Routing protocol for anycast communications in a wireless sensor network

Abstract. In wireless sensor networks, there is usually a sink which gathers data from the battery-powered sensor nodes. As sensor nodes around the sink consume their energy faster than the other nodes, several sinks have to be deployed to increase the network lifetime. In this paper, we motivate the need of anycast communications in wireless networks, where all the sinks are identical and can gather data from any source. To reduce interference and congestion areas on the wireless medium, the path from a source to a sink has to be distant from the path connecting another source to another sink. We show that determining distant paths from sources to sinks is an NP-hard problem, and we propose a linear formulation in order to obtain optimal solutions. Then, we propose a sink selection and routing protocol called S4 and based on realistic assumptions and we evaluate it through simulations. Finally, we conclude that anycast routing protocols in wireless sensor networks should not compute paths independently for each source, but rather consider all the sources simultaneously

SLA4CLOUD: Measurement and SLA Management of Heterogeneous Cloud Infrastructures Testbeds

International audienceThere is an increasing number of cloud platforms emerging in both academia and industry. They often allow the collaboration of a pool of resources from multiple infrastructures (IaaS) in order to benefit from the unique features that each presents. AmSud SLA4CLOUD project is a collaboration between research groups from South America and France on Cloud Computing with the aim to develop different offers of Cloud Service with Service a Level Agreement (SLA) representation. This project builds on different existing projects such as the EU Easi-Clouds project. After introducing the main capabilities and features of OpenStack, this document addresses the integration of OpenStack-based platforms into a larger and heterogeneous multi-cloud infrastructures distributed in different continents. Finally, we aim to implement a strategy for dynamic services composition and optimal placement of virtual machines in order to improve network capabilities without compromising performance requirements as specified in a SLA

Humoral Autoimmune Responses to the Squamous Cell Carcinoma Antigen Protein Family in Psoriasis

Substantial evidence indicates that psoriasis is a T-lymphocyte-mediated autoimmune disease. However, longstanding data also indicate IgG and complement deposition in upper epidermis of psoriasis plaques. This led us to propose that autoantigen–autoantibody interactions in the skin may also be of pathogenic importance. Here, we have confirmed the presence of IgG in upper lesional epidermis and used high-resolution two-dimensional immunoblotting of extracts from this tissue, and laser desorption mass spectrometry of tryptic peptides, to define a series of epidermal proteins that bind IgG from psoriatic serum. The most prominent of these autoantigens are homologues of the serpin, squamous cell carcinoma antigen (SCCA), the other autoantigens identified including arginase 1, enolase 1, and keratin 10. Blood levels of IgG autoantibodies that bind to SCCA proteins were significantly higher in psoriasis than healthy controls (P=0.005), but were not detectable in sera from patients with active atopic dermatitis. To our knowledge, SCCA proteins have not previously been described as autoantigenic in animals or humans and form complexes with IgG that are associated with complement deposition. These findings expose potentially pathogenic humoral immunologic events and thus possible therapeutic targets in psoriasis

Pneumolysin Activates the NLRP3 Inflammasome and Promotes Proinflammatory Cytokines Independently of TLR4

Pneumolysin (PLY) is a key Streptococcus pneumoniae virulence factor and potential candidate for inclusion in pneumococcal subunit vaccines. Dendritic cells (DC) play a key role in the initiation and instruction of adaptive immunity, but the effects of PLY on DC have not been widely investigated. Endotoxin-free PLY enhanced costimulatory molecule expression on DC but did not induce cytokine secretion. These effects have functional significance as adoptive transfer of DC exposed to PLY and antigen resulted in stronger antigen-specific T cell proliferation than transfer of DC exposed to antigen alone. PLY synergized with TLR agonists to enhance secretion of the proinflammatory cytokines IL-12, IL-23, IL-6, IL-1β, IL-1α and TNF-α by DC and enhanced cytokines including IL-17A and IFN-γ by splenocytes. PLY-induced DC maturation and cytokine secretion by DC and splenocytes was TLR4-independent. Both IL-17A and IFN-γ are required for protective immunity to pneumococcal infection and intranasal infection of mice with PLY-deficient pneumococci induced significantly less IFN-γ and IL-17A in the lungs compared to infection with wild-type bacteria. IL-1β plays a key role in promoting IL-17A and was previously shown to mediate protection against pneumococcal infection. The enhancement of IL-1β secretion by whole live S. pneumoniae and by PLY in DC required NLRP3, identifying PLY as a novel NLRP3 inflammasome activator. Furthermore, NLRP3 was required for protective immunity against respiratory infection with S. pneumoniae. These results add significantly to our understanding of the interactions between PLY and the immune system

Circulating Pneumolysin Is a Potent Inducer of Cardiac Injury during Pneumococcal Infection

