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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Étude de la pulvérisation et de l'émission de la matière sous bombardement Cs+ / Study of sputtering and emission of matter under Cs+ bombardment

Verdeil, Christophe 30 October 2008 (has links)
La technique Storing Matter a pour objectif d’améliorer la sensibilité et la quantification des analyses par SIMS. Elle consiste à découpler la phase de pulvérisation de l’échantillon de la phase d’analyse. Pour cela, la matière pulvérisée par bombardement ionique est déposée en sous-monocouche sur un collecteur optimisé. Le dépôt est ensuite analysé par SIMS. La probabilité d’ionisation de la matière ne dépend plus de son environnement initial (“effet de matrice”), mais de la surface du collecteur. Le choix du collecteur permet un gain de sensibilité et la quantification des concentrations de l’échantillon initial. L’efficacité de la technique dépend du choix du collecteur et d’un facteur de collection ? caractérisant la phase de pulvérisation-dépôt. Dans ce travail, nous avons étudié la pulvérisation et l’émission de la matière sous bombardement ionique pour optimiser ce facteur ?. Nous avons mis au point un dispositif expérimental ainsi qu’un protocole d’analyse par SIMS qui nous a permis d’étudier la distribution angulaire sous un bombardement d’ions Cs+ avec une incidence oblique pour différents paramètres d’impact. L’étude menée sur quatre cibles (Si, Ge, InP et GaAs) a montré que la distribution angulaire est de forme cosn (?-?Max) pour une énergie et un angle d’impact de respectivement 2 à 10 keV et 30° à 60°. L’exposant n est ~2 tandis que la direction d’émission préférentielle ?Max varie de la normale à la surface (0°) jusqu’à un angle d’émission de 35° dans la direction spéculaire au faisceau en fonction de l’énergie d’impact et de l’angle d’incidence. Ces résultats appliqués à Storing Matter ont permis de déterminer la configuration optimum pour une collection maîtrisée en fonction du bombardement / The Storing Matter technique aims at optimising the sensitivity and quantitativeness of SIMS analysis. It consists in decoupling the sputtering of the specimen from the subsequent analysis step. The specimen is sputtered by means of an ion beam. The emitted particles are deposited at a sub-monolayer level on an optimised collector. The deposit is subsequently analysed in a SIMS instrument. The ionisation probability in SIMS does not depend anymore on the initial sample composition (“Matrix effect”), but on the collector surface chemistry. The collector is chosen in order to increase the sensitivity and to quantify the specimen. The efficiency of this new technique depends on the collector choice and on the collection factor ? characterising the sputter-deposition step. In this work, the sputtering and emission processes under ionic bombardment have been studied in order to optimise this factor ?. We developed an experimental set-up and an analysis protocol based on SIMS that allows us to study the angular distribution under Cs+ bombardment with an oblique incidence for different impact parameters. Four targets (Si, Ge, InP and GaAs) were studied. The results show that the angular distribution is shaped as a cosine function cosn (?-?Max) for impact energies between 2 and 10 keV and for incidence angles from 30 to 60°. Under these conditions, the exponent n is ~2 and the preferential direction of emission ?Max varies from the normal to the surface to 35° in the specular direction in function of the impact energy and the incidence angle. The results allowed to find the best settings for the Storing Matter technique to control the sputtered matter collection in function of the bombardment parameters
22

Gottfried Winkler ou L'écriture oblique - Lire entre les lignes / Gottfried Winkler ou L'écriture oblique - Lire entre les lignes

