RESTRICTIONS POTENTIELLES DE L'APPLICATION DE LA THEORIE DES LIGNES DE TRANSMISSION: QUANTIFICATION DES ERREURS D'APPROXIMATION ET INTERET DES APPROCHES CORRECTIVES

International audienceCette communication traite des conditions d'application de la théorie des lignes de transmission classique. Il présente une évaluation des erreurs commises lors de l'utilisation de cette théorie dans certaines conditions particulières. L'objectif est de cerner les situations pour lesquelles une solution alternative à la théorie des lignes de transmission classique (TLT) doit être recherchée

A Functional Genomics Approach Identifies Candidate Effectors from the Aphid Species Myzus persicae (Green Peach Aphid)

Aphids are amongst the most devastating sap-feeding insects of plants. Like most plant parasites, aphids require intimate associations with their host plants to gain access to nutrients. Aphid feeding induces responses such as clogging of phloem sieve elements and callose formation, which are suppressed by unknown molecules, probably proteins, in aphid saliva. Therefore, it is likely that aphids, like plant pathogens, deliver proteins (effectors) inside their hosts to modulate host cell processes, suppress plant defenses, and promote infestation. We exploited publicly available aphid salivary gland expressed sequence tags (ESTs) to apply a functional genomics approach for identification of candidate effectors from Myzus persicae (green peach aphid), based on common features of plant pathogen effectors. A total of 48 effector candidates were identified, cloned, and subjected to transient overexpression in Nicotiana benthamiana to assay for elicitation of a phenotype, suppression of the Pathogen-Associated Molecular Pattern (PAMP)–mediated oxidative burst, and effects on aphid reproductive performance. We identified one candidate effector, Mp10, which specifically induced chlorosis and local cell death in N. benthamiana and conferred avirulence to recombinant Potato virus X (PVX) expressing Mp10, PVX-Mp10, in N. tabacum, indicating that this protein may trigger plant defenses. The ubiquitin-ligase associated protein SGT1 was required for the Mp10-mediated chlorosis response in N. benthamiana. Mp10 also suppressed the oxidative burst induced by flg22, but not by chitin. Aphid fecundity assays revealed that in planta overexpression of Mp10 and Mp42 reduced aphid fecundity, whereas another effector candidate, MpC002, enhanced aphid fecundity. Thus, these results suggest that, although Mp10 suppresses flg22-triggered immunity, it triggers a defense response, resulting in an overall decrease in aphid performance in the fecundity assays. Overall, we identified aphid salivary proteins that share features with plant pathogen effectors and therefore may function as aphid effectors by perturbing host cellular processes

Etude phenomenologique de la sensibilite electromagnetique de composants electroniques logiques implantes sur circuits imprimes

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 84523 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Some Limiting Aspects of Transmission Line Theory and Possible Improvements

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DESCRIPTION D’UNE METHODE EXPERIMENTALE PERMETTANT DE QUALIFIER LES SEUILS DE SENSIBILITE DES RECEPTEURS FM EN PRESENCE D’INTERFERENCES PAR VOIE RAYONNEE

International audienceL’évaluation de la qualité de la réception radio représente une étape cruciale dans le processus de production d’un véhicule. Pour évaluer la réception radio, plusieurs paramètres entrent en jeu. Le lien radio dépend en effet de la nature du canal de propagation électromagnétique, des caractéristiques des antennes et plus généralement de la chaine électronique de réception. La qualité de la réception est également potentiellement affectée par les interférences générées à l’entrée de l’autoradio par l'électronique de bord. Les méthodes actuelles d’évaluation de la réception radio ne lient pas expérimentalement les phénomènes d’interférence électromagnétique du véhicule au signal radioélectrique contenant l’information utile (signal en bande de base). Cette communication présente un banc d'essai original permettant l'évaluation de la qualité de réception radio d'un véhicule dans une chambre semi-anéchoïque. Ce banc d'essai constitue une brique de base essentielle d'un processus méthodologique global. Son objectif est de mesurer le seuil de sensibilité de la chaîne de réception radio du véhicule et d’évaluer l’évolution de ce seuil en fonction de l’interférence générée par les différents organes du véhicule. Nous avons mis en place deux méthodes pour réaliser cette expérience : l’injection du signal radioélectrique directement au niveau de l’autoradio (mode conduit) et l’injection du signal radioélectrique à l’aide une antenne (mode rayonné). Dans cet article seul le mode rayonné est présenté

An Embedded Double Reference Transmission Line Theory Applied to Cable Harnesses

International audienceIn this paper, an embedded double reference transmission line theory (EDRTLT) is presented. This approach is based upon taking an arbitrary wire among the í µí² wires constituting the harness and considering it as an internal reference conductor. Then the initial transmission line of í µí² wires above a ground reference is split into two coupled subsets of wires. The internal subset is composed of í µí² − í µí¿ wires with the internal reference wire as the return wire. The per unit length (p.u.l.) parameters of this internal transmission line are calculated with respect to this internal reference wire. They do not depend on the ground reference. The external subset is composed of only the internal reference wire with the ground plane as a reference. As a result, any change of relative position of the bundle and the ground reference involves the p.u.l. calculation of a mono-conductor transmission line. This double reference transmission line theory is shown to be equivalent to the classical single reference approach and the corresponding p.u.l. parameters are approximately retrieved from those of the single reference transmission lines to form the EDRTLT. The results obtained by this theory are in good agreement with those obtained from the single reference case where all p.u.l. parameters are directly calculated using the ground plane as a single reference. The main advantage provided by the EDRTLT is to reduce the complexity of analysis of the bundle-to-ground interaction

Enhanced Transmission Line Theory: Frequency-Dependent Line Parameters And Their Insertion in a Classical Transmission Line Equation Solver

International audienceIn this paper, a modified enhanced transmission-line theory taking into account higher-order modes is described. The new equations are based on the correction of the per-unit-length parameters that become frequency dependent and contain the radiation resistance. In particular, the per-unit-length resistance takes into account this radiation resistance and an additional resistance proportional to the imaginary part of the characteristic impedance. This additional resistance is identified as responsible of the current attenuation on the line. These new parameters are described in a per-unit-length RLCG form and can then easily be introduced in a classical transmission-line equation solver. Satisfactory results are obtained when comparing this new model to a full-wave model

Limitations of the transmission line theory application: Approximation errors quantification and relevance of remedial approaches

Workshop on automotive EMCInternational audienceThe objective of this communication is to recall the applicability conditions of the classical transmission line theory. The main assumptions are reviewed with the approximation made when deriving the classical transmission line equations from Maxwell's equations. Some practical situations where the classical transmission line theory is limited are shown. These situations include the resonance frequencies and high frequency regions (when the height of the line is no longer smaller than the minimum significant wavelength.

Description d'une méthode expérimentale permettant de qualifier les seuils de sensibilité des récepteurs FM en présence d'interférences par voie rayonnée.

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