Efficient Actor Recovery Paradigm For Wireless Sensor And Actor Networks

Wireless sensor networks (WSNs) are becoming widely used worldwide. Wireless Sensor and Actor Networks (WSANs) represent a special category of WSNs wherein actors and sensors collaborate to perform specific tasks. WSANs have become one of the most preeminent emerging type of WSNs. Sensors with nodes having limited power resources are responsible for sensing and transmitting events to actor nodes. Actors are high-performance nodes equipped with rich resources that have the ability to collect, process, transmit data and perform various actions. WSANs have a unique architecture that distinguishes them from WSNs. Due to the characteristics of WSANs, numerous challenges arise. Determining the importance of factors usually depends on the application requirements. The actor nodes are the spine of WSANs that collaborate to perform the specific tasks in an unsubstantiated and uneven environment. Thus, there is a possibility of high failure rate in such unfriendly scenarios due to several factors such as power fatigue of devices, electronic circuit failure, software errors in nodes or physical impairment of the actor nodes and inter-actor connectivity problem. It is essential to keep inter-actor connectivity in order to insure network connectivity. Thus, it is extremely important to discover the failure of a cut-vertex actor and network-disjoint in order to improve the Quality-of-Service (QoS). For network recovery process from actor node failure, optimal re-localization and coordination techniques should take place. In this work, we propose an efficient actor recovery (EAR) paradigm to guarantee the contention-free traffic-forwarding capacity. The EAR paradigm consists of Node Monitoring and Critical Node Detection (NMCND) algorithm that monitors the activities of the nodes to determine the critical node. In addition, it replaces the critical node with backup node prior to complete node-failure which helps balances the network performance. The packet is handled using Network Integration and Message Forwarding (NIMF) algorithm that determines the source of forwarding the packets (Either from actor or sensor). This decision-making capability of the algorithm controls the packet forwarding rate to maintain the network for longer time. Furthermore, for handling the proper routing strategy, Priority-Based Routing for Node Failure Avoidance (PRNFA) algorithm is deployed to decide the priority of the packets to be forwarded based on the significance of information available in the packet. To validate the effectiveness of the proposed EAR paradigm, we compare the performance of our proposed work with state-of the art localization algorithms. Our experimental results show superior performance in regards to network life, residual energy, reliability, sensor/ actor recovery time and data recovery

Isolation, cultivation and characterization of cells originating from tumor and tumor margin of patients with basal cell carcinoma in vitro