Thirion, François 12 December 2011 (has links)
Cette thèse propose une recherche en deux temps, tout d'abord la reconstructionde la biographie et bibliographie complète du philosophe et pédagogue allemandGottfried Winkler (1739-1814), notamment par des documents inédits. Père du francmaçon,librettiste de Karl Maria von Weber et citoyen d'honneur de Dresde TheodorHell (1775-1856), son oeuvre n'est aujourd'hui connue que par un ouvrage considérépeut-être à tort comme une simple réédition du théologien réputé Johann Lorenz Mosheim(1693-1755). Cette mécompréhension de son oeuvre littéraire découle d'unetechnique d'écriture particulière que nous avons cherché à décoder.C'est pour cette raison que nous proposons dans un deuxième temps l'élaborationd'une méthodologie d'analyse littéraire fondée sur la théorie de l'« écritureoblique » ainsi que l'a formulée le philosophe Léo Strauss dans son essai La persécutionet l'art d'écrire. Cette méthode nous permet un éclairage différent des textes deGottfried Winkler ainsi qu'une analyse historique et philosophique nouvelle de l'auteur.L'accent de la recherche est donc mis sur une méthode de lecture « post-straussienne», augmentée de concepts anthropologiques, sociologiques et philosophiquesmodernes de l'oeuvre majeure de Winkler pour démontrer qu'il ne s'agit nullementd'un simple éditeur de Mosheim, mais bien d'un penseur représentatif, presque symptomatique,de la réalité d'une génération philosophique discrète, déchirée entre l'espritdes Lumières et la peur de la censure. / This thesis was conducted to determine the real content of a book of questionableidentity. To do this we proceed in two steps: At first with a complete reconstructionof the biography and the complete work, inclusive some inedited documents,of the author the german philosopher and pedagogue Gottfried Winkler (1739-1814).Indeed the father of the freemason and librettist Theodor Hell (1775-1856) is consideredtoday as a simple editor of the wellknown theologian Johann Lorenz Mosheim(1693-1755). The reason for this « reductio ad Mosheimium » of his work is probablydue to a false interpretation of his philosophical position, as the consequence of aspecial writing technic used by Winkler.So, in a second step, we tried to elaborate a decoding system, which shouldallow us to understand the content « between the lines », as the philosopher LeoStrauss defined it in his essay Persecution and the Art of Writing, of Winklers mainwork. This new approach of understanding Winklers writing with our « post-straussian» hermeneutical system, enriched by modern anthropological, sociologicaland philosophical principles, sets itself the goal to answer the main question of ourthesis:Was Winkler really just an editor of Mosheim or perhaps representative foran underground free-thinker generation at the dawn of a new century, torn betweenthe need of freedom of thinking and the fear of persecution ?
23

A Numerical Analysis of Shock Angles from Inward Turning Axisymmetric Flows

Hilal, William L. 01 January 2023 (has links) (PDF)
Detonation-based propulsion systems are known for their high efficiency and energy release when compared to deflagrative systems, making them an ideal candidate in hypersonic propulsion applications. One such engine is the Oblique Detonation Wave (ODW) engine, which has a similar architecture to traditional scramjets but shortens the combustor and isolator to an anchored ODW after fuel injection. Previous research has focused on using a two-dimensional wedge to induce an ODW while limiting total losses through the combustor. In this configuration, a two-dimensional wedge-based architecture entails a rectangular duct, limiting potential inlet design and increasing overall skin friction. However, an inward-turning axisymmetric ODW wedge architecture, where a two-dimensional wedge is revolved around a central axis, has yet to be examined in detail. The work at present aims to investigate the fundamental physics required to predict the Oblique Shock Wave (OSW) for an inward-turning axisymmetric flow, which is critical for designing a circular ODW engine combustor. Multiple steady simulations of inviscid and ideal air at Mach 4, 6, and 8 were performed over a 1-inch wedge with wedge angles of 16°, 18°, and 20°. The radius of the inlet boundary was also varied between 1, 3, and 5 inches to examine the effect of increasing the blockage ratio. The results showed that the shock angle for an inward-turning axisymmetric flow was up to 8% steeper than the analytical, two-dimensional wedge solution. Additionally, it was found that the OSW diverged further from the two-dimensional solution when the blockage ratio was increased. These findings provide insight into the flow physics that must be considered when designing inward-turning axisymmetric ODW engines.
24

Rupture continentale oblique : évolution tectonique du Golfe de Californie (Basse californie du Sud) du Néogène à l'actuel / Mechanisms of oblique breakup : a tectonic study of the Gulf of California from Neogene to present

