Avec le développement de l'IoT, des Smart Cities, et d'autres systèmes large-échelle extrêmement hétérogènes, les systèmes distribués deviennent à la fois plus complexes et plus omniprésents de jour en jour et seront bientôt difficiles à gérer avec les approches courantes. Pour masquer cette difficulté croissante et faciliter leur gestion à tous les stages de leur cycle de vie, cette thèse soutient qu'une approche holistique est nécessaire, où la fonction d'un système est considérée comme un tout, et qui se détache du comportement des composants individuels. En parallèle à cette montée en abstraction, les blocs de base doivent devenir plus autonomes, capable de réagir aux circonstances et d'automatiser la plupart des tâches de bas niveau. Nous proposons trois contributions vers cette vision : 1) Pleiades : une approche holistique pour construire des structures complexes par assemblage, facile à programmer et soutenue par un moteur d'exécution auto-organisant et efficace, basé sur des protocoles épidémiques. 2) Mind-the-Gap : un protocole épidémique de détection des partitions dans les MANETs, grâce à des agrégations opportunistes et à une représentation stochastique compacte du réseau. 3) HyFN: une extension des protocoles épidémiques traditionnels, capable de résoudre efficacement le problème des k-plus-lointains-voisins, ce dont les méthodes standards s'étaient révélées incapables jusqu'à maintenant. Nous considérons que ces trois contributions montrent que notre vision est réaliste, et mettent en valeur ses qualités. / With the advent of the IoT, Smart Cities, and other large-scale extremely heterogeneous systems, distributed systems are becoming both more complex and pervasive every day and will soon be intractable with current approaches. To hide this growing complexity and facilitate the management of distributed systems at all stages of their life-cycle, this thesis argues for a holistic approach, where the function of a system is considered as a whole, moving away from the behavior of individual components. In parallel to this rise in abstraction levels, basic building blocks need to become more autonomous and able to react to circumstances, to alleviate developers and automate most of the low level operations. We propose three contributions towards this vision : 1) Pleiades: a holistic approach to build complex structures by assembly, easily programmable and supported by an efficient, self-organizing gossip-based run-time engine. 2) Mind-the-Gap: a gossip-based protocol to detect partitions and other large connectivity changes in MANETs, thanks to periodic opportunistic aggregations and a stochastic representation of the network membership. 3) HyFN: an extension to traditional gossip protocols that is able to efficiently solve the k-Furthest-Neighbors problem, which standard methods have been unable to up to now. We believe these three contributions demonstrate our vision is realistic and highlight its attractive qualities.

Por serem as manifestações pulmonares de etiologia infecciosas muito freqüentes e potencialmente graves nas crianças com aids, o diagnóstico deve ser precoce para uma rápida e efetiva intervenção terapêutica. A proteína C reativa (PCR), um dos marcadores das provas de fase aguda, tem sido usada na prática clínica como um recurso diagnóstico na diferenciação entre patologias sistêmicas de etiologia viral e bacteriana, bem como na monitorização da eficácia da terapêutica antimicrobiana frente a uma infecção. Apesar da proteína C reativa ser um exame inespecífico e poder estar aumentada em diferentes situações clínicas (infecções sistêmicas, doenças inflamatórias e neoplásicas, isquemias, queimaduras), a infecção bacteriana é a causa mais freqüente para o seu aumento. A PCR eleva-se rapidamente após a injúria tecidual, atingindo valores 10 a 1000 vezes superiores a seu nível basal: em virtude de sua curta meia vida, retorna em pouco tempo aos valores prévios após o fim