Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2018-06-07T20:50:15Z No. of bitstreams: 1 Alessandra_Silva_2018.pdf: 2406267 bytes, checksum: fdec397e3ca9dc1b624c4be16eda7aac (MD5) / Made available in DSpace on 2018-06-07T20:50:15Z (GMT). No. of bitstreams: 1 Alessandra_Silva_2018.pdf: 2406267 bytes, checksum: fdec397e3ca9dc1b624c4be16eda7aac (MD5) Previous issue date: 2018-03-22 / The presence of medicines in potable water is one of the biggest concernings in public health, once that there is not a lot knownledge about their chronical effects in a long term intake. The potential risk of contamination in the supplied water has motivated new researches aiming the increasing of the efficiency on removing these emerging pollutants. Among these researches the photocathalysis has widelly been studied due its efficiency on decontaminating chemical pollutants, effluents treatment and residual water purification. Photochemical processes presents positive results on the degradation of organic pollutants compounds and the possibility of obtaining photocataliysts in nanometric scales through the electrophase makes it even more efficient. In this work, by electrophase, was obtained a polimeric solution containing PBAT/ZnO, ZnO particlules with reduced scales. The charcterization of the synthetized material was made by X-Ray Difraction (XRD), Differential Thermal Analysis (DTA) Differential Scanning Calorimetry (DSC), Scanning Electronic Microscopy (SEM) and UV-Vis Spectrophotometry. From the obtained results it was possible to conclude that, the reduced distance between the needle and the collector and electric tension used during the electronspinning of ZnO/PBAT nanowires, influency on getting fibres with smaller diameters, from which there is a possibility of obtaining nanoparticles of ZnO, with mean diameter of 46,96 nm, in its crystalline characteristic phase and equivalent to the commercial material by the electrophased process, however, with the smaller particules, which suggests that with the increasing of the contact surface the compound to be oxidized, the phocatalysis process may be favored. / A presença de fármacos em água potável e de abastecimento é uma preocupação de saúde pública, visto que pouco se sabe sobre os efeitos crônicos do consumo ao longo prazo desses contaminantes. O potencial risco de contaminação da água de abastecimento, tem incentivado estudos com o objetivo de aumentar a eficiência na remoção desses poluentes emergentes. Dentre esses estudos, a fotocatálise vem sendo amplamente estudada devido a sua eficiência na descontaminação ambiental, redução, degradação, remediação ou transformação de resíduos químicos poluentes, tratamento de efluentes e purificação de águas residuárias. Os processos fotoquímicos apresentam bons resultados na degradação de compostos poluentes orgânicos e a possibilidade de obter fotocatalisadores em escala nanométrica através da técnica da eletrofiação pode torná-la ainda mais eficiente. Neste trabalho foi obtido através da eletrofiação de uma solução polimérica contendo PBAT/ZnO partículas de ZnO com escala reduzida. A caracterização do material sintetizado foi realizada por Microscopia Optica, Difração de Raios-X (DRX), Análise Térmica Gravimétrica (TGA), Calorimetria Exploratória Diferencial (DSC), Microscopia Eletrônica de Varredura (MEV) e Espectrofotometria UV-Vis. A partir dos resultados obtidos foi possível concluir que, a diminuição da distância entre a agulha e o coletor e tensão elétrica utilizadas durante a eletrofiação dos nanofios de ZnO/PBAT, influencia na obtenção de fios com diâmetros menores e que a partir destas fibras há possibilidade de obtenção de nanopartículas de ZnO, com diâmetro médio de 46,69 nm, com fase cristalina característica e equivalente ao material comercial, porém com tamanho de partículas menores, o que sugere aumento da superfície de contato do material particulado com o composto a ser oxidado, favorecendo o processo de fotocatálise.

