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Opportunistic networks are constructed by devices carried by people and vehicles. The devices use short range radio to communicate. Since the network is mobile and often sparse in terms of node contacts, nodes store messages in their buffers, carrying them, and forwarding them upon node encounters. This form of communication leads to a set of challenging issues that we investigate: congestion, transfer ordering, and resilience. Congestion occurs in opportunistic networks when a node's buffers becomes full. To be able to receive new messages, old messages have to be evicted. We show that buffer eviction strategies based on replication statistics perform better than strategies that evict messages based on the content of the message. We show that transfer ordering has a significant impact on the dissemination of messages during time limited contacts. We find that transfer strategies satisfying global requests yield a higher delivery ratio but a longer delay for the most requested data compared to satisfying the neighboring node's requests. Finally, we assess the resilience of opportunistic networks by simulating different types of attacks. Instead of enumerating all possible attack combinations, which would lead to exhaustive evaluations, we introduce a method that use heuristics to approximate the extreme outcomes an attack can have. The method yields a lower and upper bound for the evaluated metric over the different realizations of the attack. We show that some types of attacks are harder to predict the outcome of and other attacks may vary in the impact of the attack due to the properties of the attack, the forwarding protocol, and the mobility pattern. / WISENET

Consumer electronics such as cellular phones and portable computers with short-range communication capabilities have enabled the large-scale information dissemination through user mobility and contact, without the assistance of communication infrastructures. In such a new communication paradigm, one challenge is to determine when and how to forward a message to the destination, possibly through a series of third parties. This problem has attracted a lot of attention in the literature lately, with proposals ranging from epidemic to single or multi-copy spray and wait or focus strategies. However most existing work assumed independent or identically distributed mobility. Observing most human mobility and interaction are interest-driven in the real world, in this research, we evaluate the performance of these schemes with an interest-driven mobility model. We further propose to take the user interest into account when determining routing strategies to further improve the performance of these schemes for mobile social networks. Simulation results have demonstrated the efficacy of the interest-aware routing strategies. / Graduate

Infection due to Penicillium marneffei (renamed to Talaromyces marneffei in 2011) has emerged as an important public health problem over the past two decades due to the arrival of the HIV epidemic in Asia. Since 2004, P. marneffei has become the second most common pathogen isolated from routine blood culture, after Cryptococcus neoformans, at the Hospital for Tropical Diseases in Ho Chi Minh City, the largest referral centre for HIV care in southern Vietnam. The clinical epidemiology of P. marneffei infection has not been studied in Vietnam. The fundamental epidemiological questions regarding the pathogen reservoirs and risks of acquisition remain poorly understood. The diagnosis relies on isolation of the pathogen from clinical specimens and can take up to 14 days to identify, resulting in delayed initiation of therapy which is associated with worse treatment outcomes. This thesis aims to increase knowledge and understanding of the clinical and environmental epidemiology of P. marneffei infection and to improve the speed and accuracy of diagnosis of P. marneffei infection. The Précis provides a brief background and rationale for the thesis. Chapter 1 is an introductory chapter and provides an overview of the epidemiology, ecology, mycology, pathology, immunology, clinical features, diagnosis, and treatment of P. marneffei infection. Chapter 2 summarizes the incidence and features of P. marneffei admissions at the Hospital for Tropical Diseases in Ho Chi Minh City over a 13 year period. During this period, 795 patients with P. marneffei infection were identified and hospital charts were obtainable for 513 (65%) patients. The data showed clear seasonality with an increase in incidence of approximately 30% during the rainy season compared to the dry season. The clinical and microbiological features and treatment outcomes of the patients were characterised. Poor outcome, defined as death or worsening disease at hospital discharge, occurred in 28% of patients. History of injection drug use, shorter duration of illness, absence of fever or skin lesions, higher respiratory rates, and lower platelet counts independently predicted poor outcome. Chapter 3 describes an analysis of meteorological factors that determine penicilliosis incidence in Ho Chi Minh City. Humidity, rather than precipitation, was the most important factor that governs the seasonality of penicilliosis. Higher humidity was associated with increased odds of penicilliosis versus cryptococcosis admissions. The infection incubation period was estimated to be between one and three weeks. Chapter 4 describes an analysis of exposure and behavioural risk factors for penicilliosis based on a matched case control study of 205 culture-confirmed HIV-infected penicilliosis cases and 405 HIV-infected controls recruited from two major HIV referral centres in Hanoi and Ho Chi Minh City. Penicilliosis was independently associated with proximity or exposure to tropical plants and exposure to farmed animals. The geographical analysis showed that patients living in or traveling to the highland regions were at increased risk for penicilliosis in southern Vietnam. Chapter 5 describes the development of a Taqman real-time PCR assay based on a novel Mp1 gene target unique to P. marneffei for rapid detection of P. marneffei infection in patient plasma. The assay was tested in 70 plasma samples from HIV-infected patients (50 with culture-confirmed penicilliosis, 20 with other opportunistic infections) and showed a clinical specificity of 100% (20/20) and sensitivity of 70.4% (19/27) and 52.2% (12/23) prior to and within 24-48 hours of antifungal therapy administration, respectively. Chapter 6 is an overview discussion interpreting the implications of the major findings and the future direction of P. marneffei research. The work of this thesis increases knowledge of the clinical epidemiology of P. marneffei infection in Vietnam, providing essential data for the design of prospective studies to improve the diagnosis and treatment of P. marneffei infection in Asia. The data suggest that multiple environmental factors including humidity, tropical plants, farmed animals, and highland location, are important drivers of P. marneffei infection in southern Vietnam. The real-time PCR assay showed potential as a rapid ‘rule-in' test for P. marneffei in this pilot study and should be prospectively evaluated in a large cohort to determine if it can improve diagnostic speed and crucially, impact patient outcomes. Prevention, diagnosis and elimination all require further research to reduce the high mortality following clinical disease caused by P. marneffei in Asia.

