115 research outputs found
Le contrÎle d'accÚs des réseaux et grandes infrastructures critiques distribuées
La stabilitĂ© et le dĂ©veloppement des nations dĂ©pendent grandement de leurs Infrastructures Critiques (IC). Vu leur importance, de nombreuses menaces guettent leurs systĂšmes dâinformation - aussi appelĂ©s Infrastructures dâInformation Critiques (IIC) -, parmi elles: les atteintes Ă lâintĂ©gritĂ© de leurs donnĂ©es et processus informatisĂ©s ainsi que les abus pouvant survenir au cours des collaborations avec dâautres parties. LâintĂ©gritĂ© dâune information, qui est sa propriĂ©tĂ© de ne pas ĂȘtre altĂ©rĂ©e, est primordiale pour les IIC puisquâelles manipulent et gĂ©nĂšrent des informations devant nĂ©cessairement ĂȘtre correctes et fiables. Dans un contexte de mondialisation et dâouverture, les IC ne peuvent Ă©voluer sans collaborer avec leur environnement. Toutefois, cela nâest pas sans risques puisque les ressources quâelles engagent peuvent faire lâobjet de corruptions et de sabotages. Tentant de rĂ©duire les risques de corruptions pouvant Ă©maner de lâintĂ©rieur comme de lâextĂ©rieur, nous avons ĆuvrĂ© Ă lâamĂ©lioration du mĂ©canisme de contrĂŽle dâaccĂšs. Incontournable, il vise Ă limiter les actions auxquelles peuvent prĂ©tendre les utilisateurs lĂ©gitimes du systĂšme, conformĂ©ment Ă la politique de sĂ©curitĂ© de lâorganisation. La pertinence et la finesse de cette derniĂšre impacte grandement lâefficacitĂ© du mĂ©canisme. Ainsi, les modĂšles de contrĂŽle dâaccĂšs sont utilisĂ©s pour faciliter lâexpression et lâadministration desdites politiques. OrBAC est un modĂšle riche et dynamique, satisfaisant plusieurs besoins des IIC, en revanche il reste limitĂ© quant Ă la prise en charge de lâintĂ©gritĂ©, aussi bien en contexte localisĂ© que distribuĂ©. Ainsi, nous avons proposĂ© une extension dâOrBAC pour les environnements localisĂ©s, Integrity-OrBAC (I-OrBAC), qui tient compte de contraintes rĂ©elles liĂ©es Ă lâintĂ©gritĂ© pour statuer sur les requĂȘtes dâaccĂšs. I-OrBAC intĂšgre des paramĂštres issus de lâapplication de mĂ©thodes dâanalyse de risques pour reflĂ©ter les besoins des ressources passives et apprĂ©cier, Ă leur juste valeur, les habilitations des sujets. Cela nous a orientĂ©s vers une modĂ©lisation en multi-niveaux dâintĂ©gritĂ© qui favorisera la priorisation des biens sensibles, comme la stipule les programmes de protection des IC. Dans I-OrBAC, les niveaux dâintĂ©gritĂ© servent aussi bien Ă contraindre lâattribution des privilĂšges quâĂ la rendre plus flexible : ces niveaux restreignent les accĂšs pour garantir que seuls les utilisateurs chevronnĂ©s accĂšdent aux ressources sensibles, mais permettent aussi aux sujets de diffĂ©rents rĂŽles de rĂ©aliser une mĂȘme tĂąche, Ă©tant bien sĂ»r assujettis Ă des niveaux seuils diffĂ©rents. Pour rendre I-OrBAC proactif - non limitĂ© Ă statuer uniquement sur les requĂȘtes dâaccĂšs - nous avons proposĂ© un algorithme qui vise Ă dĂ©terminer le sujet le plus adĂ©quat, parmi les rĂŽles prioritaires, pour la rĂ©alisation dâune tĂąche sans attendre que les sujets nâen fassent la requĂȘte. Lâalgorithme est dĂ©crit par un systĂšme dâinfĂ©rence pour faciliter sa comprĂ©hension tout en favorisant la conduite de raisonnements logiques et la dĂ©rivation de conclusions. Nous avons proposĂ© une implĂ©mentation de notre modĂšle dans le cadre dâune Ă©tude de cas tirĂ©e du projet europĂ©en FP7 CRUTIAL relatif aux rĂ©seaux de transport et de distribution dâĂ©lectricitĂ©. Finalement, pour pallier les problĂšmes issus des collaborations, nous avons fait appel aux contrats Ă©lectroniques pour Ă©tendre I-OrBAC aux environnements distribuĂ©s - lâextension Distributed IOrBAC (DI-OrBAC). Ces pactes servent non seulement Ă dĂ©finir le contexte, les clauses ainsi que les activitĂ©s Ă rĂ©aliser mais aussi Ă prĂ©venir lâoccurrence de litiges et Ă les rĂ©soudre. Toutefois, nous avons dĂ» concevoir des mĂ©canismes adaptĂ©s Ă notre modĂšle I-OrBAC pour leur nĂ©gociation et leur application
When an Intramolecular Disulfide Bridge Governs the Interaction of DUOX2 with Its Partner DUOXA2
