Study of the factors involved in the aggregation of Harmonia axyridis Pallas (Coleoptera : Coccinellidae)

in Communications in Agricultural and Applied Biological Sciences (2012), 77(1), 101-104

The aggregative behaviour of the multicoloured Asian ladybeetle, Harmonia axyridis Pallas, during winters, is still misunderstood. Our study was focused on the chemical and physical factors involved in ... [more ▼]

The aggregative behaviour of the multicoloured Asian ladybeetle, Harmonia axyridis Pallas, during winters, is still misunderstood. Our study was focused on the chemical and physical factors involved in the selection of its aggregation sites. Chemical and behavioural analyses highlighted that long-chain hydrocarbons lead congeners towards aggregations and ensure the cohesion of the cluster. On the other hand, we investigated the influence of (1) the density of individuals and (2) the quality of available shelters on H. axyridis decision to settle and aggregate under shelters. A binary choice experiment conducted in laboratory highlighted a permanent aggregative behaviour of H. axyridis, even during non-wintering conditions, and the existence of social interactions between individuals. [less ▲]

Study of the flavonoids effect on the AhR-dependent transcription using reporter gene assays

in Journal of Biotechnology (2007), 131(2, Suppl. S), 6

Study of the forbidden oxygen lines in a sample of cometary spectra obtained at the VLT (ESO)

Poster (2012)

Study of the geometrical inaccuracy on a SPIF two-slope pyramid by finite element simulations

in International Journal of Solids and Structures (2012)

Single Point Incremental Forming (SPIF) is a recent manufacturing process which can give a symmetrical or asymmetrical shape to an undeformed metal sheet by using a relative small tool. In this article, a ... [more ▼]

Single Point Incremental Forming (SPIF) is a recent manufacturing process which can give a symmetrical or asymmetrical shape to an undeformed metal sheet by using a relative small tool. In this article, a two-slope SPIF pyramid with two different depths, which suffers from large geometric deviations when comparing the intended and final shapes, is studied. The article goal is to detect if these divergences are due to new plastic strain while forming the second angle pyramid by using finite elements simulations. To validate the numerical results, both the shape and the forces are compared with experimental measurements. Then, an analysis of the material state is carried out taking the equivalent plastic strain, von Mises effective stress and yield stress distribution through a cut in the mesh. It is noticed that there is plastic deformation in the center of the pyramid, far from the tool neighbourhood. Also, high values of stresses are observed under the yield stress in other parts of the sheet. As a strong bending behaviour plus membrane tension is found in some sheet elements, these elastic stresses are due to a bending action of the tool. It is concluded that the main shape deviations come from elastic strains due to structural elastic bending, plus a minor contribution of localized springback, as no plastic deformation is observed in the angle change zone. Future developments in toolpath designs should eventually consider these elastic strains in order to achieve the intended geometry. [less ▲]

Study of the impact of constant and pulsating flows of organic and water vapours on carbon filters breakthrough curves

Conference (2010)

Study of the impact of satellite data assimilation into a hydrodynamical model of the ligurian sea. Comparison between sst fields and sst satellite-based predicted fields

Conference (2004)

The verification of a 3D hydrodynamic model of the Ligurian Sea is presented. Two assimilation experiments have been carried out with this model: the assimilation of real SST, and the assimilation of SST ... [more ▼]

The verification of a 3D hydrodynamic model of the Ligurian Sea is presented. Two assimilation experiments have been carried out with this model: the assimilation of real SST, and the assimilation of SST forecasted by a statistical predictor. The aim of the study is to establish the skill of the model in these two configurations. The assimilation of predicted SST can help to increase the model skill when observations are not available, and preliminary results show that both approaches obtained similar results. The verification is done in a multi-scale approach, by decomposing the model results and the observations into several spatial scales, using 2D discrete wavelet transforms. At each scale the error between the model and the observations is calculated, and the scales where the biggest errors occur can be identified. The variability distribution of the model and the observations is also examined at each scale, to study the impact of the assimilation on the model variability. This methodology provides a scale-dependent insight in the study of the assimilation of SST and predicted SST. The differences between both assimilated data and how these differences affect the model results are examined. [less ▲]

Study of the in vitro conditions promoting hypertrophic differentiation of osteoarthritic articular chondrocytes

Poster (2008)

Study of the induced systemic resistance of plants: molecular aspects of the interaction between plant cells and amphiphilic elicitors produced by non-pathogenic rhizobacteria

Doctoral thesis (2013)

Some non pathogenic rhizobacteria could locally interact with plants, leading to the stimulation of a primed protection state in the host plant. Upon subsequent pathogen attack, this priming state allows ... [more ▼]

Some non pathogenic rhizobacteria could locally interact with plants, leading to the stimulation of a primed protection state in the host plant. Upon subsequent pathogen attack, this priming state allows an accelerated activation of defense responses extending to all organs of the plant. Fundamental as well as applied research about this induced systemic resistance (ISR) has been tremendously boosted in the past decades, driven by its evident potential for biological control of plant diseases in agriculture. However very little information is available about molecular mechanisms governing the recognition by plant cells of ISR-specific elicitors. Various compounds retaining the ability to elicit ISR have been isolated, among which the recently emerged class of biosurfactants. We conducted the present thesis work with the scope to highlight how such amphiphilic compounds are perceived at the plant cell surface to stimulate the systemic plant immune system. In the first part, the strain B. amyloliquefaciens was selected out of other isolates for its technological traits and previously characterized ISR activity. We demonstrated that surfactin is the most competent cyclic lipopeptide (cLP) family produced by this strain to confer ISR on the selected plant model, tobacco. In order to improve our knowledge about the mechanism governing the perception of this biosurfactant at the plant cell surface, we have combined various approaches such as structure/activity (stimulation of the defense-related oxidative burst) relationship, insertion kinetics within membranes of tobacco cultured cells and thermodynamic determination of binding parameters on various model membranes via isothermal titration calorimetry. Our data indicate that surfactin perception relies on a lipid-driven process which is quite uncommon regarding the typical proteic receptor-mediated recognition of molecular patterns governing the plant basal immunity. We then demonstrate that cLPs induce some enrichment or depletion into specific lipid platforms of different proteins. We hypothesize that it may be: (1) the direct consequence of the generation of insertion sites for some proteins in the entire plasma membrane due to specific cLP segregation at lipid phase interfaces; or (2) result from the indirect adjustment of lipid-modifying enzymes activities through an induced rearrangement of the plasma membrane lipid organization. It reinforces the current hypothesis of a role for lipid microdomains-driven lateral compartmentalization in plant cell signaling. The lipid bilayer of target cells could now be considered as the focal point of cLPs perception from where start cellular responses. As they display an original mechanism of action, the class of amphiphilic ISR elicitors to which they belong become more attractive than ever for further development of innovative biopesticides. [less ▲]

Study of the influence of coloured road surfaces on the efficiency of road lighting installations

in Proceedings of the 9th Lux Europa Congress (2001)

Study of the influence of friction in imperfect conical indentation for elasto-plastic material

in Proceedings of VIENNANO’09 – 3rd Vienna International Conference on Nano Technology (2009)