O objetivo desta tese é analisar a relação dos fatores do ambiente externo da empresa no país de origem, fatores organizacionais e fatores do empreendedor pelos quais algumas empresas de base tecnológica (EBTs) se internacionalizam de maneira acelerada desde sua fundação ou poucos anos após sua fundação. Cerca de 1000 EBTs foram aleatoriamente convidadas para responder o questionário. Ao final da coleta de dados a primeira base de dados gerada continha 214 respostas, das quais 85 foram obtidas de empresas com algum tipo de negócio no exterior, 39,7%. Destes, 54 questionários foram considerados válidos para esta pesquisa. Os resultados mostram que os fatores externos à empresa influenciam mais na internacionalização das EBTs em relação aos fatores internos. Assim, o habitat de localização, as parcerias, as políticas governamentais e a integração na cadeia de valor explicam de maneira significativa o processo de internacionalização das EBTs brasileiras. Porém, é a integração em cadeias produtivas globais o fator que melhor discrimina a internacionalização das EBTs born globals. Em relação aos fatores do empreendedor, as habilidades gerenciais internacionais do empreendedor também apareceram como importantes no processo acelerado de entrada no exterior das EBTs. Além disso, a tese apresenta uma taxonomia resultante de uma análise de clusters. Foram identificados três clusters: EBTs Born globals puxadas por cadeias globais, EBTs Born globals incentivadas por habitats de inovação e EBTs internacionalizadas não born globals. Portanto, esta pesquisa contribui para a discussão do processo de internacionalização acelerada das EBTs, contribuindo para suprir a lacuna da importância dos fatores externos, internos e do empreendedor no processo de internacionalização dessas empresas e apresentando uma taxonomia baseada em dados de born globals em mercados emergentes. / The objective of this thesis is to analyze the relation of factors external to the firm in the country of origin, organizational factors and entrepreneurial factors through which some technology-based firms (TBFs) internationalize in an accelerated manner since their foundation or a few years after their foundation. Approximately 1,000 TBFs were randomly invited to answer a questionnaire. At the end of data collection, the first database generated held 214 answers, of which 85 were obtained from firms which had some kind of business abroad (39.7%). Of those, 54 questionnaires were considered valid for this research. The results show that factors external to the firms influence more in the internationalization process of the TBFs in relation to internal factors. Therefore, location, partnerships, government policies and integration in the value chain significantly explain the internationalization process of Brazilian TBFs. However, integration in the value chain is the factor that best discriminates the internationalization of born global TBFs. In relation to entrepreneurial factors, international managing skills of the entrepreneur are also important to the accelerated internationalization process of the TBFs. Moreover, a taxonomy resulting of the analysis of clusters is presented in the thesis. Three clusters were identified: born-global TBFs generated by global chains, born-global TBFs motivated by innovation habitats and internationalized non-born global TBFs. Therefore, this paper contributes to the discussion of the accelerated internationalization process of TBFs, filling the gap regarding the importance of external, internal and entrepreneurial factors in the internationalization process of these firms and presenting a taxonomy based on data from born globals in emerging markets.

Orientador: Wilson de Figueiredo Jardim / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-19T06:01:40Z (GMT). No. of bitstreams: 1 Raimundo_CassianaCarolinaMontagner_D.pdf: 6486329 bytes, checksum: eb2082b97701f19b66fc4e6dc033da3f (MD5) Previous issue date: 2011 / Resumo: O objetivo deste trabalho foi avaliar, através de um perfil anual, a qualidade dos mananciais e da água tratada de Campinas (SP) em relação à presença de cafeína, estrona, 17b-estradiol, estriol, progesterona, testosterona, 17a-etinilestradiol, mestranol, levonorgestrel, dietilestilbestrol, triclosan, 4-n-octilfenol, 4-n-nonilfenol, bisfenol A, fenolftaleína e atrazina empregando extração em fase sólida (SPE) e cromatografia líquida acoplada ao espectrômetro de massas (LC-MS/MS), e verificar o potencial estrogênico das amostras usando o bioensaio Bioluminesce Yeast Estrogen Screening (BLYES). Os resultados mostraram a presença de seis dos 16 compostos investigados