da agressão. Com o objetivo de encontrar um método laboratorial auxiliar para as infecções pulmonares nas crianças com infecção pelo HIV foi estudada a proteína C reativa, pela técnica de nefelometria, em dois momentos distintos: na ausência de quadro infeccioso concomitante (grupo 1) e na vigência de pneumonia aguda (grupo 2). O grupo 1 envolveu o estudo de 66 crianças com infecção pelo HIV, resultando em 84 amostras de PCR coletadas na ausência de quadro infeccioso concomitante.No grupo 2 foram analisadas 6 crianças com infecção pelo HIV com 9 episódios de pneumonia aguda. As crianças com infecção pelo HIV foram classificadas de acordo com as categorias clínicas e imunológicas da classificação do CDC para infecção pelo HIV em crianças. Dentre as 66 crianças incluídas no grupo 1, 6 pertenciam à categoria N, 11 à categoria A, 27 à categoria B e 22 à categoria C. Das 84 amostras de PCR coletadas no grupo 1, 76 (90,48%) encontravam-se abaixo de 5 mg/l, 7 amostras entre 5 a 20 mg /l e, apenas 1 amostra entre 20 a 40 mg/l (1,15%). No grupo 2, todas as crianças eram pertencentes às categorias B3 (1/6) ou C3 (5/6), refletindo um estágio mais avançado da doença. Das 9 amostras de PCR, 6 apresentavam valores maiores que 40 mg/l, 1 entre 20 e 40 mg/l e as 2 amostras restantes, entre 5 e 20 mg/l. Os dados sugerem portanto que a infecção pelo HIV por si só não é acompanhada de aumento da PCR, bem como não existe relação com a classificação imunológica em que o paciente se encontre. Pacientes com infecção pelo HIV na vigência de pneumonia aguda apresentam níveis aumentados de PCR. Neste estudo, o ponto de corte que diferenciou os grupos 1 e 2 foi PCR = 28,9 mg/l com sensibilidade de 77,8% e especificidade de 100% (IC 95%) / As pulmonary infection is a common and potentially serious condition in HIV-infected children, effectiveness of treatment of this kind of affection depends to a large extent on the promptness of accurate diagnosis. The C-Reactive Protein (CRP), a reasonably well-established acute phase marker, has long been used to differentiate bacterial from viral infections. Despite its lack of specifity, that is, the fact that other conditions like inflammatory diseases, neoplasms, ischemia and burns may also increase CRP levels, Bacterial infections are the most frequent cause of increased CRP found in daily clinical practice. Shortly after any tissular injury, CRP increases considerably, reaching up to 10-1000 times its previous levels. Due to its short half-life, its decrease after the end of the affection is quick as well. This study aimed at evaluating the CRP (assessed by nephelometry) as an auxiliary tool to diagnose pulmonary infection in HIV-infected children. Two groups of patients were considered in this study: group 1 was constituted by 66 HIV-infected children with no clinical signs of concomitant infection (amounting to 84 CRP samples) and group 2 was constituted by 6 HIV-infected children with pneumonia (amounting to 9 CRP samples). All the subjects were assigned to categories according to the pediatric HIV classification system (CDC, 1994). Among the 66 children from group 1, 6 were assigned to categories N, 11 to A, 27 to B and 22 to C. Regarding the levels of CRP in group 1 it was found: 76 samples (90.48%) < 5 mg/l, 7 (8.33%) in the range between 5 and 20 mg/l and 1 sample between 20 and 40 mg/l. In the group 2, all the children were assigned either to category B3 (1/6) or C3 (5/6) and the CRP level distribution was the following: 6 (6/9) > 40 mg/l, 1 (1/6) between 20 and 40 mg/l and 2 (2/6) between 5 and 20 mg/l. These results suggest that 1.HIV infection by itself does not increase the levels of CRP, regardless the immunologic classification of the patient; 2.HIV-infected children with pneumonia present increased levels of CRP 3.In this study, the cut-off point to differentiate groups 1 and 2 was 28,9 mg/l, with sensitivity of 77,8% and specificity of 100% (p < 0.05)