Made available in DSpace on 2014-06-11T19:27:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-07-15Bitstream added on 2014-06-13T18:31:36Z : No. of bitstreams: 1 salvia_acrd_me_sjc.pdf: 748582 bytes, checksum: c8eb5b5ba196067377171ac7b51599c6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Considerando-se que portadores de anemia falciforme apresentam relatado aumento da suscetibilidade às infecções e que reservatórios bucais de microrganismos patogênicos podem representar uma porta de entrada para doenças, a avaliação da microbiota bucal potencialmente patogênica ganha relevância. O objetivo deste estudo foi avaliar a presença de leveduras do gênero Candida, estafilococos, enterobactérias e Pseudomonas spp. na cavidade bucal de pacientes com anemia falciforme em tratamento com hidroxiuréia, comparando os resultados com indivíduos controle. Foram incluídos no estudo 69 pacientes, com idades entre 15 a 60 anos, portadores de anemia falciforme, confirmados por exames clínicos e laboratoriais. Estes foram divididos em dois grupos: em tratamento com hidroxiuréia (HU) por no mínimo 90 dias (n=30); sem tratamento com HU (n=39). Foram também incluídos dois grupos controle pareados (controle I e II, respectivamente), sendo indivíduos saudáveis com perfil semelhante (quanto à idade, sexo e condições bucais) aos dos grupos em estudo. Não foram incluídos pacientes diabéticos, portadores de próteses bucais totais, outras doenças sistêmicas e que estivessem sob terapia com medicamentos que podem interferir com as condições bucais. Foram realizados exame clínico, anamnese e coleta de enxágüe bucal de cada paciente. Este foi semeado em meios de cultura específicos para cada microrganismo e, após incubação, foram obtidos valores de UFC/mL. Os isolados foram identificados pelo sistema API. A prevalência das espécies de microrganismos isolados foi comparada entre os grupos anemia falciforme com HU (AnF/HU+), sem HU (AnF/HU-) com seus respectivos controles. Foram realizados testes de suscetibilidade aos antimicrobianos segundo metodologia CLSI. Não foram observadas diferenças estatisticamente significativas entre as contagens de estafilococos... / Considering that sickle cell anemia patients have reported increased susceptibility to infections and oral reservoirs of pathogens may represent a gateway for disease, evaluation of potentially pathogenic oral flora becomes relevant. The aim of this study was to evaluate the presence of Candida species, staphylococci, Enterobacteriaceae and Pseudomonas spp. in the oral cavity of patients with sickle cell disease under treatment with hidroxyurea (HU), comparing the results with control subjects. The study included 69 patients aged 15-60 years, with sickle cell disease, confirmed by clinical and laboratory examinations. These were divided into two groups:under treatment with HU for at least 90 days (n=30), and without HU (n=39). Two matched controls (control I and II, respectively), composed of healthy individuals with similar profile (age, gender and oral conditions) to the study groups were included. Diabetic patients, patients with dentures, and other systemic diseases and those under treatment with medications that can interfere with oral conditions were not included. Clinical examination and anamnese were performed and mouthrinse sample was collected from each patient. The sample was plated into specific culture media for each microorganism and, after incubation values of cfu/ml were obtained. Isolates were identified by API system. The prevalence of the species were compared between groups with sickle cell anemia HU (AnF/HU+) and without HU (AnF/HU-) and the respective control groups. Antimicrobial susceptibility testings were performed according to the CLSI methodology. There were no statistically significant differences counts of staphylococci and Enterobacteriaceae/Pseudomonas between the groups AnF/HU+ and AnF/HU- and the respective control groups. Significant differences in the counts of yeasts were observed between AnF/HU- group and the respective control, however... (Complete abstract click electronic access below)