Streptococcus pneumoniae accounts for more deaths worldwide than any other single pathogen through diverse disease manifestations including pneumonia, sepsis and meningitis. Life-threatening acute cardiac complications are more common in pneumococcal infection compared to other bacterial infections. Distinctively, these arise despite effective antibiotic therapy. Here, we describe a novel mechanism of myocardial injury, which is triggered and sustained by circulating pneumolysin (PLY). Using a mouse model of invasive pneumococcal disease (IPD), we demonstrate that wild type PLY-expressing pneumococci but not PLY-deficient mutants induced elevation of circulating cardiac troponins (cTns), well-recognized biomarkers of cardiac injury. Furthermore, elevated cTn levels linearly correlated with pneumococcal blood counts (r=0.688, p=0.001) and levels were significantly higher in non-surviving than in surviving mice. These cTn levels were significantly reduced by administration of PLY-sequestering liposomes. Intravenous injection of purified PLY, but not a non-pore forming mutant (PdB), induced substantial increase in cardiac troponins to suggest that the pore-forming activity of circulating PLY is essential for myocardial injury in vivo. Purified PLY and PLY-expressing pneumococci also caused myocardial inflammatory changes but apoptosis was not detected. Exposure of cultured cardiomyocytes to PLY-expressing pneumococci caused dose-dependent cardiomyocyte contractile dysfunction and death, which was exacerbated by further PLY release following antibiotic treatment. We found that high PLY doses induced extensive cardiomyocyte lysis, but more interestingly, sub-lytic PLY concentrations triggered profound calcium influx and overload with subsequent membrane depolarization and progressive reduction in intracellular calcium transient amplitude, a key determinant of contractile force. This was coupled to activation of signalling pathways commonly associated with cardiac dysfunction in clinical and experimental sepsis and ultimately resulted in depressed cardiomyocyte contractile performance along with rhythm disturbance. Our study proposes a detailed molecular mechanism of pneumococcal toxin-induced cardiac injury and highlights the major translational potential of targeting circulating PLY to protect against cardiac complications during pneumococcal infections

Cross-Layering and routing in an ad hoc network : frame relay policy on a wireless sensor network organized according to a tree topology

La tendance actuelle des réseaux de capteurs sans fil est d’avoir un seul réseau supportant plusieurs applications et fournissant plusieurs QoS. Dans cette thèse, nous étudions les techniques de cross-layering afin d’améliorer les performances et de fournir de la QoS. Tout d’abord, nous généralisons le concept de la méthode d’accès MaCARI en proposant une architecture multi-couches où plusieurs combinaisons de protocoles MAC-routage sont utilisées. Une file d’attente est associée à chaque combinaison, et chaque combinaison est activée pour une période précise. Le but est de profiter de ces combinaisons pour offrir différentes QoS. Cependant, cette architecture cause un problème de dimensionnement des périodes, ce qui a un impact sur les performances du réseau. Nous proposons, ensuite, des techniques de cross-layering en échangeant les paquets entre les différentes files d’attente afin de résoudre le problème de dimensionnement. Durant sa période, chaque combinaison traite tous les paquets de sa file d’attente ainsi que les paquets des files d’attente d’autres périodes. Nous montrons par simulation que notre approche améliore les performances du réseau.The current trend in wireless sensor networks is to have a single network supporting serveral applications and providing several QoS. In this thesis, we study the cross-layering techniques in order to improve the network performance and provide several QoS. Fistly, we generalize the concept of the access method MaCARI by proposing a multi-stack architecture in which several MAC-routing combination protocols are used. A queue is associated to each combination, and each combination is active for a specified period. The purpose consists in using these combinations in order to provide different QoS. However, this architecture yields to a dimensioning problem for the periods reducing the network performance. Secondly, we propose cross-layering techniques by exchanging packets between different queues to solve the dimensioning problem. During its period, each combination treats all the packets of its queue and the packets related to queues associated to other periods. We show by simulations that our approach improves the network performance

Cross-Layering et routage dans un réseau ad hoc : politique de relais de trame sur un réseau de capteurs sans fil organisé selon une topologie en arbre

The current trend in wireless sensor networks is to have a single network supporting serveral applications and providing several QoS. In this thesis, we study the cross-layering techniques in order to improve the network performance and provide several QoS. Fistly, we generalize the concept of the access method MaCARI by proposing a multi-stack architecture in which several MAC-routing combination protocols are used. A queue is associated to each combination, and each combination is active for a specified period. The purpose consists in using these combinations in order to provide different QoS. However, this architecture yields to a dimensioning problem for the periods reducing the network performance. Secondly, we propose cross-layering techniques by exchanging packets between different queues to solve the dimensioning problem. During its period, each combination treats all the packets of its queue and the packets related to queues associated to other periods. We show by simulations that our approach improves the network performance.La tendance actuelle des réseaux de capteurs sans fil est d’avoir un seul réseau supportant plusieurs applications et fournissant plusieurs QoS. Dans cette thèse, nous étudions les techniques de cross-layering afin d’améliorer les performances et de fournir de la QoS. Tout d’abord, nous généralisons le concept de la méthode d’accès MaCARI en proposant une architecture multi-couches où plusieurs combinaisons de protocoles MAC-routage sont utilisées. Une file d’attente est associée à chaque combinaison, et chaque combinaison est activée pour une période précise. Le but est de profiter de ces combinaisons pour offrir différentes QoS. Cependant, cette architecture cause un problème de dimensionnement des périodes, ce qui a un impact sur les performances du réseau. Nous proposons, ensuite, des techniques de cross-layering en échangeant les paquets entre les différentes files d’attente afin de résoudre le problème de dimensionnement. Durant sa période, chaque combinaison traite tous les paquets de sa file d’attente ainsi que les paquets des files d’attente d’autres périodes. Nous montrons par simulation que notre approche améliore les performances du réseau