Made available in DSpace on 2016-08-19T18:15:59Z (GMT). No. of bitstreams: 1 FLAVIA LOPES CARVALHO.pdf: 442162 bytes, checksum: b9d2b399e741a894bb9550e5094975a0 (MD5) Previous issue date: 2009-11-18 / Co-infection Leishmania-HIV/Aids is a serious public health problem in almost of the world. The visceral leishmaniasis is the clinical form of leishmaniosis hat is most associated with HIV/Aids cases being the co-infection understated, since the leishmaniasis is not AIDS-defining illness. This was a descriptive cross sectional study from March 2006 to December 2008, aiming to investigate the occurrence of co-infection Leishmania-HIV in individuals living with HIV/Aids in a Reference Center in São Luís-MA. The population studied was composed of 287 individuals. It was used a questionnaire to collect demographic, epidemiological and socioeconomic data. The physical examination was performed and biological material for detection of infection by Leishmania chagasi was collected by indirect immunofluorescence technique (IIFT), and laboratory tests (blood count, CD4 and CD8, viral load, myelography) were found in charts. We used the chi-square test to assess association of demographic, socioeconomic and epidemiological variables between women and men, whereas p ≥ 0.05 for significance. Women and men had a statistically significant difference in color, destination of waste, occupation and family income. The presence of pen and near the residence showed statistically significant differences when comparing men and women. The prevalence of infection with Leishmania sp, detected by Montenegro Skin Test (MST) was 1,4%. All co-infected showed RIFI and as well as the bone marrow aspirate (myelogram) positives. This study helped identify the magnitude of the prevalence of co-infection Leishmania/HIV. Thus, we suggest that the anti-Leishmania has to be part of the differential diagnosis of individuals with HIV / AIDS and those public policies are increased for this problem. / A co-infecção Leishmania-HIV/Aids é um sério problema de saúde pública em quase todo o mundo. A Leishmaniose Visceral é a forma clínica das leishmanioses que está mais associada ao HIV/Aids, sendo os casos de co-infecção considerados subestimados, uma vez que, a leishmaniose não se constitui doença definidora de Aids. Foi realizado um estudo descritivo transversal de março de 2006 a dezembro de 2008, com o objetivo de investigar a ocorrência de co-infecção Leishmania-HIV em indivíduos convivendo com HIV/Aids, atendidas em um Centro de Referência em São Luís-MA. A população do estudo foi constituída por 287 indivíduos. A coleta de dados foi feita por meio de um questionário para a obtenção de dados demográficos, socioeconômicos e epidemiológicos, bem como foi realizado exame físico e coleta de material biológico para detecção da infecção por Leishmania sp , por meio da Intradermorreação de Montenegro (IDRM), Reação de Imunofluorescência Indireta (RIFI) e os exames laboratoriais (hemograma, contagem de CD4 e CD8, carga viral, mielograma) foram consultados nos prontuários. Através do teste qui-quadrado foi avaliado as variáveis demográficos, socioeconômicas e epidemiológicas entre mulheres e homens convivendo com HIV/Aids, considerando p ≥ 0,05 de significância. Houve diferença estatística significante na cor da pele, no destino dos dejetos, na ocupação e na renda familiar; como também na presença de chiqueiro em local próximo à residência. A prevalência da infecção por Leishmania sp detectada pela Intradermorreação de Montenegro (IDRM) foi de 1,4% e a prevalência da co-infecção Leishmania-HIV/Aids foi de 4,2%. Todos os co-infectados apresentaram RIFI e o aspirado de medula óssea (mielograma) positivos. Este estudo permitiu conhecer a magnitude da prevalência da co-infecção Leishmania/HIV. Assim, sugerimos que o teste anti-Leishmania seja realizado em todos os indivíduos com HIV/Aids, e que sejam incrementadas políticas públicas voltadas para essa problemática.

