Adaptive and occupancy-based channel selection for unreliable cognitive radio networks

In this paper, we propose an adaptive and occupancy-based channel selection for unreliable cognitive radio networks

Toward Reliable Contention-aware Data Dissemination in Multi-hop Cognitive Radio Ad Hoc Networks

This paper introduces a new channel selection strategy for reliable contentionaware data dissemination in multi-hop cognitive radio network. The key challenge here is to select channels providing a good tradeoff between connectivity and contention. In other words, channels with good opportunities for communication due to (1) low primary radio nodes (PRs) activities, and (2) limited contention of cognitive ratio nodes (CRs) acceding that channel, have to be selected. Thus, by dynamically exploring residual resources on channels and by monitoring the number of CRs on a particular channel, SURF allows building a connected network with limited contention where reliable communication can take place. Through simulations, we study the performance of SURF when compared with three other related approaches. Simulation results confirm that our approach is effective in selecting the best channels for efficient and reliable multi-hop data dissemination

Architectural Considerations for a Self-Configuring Routing Scheme for Spontaneous Networks

Decoupling the permanent identifier of a node from the node's topology-dependent address is a promising approach toward completely scalable self-organizing networks. A group of proposals that have adopted such an approach use the same structure to: address nodes, perform routing, and implement location service. In this way, the consistency of the routing protocol relies on the coherent sharing of the addressing space among all nodes in the network. Such proposals use a logical tree-like structure where routes in this space correspond to routes in the physical level. The advantage of tree-like spaces is that it allows for simple address assignment and management. Nevertheless, it has low route selection flexibility, which results in low routing performance and poor resilience to failures. In this paper, we propose to increase the number of paths using incomplete hypercubes. The design of more complex structures, like multi-dimensional Cartesian spaces, improves the resilience and routing performance due to the flexibility in route selection. We present a framework for using hypercubes to implement indirect routing. This framework allows to give a solution adapted to the dynamics of the network, providing a proactive and reactive routing protocols, our major contributions. We show that, contrary to traditional approaches, our proposal supports more dynamic networks and is more robust to node failures

Revisão bibliográfica : hemolinfa de artrópodes com ênfase em aranhas, escorpiões e insetos venenosos

Orientadora : Dilza Trevisan SilvaCo-orientadora: Andrea Senff RibeiroMonografia (especialização) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Curso de Especialização em Biologia Celular e TecidualInclui referência

Avaliação do perfil lipídico e proteico e caracterização dos hemócitos da hemolinfa de aranha marrom (Loxosceles intermedia)