Resumo: Considerando-se que portadores de anemia falciforme apresentam relatado aumento da suscetibilidade às infecções e que reservatórios bucais de microrganismos patogênicos podem representar uma porta de entrada para doenças, a avaliação da microbiota bucal potencialmente patogênica ganha relevância. O objetivo deste estudo foi avaliar a presença de leveduras do gênero Candida, estafilococos, enterobactérias e Pseudomonas spp. na cavidade bucal de pacientes com anemia falciforme em tratamento com hidroxiuréia, comparando os resultados com indivíduos controle. Foram incluídos no estudo 69 pacientes, com idades entre 15 a 60 anos, portadores de anemia falciforme, confirmados por exames clínicos e laboratoriais. Estes foram divididos em dois grupos: em tratamento com hidroxiuréia (HU) por no mínimo 90 dias (n=30); sem tratamento com HU (n=39). Foram também incluídos dois grupos controle pareados (controle I e II, respectivamente), sendo indivíduos saudáveis com perfil semelhante (quanto à idade, sexo e condições bucais) aos dos grupos em estudo. Não foram incluídos pacientes diabéticos, portadores de próteses bucais totais, outras doenças sistêmicas e que estivessem sob terapia com medicamentos que podem interferir com as condições bucais. Foram realizados exame clínico, anamnese e coleta de enxágüe bucal de cada paciente. Este foi semeado em meios de cultura específicos para cada microrganismo e, após incubação, foram obtidos valores de UFC/mL. Os isolados foram identificados pelo sistema API. A prevalência das espécies de microrganismos isolados foi comparada entre os grupos anemia falciforme com HU (AnF/HU+), sem HU (AnF/HU-) com seus respectivos controles. Foram realizados testes de suscetibilidade aos antimicrobianos segundo metodologia CLSI. Não foram observadas diferenças estatisticamente significativas entre as contagens de estafilococos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Considering that sickle cell anemia patients have reported increased susceptibility to infections and oral reservoirs of pathogens may represent a gateway for disease, evaluation of potentially pathogenic oral flora becomes relevant. The aim of this study was to evaluate the presence of Candida species, staphylococci, Enterobacteriaceae and Pseudomonas spp. in the oral cavity of patients with sickle cell disease under treatment with hidroxyurea (HU), comparing the results with control subjects. The study included 69 patients aged 15-60 years, with sickle cell disease, confirmed by clinical and laboratory examinations. These were divided into two groups:under treatment with HU for at least 90 days (n=30), and without HU (n=39). Two matched controls (control I and II, respectively), composed of healthy individuals with similar profile (age, gender and oral conditions) to the study groups were included. Diabetic patients, patients with dentures, and other systemic diseases and those under treatment with medications that can interfere with oral conditions were not included. Clinical examination and anamnese were performed and mouthrinse sample was collected from each patient. The sample was plated into specific culture media for each microorganism and, after incubation values of cfu/ml were obtained. Isolates were identified by API system. The prevalence of the species were compared between groups with sickle cell anemia HU (AnF/HU+) and without HU (AnF/HU-) and the respective control groups. Antimicrobial susceptibility testings were performed according to the CLSI methodology. There were no statistically significant differences counts of staphylococci and Enterobacteriaceae/Pseudomonas between the groups AnF/HU+ and AnF/HU- and the respective control groups. Significant differences in the counts of yeasts were observed between AnF/HU- group and the respective control, however... (Complete abstract click electronic access below) / Orientador: Cristiane Yumi Koga Ito / Coorientador: Maria Stella Figueiredo / Banca: Fernanda Lourenção Brigheti / Banca: Karen Regina Carim da Costa / Mestre