Homeostaza kože direktno zavisi od mehanizma kontinuiranog obnavljanja ćelijske populacije kože i njene sposobnosti regeneracije. U epidermisu je prisutna posebna populacija ćelija zadužena za proces samoobnavljanja kože, tzv. epidermalne matične ćelije koje imaju sposobnost proliferacije, migracije, diferencijacije i programirane ćelijske smrti. Ukoliko dođe do narušavanja ravnoteže između ovih procesa, može doći do maligne transformacije zdrave matične ćelije u kancersku matičnu ćeliju. Poznato je da za hemorezistenciju, metastaziranje i recidiviranje tumora odgovornost nosi posebna populaciju tumorskih ćelija koje se nazivaju kancerske matične ćelije. Istraživanja pokazuju da bazocelularni karcinom kože vodi poreklo od matičnih ćelija ispupčenja folikula dlake, infundibuluma dlake i interfolikularnog epidermisa. Bazocelularni karcinom (BCK) je najčešći maligni tumor kože, pa i ako retko metastazira karakteriše ga invazivni rast pri čemu infiltriše okolne strukture i dovodi do ozbiljnih funkcionalnih i estetskih defekata. U literaturi se kao jedan od ključnih faktora odgovornih za recidiviranje navodi neadekvatna širina margine resekcije tumora. Istraživanja su pokazala da je za primarne BCK na koži lica veličine do 20 mm preporučena širina margine 3 mm. Cilj ovog istraživanja bio je identifikacija i karakterizacija subpopulacije ćelija sa osobinama matičnosti izolovanih iz BCK-a i bliske margine od 3 mm, ispitivanjem proliferativnog, klonogenog i migratornog potencijala, analizom ekspresije embrionalnih, mezenhimskih i tumorskih markera, analizom biohemijske strukture ćelija, ispitivanjem sposobnosti diferencijacije u više ćelijskih linija kao i stepena otpornosti ćelija na dejstvo citostatika. U istraživanju je učestvovalo 13 pacijenata sa primarnim bazocelularnim karcinomom na koži lica veličine do 20 mm. Nakon detaljno uzete anamneze i potpisanog informisanog pristanka pristupalo se hirurškoj eksciziji tumorske promene, koja se smatra zlatnim standardom u terapiji BCK-a. Iz svih ekscidiranih uzorka za izolaciju ćelija uzet je deo tumorskog tkiva, tkiva bliske margine (udaljene 3 mm od makroskopske granice tumora) i deo zdrave kože obuhvaćen oblikom resekcije (udaljen od makroskopske granice tumora više od 5 mm), dok je preostali deo tkiva poslat na histopatološku analizu. Za karakterizaciju ćelija u kulturi korišćeni su testovi proliferacije, migracije, formiranja kolonija, sfera i ramanska spektroskopija. Markeri kancerskih matičnih ćelija (KMĆ) analizirani su ,,Real-Time PCR” metodom i protočnom citometrijom...renewal and regeneration and the epidermis harbors a special cell population responsible for the process of self-renewal and regeneration of the skin, so called epidermal stem cells that have the ability to proliferate, migrate, differentiate, and undergo programmed cell death. If imbalance between these processes occurs, malignant transformation of healthy stem cell into the cancerous stem cell may happen. It is also known that a specific population of tumor cells called cancer stem cells is responsible for the hemoresistance, metastasis, and recurrence. Studies have shown that skin basal cell carcinoma is caused by stem cells of hair follicle, hair infundibulum and interfollicular epidermis. Basocellular carcinoma (BCC) is the most common malignant tumor of the skin, but it rarely gives metastases It is characterized by invasive growth, infiltrating surrounding structures and leading to serious functional and aesthetic defects. In the literature, inadequate margins are indicated as one of the key factors responsible for tumor recurrences. Studies have shown that for the primary facial skin BCC of less than 20 mm a margin of 3 mm is recommended. The aim of this study was to identify and characterize the cell subpopulation with stem characteristics whithin BCC and its margins (3 mm close) by testing proliferative, clonogenic and migratory potential, by analyzing the expression of embryonic, mesenchymal and tumor markers, by analizing biochemical structure of cells, by examining the differentiation potential of generated cell lines and by testing the degree of chemo-resistance. The study included 13 patients with primary BCC of face skin of less than 20 mm. Following a detailed anamnesis and a signed informed consent, the surgical excision which is considered a gold standard in BCC therapy, was done. A portion of the tumor tissue, of close margin (3 mm from the macroscopic tumor limit), and of healthy skin included in the resecion (at least 5mm from the macroscopic tumor limit), were obtained from all the patients. The remaining of the tissue was subjected to histopathological analysis. For cell phenotype characterization, tests of proliferation, colony formation, scratch assay, and sphere formation were used..