Aims: The dual oxidase 2 (DUOX2) protein belongs to the NADPH oxidase (NOX) family. As H2O2 generator, it plays a key role in both thyroid hormone biosynthesis and innate immunity. DUOX2 forms with its maturation factor, DUOX activator 2 (DUOXA2), a stable complex at the cell surface that is crucial for the H2O2-generating activity, but the nature of their interaction is unknown. The contribution of some cysteine residues located in the N-terminal ectodomain of DUOX2 in a surface protein?protein interaction is suggested. We have investigated the involvement of different cysteine residues in the formation of covalent bonds that could be of critical importance for the function of the complex. Results: We report the identification and the characterization of an intramolecular disulfide bond between cys-124 of the N-terminal ectodomain and cys-1162 of an extracellular loop of DUOX2, which has important functional implications in both export and activity of DUOX2. This intramolecular bridge provides structural support for the formation of interdisulfide bridges between the N-terminal domain of DUOX2 and the two extracellular loops of its partner, DUOXA2. Innovation: Both stability and function of the maturation factor, DUOXA2, are dependent on the oxidative folding of DUOX2, indicating that DUOX2 displays a chaperone-like function with respect to its partner. Conclusions: The oxidative folding of DUOX2 that takes place in the endoplasmic reticulum (ER) appears to be a key event in the trafficking of the DUOX2/DUOXA2 complex as it promotes an appropriate conformation of the N-terminal region, which is propitious to subsequent covalent interactions with the maturation factor, DUOXA2. Antioxid. Redox Signal. 23, 724?733.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140308/1/ars.2015.6265.pd
Pharmacological evidence for the stimulation of NADPH oxidase by P2X7 receptors in mouse submandibular glands
ATP in the 100 ΌM-1 mM concentration range provoked a calcium-independent increase of the oxidation of dichlorodihydrofluorescein (DCFH) to dichlorofluorescein (DCF) by mouse submandibular cells. 3âČ-O-(4-benzoyl)benzoyl adenosine 5âČ-triphosphate (BzATP), a P2X7 agonist, but not a muscarinic or an adrenergic agonist, reproduced the effect of ATP. The inhibition of phospholipase C by U73122 or the potentiation of P2X4 receptor activation with ivermectin did not modify the response to ATP. ATP did not increase the oxidation of DCFH in cells isolated from submandibular glands of P2X7 knockout mice or in cells pretreated with a P2X7 antagonist. The inhibition of protein kinase C or of mitogen-activated protein kinase (MAP kinase) or of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase blocked the oxidation of DCFH without affecting the increase of the intracellular concentration of calcium or the uptake of ethidium bromide in response to extracellular ATP. From these results it is concluded that the activation of the P2X7 receptors from submandibular glands triggers an intracellular signalling cascade involving protein kinase C and MAP kinase leading to the stimulation of NADPH oxidase and the subsequent generation of reactive oxygen species
Genetic polymorphisms and susceptibility to lung disease
Susceptibility to infection by bacterium such as Bacillus anthracis has a genetic basis in mice and may also have a genetic basis in humans. In the limited human cases of inhalation anthrax, studies suggest that not all individuals exposed to anthrax spores were infected, but rather, individuals with underlying lung disease, particularly asthma, sarcoidosis and tuberculosis, might be more susceptible. In this study, we determined if polymorphisms in genes important in innate immunity are associated with increased susceptibility to infectious and non-infectious lung diseases, particularly tuberculosis and sarcoidosis, respectively, and therefore might be a risk factor for inhalation anthrax. Examination of 45 non-synonymous polymorphisms in ten genes: p47phox (NCF1), p67phox (NCF2), p40phox (NCF4), p22phox (CYBA), gp91phox (CYBB), DUOX1, DUOX2, TLR2, TLR9 and alpha 1-antitrypsin (AAT) in a cohort of 95 lung disease individuals and 95 control individuals did not show an association of these polymorphisms with increased susceptibility to lung disease
