX ÉLÉMENTS MINÉRAUX DU MAIS ENSILÉ PAR LE MOUTON EN CROISSANCE

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Truncated Gaussian beams through microlenses based on a graded-index section

Topic: optical interconnectsInternational audienceWe have developed a simple and low-cost microlens for optical communication systems involving the coupling of laser diodes or integrated waveguides to single-mode fibers (SMFs), and fiber-to-fiber interconnection. More generally, the applications concern coupling active or passive components to SMFs. The novelty consists in using a graded-index section of 125-µm core diameter without cladding and taking into account the diffraction effects. This new microlens offers a wider range of mode field diameters (from around 5 to 90 µm) and working distances (up to 2000 µm) than previously demonstrated. This paper investigates the influence of the Fresnel diffraction of a Gaussian beam, during its propagation through the microlens, on the mode field intensity profile, the working distance, and the coupling efficiency of this kind of microlens in front of a SMF. It shows that while truncation causes multiple maxima of the coupling efficiency as a function of z displacement, it does not decrease the maximum coupling efficiency

Simultaneous Measurement of Group Velocity Dispersion and Nonlinear Coefficient in Optical Fiers Based on the Self-Phase Modulation

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Numerical method for simultaneous measurement of dispersion and nonlinear coefficient in optical fibers

International audienceA new and simple numerical method to measure simultaneously the dispersion and the third-order Kerr nonlinear coefficient in optical fibers is presented. This method is based on self-phase-modulation-induced spectral broadening experiments and an iterative numerical technique. A standard single mode fiber, a dispersion-shifted fiber and a highly nonlinear chalcogenide photonic crystal fiber are measured using this method

Specificity and genetic polymorphism in the Vfm quorum sensing system of plant pathogenic bacteria of the genus Dickeya

International audienceThe Vfm quorum sensing (QS) system is preponderant for the virulence of different species of the bacterial genus Dickeya. The vfm gene cluster encodes 26 genes involved in the production, sensing or transduction of the QS signal. To date, the Vfm QS signal has escaped detection by analytical chemistry methods. However, we report here a strain-specific polymorphism in the biosynthesis genes vfmO and vfmP, which is predicted to be related to the production of different analogues of the QS signal. Consequently, the Vfm communication could be impossible between strains possessing different variants of the genes vfmO/P. We constructed three Vfm QS biosensor strains possessing different vfmO/P variants and compared these biosensors for their responses to samples prepared from 34 Dickeya strains possessing different vfmO/P variants. A pattern of specificity was demonstrated, providing evidence that the polymorphism in the genes vfmO/P determines the biosynthesis of different analogues of the QS signal. Unexpectedly, this vfmO/P-dependent pattern of specificity is linked to a polymorphism in the ABC transporter gene vfmG, suggesting an adaptation of the putative permease VfmG to specifically bind different analogues of the QS signal. Accordingly, we discuss the possible involvement of VfmG as co-sensor of the Vfm two-component regulatory syste

A natural single nucleotide mutation in the small regulatory RNA ArcZ of Dickeya solani switches off the antimicrobial activities against yeast and bacteria

International audienceThe necrotrophic plant pathogenic bacterium Dickeya solani emerged in the potato agrosystem in Europe. All isolated strains of D . solani contain several large polyketide synthase/non-ribosomal peptide synthetase (PKS/NRPS) gene clusters. Analogy with genes described in other bacteria suggests that the clusters ooc and zms are involved in the production of secondary metabolites of the oocydin and zeamine families, respectively. A third cluster named sol was recently shown to produce an antifungal molecule. In this study, we constructed mutants impaired in each of the three secondary metabolite clusters sol , ooc , and zms to compare first the phenotype of the D . solani wild-type strain D s0432-1 with its associated mutants. We demonstrated the antimicrobial functions of these three PKS/NRPS clusters against bacteria, yeasts or fungi. The cluster sol , conserved in several other Dickeya species, produces a secondary metabolite inhibiting yeasts. Phenotyping and comparative genomics of different D . solani wild-type isolates revealed that the small regulatory RNA ArcZ plays a major role in the control of the clusters sol and zms . A single-point mutation, conserved in some Dickeya wild-type strains, including the D . solani type strain IPO 2222, impairs the ArcZ function by affecting its processing into an active form

Errors generated by a point-of-care CD4+ T-lymphocyte analyser: a retrospective observational study in nine countries

Abstract Objective To estimate the proportion of invalid results generated by a CD4+ T-lymphocyte analyser used by Médecins Sans Frontières (MSF) in field projects and identify factors associated with invalid results. Methods We collated 25 616 CD4+ T-lymphocyte test results from 39 sites in nine countries for the years 2011 to 2013. Information about the setting, user, training, sampling technique and device repair history were obtained by questionnaire. The analyser performs a series of checks to ensure that all steps of the analysis are completed successfully; if not, an invalid result is reported. We calculated the proportion of invalid results by device and by operator. Regression analyses were used to investigate factors associated with invalid results. Findings There were 3354 invalid test results (13.1%) across 39 sites, for 58 Alere PimaTM devices and 180 operators. The median proportion of errors per device and operator was 12.7% (interquartile range, IQR: 10.3-19.9) and 12.1% (IQR: 7.1-19.2), respectively. The proportion of invalid results varied widely by country, setting, user and device. Errors were not associated with settings, user experience or the number of users per device. Tests performed on capillary blood samples were significantly less likely to generate errors compared to venous whole blood. Conclusion The Alere Pima CD4+ analyser generated a high proportion of invalid test results, across different countries, settings and users. Most error codes could be attributed to the operator, but the exact causes proved difficult to identify. Invalid results need to be factored into the implementation and operational costs of routine CD4+ T-lymphocyte testing

Identification des végétaux où des structures intéréssantes sont présentes

Atelier de Réflexion Prospective VegAInternational audienc