Tesi sul tema "Résistance au vert profond"
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Demolon, Pierre. "Élaboration de structures laser d'éléments III-N émettant dans le vert". Nice, 2010. http://www.theses.fr/2010NICE4101.
Testo completoThis work deals with the metalorganic vapour phase epitaxy (MOVPE) of nitride laser diodes working under electrical injection. The doping of GaN:Si and GaN:Mg layers has been optimized in order to reduce the access resistances of the laser. The structure of the (In,Ga)N active area has been calibrated to control the optical emission from violet to yellow wavelengths. A strong electric field has been observed in the quantum well (QW) during this study. Due to Quantum Confined Stark Effect a compromise between the thickness and the In composition of QWs is essential in order to obtain a strong radiative efficiency. Phenomena relating to (Al,Ga,In)N confinement layers have been treated. Theorical and experimental studies allowed pointing out the key points to optimize the vertical conduction of AlGaN/GaN superlattices. A study regarding AlInN layers lattice matched with GaN has been made to limit the crystallographic defects and to increase the optical confinement of the confinement layers. To validate the optimization of each building block, we have grown several laser structures, and the devices have generated a laser emission under electrical injection
Le, Roncé Iris. "Déterminisme environnemental de la fécondité du chêne vert". Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTG020.
Testo completoClimate change is placing increasing pressure on forests around the world, and its potential impacts on the reproductive capacity of individuals are yet poorly understood. Many forest tree species reproduce following so-called masting patterns, in which seed production is intermittent and synchronized among individuals, whose drivers need to be identified in order to better understand the impact of climate on the fecundity of forest trees. The general objective of this thesis is to deepen our knowledge of the environmental drivers of the fecundity of forest trees and their interactions, by focusing on the holm oak, a widespread species in the Mediterranean basin. It also aimed to determine how fecundity could be impacted by climate change, and to develop a process-based model capable of predicting this impact. This thesis work combines analyses of long-term monitoring in a holm oak forest exposed to a rainfall exclusion experiment, experimental manipulations of source-sink interactions involved in the resource allocation to reproduction, and modelling. I have shown that reproduction was strongly regulated by weather conditions during the reproductive cycle and in particular by the water availability in summer-autumn, and to a lesser extent by the availability of carbon and nutrients, as well as by competition between fruits and new buds. My experimental results show that the allocation of resources to reproduction could be modified in case of resource limitation due to defoliation; and that developing fruits have a negative impact on the dynamics of nitrogen and zinc reserves in branches, as well as on the production of female flowers the following year. Long-term observations show that multi-year rainfall reduction induce a decrease in the number of fruits produced which is additional to the interannual variability and that tree reproduction does not acclimate to drought. Finally, within the PHENOFIT model, I have developed a fecundity model based on the assumptions and results from my work and from the literature
kfoury, Linda. "Analyse des causes de la résistance du pêcher, Prunus (L) Batsch, au puceron vert du pêcher, Myzus persicae Sulzer". Toulouse 3, 1992. http://www.theses.fr/1992TOU30085.
Testo completoPloquin, Mickaël. "Etudes des interactions précoces virus/hôte associées à la résistance au SIDA du singe vert d'Afrique infecté par le SIVagm". Paris 7, 2006. http://www.theses.fr/2006PA077148.
Testo completoThe non-pathogenic SlVagm infection in African Green Monkeys (AGM) is associated with high viremia as observed in pathogenic HIV-1 and SlVmac infections in humans and macaques. However, AGM display lower viral loads in lymph nodes and lack of signs of aberrant and chronic generalized T cell activation. In primary HIV-1 infection in humans, T cell activation levels determine the rate of disease progression. We raised the hypothesis that AGM do not develop AIDS due to (i) the absence of viral dissemination from myeloid dendritic cells (mDC) expressing DC-SIGN (CD209) to CD4+ T cells in lymph nodes and/or due to (ii) a rapid control of T cell activation decreasing the pool of target T cells and preventing the loss of CD4+ T cells. This study shows that the capacity of DC-SIGN from AGM to capture and transmit HIV/SIV is not linked to levels of viral load in lymph nodes and suggests that others factors such as levels of T cell activation might explain thé different profiles of viral replication in lymph nodes between pathogenic and non-pathogenic HIV/SIV infections. The study of SlVagm infection revealed an early induction of an anti-inflammatory environment (TGF-p, Foxp3) at 24 hours after infection followed by a strong IL-10 response in plasma. In contrast to SlVagm infection, this induction is delayed during primary pathogenic SlVmac infection. According to our data, the early response in anti-inflammatory cytokines that correlates with the induction of regulatory T cells might play a crucial role for preventing the harmful chronic T-cell activation observed during pathogenic HIV-1/SIVmac infections. 1624 caractères espaces compris receptor that ultimately accounts for virus internalization. Key-words: Dengue virus, dendritic cells, DC-SIGN, E protein, virus internalization
Le, boulch Pauline. "Déterminants moléculaires de la résistance au puceron vert (Myzus persicae) chez le pêcher (Prunus persica) : étude multi-omique des réponses à l'infestation". Electronic Thesis or Diss., Avignon, 2022. http://www.theses.fr/2022AVIG0371.