Relationship of structure to function in the pore-forming toxin Pneumolysin from Streptococcus pneumoniae

Pneumolysin is an important virulence factor produced by the human pathogen Streptococcus pneumoniae. It belongs to the family of cholesterol dependent cytolysins (CDCs) that damage the target cell membrane, by forming large oligomeric pores of 30 to 80 toxin monomers, where each monomer is thought to contribute at least two p-hairpins. A panel of mutations was done in the two putative transmembrane region of pneumolysin TMH1 and TMH2 located in domain 3 of the toxin monomer, and believed to be lining the pore lumen. The generated mutants exhibited different levels of haemolytic activity, particularly the single mutation W278F, W278D, and the triple mutation (D257N-E258Q-E260Q), largely impaired the haemolytic activity of the wild-type toxin. These mutant toxins along with a previously made lytic deficient mutant W433F were subjected to further studies. Circular dichroism analysis done with those mutants showed that the secondary structure of the native toxin was conserved. The kinetics of release of calcein from liposomes along with the kinetics of lysis of erythrocytes exposed to these mutants was substantially slower than that of the wild-type toxin. Pneumolysin and other CDCs induced pores were studied on model systems like lipid bilayer and liposomes. In this thesis, I demonstrated the formation of pores by pneumolysin on the membrane of a 'real' cell by using the patch-clamp technique. Pneumolysin induced heterogeneous pore on either side of the membrane, of different conductance states, classified as small, medium and large. A stepwise increase in current was observed with early appearance of small conductance channels followed by larger ones. The mutant toxins generated in this work and W433F were also tested with patch clamping. They formed pores of various conductance states with a decrease in the occurrence of large channels, in comparison to the wild-type

Cross-Layering et routage dans un réseau ad hoc (politique de relais de trame sur un réseau de capteurs sans fil organisé selon une topologie en arbre)

La tendance actuelle des réseaux de capteurs sans fil est d avoir un seul réseau supportant plusieurs applications et fournissant plusieurs QoS. Dans cette thèse, nous étudions les techniques de cross-layering afin d améliorer les performances et de fournir de la QoS. Tout d abord, nous généralisons le concept de la méthode d accès MaCARI en proposant une architecture multi-couches où plusieurs combinaisons de protocoles MAC-routage sont utilisées. Une file d attente est associée à chaque combinaison, et chaque combinaison est activée pour une période précise. Le but est de profiter de ces combinaisons pour offrir différentes QoS. Cependant, cette architecture cause un problème de dimensionnement des périodes, ce qui a un impact sur les performances du réseau. Nous proposons, ensuite, des techniques de cross-layering en échangeant les paquets entre les différentes files d attente afin de résoudre le problème de dimensionnement. Durant sa période, chaque combinaison traite tous les paquets de sa file d attente ainsi que les paquets des files d attente d autres périodes. Nous montrons par simulation que notre approche améliore les performances du réseau.The current trend in wireless sensor networks is to have a single network supporting serveral applications and providing several QoS. In this thesis, we study the cross-layering techniques in order to improve the network performance and provide several QoS. Fistly, we generalize the concept of the access method MaCARI by proposing a multi-stack architecture in which several MAC-routing combination protocols are used. A queue is associated to each combination, and each combination is active for a specified period. The purpose consists in using these combinations in order to provide different QoS. However, this architecture yields to a dimensioning problem for the periods reducing the network performance. Secondly, we propose cross-layering techniques by exchanging packets between different queues to solve the dimensioning problem. During its period, each combination treats all the packets of its queue and the packets related to queues associated to other periods. We show by simulations that our approach improves the network performance.CLERMONT FD-Bib.électronique (631139902) / SudocSudocFranceF

SF-DS: A Slot-Free Decoding Scheme for Collided LoRa Transmissions

International audienceRecent monitoring applications extensively rely on low-power wide-area networks, such as those provided by LoRa and LoRaWAN, in order to enable end-devices to communicate over long distances. However, in large-scale deployments, the small throughput of LoRa is further reduced due to collisions. In this paper, we propose a new scheme SF-DS that aims to decode colliding frames. SF-DS relies on frequency detection at each symbol frontier. It reduces detection errors when symbols of similar values are superposed. It is compatible with legacy LoRaWAN communications, and only requires modifications at the gateway. Our simulation results show that SF-DS is able to decode more collisions than the other protocols from the literature (about twice more for 16 nodes and SF12), therefore increasing the throughput and thus the scalability of the network