Orientadora : Profª. Drª. Andrea Senff RibeiroCo-orientadora : Profª. Drª. Olga Meiri ChaimDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Biologia Celular e Molecular. Defesa: Curitiba, 28/02/2013Bibliografia: f. 83-95Área de concentração: biologia celularResumo: No Paraná, ocorrem apenas quatro espécies de aranhas do gênero Loxosceles: L. gaucho, L. laeta, L. hirsuta e L. intermedia, sendo essa ultima espécie a mais abundante em Curitiba-PR e região metropolitana. Essas aranhas também são conhecidas como aranhas-marrons devido a sua coloração que varia de marrom claro a marrom escuro. Atualmente, acidentes com aranha-marrom é um problema de saúde publica devido aos inúmeros casos de envenenamento. O veneno dessas aranhas já foi caracterizado e diversas toxinas foram estudadas. Contudo, a hemolinfa de Loxosceles nunca foi pesquisada e de forma geral a hemolinfa de artrópodes é pouco investigada. Hemolinfa de diferentes animais tem sido alvo de estudos que envolvem diversas aplicações biotecnológicas, tais inibição de proteases e aplicação dos peptídeos antimicrobianos nas áreas médicas. Portanto, esse trabalho teve como objetivo determinar as características bioquímicas e biológicas da hemolinfa da aranha-marrom L. intermedia. A hemolinfa de L. intermedia apresentou um perfil proteico com amplo espectro de proteínas. O componente proteico mais representativo foi identificado na região de 66 kDa. Alguns autores mostraram que essa região refere-se às subunidades de hemocianina, que é a proteína mais abundante na hemolinfa dos artrópodes. Além disso, o perfil proteico apresentou outras duas bandas bem características da hemolinfa de outros artrópodes em 116 e 97 kDa. O perfil em gel 2D revelou que as proteínas totais da hemolinfa de L. intermedia estão distribuídas principalmente na faixa de pH ácido e neutro. A análise lipídica da hemolinfa foi realizada através de HPTLC e foram identificados fosfolipídios como fosfatidilcolina, fosfatidil-inositol e fostatidiletanolamina. Os esteróis identificados nesse trabalho foram colesterol, ergosterol e triacilglicerol; e não foram identificados glicolipídios. O perfil de glicosilação proteica foi avaliado através de Lectin Blot e as proteínas totais da hemolinfa de L. intermedia apresentaram resíduos de alta manose e N-acetilglucosamina. Não foram identificados resíduos de ácido siálico, corroborando com dados de glicosilação de toxinas do veneno dessa mesma aranha. Através de microscopia de luz foram identificados pró-hemócitos, que são células precursoras dos outros tipos celulares. Também foi constatada a presença de plasmatócitos e granulócitos, que são células envolvidas na imunidade inata, realizando fagocitose, nodulação, encapsulação e melanização. Esse trabalho foi o primeiro a estudar a hemolinfa da aranha-marrom caracterizando o perfil proteico, lipídico e de glicosilação de seus componentes. Além disso, a fração celular também foi investigada e diferentes hemócitos identificados. Dessa forma esse estudo inicia uma nova linha de pesquisa no estudo de Loxosceles, ampliando o conhecimento e as fontes naturais de moléculas bioativas com potenciais biotecnológicos.Abstract: In Paraná there are only four species of Loxosceles spiders: L. gaucho, L. laeta, L. hirsuta e L. intermedia, being the last one more abundant in Curitiba and metropolitan region. Loxosceles spiders are commonly known as brown spiders regarding their body color which ranges from a fawn to dark brown. The current increasing number of envenomations after brown spider accidents is a problem of public health. Venom from these spiders has already been characterized and a great number of toxins have been studied. However, Loxosceles hemolymph has never been investigated; and in general, hemolymph from arthropods are poorly studied. Hemolymphs from distinct animals have been focus of studies concerning biotechnology applications, such as inhibition of proteases and application of the antimicrobial peptides in the medical. Thus, this work aimed the determination of biochemical and biological characteristics of the hemolymph from L. intermedia brown spider. The protein profile of L. intermedia hemolymph presented a broad range of proteins. The major proteic component was detected at 66 kDa region. Some authors showed that this region is rich in hemocyanin subunits and that this protein is the most abundant component in arthropods hemolymph. Furthermore, the protein profile depicted two other bands, which are hallmarks in other arthropods hemolymph, in 116 and 97 kDa. The bidimensional protein profile showed that hemolymph proteins from L. intermedia are mainly distributed among acid to neutral pH. Lipid analysis was performed by HPTLC technique and several phospholipids were identified, such as phosphatidylcholine, phosphatidylinositol and phosphatidylethanolamine. Sterols identified in this work were cholesterol, ergosterol and triacylglycerol, and no glycolipids were identified. Protein glycosylation profile was evaluated by Lectin Blot assays and only high manose and N-acetylglucosamine residues were identified. Sialic acid residues were not found, corroborating with L intermedia glycosylation data obtained using venom toxins. Using light microscopy analysis, phohemocytes were identified, which are the precursor cells. Plasmatocytes and granulocytes were also detected, these cells are involved in innate immunity, acting in phagocytosis, nodulation, encapsulation and melanization. This work was the first one to study the brown spider hemolymph, characterizing the protein, lipid and glycosilation profiles of its components. Furthermore, the cellular fraction was also investigated and different hemocytes were identified. Thereby, this study starts a new research line in Loxosceles field, extending the knowledge and the natural source of bioactive molecules with biotechnological potentials