em pelo menos uma amostra de água tratada. A estrona foi detectada apenas uma vez. Concentrações de atrazina de até 687 ng L foram determinadas nas amostras provenientes do rio Capivari, e nas amostras de água tratada provenientes do rio Atibaia as concentrações não passaram de 42 ng L. A fenolftaleína foi determinada em apenas uma campanha em todas as amostras provenientes do rio Atibaia em concentrações de até 20 ng L. As concentrações médias de bisfenol A e triclosan foram 7 e 17 ng L, respectivamente. Nos mananciais foram determinados 13 dos 16 compostos investigados. Todas as amostras de água bruta e tratada apresentaram concentrações de cafeína que variaram significativamente entre os períodos de seca e cheia dos rios. As estações de tratamento de água de Campinas, operando no sistema convencional foram capazes de remover entre 30 e 99% dos contaminantes investigados. No mais, 40 % das amostras de água tratada apresentaram atividade estrogênica positiva (entre 0,01 e 1,33 ngE2equiv L) e todas as amostras de água bruta apresentaram estrogenicidade entre 0,06 e 6,54 ngE2equiv L. Sendo que estas foram maiores nos períodos de estiagem / Abstract: The purpose of this work was to evaluate an annual profile of both source of supply and drinking water quality in the city of Campinas (São Paulo State) in relation to the presence of caffeine, estrone, 17b-estradiol, estriol, progesterone, testosterone, 17a-ethynylestradiol, mestranol, levonorgestrel, diethylstilbestrol, triclosan, 4-n-octylphenol, 4-n-nonylphenol, bisphenol A, phenolphthalein and atrazine using Solid Phase Extraction (SPE) and Liquid Chromatography with Tandem Mass Spectrometry Detection (LC-MS/MS), and make sure the estrogenic potential of samples using Bioluminesce Yeast Estrogen Screening bioassay (BLYES). Results showed the presence of six of the 16 compounds investigated in least one sample of drinking water (estrone, triclosan, bisphenol A, phenolphthalein, atrazine and caffeine). Atrazine concentrations up to 687 ng L were found in drinking water samples from the Capivari River. In drinking water samples from the Atibaia River, the concentrations did not exceed 42 ng L. Phenolphthalein was determined in only one campaign in both raw and treated water from the Atibaia River at concentrations around 20 ng L. Average concentrations of bisphenol A and triclosan in drinking water samples were 7 and 17 ng L, respectively. Thirteen of the 16 investigated compounds were determined in surface waters. All samples of raw and treated water showed concentrations of caffeine that varied significantly between dry and wet seasons. The conventional water treatment plants in Campinas were able to remove between 30 and 99 % of the investigated contaminants. The estrogenic activity was evaluated using BLYES bioassay, where 40% of drinking water samples showed positive estrogenic activity (between 0.01 and 1.33 ngE2equiv L) and all samples of surface water presented estrogenic activity between 0.06 and 6.54 ngE2equiv L. These values were higher in dry winter periods / Doutorado / Quimica Analitica / Doutor em Ciências

Submitted by Roman Goossens (roman.goossens@gmail.com) on 2013-08-23T21:08:57Z No. of bitstreams: 1 Roman Goossens Do Capital Controls Boost Reslience to Crises 20130823.pdf: 704128 bytes, checksum: 6f940315e4f866fbc901872143770b70 (MD5) / Rejected by Suzinei Teles Garcia Garcia (suzinei.garcia@fgv.br), reason: Prezado Roman, A ficha catalográfica na não tem o número e seu nome da segunda página subiu par a primeira página. Att. Suzi 3799-7876 on 2013-08-27T13:04:32Z (GMT) / Submitted by Roman Goossens (roman.goossens@gmail.com) on 2013-08-27T14:22:16Z No. of bitstreams: 1 Roman Goossens Do Capital Controls Boost Reslience to Crises 20130823.pdf: 731111 bytes, checksum: 751d28a481a97d4776e7d5bd503e9d88 (MD5) / Approved for entry into archive by Suzinei Teles Garcia Garcia (suzinei.garcia@fgv.br) on 2013-08-27T14:45:42Z (GMT) No. of bitstreams: 1 Roman Goossens Do Capital Controls Boost Reslience to Crises 20130823.pdf: 731111 bytes, checksum: 751d28a481a97d4776e7d5bd503e9d88 (MD5) / Made available in DSpace on 2013-08-27T15:00:38Z (GMT). No. of bitstreams: 1 Roman Goossens Do Capital Controls Boost Reslience to Crises 20130823.pdf: 731111 bytes, checksum: 751d28a481a97d4776e7d5bd503e9d88 (MD5) Previous issue date: 2013-07-26 / Capital controls are back in vogue and a number of emerging markets reintroduced these measures in recent years in the face of a 'flood' of international capital. Policymakers argue that these tools buttress their economies from the risk of a 'sudden stop' in capital flows. We