Testo completoOf the many pests that plants face, aphids are certainly the most damaging to crops due to their rapid multiplication, the direct damage they cause and the plant pathogenic viruses they transmit. The green peach aphid (Myzus persicae, Sulzer) is a generalist pest that attacks a wide range of plants including peach, its primary host, but also numerous secondary hosts from various botanical families including different cultivated species. Previous work has highlighted peach accessions with resistance to M. persicae conferred by the Rm locus that was characterised by an antixenosis phenomenon that rapidly causing the aphids to leave. The objective of our study was to identify, using an integrated transcriptomics and metabolomics approach, the factors involved in the expression of resistance to M. persicae in peach trees in order to obtain a quasi-exhaustive description of the biological functions activated or repressed by the infestation. We compared the responses to infestation of two peach genotypes, GF305 susceptible to M. persicae and Rubira carrying the Rm2 resistance gene, 48 h post-infestation, a period corresponding to the effective establishment of Rm2-induced resistance.Comparative transcriptomic and metabolomic analysis of the two peach varieties revealed a very limited response of GF305 to infestation while profound reconfigurations in Rubira were observed. The transcriptional reconfiguration resulted in a repression of genes involved in growth and development functions and an overexpression of defence genes, indicating a reorientation of cell function towards defence. This observation was confirmed by the significant reduction in metabolic pools of carbon, nitrogen and sulphur and by the accumulation of caffeic acid conjugates with anti-appetent or toxic properties towards aphids. Among the defence genes, the overexpression of PRR and NLR receptors suggested a joint activation of both branches of the plant immune system, PTI and ETI. Furthermore, the enrichment of oxidative stress-related genes, coupled with the activation of H2O2-generating metabolic pathways such as photorespiratory glyoxylate synthesis and P5C/proline futile cycle activation, underlineed the probable involvement of ROS synthesis in Rubira resistance to M. persicae. The appearance of necrotic lesions indicative of a hypersensitive reaction could also be attributed to an oxidative burst in response to infestation. The triggering of an acquired systemic response was also suggested by the activation of salicylic and pipecolic acid metabolism. Finally, as the involvement of pipecolic acid in plant resistance to aphids is poorly documented and in order to determine the role of this compound in peach resistance, the effect of an exogenous supply of pipecolic acid on the escape behaviour of M. persicae and on the development of aphid colonies, as well as on the metabolic profile of the apices was investigated. Although this experiment did not show the capacity of pipecolic acid to induce resistance, it provided new informations concerning the metabolic markers inducible by this molecule. To conclude, this work illustrates the extent and complexity of the expression of resistance to M. persicae conferred by Rm2 and underlines the interest of integrating transcriptomic and metabolomic data for the analysis of the plant/aphid interaction. This functional knowledge will be crucial in order to exploit natural sources of resistance and sustainably control aphid populations
Daya, Abdelmajid. "Études des contraintes de croissance des arbres sur pied d'eucalyptus grandis et du chêne vert : caractérisation et valorisation sous forme de bois collé". Metz, 2006. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2006/Daya.Abdelmajid.SMZ0615.pdf.