The Power of Hood Friendship for Opportunistic Content Dissemination in Mobile Social Networks

We focus on dissemination of content for delay tolerant applications/services, (i.e. content sharing, advertisement propagation, etc.) where users are geographically clustered into communities. Due to emerging security and privacy related issues, majority of users are only willing to share information/content with the users who are previously identified as friends. In this environment, opportunistic communication will not be effective due to the lack of known friends within the communication range. In this paper, we propose a novel architecture that addresses the issues of lack of trust, timeliness of delivery, loss of user control, and privacy-aware distributed mobile social networking by combining the advantages of distributed decentralised storage and opportunistic communications. We formally define a content replication problem in mobile social networks and show that it is computationally hard to solve optimally. Then, we propose a community based greedy heuristic algorithm with novel dynamic centrality metrics to replicate content in well-selected users, to maximise the content dissemination with limited number of replication. Using both real world and synthetic traces, we show that content replication can attain a large coverage gain and reduce the content delivery latency

Knowledge Organization and the Bakhtin Circle?s theory

[Resumo] O estudo traz resultados de uma leitura sobre elementos da teoria do Círculo de Bakhtin (CB) aplicados a conceitos relacionados à área de Organização do Conhecimento (OC), expressos na literatura da Ciência da Informação. Procura compreender como os autores se reportam ao CB, como se configuram os conceitos e quais as possibilidades de interpretação oferecidas. Utiliza a análise das citações dos autores do Círculo como método para construção de um corpus, do qual foram extraídos os dados que subsidiaram os processos de sistematização, análise e interpretação dos resultados. Foi possível explorar de maneira qualitativa e ampla aspectos que no seu conjunto oferecem possibilidades de aplicação da teoria do CB no domínio da OC. A trajetória permitiu acompanhar a tomada de consciência das categorias de análise, com a ênfase no enunciado quando assumido pelos participantes do processo de construção cognitiva da OC. São discutidos também os conceitos de informação e linguagem, diálogo a partir do qual se procedeu a análise dos dados. Buscando aporte nos autores do CB, observa-se a defesa de uma concepção social e historicamente contextualizada dos processos inerentes às teorias e práticas de organização e representação do conhecimento.[Abstract] This study presents results from a reading on some elements from Bakhtin Circle?s (BC) theory applied to concepts related to the area of Knowledge Organization (KO), as expressed in the literature on the field of Information Science (IS). It aims to understand how the authors in this field allude to BC, how its concepts are configured by them and what are its possible interpretations. It takes the analysis of citations from Bakhtin as a method to construct a corpus of research, from which the data that were taken as the basis for the systematization process were extracted, as well as the analysis and interpretation of results. Thus, it was possible to explore in a wide and qualitative manner some aspects that offered, as a whole, the possibility of apply CB theory in the domain of KO. The course adopted allowed us to follow the realization process of the categories in analysis, emphasizing the enunciation when it is assumed by the participants in the process of cognitive construction of KO. It is also discussed the concepts of information and language, a dialogue from which it was performed the analysis of the data obtained. Recurring to Bakhtin?s support, it was observed, in this field, the defense of a socially and historically contextualized conception of the inherent processes in both theories and practices of organization and representation of knowledge

Proactive Data Dissemination in Wireless Sensor Networks with Uncontrolled Sink Mobility

This paper investigates Wireless Sensor Networks (WSNs) with mobile sinks that collect data from sensors by following uncontrolled trajectories. In particular, the paper focuses on proactive data dissemination strategies in which the trajectory of the mobile sink is unknown to the sensors. These strategies attempt to obtain a good trade-off between the number of sensors the mobile sinks has to visit in order to collect representative data of all sensors, and the communication effort required by the sensors. All the investigated techniques also avoid the use of multi-hop routing, due to its high cost. Some of them are based on random walks whereas others are based on a combination of probabilistic forwarding and probabilistic storage. An analysis of the various methods in terms of the performance trade-off between the efficiency of the data gathering and communication overhead is also presented