show that capital controls seem to make emerging market economies (EMEs) more resistant to financial crises (i.e. that output loss following a crisis is lower when controls are higher). However that they also seem to make EMEs more crisis-prone, increasing the probability of crises. Policymakers should hence carefully evaluate whether the benefits of capital controls outweigh the costs before implementing them. / Os controles de capitais estão novamente em voga em razão dos países emergentes reintroduzirem essas medidas nos últimos anos face a abundante entrada de capital internacional. As autoridades argumentam que tais medidas protegem as economias no caso de uma 'parada abrupta' desses fluxos. Será demonstrado que os controles de capitais parecem fazer com que as economias emergentes (EMEs) fiquem mais resistentes diante de uma crise financeira (por exemplo, uma queda na atividade econômica seguida de uma crise é menor quando o controle é maior). No entanto, os controles de capitais parecem deixar as economias emergentes (EMEs) também mais propícias a uma crise. Deste modo, as autoridades devem ser cautelosas na avaliação quanto aos riscos e benefícios relativos a aplicação das medidas dos controles de capitais.

Philosophiae Doctor - PhD / Bionomics of vector-borne pathogens (VBPs) is a complex phenomenon that involves understanding the ecology of arthropod borne pathogens and vertebrate hosts potentially involved in their transmission cycles. Investigations into the bionomics of viral and bacterial VBPs circulating in Baringo and Homa Bay Counties of Kenya were carried out. Specifically, vertebrate hosts represented in mosquito bloodmeals, presence of arboviruses in blood fed mosquitoes and patients presenting with acute undiagnosed febrile illnesses in rural health facilities, and tick borne pathogens (TBPs) diversity in ticks of animals were identified. Mosquitoes were trapped by BG sentinel and CDC light traps, while ticks were sampled directly from domestic animals and tortoises close to human habitation along the shores and adjacent islands of Lakes Victoria and Baringo in Kenya. Blood and sera were also sampled from patients presenting with acute febrile illnesses visiting four rural health facilities in Homa Bay County. Mosquitoes and ticks were sorted and identified to species using standard morphological taxonomic keys. All the biological samples (blood-fed mosquitoes, ticks and blood/sera) were processed using molecular and culture procedures for detection of VBPs (arboviruses, Ehrlichia, Anaplasma, Rickettsia and protozoa). Among 445 blood-fed Aedeomyia, Aedes, Anopheles, Culex, Mansonia, and Mimomyia mosquitoes, 33 bloodmeal hosts were identified including humans, eight domestic animal species, six peridomestic animal species and 18 wildlife species. Further detection of Sindbis and Bunyamwera viruses was done on blood-fed mosquito homogenates by Vero cell culture and RTPCR in Culex, Aedeomyia, Anopheles and Mansonia mosquitoes from Baringo that had fed on humans and livestock. In TBPs assay, 585 tick pools were analysed consisting of 4,126 ticks collected in both study areas. More ticks were sampled in Baringo (80.5%), compared to Homa Bay (19.5%). In Baringo, agents of ehrlichiosis were detected from Amblyomma and Rhipicephalus ticks including Ehrlichia ruminantium (12.3%), Ehrichia canis (10.5%) and Paracoccus sp. (4.4%). Agents of anaplasmosis included Anaplasma ovis (7.2%), Anaplasma platys (4.4%) and Anaplasma bovis (4.0%), all from Hyalomma, Amblyomma and Rhipicephalus ticks, as well as agents of rickettsiosis, including Rickettsia africae, Rickettsia aeschlimannii, Rickettsia rhipicephali, Rickettsia montanensis and a Rickettsia sp. that was not conclusively characterized. Babesia caballi, Theileria sp. and Hepatozoon fitzsimonsi were also detected from both Rhipicephalus ticks and Amblyomma ticks. In Homa Bay, Ehrichia ruminantium (17.5%) and Ehrichia canis (9.3%) were isolated from Amblyomma latum and Rhipicephalus pulchellus, as well as Anaplasma platys (14.4%) and Anaplasma ovis (14.4%) from Amblyomma and Rhipicephalus species. In determination of the occurrence of arboviruses among patients presenting with acute febrile illnesses, acute Bunyamwera 3 (0.9%) and Sindbis 2 (0.6%) infections were detected by RT-PCR and cell culture and Sindbis seroprevalence was determined by plaque assay. Though a significant proportion of these patients tested positive for low Plasmodium parasitemia, none were co-infected with Plasmodium parasites and arboviruses. This study highlights the presence and relative importance of zoonotic VBPs in both study areas.