Contribution Ă la rĂ©alisation dâun oscillateur push-push 80GHz synchronisĂ© par un signal subharmonique pour des applications radars anticollisions
Ce travail de thĂšse sâinscrit dans le cadre dâun projet Français « VĂ©Lo » qui est une collaboration entre lâindustriel STMicroelectronics et plusieurs laboratoires dont les laboratoires IMS-bordeaux et LAAS. Le but du projet est de concevoir un prototype de radar anticollision millimĂ©trique. Dans ce travail un synthĂ©tiseur de frĂ©quence est implĂ©mentĂ©. Ce dernier sera intĂ©grĂ© dans la chaine de rĂ©ception du dĂ©monstrateur. Une Ă©tude bibliographique des architectures classiques de systĂšme de radiocommunication a Ă©tĂ© rĂ©alisĂ©e. Des exemples dâarchitectures rencontrĂ©es dans le domaine millimĂ©trique ont Ă©tĂ© Ă©tudiĂ©s.Lâobjet principal de cette thĂšse est lâĂ©tude des oscillateurs synchronisĂ©s par injection ILO. Lâobjectif est de rĂ©aliser un oscillateur verrouillĂ© par injection qui sera pilotĂ© par un oscillateur de frĂ©quence plus basse possĂ©dant des caractĂ©ristiques de stabilitĂ© et de bruit meilleures.Dans ce travail de thĂšse, le mĂ©canisme de verrouillage des oscillateurs par injection a Ă©tĂ© dĂ©crit. Un modĂšle de synchronisation par injection sĂ©rie, basĂ© sur la thĂ©orie de Huntoon Weiss et inspirĂ© du travail de Badets rĂ©alisĂ© sur les oscillateurs synchrones verrouillĂ©s par injection parallĂšle, est proposĂ©. La thĂ©orie Ă©tablie a permis dâexprimer la plage de synchronisation en fonction de la topologie utilisĂ©e et des composants de la structure. La validitĂ© de la thĂ©orie a Ă©tĂ© Ă©valuĂ©e par la simulation de la structure. Les rĂ©sultats prĂ©sentĂ©s montrent une bonne concordance entre la simulation et la thĂ©orie et permettent de valider le principe de synchronisation par injection. La faisabilitĂ© de lâintĂ©gration dâun ILO millimĂ©trique synchronisĂ© par lâharmonique dâun signal de rĂ©fĂ©rence de frĂ©quence plus basse a Ă©tĂ© dĂ©montrĂ©e expĂ©rimentalement. Le synthĂ©tiseur de frĂ©quence est rĂ©alisĂ© en technologie BiCMOS 130nm pour des applications millimĂ©triques de STMicroelectronics. Ce dernier opĂšre dans une plage de 2GHz autour de la frĂ©quence 82,5GHz. Les performances en bruit du synthĂ©tiseur sont satisfaisantes. Le bruit de phase de lâILO recopie celui du signal injectĂ©. Les Ă©quipements de mesures utilisĂ©s, le bruit de phase de lâoscillateur atteint des valeurs infĂ©rieures Ă -110dBc/Hz Ă 1MHz de la porteuse.This thesis is a part of a French project "VELO". The project is collaboration between STMicroelectronics and several laboratories including IMS-Bordeaux and LAAS laboratories. The aim of this project is to achieve a prototype of millimeter anti-collision radar. In this work a frequency synthesizer is implemented. This circuit will be incorporated in the reception chain of the demonstrator. A bibliographical study of classical architecture was completed. Examples of architectures encountered in the millimeter frequency range have been studied. The purpose of this thesis is to study the phenomena of synchronization in oscillators. The objective is to design an injection locked oscillator ILO driven by another oscillator, the second oscillator operates at lower frequency and offers better stability and noise characteristics.In this thesis, the injection locking mechanism of the oscillators has been described. A model of synchronization by series injection is proposed. The model is based on the theory of Huntoon and Weiss and inspired by Badetsâ work performed on parallel injection. The theory expresses the synchronized frequency range depending on the used topology and the values of the components. The validity of the theory was evaluated by simulation. The results show good agreement between simulation and theory and validate the principle of synchronization by injection.The feasibility of a millimeter ILO synchronized by the harmonic of a reference signal operating at lower frequency has been demonstrated experimentally. The synthesizer was implemented in BiCMOS technology for 130nm applications millimeter of STMicroelectronics. The oscillator operates at 82.5 GHz and performs a frequency range of 2GHz. The noise performance of the synthesizer is satisfactory. The phase noise of the ILO depends on the reference phase noise, and reaches values of -110dBc/Hz at 1MHz from the carrier frequency