The popularity of ubiquitous Internet services has spurred the fast growth of wireless communications by launching data hungry multimedia applications to mobile devices. Powered by spectrum agile cognitive radios, the newly emerged cognitive radio networks (CRN) are proposed to provision the efficient spectrum reuse to improve spectrum utilization. Unlicensed users in CRN, or secondary users (SUs), access the temporarily idle channels in a secondary and opportunistic fashion while preventing harmful interference to licensed primary users (PUs). To effectively detect and exploit the spectrum access opportunities released from a wide spectrum, the heterogeneous wireless channel characteristics and the underlying prioritized spectrum reuse features need to be considered in the protocol design and resource management schemes in CRN, which plays a critical role in unlicensed spectrum sharing among multiple users. The purpose of this dissertation is to address the challenges of utilizing heterogeneous wireless channels in CRN by its intrinsic dynamic and diverse natures, and build the efficient, scalable and, more importantly, practical dynamic spectrum access mechanisms to enable the cost-effective transmissions for unlicensed users. Note that the spectrum access opportunities exhibit the diversity in the time/frequency/space domain, secondary transmission schemes typically follow three design principles including 1) utilizing local free channels within short transmission range, 2) cooperative and opportunistic transmissions, and 3) effectively coordinating transmissions in varying bandwidth. The entire research work in this dissertation casts a systematic view to address these principles in the design of the routing protocols, medium access control (MAC) protocols and radio resource management schemes in CRN. Specifically, as spectrum access opportunities usually have small spatial footprints, SUs only communicate with the nearby nodes in a small area. Thus, multi-hop transmissions in CRN are considered in this dissertation to enable the connections between any unlicensed users in the network. CRN typically consist of intermittent links of varying bandwidth so that the decision of routing is closely related with the spectrum sensing and sharing operations in the lower layers. An efficient opportunistic cognitive routing (OCR) scheme is proposed in which the forwarding decision at each hop is made by jointly considering physical characteristics of spectrum bands and diverse activities of PUs in each single band. Such discussion on spectrum aware routing continues coupled with the sensing selection and contention among multiple relay candidates in a multi-channel multi-hop scenario. An SU selects the next hop relay and the working channel based upon location information and channel usage statistics with instant link quality feedbacks. By evaluating the performance of the routing protocol and the joint channel and route selection algorithm with extensive simulations, we determine the optimal channel and relay combination with reduced searching complexity and improved spectrum utilization. Besides, we investigate the medium access control (MAC) protocol design in support of multimedia applications in CRN. To satisfy the quality of service (QoS) requirements of heterogeneous applications for SUs, such as voice, video, and data, channels are selected to probe for appropriate spectrum opportunities based on the characteristics and QoS demands of the traffic along with the statistics of channel usage patterns. We propose a QoS-aware MAC protocol for multi-channel single hop scenario where each single SU distributedly determines a set of channels for sensing and data transmission to satisfy QoS requirements. By analytical model and simulations, we determine the service differentiation parameters to provision multiple levels of QoS. We further extend our discussion of dynamic resource management to a more practical deployment case. We apply the experiences and skills learnt from cognitive radio study to cellular communications. In heterogeneous cellular networks, small cells are deployed in macrocells to enhance link quality, extend network coverage and offload traffic. As different cells focus on their own operation utilities, the optimization of the total system performance can be analogue to the game between PUs and SUs in CRN. However, there are unique challenges and operation features in such case. We first present challenging issues including interference management, network coordination, and interworking between cells in a tiered cellular infrastructure. We then propose an adaptive resource management framework to improve spectrum utilization and mitigate the co-channel interference between macrocells and small cells. A game-theory-based approach is introduced to handle power control issues under constrained control bandwidth and limited end user capability. The inter-cell interference is mitigated based upon orthogonal transmissions and strict protection for macrocell users. The research results in the dissertation can provide insightful lights on flexible network deployment and dynamic spectrum access for prioritized spectrum reuse in modern wireless systems. The protocols and algorithms developed in each topic, respectively, have shown practical and efficient solutions to build and optimize CRN.

Cooperative relaying systems aim to improve weak communication links by exploiting the spatial diversity obtained by the statistically independent channels between relays and the destination. In this thesis a cooperative relaying scheme called the Opportunistic Multiple Relaying (OMR) is proposed with its special receiver structure. Unlike most relaying schemes in the literature, multiple relay nodes are allowed to transmit in nonorthogonal channels in OMR without requiring any control overhead for relay coordination. OMR is compared to a benchmark scheme called the Selection Relaying (SR) in which the relay node is preselected by the source before transmission according to the average channel quality information. It is observed that OMR performs significantly better than SR in terms of error performance.