Testo completoThe aim of this study is to measure the growth stress indicators (GSI) of the wood of grown Eucalypti and holm oak and to determine the technological properties for the valorization of these two species in the form of glued wood. Three trees of grown Eucalypti and holm oak were studied. Tensile specimens with massive wood and glued wood (end to end and in bevel), and DCB specimens with massive wood and glued wood were prepared. The quality of the assembly is treated by a probabilistic model based on the Weibull's statistical approach permitting to predict the reliability of the glued systems. The GSI, measured in the periphery of the trees, characterize the state of the wood formed in the very last years. The GSI distribution revealed generally that these two species have different behaviours. The grown Eucalyptus and the holm oak present a high nervousness. These obtained characteristics allowed us to classify them in a hard to half-hard wood, nervous, of strong shrinkage and an average rigidity. The massive wood presents a brittle behaviour with a fracture stress of the holm-oak twice bigger than that of the grown eucalyptus , although the glued wood (end to end or beveled) presents a ductile behaviour with a fracture stress almost the same for these two types of assembly. The Weibull coefficient m of the massive wood of these two species is weaker than that of the glued wood. The measurement of the restitution rate of the energy (toughness) of the massive wood and glued wood of grown eucalyptus and holm-oak has been experimentally achieved using the compliance method. The massive wood of these species is stronger than the glued wood. This latter has a higher toughness than that of the glued polyurethane. The average value of the experimentally determined toughness is very close to that calculated by the finite element code CASTEM 2000, which is greater than those found by ASTM and two embedded beams methods. In the massive wood, the crack initiates in the plan of low strength and the types of fracture observed during its propagation are intercellular and transcellular. In the glued wood the crack starts in the glue joint for the holm-oak, and both in the glue and wood for the grown eucalyptus. Whereas, its propagation is always adhesive for the holm-oak and mixed for the grown eucalyptus (alternately in wood and glue)
Le, Manh Hai. "Caractérisation physique et mécanique des sols marins d'offshore profond". Phd thesis, Paris Est, 2008. https://pastel.hal.science/pastel-00003828.
Testo completoLe, Manh Hai. "Caractérisation physique et mécanique des sols marins d'offshore profond". Phd thesis, Ecole des Ponts ParisTech, 2008. http://pastel.archives-ouvertes.fr/pastel-00003828.
Testo completoLlanos, Villarreal Jenny A. "Comportement vis-à-vis des métaux lourds de micro-organismes thermophiles isoles d'un site hydrothermal profond". Brest, 2000. http://www.theses.fr/2000BRES2021.
Testo completoBonato, Olivier. "Dynamique des populations de l'acarien vert du manioc "Mononychellus progresivus" et de l'acarien rouge "Oligonychus gossypii" au Congo. Modélisation du sous-système acariens phytophages-manioc". Montpellier 2, 1993. http://www.theses.fr/1993MON20049.
Testo completoRousselin, Aurélie. "Contribution des pratiques culturales (irrigation et fertilisation azotée) à la gestion des populations de pucerons en verger fruitier : Cas des systèmes pêcher - puceron vert du pêcher (Prunus persica - Myzus persicae) et pommier - puceron cendré (Malus domestica - Dysaphis plantaginea)". Thesis, Avignon, 2016. http://www.theses.fr/2016AVIG0681/document.
Testo completoAphids are major pests of important fruit trees in France, especially peach and appletrees. In order to reduce chemical use, various alternatives can be implemented for themanagement of aphids in orchards. This thesis starts by a review of the different alternativemanagement methods and their positioning at different aphid life cycle stages. Then our workfocuses on the study of the effects of modulation of host plant characteristics, through culturalpractices, on aphid abundance. Our study is based on the Plant Vigor Hypothesis which statesthat phytophagous insects are more performant on vigorous plant or organ. Thus, in theexperimental part we combined dynamic assessment of vegetative growth and aphid abundanceduring two factorial experiments: Prunus persica – Myzus persicae (2 levels of water supply ×2 levels of nitrogen supply) and Malus domestica – Dysaphis plantaginea (2 levels of watersupply × 2 tree genotypes). We chose those factors for their possible impact on vegetativegrowth and nutritional quality of the host plant. We conducted the experiments on young nonbearingpotted trees. At shoot scale, aphid abundance is positively correlated to vegetativegrowth for both studied systems. On peach tree, the positive impact of nitrogen availability onaphid abundance seems to be mediated by the strong positive impact of nitrogen on vegetativegrowth. The negative effect of water restriction on aphid abundance seems to be unrelated toan impact of water availability on vegetative growth. Thus on the second studied system: appletree – rosy apple aphid, we chose to vary water supply and to work on two genotypes to test thegenericity of the observed pattern. At shoot scale, water restriction has a positive effect on aphidabundance on one tree genotype and a negative effect on the other one, whereas at tree scalefor both tree genotypes aphid abundance is positively correlated to vegetative growth and waterrestriction negatively impacts aphid abundance. These results suggest that aphid performanceon water restricted trees is limited by another host plant characteristics than vegetative growth.This thesis shows that water restriction and vigour management through nitrogen fertilizationcan be implemented to manage aphids in fruit orchards. However, the patterns evidenced aredependent on tree genotype and on the scale of analysis. The applicability of these alternativemethods remains to be assessed in producing orchards, taking into account the effects of waterand nitrogen restrictions on fruit production
Elhajjar, Samer. "Compréhension de la contestation de la publicité environnementale : principes et conséquences". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAB007/document.