The previous research, in the internationalization area, indicates that there are both opportunities and challenges when companies operate abroad. By using a SLEPT analysis model, which studies the effect from the countries’ social/cultural, legal, economic, political and technological environments and their effects, it makes the opportunities and challenges more depletive. This makes it easier for companies, which are operating in a foreign country, to handle the situation and therefore, saves both time and money for the companies. The purpose of this study is to present a more conspicuous representation of the opportunities and challenges that companies in an industrial market have to face, during their operation in an emerging market. To gather the necessary information a multiple case study was implemented with three Swedish companies, who all are within the business to business (B2B) area. This study was conducted by interviewing the case companies, which are all established in India. These companies are Bufab AB and two from the Volvo Group (Volvo 3P and Volvo Powertrain). This study demonstrates that the main opportunities are the Indian population, highly educated people, the complaisant government and the fact that it is a low cost market. The challenges that these case companies had to deal with are lack of experience, the law and tariff system is difficult to understand, the laws change frequently, the economic development is rapid and the infrastructure is poor.

Cette thèse étudie le financement obligataire des entreprises. Les résultats soulignent le rôle de l’environnement légal et de la gouvernance. Le premier chapitre démontre le rôle de la protection et l’information des créanciers sur le marché obligataire. Il identifie un impact non homogène entre les firmes. Le second chapitre analyse l’impact d’une émission obligataire sur la valeur d’une entreprise à l’aide d’une méta-analyse. Il souligne les facteurs expliquant des résultats jusqu’alors divergents dans la littérature. Le troisième chapitre se focalise sur le marché des émissions obligataires des entreprises chinoises et met en exergue le rôle de la propriété étatique et managérial sur la valeur créée par une émission obligataire. Enfin, le quatrième chapitre isole un biais religieux des investisseurs professionnels, et contribue à la littérature comportementale s’intéressant à la valeur de l’entreprise. / This dissertation studies the corporate bond market. Results emphasize the role of legal environment and governance. The first chapter demonstrates the role of creditors’ protection and information on the corporate bond market. It identifies a non-homogenous impact across firms. The second chapter uses a meta-analysis to scrutinize the effect of a bond offering on the firm’s value. It stresses the reasons underlying diverging results in the literature so far. The third chapter focuses on the Chinese corporate bond market and highlights the role of state and management ownership on the value created by a bond offering. The fourth chapter isolates a religious bias from professional investors and contributes to the literature on the impact of behavioural biases on the firm’s value.