Solving the key issue of sustainability of battery-powered sensors continues to attract significant research attention. The prevailing theme of this research is to address this concern using energy-efficient protocols based on a form of simple cooperative transmission (CT) called the opportunistic large arrays (OLAs), and intelligent exploitation of energy harvesting and hybrid energy storage systems (HESSs). The two key contributions of this research, namely, OLA with transmission threshold (OLA-T) and alternating OLA-T (A-OLA-T), offer an signal-to-noise ratio (SNR) advantage (i.e., benefits of diversity and array (power) gains) in a multi-path fading environment, thereby reducing transmit powers or extending range. Because these protocols do not address nodes individually, the network overhead remains constant for high density networks or nodes with mobility. During broadcasting across energy-constrained networks, while OLA-T saves energy by limiting node participation within a single broadcast, A-OLA-T optimizes over multiple broadcasts and drains the the nodes in an equitable fashion. Another important contribution of this research is the design and analysis of a novel routing metric called communications using HESS (CHESS), which extends the rechargeable battery (RB)-life by relaying exclusively with supercapacitor (SC) energy, and is asymptotically optimal with respect to the number of nodes in the network.

Gram-negative infection has been linked to hospital water although few studies have examined whether water systems are reservoirs of nosocomial pathogens. This study investigated longitudinal recovery of the opportunistic pathogens Pseudomonas aeruginosa, Stenotrophomonas maltophilia and Acinetobacter baumannii from water outlets of a haematology unit and evaluated Point-Of-Use Filtration (POU-F) as a control measure. In a two-year double cross-over trial, water samples and swabs were taken weekly from 39 showers/taps on the unit. Four study phases alternated between non-filtered (Phases 1 &amp; 3), and filtered outlets (Phases 2 &amp; 4) using Pall AquasafeTM 14-day filters. In Phases 1 &amp; 3; 99% of 1396 samples yielded bacterial growth, with colonies generally too numerous to count. Target species were isolated from 22% of water samples (P. aeruginosa 14%; S. maltophilia 10%) and 10% of swabs. P. aeruginosa was particularly associated with handwash stations and S. maltophilia with showers. A. baumannii was not isolated. With POU-F; 22% of 1242 samples yielded bacterial growth (mean CFU/100ml ,4.6). S. maltophilia was isolated only once from water but never from outlet swabs. PCR typing identified clusters of isolates colonizing different outlets over time but no clear association between water and patient isolates was identified. The incidence of Gram negative infections remained low throughout the study. Without POU-F, water from taps/showers represented a source of bacteria including the target species. POU-F substantially reduced the frequency and number of target species from every outlet, and merits further investigation as an intervention to protect immunocompromised patients from opportunistic pathogens.

No description available.

The popularity of ubiquitous Internet services has spurred the fast growth of wireless communications by launching data hungry multimedia applications to mobile devices. Powered by spectrum agile cognitive radios, the newly emerged cognitive radio networks (CRN) are proposed to provision the efficient spectrum reuse to improve spectrum utilization. Unlicensed users in CRN, or secondary users (SUs), access the temporarily idle channels in a secondary and opportunistic fashion while preventing harmful interference to licensed primary users (PUs). To effectively detect and exploit the spectrum access opportunities released from a wide spectrum, the heterogeneous wireless channel characteristics and the underlying prioritized spectrum reuse features need to be considered in the protocol design and resource management schemes in CRN, which plays a critical role in unlicensed spectrum sharing among multiple users. The purpose of this dissertation is to address the challenges of utilizing heterogeneous wireless channels in CRN by its intrinsic dynamic and diverse natures, and build the efficient, scalable and, more importantly, practical dynamic spectrum access mechanisms to enable the cost-effective transmissions for unlicensed users. Note that the spectrum access opportunities exhibit the diversity in the time/frequency/space domain, secondary transmission schemes typically follow three design principles including 1) utilizing local free channels within short transmission range, 2) cooperative and opportunistic transmissions, and 3) effectively coordinating transmissions in varying bandwidth. The entire research work in this dissertation casts a systematic view to address these principles in the design of the routing protocols, medium access control (MAC) protocols and radio resource management schemes in CRN. Specifically, as spectrum access opportunities usually have small spatial footprints, SUs only communicate with the nearby nodes in a small area. Thus, multi-hop transmissions in CRN are considered in this dissertation to enable the connections between any unlicensed users in the network. CRN typically consist of intermittent links of varying bandwidth so that the