Bot, Anna 01 September 2016 (has links)
Le Golfe de Californie (GOC) est un exemple de rift très oblique, au stade d'accrétion depuis 3,6 Ma au sud. La déformation continentale débute au Miocène dans un contexte arrière-arc, en relation avec la subduction de la plaque Pacifique sous la Plaque Nord-Américaine. L'objectif de cette thèse est de déterminer I'histoire de la déformation à I'origine de la rupture continentale ainsi que les phénomènes post-rupture. Cette étude utilise des données tectoniques, sismologiques et géomorphologiques sur la marge Ouest du GOC en Basse Californie du Sud. Elles sont calées temporellement par des datations d'isotopes radiogéniques et cosmogéniques. Une histoire polyphasée de la déformation, essentiellement post-magmatique, est proposée en termes d'évolution des directions des failles et de déformations relativement à la cinématique des plaques. Je démontre dans cette zone que la déformation qui conduit à l'amincissement et à l'étirement lithosphérique est d'abord fortement oblique et devient transtensive et moins oblique relativement à la cinématique à partir de 7-8 Ma. La marge étudiée est intégrée de manière cohérente à I'ensemble des domaines déformés associés à la formation du GOC. On montre notamment que les marges du GOC sont diachrones et qu'elles se forment par migration vers I'Ouest de la déformation vers la zone de subduction, qui devient inactive vers 12 Ma. La dynamique post-breakup du GOC est interprétée en termes de mobilisation par fluage de la croûte inférieure en relation avec un évènement thermique lié à la rupture du slab. En conclusion, l'évolution du GOC ne peut s'expliquer par les modèles simples de rifting oblique et de formation de marges passives. / The Gulf of California (GOC) is an example of highly-oblique rift. Oceanic accretion started 3.6 Ma ago at its southern end. The earliest continental extension started during the Miocene, in a back-arc setting, in connection with the subduction of the Pacific plate (PAC) beneath North America (NAM). ln this study, I reconstitute the strain evolution along the proximal Baja California margin. For this, I used original tectonic and seismological data which I collected in Baja California Sur (BCS). Those data were time-constrained with absolute dating (radiogenic and cosmogenic isotopes). I outline that the main stretching and thinning of the Late Miocene-Pliocene Baja California margin was highly oblique regarding NAM-PAC kinematic vector, turning less oblique. By integrating the studied margin in the evolution of the GOC, it is proposed that the final break-up mechanism occurred within a broad semi-ductile right-lateral central shear-zone. lt is shown that the two GOC passive margins didn't form at the same time, crustal strain migrating westward during the Miocene in response to a probable retreat of the dying slab. The active post-breakup deformation in the proximal BCS is best interpreted in connection with an outward flow of the lower crust in a trend compatible with the margin shaping inherited from the major GOC-normal to GOC-oblique Miocene crustal deformation. This ductile flow would be enhanced by the heat input from the slab rupture. To conclude, the GOC evolution as an oblique rift system adjusts with no existing analogical or numerical model of strain field evolution of oblique rifting, a probable consequence to the complex dynamics in back-arc settings.
25

Oblique decision trees in transformed spaces.

Wickramarachchi, Darshana Chitraka January 2015 (has links)
Decision trees (DTs) play a vital role in statistical modelling. Simplicity and interpretability of the solution structure have made the method popular in a wide range of disciplines. In data classification problems, DTs recursively partition the feature space into disjoint sub-regions until each sub-region becomes homogeneous with respect to a particular class. Axis parallel splits, the simplest form of splits, partition the feature space parallel to feature axes. However, for some problem domains DTs with axis parallel splits can produce complicated boundary structures. As an alternative, oblique splits are used to partition the feature space potentially simplifying the boundary structure. Various approaches have been explored to find optimal oblique splits. One approach is based on optimisation techniques. This is considered the benchmark approach, however, its major limitation is that the tree induction algorithm is computationally expensive. On the other hand, split finding approaches based on heuristic arguments have gained popularity and have made improvements on benchmark methods. This thesis proposes a methodology to induce oblique decision trees in transformed spaces based on a heuristic argument. As the first goal of the thesis, a new oblique decision tree algorithm, called HHCART (\underline{H}ouse\underline{H}older \underline{C}lassification and \underline{R}egression \underline{T}ree) is proposed. The proposed algorithm utilises a series of Householder matrices to reflect the training data at each non-terminal node during the tree construction. Householder matrices are constructed using the eigenvectors from each classes' covariance matrix. Axis parallel splits in the reflected (or transformed) spaces provide an efficient way of finding oblique splits in the original space. Experimental results show that the accuracy and size of the HHCART trees are comparable with some benchmark methods in the literature. The appealing features of HHCART is that it can handle both qualitative and quantitative features in the same oblique split, conceptually simple and computationally efficient. Data mining applications often come with massive example sets and inducing oblique DTs for such example sets often consumes considerable time. HHCART is a serial computing memory resident algorithm which may be ineffective when handling massive example sets. As the second goal of the thesis parallel computing and disk resident versions of the HHCART algorithm are presented so that HHCART can be used irrespective of the size of the problem. HHCART is a flexible algorithm and the eigenvectors defining Householder matrices can be replaced by other vectors deemed effective in oblique split finding. The third endeavour of this thesis explores this aspect of HHCART. HHCART can be used with other vectors in order to improve classification results. For example, a normal vector of the angular bisector, introduced in the Geometric Decision Tree (GDT) algorithm, is used to construct the Householder reflection matrix. The proposed method produces better results than GDT for some problem domains. In the second case, \textit{Class Representative Vectors} are introduced and used to construct Householder reflection matrices. The results of this experiment show that these oblique trees produce classification results competitive with those achieved with some benchmark decision trees. DTs are constructed using two approaches, namely: top-down and bottom-up. HHCART is a top-down tree, which is the most common approach. As the fourth idea of the thesis, the concept of HHCART is used to induce a new DT, HHBUT, using the bottom-up approach. The bottom-up approach performs cluster analysis prior to the tree building to identify the terminal nodes. The use of the Bayesian Information Criterion (BIC) to determine the number of clusters leads to accurate and compact trees when compared with Cross Validation (CV) based bottom-up trees. We suggest that HHBUT is a good alternative to the existing bottom-up tree especially when the number of examples is much higher than the number of features.
26