Magister Artium - MA / This study falls within the framework of the larger multidisciplinary university health initiative (MUTHI) objectives to investigate and document the use of local medicinal plants for the treatment of HIV and symptoms of related opportunistic infections such as tuberculosis, thrush and shingles in the Western Cape. The study stems from twelve months fieldwork in Strand, Western Cape and the collection of plants from Mpoza, Eastern Cape for a variety of reasons. The study ethnographically documents when, under which circumstances and where plants are collected for use.As far as I am aware this is the first anthropological study which "follows" traditional healers in the Western Cape to a site in the Eastern Cape where they collect plants. Seventeen plants were collected from different genera which traditional healers reported to use as treatment for suspected HIV and related symptoms. For each plant I describe the medicinal uses,preparatory techniques and plant parts used as suggested by traditional healers. I also explore healer's aetiologies concerning plants, treatments and the social-material relations which are prevalent in my research settings.

Opportunistic Routing (OR) is an effective and enhanced routing scheme for wireless multihop environment. OR is an approach that selects a certain number of best forwarders (candidates) at each hop by taking the advantage of the broadcast nature of the wireless medium to reach the destination. When a set of candidates receive the packet, they coordinate with each other to figure out which one has to forward the packet toward the destination. Most of the research in this area has been done in mesh networks where nodes do not have mobility. In this survey, we propose a new OR protocol for mobile ad hoc scenarios called as Enhanced Mobility-based Opportunistic Routing (EMOR) protocol. To deal with the node mobility, we have proposed a new metric which considers the following: geographical position of the candidates; the link delivery probability to reach them; the number of neighboring nodes of candidates; and the predicted position of nodes using the motion vector of the nodes. We have compared EMOR with five other well-known routing protocols in terms of delivery ratio, end-to-end delay, and expected number of transmissions from source to the destination. Our simulation results show that proposed protocol improves delivery ratio and number of expected transmission in terms of different type of mobility models.

Master of Public Health - MPH / Meningitis is a common opportunistic infection and an important cause of mortality among people living with HIV and AIDS globally. This study investigated meningitis in adults living with HIV and AIDS admitted to the medical wards of Livingstone tertiary hospital in Port Elizabeth in 2018 and determined the prevalence of its aetiological types, clinical presentations, diagnostic challenges, treatment outcomes and predictors of prognosis.

Efficient implementation of resource sharing strategies in a multi-user wireless environment can improve the performance of a network significantly. In this thesis we study various scheduling strategies for wireless networks and handle the problem of opportunistically scheduling transmissions using channel aware schemes. First we propose a scheme that can handle users with asymmetric channel conditions and is opportunistic in the sense that it exploits the multi-user diversity of the network. The scheme requires the users to have a priori knowledge of their channel distributions. The associated overhead is limited meaning it offers reduced feedback load, that does not scale with the increasing number of users. The main technique used to shrink the feedback load is the contention based distributed implementation of a splitting algorithm that does not require explicit feedback to the scheduler from every user. The users find the best among themselves, in a distributed manner, while requiring just a ternary broadcast feedback from the scheduler at the end of each mini-slot. In addition, it can also handle fairness constraints in time and throughput to various degrees. Next we propose another opportunistic scheduler that offers most of the benefits of the previously proposed scheme but is more practical because it can also handle heterogenous users whose channel distributions are unknown. This new scheme actually reduces the complexity and is also more robust for changing traffic patterns. Finally we extend both these schemes to the scenario where there are fixed thresholds, this enables us to handle opportunistic scheduling in practical systems that can only transmit over finite number of discrete rates with the additional benefit that full feedback session, even from the selected user, is never required.