decision of routing is closely related with the spectrum sensing and sharing operations in the lower layers. An efficient opportunistic cognitive routing (OCR) scheme is proposed in which the forwarding decision at each hop is made by jointly considering physical characteristics of spectrum bands and diverse activities of PUs in each single band. Such discussion on spectrum aware routing continues coupled with the sensing selection and contention among multiple relay candidates in a multi-channel multi-hop scenario. An SU selects the next hop relay and the working channel based upon location information and channel usage statistics with instant link quality feedbacks. By evaluating the performance of the routing protocol and the joint channel and route selection algorithm with extensive simulations, we determine the optimal channel and relay combination with reduced searching complexity and improved spectrum utilization. Besides, we investigate the medium access control (MAC) protocol design in support of multimedia applications in CRN. To satisfy the quality of service (QoS) requirements of heterogeneous applications for SUs, such as voice, video, and data, channels are selected to probe for appropriate spectrum opportunities based on the characteristics and QoS demands of the traffic along with the statistics of channel usage patterns. We propose a QoS-aware MAC protocol for multi-channel single hop scenario where each single SU distributedly determines a set of channels for sensing and data transmission to satisfy QoS requirements. By analytical model and simulations, we determine the service differentiation parameters to provision multiple levels of QoS. We further extend our discussion of dynamic resource management to a more practical deployment case. We apply the experiences and skills learnt from cognitive radio study to cellular communications. In heterogeneous cellular networks, small cells are deployed in macrocells to enhance link quality, extend network coverage and offload traffic. As different cells focus on their own operation utilities, the optimization of the total system performance can be analogue to the game between PUs and SUs in CRN. However, there are unique challenges and operation features in such case. We first present challenging issues including interference management, network coordination, and interworking between cells in a tiered cellular infrastructure. We then propose an adaptive resource management framework to improve spectrum utilization and mitigate the co-channel interference between macrocells and small cells. A game-theory-based approach is introduced to handle power control issues under constrained control bandwidth and limited end user capability. The inter-cell interference is mitigated based upon orthogonal transmissions and strict protection for macrocell users. The research results in the dissertation can provide insightful lights on flexible network deployment and dynamic spectrum access for prioritized spectrum reuse in modern wireless systems. The protocols and algorithms developed in each topic, respectively, have shown practical and efficient solutions to build and optimize CRN.

An Opportunistic Large Array (OLA) is a form of cooperative diversity in which a large group of simple, inexpensive relays operate without any mutual coordination, but naturally fire together in response to the energy received from a single source or another OLA. The main contributions of this thesis are the introduction of two OLA-based routing protocols: OLA Concentric Routing Algorithm (OLACRA), which is an upstream routing algorithm suitable for static wireless sensor networks (WSNs), and OLA Routing On-Demand (OLAROAD), which is a robust reactive routing scheme suitable for mobile ad hoc networks (MANETs). In fixed multi-hop wireless sensor networks with a single sink, where energy conservation is often a concern, simulations of the new algorithms show as much as 80% of the transmit energy required to broadcast data can be saved, relative to existing OLA-based broadcasting approaches. In MANETs, where robustness of the routes is an important performance indicator, OLAROAD-based cooperative routes last much longer compared to their state-of-art multi-hop non-cooperative transmission (CT)-based counterparts. However, OLACRA and OLAROAD have higher node participation, and thereby lower throughput, in comparison with the non-CT schemes. To improve the throughput, and thereby bandwidth utilization, the properties of uplink OLAs and their suppression regions are carefully studied. Based on the observations, Hop-Optimized OLACRA (HOLA), which is a variant of OLACRA, and has the maximum bandwidth utilization amongst all the OLA unicast schemes studied, is proposed. HOLA routes have bandwidth utilization comparable to non-CT schemes, but a much lower (~10 dB less) transmit power per node. The last section of this thesis treats the MAC design for OLA-based networks. In contrast to non-CT networks, a 802.11-based RTS/CTS MAC scheme is shown to reduce the reliability in OLA unicast schemes. A distributed cluster-head-based MAC scheme for channel reservation and OLA Size Adaptation Mechanism for link repair/maintenance are proposed for OLA-based networks. The performances of these protocols are shown to be comparable to a non-CT multihop scheme using the RTS/CTS/DATA/ACK handshake-based link layer design.