Contribution a l'etude du selenium en couches minces : influence de l'oxygene et des contacts metalliques sur ses proprietes electriques
SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Access control in distributed networks and critical infrastructures
La stabilitĂ© et le dĂ©veloppement des nations dĂ©pendent grandement de leurs Infrastructures Critiques (IC). Vu leur importance, de nombreuses menaces guettent leurs systĂšmes dâinformation - aussi appelĂ©s Infrastructures dâInformation Critiques (IIC) -, parmi elles: les atteintes Ă lâintĂ©gritĂ© de leurs donnĂ©es et processus informatisĂ©s ainsi que les abus pouvant survenir au cours des collaborations avec dâautres parties. LâintĂ©gritĂ© dâune information, qui est sa propriĂ©tĂ© de ne pas ĂȘtre altĂ©rĂ©e, est primordiale pour les IIC puisquâelles manipulent et gĂ©nĂšrent des informations devant nĂ©cessairement ĂȘtre correctes et fiables. Dans un contexte de mondialisation et dâouverture, les IC ne peuvent Ă©voluer sans collaborer avec leur environnement. Toutefois, cela nâest pas sans risques puisque les ressources quâelles engagent peuvent faire lâobjet de corruptions et de sabotages. Tentant de rĂ©duire les risques de corruptions pouvant Ă©maner de lâintĂ©rieur comme de lâextĂ©rieur, nous avons ĆuvrĂ© Ă lâamĂ©lioration du mĂ©canisme de contrĂŽle dâaccĂšs. Incontournable, il vise Ă limiter les actions auxquelles peuvent prĂ©tendre les utilisateurs lĂ©gitimes du systĂšme, conformĂ©ment Ă la politique de sĂ©curitĂ© de lâorganisation. La pertinence et la finesse de cette derniĂšre impacte grandement lâefficacitĂ© du mĂ©canisme. Ainsi, les modĂšles de contrĂŽle dâaccĂšs sont utilisĂ©s pour faciliter lâexpression et lâadministration desdites politiques. OrBAC est un modĂšle riche et dynamique, satisfaisant plusieurs besoins des IIC, en revanche il reste limitĂ© quant Ă la prise en charge de lâintĂ©gritĂ©, aussi bien en contexte localisĂ© que distribuĂ©. Ainsi, nous avons proposĂ© une extension dâOrBAC pour les environnements localisĂ©s, Integrity-OrBAC (I-OrBAC), qui tient compte de contraintes rĂ©elles liĂ©es Ă lâintĂ©gritĂ© pour statuer sur les requĂȘtes dâaccĂšs. I-OrBAC intĂšgre des paramĂštres issus de lâapplication de mĂ©thodes dâanalyse de risques pour reflĂ©ter les besoins des ressources passives et apprĂ©cier, Ă leur juste valeur, les habilitations des sujets. Cela nous a orientĂ©s vers une modĂ©lisation en multi-niveaux dâintĂ©gritĂ© qui favorisera la priorisation des biens sensibles, comme la stipule les programmes de protection des IC. Dans I-OrBAC, les niveaux dâintĂ©gritĂ© servent aussi bien Ă contraindre lâattribution des privilĂšges quâĂ la rendre plus flexible : ces niveaux restreignent les accĂšs pour garantir que seuls les utilisateurs chevronnĂ©s accĂšdent aux ressources sensibles, mais permettent aussi aux sujets de diffĂ©rents rĂŽles de rĂ©aliser une mĂȘme tĂąche, Ă©tant bien sĂ»r assujettis Ă des niveaux seuils diffĂ©rents. Pour rendre I-OrBAC proactif - non limitĂ© Ă statuer uniquement sur les requĂȘtes dâaccĂšs - nous avons proposĂ© un algorithme qui vise Ă dĂ©terminer le sujet le plus adĂ©quat, parmi les rĂŽles prioritaires, pour la rĂ©alisation dâune tĂąche sans attendre que les sujets nâen fassent la requĂȘte. Lâalgorithme est dĂ©crit par un systĂšme dâinfĂ©rence pour faciliter sa comprĂ©hension tout en favorisant la conduite de raisonnements logiques et la dĂ©rivation de conclusions. Nous avons proposĂ© une implĂ©mentation