Fast growing and interpretable oblique trees via logistic regression models

Truong, Alfred Kar Yin January 2009 (has links)
The classification tree is an attractive method for classification as the predictions it makes are more transparent than most other classifiers. The most widely accepted approaches to tree-growth use axis-parallel splits to partition continuous attributes. Since the interpretability of a tree diminishes as it grows larger, researchers have sought ways of growing trees with oblique splits as they are better able to partition observations. The focus of this thesis is to grow oblique trees in a fast and deterministic manner and to propose ways of making them more interpretable. Finding good oblique splits is a computationally difficult task. Various authors have proposed ways of doing this by either performing stochastic searches or by solving problems that effectively produce oblique splits at each stage of tree-growth. A new approach to finding such splits is proposed that restricts attention to a small but comprehensive set of splits. Empirical evidence shows that good oblique splits are found in most cases. When observations come from a small number of classes, empirical evidence shows that oblique trees can be grown in a matter of seconds. As interpretability is the main strength of classification trees, it is important for oblique trees that are grown to be interpretable. As the proposed approach to finding oblique splits makes use of logistic regression, well-founded variable selection techniques are introduced to classification trees. This allows concise oblique splits to be found at each stage of tree-growth so that oblique trees that are more interpretable can be directly grown. In addition to this, cost-complexity pruning ideas which were developed for axis-parallel trees have been adapted to make oblique trees more interpretable. A major and practical component of this thesis is in providing the oblique.tree package in R that allows casual users to experiment with oblique trees in a way that was not possible before.
27

Análise dos efeitos de segunda ordem em pilares solicitados a flexão oblíqua composta. / Analysis of second order in the pillars requested by oblique bending composite.

Ceccon, Jorge Luiz 04 August 2008 (has links)
Na verificação do estado limite último das estruturas reticuladas em concreto armado se tem sempre os pilares solicitados à flexão oblíqua composta, seja devido a momentos fletores transmitidos pelas vigas ou lajes ou devido a imperfeições construtivas ou por ações normais ao eixo da peça comprimida, atuantes entre seus pontos de vinculação. Neste trabalho se está comparando os resultados que se obtém por dois processos de cálculo, quais sejam, a) Integração numérica com desacoplamentos das flexões nas duas direções principais de inércia com o uso da rigidez secante obtida de diagrama momento-curvatura, ou seja, os esforços de segunda ordem são calculados em cada direção como se não houvesse a solicitação de flexão na direção ortogonal e ao final se verifica a segurança da peça no Estado Limite Último considerando a flexão oblíqua composta; b) integração numérica considerando a flexão oblíqua composta com a curvatura obtida de diagrama momento-curvatura ponto a ponto já no cálculo dos efeitos de segunda ordem. Foram processados 215.740 pilares cuja análise conduz à conclusão de que se pode usar o procedimento citado no item (a) acima, com segurança e sem prejuízo da economia. / At check reticulated reinforced concrete structures in the ultimate limit state one always have the columns requested by a compression with biaxial bending , be due bending moments transmitted bay beams or slabs or due constructions imperfections or actions normal to the axis of the compressed piece acting between its points of attachment. This work is to compare the results that are obtained by two methods of calculation, which are: a) Numerical integration in each main direction of inertia with the use of secant stiffness obtained from bending-curvature diagram, it is, the second order efforts are calculated in each direction as if there was not request bending in the orthogonal direction and the end check the safety at ultimate limit state of the column by considering the biaxial bending; b) Numerical integration in each main direction of inertia with curvatures obtained point to point of moment-curvature diagrams, that consider the biaxial bending, to calculate the second order effects. Were processed 215.740 columns whose analysis leads to the conclusion that we can use the procedure mentioned in tem a) above, safely and without prejudice to the economy.
28