Testo completoThis research seeks to analyze the phenomenon of environmental advertising contestation. In effect, there is a shortage of studies on these issues. The objective of this thesis is to explore the contours of the environmental advertising contestation concept while identifying the reasons, the manifestations and the risks associated with it. Three empirical studies, one qualitative and two experimental, show that that there are reasons of contestation related to creative elements of advertisement and discourse advertisements and others linked to advertising medium and confidence of consumer toward the advertising source. Moreover, the manifestations of contestation can range from collective and visible movements to more individual behaviors such as avoidance and the rejection of environmental advertising. In addition, the contestation seems to have a negative impact on consumer buying behavior and on the firm's image. Finally, the results indicate that provocation- a tool used by companies according to literature to avoid contestation- has negative effects on consumers‘ perceptions and attitudes toward the advertisement. In the light of the obtained results, the limitations of the thesis are outlined and future avenues of research are proposed
Blancon, Justin. "Identification des déterminants génétiques de la tolérance à la sècheresse chez le maïs par l'étude de l'évolution de l'indice foliaire vert au cours du cycle de la plante et le développement d'une méthode de phénotypage innovant". Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC026.
Testo completoBy the end of the century, climate forecasts predict a decrease in the quantity and regularity of rainfall with an increasing risk of drought in Europe and in many regions of the world. Breeding for more tolerant varieties will be an essential lever to face these future constraints. The main objective of this work is to characterize the genetic determinisms of drought tolerance in maize. To this aim, it is proposed to dissect this complex trait into underlying physiological traits whose genetic determinism is supposed to be simpler. Green Leaf Area Index (GLAI) dynamics throughout the plant cycle, through its major role in light interception, transpiration and CO2 exchange, is a promising secondary trait to identify and better understand the genetic basis of drought tolerance. During this thesis, we developed a high-throughput method for phenotyping maize GLAI dynamics in the field. This method combines UAV multispectral imagery and a simple GLAI model. It makes possible the estimation of the dynamics of GLAI continuously throughout the whole plant cycle with good accuracy, while reducing the phenotyping time twentyfold. This method was used in two well-watered and two water-deficient trials to characterize the GLAI dynamics of 324 lines from a MAGIC population (Multi-parent Advanced Generation Inter-Cross). The estimated dynamics have a high heritability and explain a significant part of grain yield under well-watered and water-stressed conditions. To characterize the genetic basis of GLAI dynamics, three longitudinal GWAS (Genome Wide Association Study) approaches were compared: a univariate two-step approach, a multivariate two-step approach and a random regression one-step approach. These three approaches, combined with the high density of available genotyping data (nearly 8 million markers), have revealed many QTL (Quantitative Trait Loci), some of which were co-localized with yield QTL. Finally, we demonstrated that the GLAI QTL identified in this study could explain nearly 20 % of the grain yield variability observed in a large network of water-stressed experiments. This work provides methods that will enable a better characterization and understanding of the genetic determinisms of GLAI dynamics, a trait that was out of reach in large populations until now. This trait presents all the characteristics required to improve the effectiveness of selection programs under water stress conditions
Khoueir, Paul. "Effets des polyphénols du thé vert et de la radiothérapie sur la progression et la résistance tumorale dans un modèle in vivo de glioblastome". Thèse, 2004. http://hdl.handle.net/1866/15763.
Testo completoBejan, Mircea. "Études sur la résistance d'accessions de Solanum sauvages envers le puceron de la pomme de terre Macrosiphum euphorbiae (Thomas) et le puceron vert du pêcher Myzus persicae (Sulzer) (Aphidae)". Mémoire, 2007. http://www.archipel.uqam.ca/4201/1/M9755.pdf.
Testo completoTon, Anh-Tien. "A multiscale framework for microbial evolution to identify the emergence of antibiotic resistance". Thèse, 2018. http://hdl.handle.net/1866/22277.
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