LOCALIZED MOVEMENT CONTROL CONNECTIVITY RESTORATION ALGORITHMS FOR WIRELESS SENSOR AND ACTOR NETWORKS

Wireless Sensor and Actor Networks (WSANs) are gaining an increased interest because of their suitability for mission-critical applications that require autonomous and intelligent interaction with the environment. Hazardous application environments such as forest fire monitoring, disaster management, search and rescue, homeland security, battlefield reconnaissance, etc. make actors susceptible to physical damage. Failure of a critical (i.e. cut-vertex) actor partitions the inter-actor network into disjointed segments while leaving a coverage hole. Maintaining inter-actor connectivity is extremely important in mission-critical applications of WSANs where actors have to quickly plan an optimal coordinated response to detected events. Some proactive approaches pursued in the literature deploy redundant nodes to provide fault tolerance; however, this necessitates a large actor count that leads to higher cost and becomes impractical. On the other hand, the harsh environment strictly prohibits an external intervention to replace a failed node. Meanwhile, reactive approaches might not be suitable for time-sensitive applications. The autonomous and unattended nature of WSANs necessitates a self-healing and agile recovery process that involves existing actors to mend the severed inter-actor connectivity by reconfiguring the topology. Moreover, though the possibility of simultaneous multiple actor failure is rare, it may be precipitated by a hostile environment and disastrous events. With only localized information, recovery from such failures is extremely challenging. Furthermore, some applications may impose application-level constraints while recovering from a node failure. In this dissertation, we address the challenging connectivity restoration problem while maintaining minimal network state information. We have exploited the controlled movement of existing (internal) actors to restore the lost connectivity while minimizing the impact on coverage. We have pursued distributed greedy heuristics. This dissertation presents four novel approaches for recovering from node failure. In the first approach, volunteer actors exploit their partially utilized transmission power and reposition themselves in such a way that the connectivity is restored. The second approach identifies critical actors in advance, designates them preferably as noncritical backup nodes that replace the failed primary if such contingency arises in the future. In the third approach, we design a distributed algorithm that recovers from a special case of multiple simultaneous failures. The fourth approach factors in application-level constraints on the mobility of actors while recovering from node failure and strives to minimize the impact of critical node failure on coverage and connectivity. The performance of proposed approaches is analyzed and validated through extensive simulations. Simulation results confirm the effectiveness of proposed approaches that outperform the best contemporary schemes found in literature

Réseaux ad hoc : système d'adressage et méthodes d'accessibilité aux données

RÉSUMÉ Au cours de la dernière décennie, un nouveau type de réseaux sans fil a suscité un grand intérêt dans la communauté scientifique: ce sont les réseaux ad hoc. Ils existent sous la variante des réseaux mobiles ad hoc (MANET), et des réseaux de capteurs sans fil (RCSF). Les réseaux mobiles ad hoc sont constitués de noeuds mobiles qui communiquent les uns avec les autres sans l‘aide d‘une d'infrastructure centralisée. Les noeuds se déplacent librement et sont soumis à des déconnexions fréquentes en raison de l'instabilité des liens. Cela a pour conséquence de diminuer l'accessibilité aux données, et de modifier la façon dont les données sont partagées dans le réseau. Comparable aux réseaux MANET, un RCSF est composé d'un ensemble d'unités de traitements embarquées, appelées capteurs, communiquant via des liens sans fil et dont la fonction principale est la collecte de paramètres relatifs à l'environnement qui les entoure, telles que la température, la pression, ou la présence d'objets. Les RCSF diffèrent des MANET de par le déploiement à grande échelle des noeuds, et trouvent leur application dans diverses activités de la société, tels les processus industriels, les applications militaires de surveillance, l'observation et le suivi d'habitat, etc. Lorsqu‘un grand nombre de capteurs sont déployés avec des dispositifs d'actionnement appelés acteurs, le RCSF devient un réseau de capteurs et d‘acteurs sans fil (RCASF). Dans une telle situation, les capteurs collaborent pour la détection des phénomènes physiques et rapportent les données afférentes aux acteurs qui les traitent et initient les actions appropriées. De nombreux travaux dans les RCSF supposent l'existence d'adresses et d'infrastructures de routage pour valider leurs propositions. Cependant, l‘allocation d‘adresses et le routage des données liées aux événements détectés dans ces réseaux restent des défis entiers, en particulier à cause du nombre élevé de capteurs et des ressources limitées dont ils disposent. Dans cette thèse, nous abordons le problème de l'accessibilité aux données dans les MANET, et les mécanismes d‘adressage et de routage dans les RCSF de grande taille.----------ABSTRACT During the last decade, a new type of wireless networks has stirred up great interest within the scientific community: there are ad hoc networks. They exist as mobile ad hoc networks (MANET), and wireless sensor (WSN). The mobile ad hoc networks consist of mobile nodes that communicate with each other without using a centralized infrastructure. The nodes move freely and are subject to frequent disconnections due to links instability. This has the effect of reducing data accessibility, and change the way data are shared across the network. Similar MANET networks, a WSN consists of a set of embedded processing units called sensors that communicate with each other via wireless links. Their main function is the collection of parameters relating to the environment around them, such as temperature, pressure, motion, video, etc. WSNs differ from the MANETs due to the large scale deployment of nodes, and are expected to have many applications in various fields, such as industrial processes, military surveillance, observation and monitoring of habitat, etc. When a large number of sensors which are resource-impoverished nodes are deployed with powerful actuation devices, the WSN becomes a Wireless Sensor and Actor Network (WSAN). In such a situation, the collaborative operation of sensors enables the distributed sensing of a physical phenomenon, while actors collect and process sensor data to perform appropriate action. Numerous works in WSN assumes the existence of addresses and routing infrastructure to validate their proposals. However, assigning addresses and delivering detected events remains highly challenging, specifically due to the sheer number of nodes. In this thesis, we address the problem of data accessibility in MANET, and that of addressing and routing in large scale WSN. This involves techniques such as data caching and replication to prevent the deterioration of data accessibility. The addressing system in WSN includes a distributed address allocation scheme and a routing infrastructure for both actors and sensors. Moreover, with the birth of the multimedia sensors, the traffic may be mixed with time sensitive packets and reliability-demanding packets. For that purpose, we also address the problem of providing quality of service (QoS) in the routing infrastructure for WSN