Le renouveau de l'action oblique / The revival of the derivative action

Ta, Isabelle 10 December 2018 (has links)
L'action oblique, ou la faculté pour le créancier de préserver son droit de gage général en exerçant les droits et actions négligés par son débiteur, est de ces mécanismes simples que l'on n'interroge plus. Le simple toilettage du texte du Code civil opéré par l'ordonnance du 10 février 2016 conforte cette attitude. La stabilité de son analyse n'est cependant due qu'à d'insatisfaisants compromis. Irréductible à une qualification unique de mesure conservatoire ou de voie d'exécution, la protection du droit de gage général que poursuit le créancier est en réalité duale : le créancier de somme d'argent cherche tantôt à assurer l'efficacité ultérieure de son droit de saisie, tantôt à obtenir immédiatement paiement. Ces fonctions traditionnelles, pour lesquelles l'action oblique est inadaptée, coexistent aux côtés d'une fonction nouvelle : prémunir le créancier d'obligation en nature et le titulaire de droits assimilés de toute atteinte à leurs droits. Mécanisme d'exécution forcée par obligation tierce préexistante, elle peut alors être utilisée en lieu et place de la responsabilité délictuelle du débiteur défaillant à l'égard de certains tiers. Cette évolution de la fonction de l'action oblique était contenue en germe dans son mécanisme. Le renouveau des fonctions s'explique par un renouveau de l'analyse de sa nature. Autorisant l'exercice des droits d'autrui, l'action oblique ne repose pas sur la représentation mais sur un droit propre original de substitution. Sans qu'ils soient réellement modifiés, cette qualification confère une acception nouvelle au domaine et une justification inédite au régime de l'action oblique, et ce tant dans ses conditions que dans ses effets. / The derivative action or the right for a creditor to claim the rights and actions of their neglectful debtor to protect their ulterior payment seems so familiar one no longer pays attention to it. This lack of attention seems all the more justified in light of the reform of February 10th 2016, which rewrote the article of the Civil Code without any real modification. But in truth, this understanding of the derivative action rests on unfulfilling compromises. Its understanding is obvious only at first glance. The derivative action can neither be reduced to a conservatory or a binding measure only, as the holder of the derivative action seeks at times to guarantee an ulterior seizing of property, and at other times to recover a debt of money. But these traditional functions, for which the derivative action may not be entirely appropriate, coexist with a newer one : allowing performance for the creditor of a debt in kind and holders of similar rights. Here the derivative action could be an answer to a debtor's liability towards specific third parties. This evolution could already be foreseen in the very mechanism of the derivative action. Actually, the renewed functions of the mechanism can be explained by the renewed attention paid to the analysis of its nature. By allowing one to exert a third party’s rights, the derivative action relies not on representation but on an original right of substitution. This new analysis brings along a new definition of the extent to which one is allowed to exert a third party’s rights, as well as a new explanation about both the circumstances and effects of the derivative action.
29

Epaminondas : Strateg och stadsgrundare

Bengtsson, Gunilla January 2009 (has links)
<p>There is an old saying, that after Epaminondas nothing was ever the same again. In this thesis I will focus on three questions: "Epaminondas the man." Who was he? "Epaminondas the general." How did he change the technique of warfare that made it possible to beat the Spartans? "Epaminondas, founder of cities and wall-builder." How did he build the walls around the cities he initiated, that made them resist enemy attacks for many years to come?</p><p>While seeking the answers to yhese questions I will make a contextual analysis to get the historical background to all the phenomina involved.</p>
30

Study of the effect of the antiangiogenic factor 16K hPRL on tumor growth and metastasis and identification of new antiangiogenic peptides/Etude de l'effet antiangiogène de la prolactine 16K sur la progression tumorale et métastatique et identification de nouveaux peptides antiangiogènes.