de notre modĂšle dans le cadre dâune Ă©tude de cas tirĂ©e du projet europĂ©en FP7 CRUTIAL relatif aux rĂ©seaux de transport et de distribution dâĂ©lectricitĂ©. Finalement, pour pallier les problĂšmes issus des collaborations, nous avons fait appel aux contrats Ă©lectroniques pour Ă©tendre I-OrBAC aux environnements distribuĂ©s - lâextension Distributed IOrBAC (DI-OrBAC). Ces pactes servent non seulement Ă dĂ©finir le contexte, les clauses ainsi que les activitĂ©s Ă rĂ©aliser mais aussi Ă prĂ©venir lâoccurrence de litiges et Ă les rĂ©soudre. Toutefois, nous avons dĂ» concevoir des mĂ©canismes adaptĂ©s Ă notre modĂšle I-OrBAC pour leur nĂ©gociation et leur application.Nations stability and development depend deeply on their Critical Infrastructures (CI). Given their importance, many threats target their information systems - also called Critical Information Infrastructures (CII) -, among them: the attacks against integrity of their data and computerized processes and the abuses that may occur during the collaborations with other parties. Information integrity, that is its property of not being corrupted, is paramount to the CII as they manipulate and generate information that must necessarily be correct and reliable. In the context of globalization and openness, CI cannot evolve without collaborating with their environment. However, this is not without risks, since their resources can be targets of corruptions and sabotages. Trying to reduce corruption risks that may occur both from inside and outside, we focused on improving the access control mechanism. Being necessary, it aims to limit the actions of the system legitimate users in accordance with the organization security policy. The relevance and the fine-grained property of the policy impact the effectiveness of the mechanism. Therefore, access control models are used to facilitate the expression and the administration of such policies. OrBAC is a rich and dynamic model, satisfying several CII needs; however it remains limited as to the support of integrity, both in local and distributed environments. Thus, we proposed an OrBAC extension for local environments, Integrity-OrBAC (IOrBAC), which takes into account real integrity constraints to rule on access requests. I-OrBAC includes some parameters extracted from the application of risk analysis methods to reflect passive resources needs and appreciate pertinently subjectsâ clearances. This led us to a multi integrity levels modeling, that promotes the prioritization of sensitive resources just like the CI protection programs do. In I-OrBAC the integrity levels are used both to constraint the assignment of privileges and to make it more flexible: these levels restrict access to ensure that only experienced users access sensitive resources but also allow subjects of different roles to perform the same task, of course being subject to different threshold levels. To make IOrBAC proactive - not only being limited to ruling on access requests - we proposed an algorithm that aims to determine the most appropriate subject, among the priority roles, for achieving a task without waiting for subjects to request it. The algorithm is described by an inference system to ease its understanding while promoting the conduct of logical reasoning and deriving conclusions. We proposed an implementation of our model through a case study drawn from the FP7 European project (CRUTIAL) on electrical energy transmission and distribution. Finally, to address problems that arise from collaborations, we used electronic contracts to enrich and extend IOrBAC to serve in distributed environments - the extension is called Distributed I-OrBAC (DI-OrBAC). These agreements aim, on the one hand, to define the context, terms and activities to be achieved and serve, on the other hand, to prevent and resolve the disputes. However, we had to design appropriate mechanisms for our I-OrBAC model in order to lead correct negotiations and rigorous enforcement of these contracts
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