Bandwidth-aware distributed ad-hoc grids in deployed wireless sensor networks

Nowadays, cost effective sensor networks can be deployed as a result of a plethora of recent engineering advances in wireless technology, storage miniaturisation, consolidated microprocessor design, and sensing technologies. Whilst sensor systems are becoming relatively cheap to deploy, two issues arise in their typical realisations: (i) the types of low-cost sensors often employed are capable of limited resolution and tend to produce noisy data; (ii) network bandwidths are relatively low and the energetic costs of using the radio to communicate are relatively high. To reduce the transmission of unnecessary data, there is a strong argument for performing local computation. However, this can require greater computational capacity than is available on a single low-power processor. Traditionally, such a problem has been addressed by using load balancing: fragmenting processes into tasks and distributing them amongst the least loaded nodes. However, the act of distributing tasks, and any subsequent communication between them, imposes a geographically defined load on the network. Because of the shared broadcast nature of the radio channels and MAC layers in common use, any communication within an area will be slowed by additional traffic, delaying the computation and reporting that relied on the availability of the network. In this dissertation, we explore the tradeoff between the distribution of computation, needed to enhance the computational abilities of networks of resource-constrained nodes, and the creation of network traffic that results from that distribution. We devise an application-independent distribution paradigm and a set of load distribution algorithms to allow computationally intensive applications to be collaboratively computed on resource-constrained devices. Then, we empirically investigate the effects of network traffic information on the distribution performance. We thus devise bandwidth-aware task offload mechanisms that, combining both nodes computational capabilities and local network conditions, investigate the impacts of making informed offload decisions on system performance. The highly deployment-specific nature of radio communication means that simulations that are capable of producing validated, high-quality, results are extremely hard to construct. Consequently, to produce meaningful results, our experiments have used empirical analysis based on a network of motes located at UCL, running a variety of I/O-bound, CPU-bound and mixed tasks. Using this setup, we have established that even relatively simple load sharing algorithms can improve performance over a range of different artificially generated scenarios, with more or less timely contextual information. In addition, we have taken a realistic application, based on location estimation, and implemented that across the same network with results that support the conclusions drawn from the artificially generated traffic

A Communication Architecture for Mobile Wireless Sensor and Actor Networks

the collaborative operation of sensors enables the distributed sensing of a physical phenomenon, while actors collect and process sensor data and perform appropriate actions. In this paper, the coordination and communication problems in WSANs with mobile actors are studied. A hybrid location management scheme is introduced to handle the mobility of actors with minimal energy expenditure. Actors broadcast location updates limiting their scope based on Voronoi diagrams, whereas sensors predict the movement of actors based on Kalman filtering of previously received updates. An optimal energy-aware forwarding rule is then derived for sensor-actor communication, based on geographical routing. The proposed scheme allows controlling the delay of the data-delivery process based on power control, and deals with network congestion by forcing multiple actors to be recipients for traffic generated in the event area. The motion of actors is coordinated to optimally accomplish the tasks based on the characteristics of the events. I