Nguyen, Ngoc-Quynh-Nhu 26 October 2006 (has links)
Angiogenesis, the formation of new blood vessels from pre-existing ones, is a crucial step in many pathologies, including tumor growth and metastasis. We developed an adenovirus vector allowing the 16K hPRL expression, an antiangiogenic factor, in situ. We show 16K hPRL inhibits oxygen-induced retinopathy in mice. Then, using the 16K-Ad vector, we investigated the ability of 16K hPRL to prevent metastatic spread through inhibition of angiogenesis. We show that 16K hPRL administered via adenovirus-mediated gene transfer inhibits tumor growth in a subcutaneous B16-F10 mouse melanoma model by reducing the size and width of tumor vessels. We also show, for the first time, that 16K hPRL considerably reduces the establishment of B16-F10 metastases in an experimental lung metastasis model. These results highlight a potential role for 16K hPRL in anticancer therapy for both primary tumors and metastases. In parallel, we have sought to identify in human 16K PRL (16K hPRL) a peptide that might be responsible for its antiangiogenic activity. Although the 16K fragments of the other three human PRL/GH-family members are also potently antiangiogenic, the sequence similarity of these fragments is low (around 35% similarity between all mammalian PRL/GH sequences). This led us to seek a peculiar common structural feature rather than a similar sequence. We demonstrate that all these fragments possess a 14-amino-acid sequence having the characteristics of a tilted peptide. We show for the first time that tilted peptides exert antiangiogenic activity. The tilted peptides of hPRL and hGH induce endothelial cell apoptosis, inhibit endothelial cell proliferation, and inhibit capillary formation both in vitro and in vivo. These antiangiogenic effects are abolished when the peptides hydrophobicity gradient is altered by mutation. We further demonstrate for the first time that the well-known tilted peptides of SIV gp32 and Alzheimers beta-amyloid peptide are also angiogenesis inhibitors. Taken together these results point to a potential new role for tilted peptides in regulating angiogenesis. Langiogenèse, la formation de nouveaux vaisseaux à partir de vaisseaux préexistants, joue un rôle important dans de nombreuses pathologies incluant la croissance tumorale et la dissémination des métastases. Nous avons développé un vecteur adénoviral (16K-Ad) nous permettant de produire le facteur antiangiogène hPRL 16K directement in situ. Une première analyse permettant détudier les effets de la hPRL 16K produite par lapproche adénovirale a été réalisée in vivo. Nous montrons tout dabord que la hPRL 16K produite est capable de prévenir la néovascularisation rétinienne dans un modèle murin de rétinopathie. Par la suite, en utilisant le vecteur 16K-Ad, nous montrons que la hPRL 16K peut inhiber le développement tumoral dans un modèle murin développant des tumeurs formées par les cellules de mélanome B16-F10 dans le tissu sous-cutané. Cette inhibition de la croissance tumorale est corrélée avec une diminution de la taille des vaisseaux. Nous montrons aussi, pour la première fois, que la hPRL 16K peut considérablement réduire létablissement des métastases B16-F10 dans un modèle expérimental de métastases se développant dans le poumon. Ces résultats soulignent le rôle potentiel de la hPRL 16K dans la thérapie anticancéreuse dirigée contre les tumeurs primaires et les métastases. Parallèlement à ces travaux, nous nous sommes attachés à identifier une région responsable de lactivité de la hPRL 16K. Partant du fait que les fragments 16K des trois autres membres de la famille humaine PRL/GH sont aussi de puissants facteurs antiangiogènes, malgré que leur similarité de séquence soit faible (environ 35% de similarité entre les séquences de la PRL et de la GH), nous avons recherché une caractéristique structurale commune partagée par ces différents fragments. Nous avons identifié un domaine susceptible d'adopter une structure en peptide oblique dans les séquences protéiques des fragments de 16 kDa de la famille PRL/GH. Leffet antiangiogène des peptides obliques de la hPRL 16K et de la hGH 16K est montré dans des expériences menées in vitro et in vivo. Nous montrons également leffet antiangiogène des peptides obliques du peptide de fusion gp 32 du virus SIV et du peptide b-amyloïde.

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