Solving the Cooling Flow Problem through Mechanical AGN Feedback

Unopposed radiative cooling of plasma would lead to the cooling catastrophe, a massive inflow of condensing gas, manifest in the core of galaxies, groups and clusters. The last generation X-ray telescopes, Chandra and XMM, have radically changed our view on baryons, indicating AGN heating as the balancing counterpart of cooling. This work reviews our extensive investigation on self-regulated heating. We argue that the mechanical feedback, based on massive subrelativistic outflows, is the key to solving the cooling flow problem, i.e. dramatically quenching the cooling rates for several Gyr without destroying the cool-core structure. Using a modified version of the 3D hydrocode FLASH, we show that bipolar AGN outflows can further reproduce fundamental observed features, such as buoyant bubbles, weak shocks, metals dredge- up, and turbulence. The latter is an essential ingredient to drive nonlinear thermal instabilities, which cause the formation of extended cold gas, a residual of the quenched cooling flow and, later, fuel for the feedback engine. Compared to clusters, groups and galaxies require a gentler mechanical feedback, in order to avoid catastrophic overheating. We highlight the essential characteristics for a realistic AGN feedback, with emphasis on observational consistency.Comment: Accepted by AN; 4 pages, 2 figure

Know Your Enemy: Stealth Configuration-Information Gathering in SDN

Software Defined Networking (SDN) is a network architecture that aims at providing high flexibility through the separation of the network logic from the forwarding functions. The industry has already widely adopted SDN and researchers thoroughly analyzed its vulnerabilities, proposing solutions to improve its security. However, we believe important security aspects of SDN are still left uninvestigated. In this paper, we raise the concern of the possibility for an attacker to obtain knowledge about an SDN network. In particular, we introduce a novel attack, named Know Your Enemy (KYE), by means of which an attacker can gather vital information about the configuration of the network. This information ranges from the configuration of security tools, such as attack detection thresholds for network scanning, to general network policies like QoS and network virtualization. Additionally, we show that an attacker can perform a KYE attack in a stealthy fashion, i.e., without the risk of being detected. We underline that the vulnerability exploited by the KYE attack is proper of SDN and is not present in legacy networks. To address the KYE attack, we also propose an active defense countermeasure based on network flows obfuscation, which considerably increases the complexity for a successful attack. Our solution offers provable security guarantees that can be tailored to the needs of the specific network under consideratio

LineSwitch: Efficiently Managing Switch Flow in Software-Defined Networking while Effectively Tackling DoS Attacks

Software Defined Networking (SDN) is a new networking architecture which aims to provide better decoupling between network control (control plane) and data forwarding functionalities (data plane). This separation introduces several benefits, such as a directly programmable and (virtually) centralized network control. However, researchers showed that the required communication channel between the control and data plane of SDN creates a potential bottleneck in the system, introducing new vulnerabilities. Indeed, this behavior could be exploited to mount powerful attacks, such as the control plane saturation attack, that can severely hinder the performance of the whole network. In this paper we present LineSwitch, an efficient and effective solution against control plane saturation attack. LineSwitch combines SYN proxy techniques and probabilistic blacklisting of network traffic. We implemented LineSwitch as an extension of OpenFlow, the current reference implementation of SDN, and evaluate our solution considering different traffic scenarios (with and without attack). The results of our preliminary experiments confirm that, compared to the state-of-the-art, LineSwitch reduces the time overhead up to 30%, while ensuring the same level of protection.Comment: In Proceedings of the 10th ACM Symposium on Information, Computer and Communications Security (ASIACCS 2015). To appea

A safe sovereign asset for the EU banks: an assessment

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Protection of the appearance of an industrial product through shape marks, industrial designs or copyrights: the EU legal perspective and practical approach

This presentation will deal with the challenges from an EU perspectiv

Interactions sociales et troubles du spectre autistique: le point de vue des professionnel(le)s

Ce travail de recherche aborde le thème de la prise en charge des enfants et des adolescent·e·s atteint·e·s des troubles du spectre autistique dans un groupe hétérogène. Il s’intéresse plus particulièrement aux interactions sociales de ces jeunes et vise à déterminer quel·le·s outils et stratégies sont utilisé·e·s par les professionnel·le·s de l’enseignement spécialisé et de l’éducation pour les favoriser

L'utilisation de la pédagogie d'expression et de son outil méthodologique de la ludocréativité au sein de l'éducation sociale

Ce travail questionne la pertinence d’utiliser la pédagogie d’expression ludocréative en tant qu’outil éducatif pour favoriser la participation des enfants. L’objectif de cette recherche est d’établir des liens entre l’éducation sociale, la ludocréativité et la participation afin d’identifier les possibilités pour les éducateurs sociaux et les éducatrices sociales de faire de la pédagogie d’expression ludocréative un outil d’intervention. Plus précisément, il s’agit de répondre à la question de recherche suivante : « En quoi la pédagogie d’expression ludocréative constitue-t-elle un outil en éducation sociale pour favoriser la participation des enfants ? ». Cette question est étudiée autravers d’une revue de littérature et d’une enquête empirique

The Design of New Adjuvants for Mucosal Immunity to Neisseria meningitidis B in Nasally Primed Neonatal Mice for Adult Immune Response

The aim of this study was to determine the value of detoxified Shiga toxins Stx1 and Stx2 (toxoids of Escherichia coli) as mucosal adjuvants in neonatal mice for immunogenicity against the outer membrane proteins (OMPs) of Neisseria meningitidis B. Mucosal immunization has been shown to be effective for the induction of antigen-specific immune responses in both the systemic and mucosal compartments. Systemic antibody levels (IgG, IgG1, IgG2a, IgG2b, IgM, and IgA) and mucosal IgM and IgA were measured by ELISA using an N. meningitidis as an antigen. In addition, IFN-γ and IL-6 production were measured after stimulated proliferation of immune cells. Intranasal administration elicited a higher anti-OMP IgA response in both saliva and vaginal fluids. Our results suggest that both Stx1 and Stx2 toxoids are effective mucosal adjuvants for the induction of Ag-specific IgG, IgM, and IgA antibodies. The toxoids significantly enhanced the IgG and IgM response against OMPs with a potency equivalent to CT, with the response being characterized by both IgG1 and IgG2a isotypes, and increased IFN-gamma production. Additionally, bactericidal activity was induced with IgG and IgM antibodies of high avidity. These results support the use of the new toxoids as potent inducing adjuvants that are particularly suitable for mucosal immunization