Introduction: Emerging adults (young people age 18 to 29) are increasingly using the Internet to seek sex partners, with over 30% having tried an online or mobile dating site. As more emerging adults use dating and sex-seeking websites (DSP) for their love and sexual pursuits, it is imperative to understand how DSPs contribute to HIV/STI risk. Objectives: The objectives of this research were accomplished by pursuing the following specific aims: Aim 1. To systematically review and quantitatively synthesize evidence from published findings to determine the association between condom use and meeting venue (online and offline). Aim 2. To determine whether condom use behaviors during the first sexual interaction among heterosexual emerging adults vary depending on the venue in which participants met their partners in the past six months. Aim 3. To describe how the Information Motivation Behavioral (IMB) Skills Model applies to the relationship between condom use and meeting venue. Methods: This mixed methods study identified sexual risk behaviors of emerging adults. Men and women—recruited via social networking, classified ad and dating and sex-seeking websites— who met a heterosexual partner on a DSP and/or in-person in the past six months completed a survey about behavioral, communication and relationship factors that influence condom use. Additionally, a subset of people who met partners on DSPs and or offline (i.e., in-person) who completed the survey participated in qualitative interviews designed to explore in-depth factors that influence condom use during the first offline sexual encounter. The Information Motivation Behavioral (IMB) skills model was used to further understand the HIV/STI sexual risk behaviors of emerging adults with sex partners they met on DSP compared to those who met partner’s offline. Results: The findings of this study were that DSP are not associated with greater risks of condomless sex compared to offline meeting venues. The qualitative findings suggest that emerging adults have an attitude that condoms are to be used in new sexual relationships. However, whenever emerging adults do not have condoms available, they are less likely to use a condom. Conclusion: Although the findings of this study suggest that there is no statistical difference in condomless sex by venue, DSPs are an important place for public health messaging about condom use for the prevention of HIV/STIs, and unintended pregnancy. DSPs can help achieve some of the objectives set by Healthy Campus 2020, Healthy People 2020, and the National HIV/AIDS Strategy. In addition to targeting DSPs, it is important to continue sexual health promotion efforts in offline meeting venues.

Alors que l’épidémiologie de la dengue dans le sud du Vietnam est caractérisée par un régime d’hyper-endémicité, la maladie est en train d’émerger dans le nord du pays depuis une quinzaine d’années. Les incidences annuelles augmentent de façon constante d’année en année et la maladie diffuse à partir de Hanoi vers les zones rurales environnantes. Le travail de recherche effectué durant cette thèse s’intéresse aux déterminants spatiaux et temporels de la transmission de la dengue dans un contexte d’émergence. Les résultats sont organisés en 3 parties. La première se concentre sur l’étude d’une épidémie qui frappa à l’automne 2013 l’île de Cat Ba, au large du Vietnam dans la baie d’Halong. Cette île est caractérisée par une population de petite taille vivant essentiellement de l’exploitation des produits de la mer ainsi que du tourisme. Une grande proportion de cette population vit sur des villages flottant au large de l’île. Nous avons comparé l’épidémiologie de la dengue sur les villages flottants et sur l’île. Pour cela nous avons testé l’agrégation spatio-temporelle des cas de dengue. Nos résultats montrent une incidence de dengue sur les villages flottant plus forte que sur l’île, malgré des densités de moustiques plus faibles. Les cas de dengue étaient également extrêmement agrégés dans le temps et l’espace, suggérant une importation de moustiques infectés plutôt qu’un cycle de transmission local complet.La seconde partie de cette thèse s’est intéressée aux déterminants environnementaux de la transmission de la dengue dans la province de Hanoi. Cette étude est basée sur l’analyse de 31906 cas de dengue géospatialisés de 2008 à 2013 et utilise des méthodes de SIG couplées avec des techniques modernes d’apprentissage automatique dans le but de quantifier en détail les influences de chaque covariable environnementale sur le risque de dengue. Nos résultats montrent une forte influence de la densité de population sur l’incidence de la dengue, comme précédemment documenté dans d’autres régions du monde. L’incidence de la dengue augmente avec la couverture végétale pour de faibles niveaux de couverture végétale et atteint de très faibles niveaux lorsque la couverture végétale est au-dessus d’un certain seuil. Une telle relation est cohérente avec ce qui est actuellement connu sur l’écologie des vecteurs de dengue. Finalement, nos résultats ont montré une forte association entre les incidences de dengue et les zones résidentielles universitaires. Ces zones sont peuplées d’étudiants venant des régions autour de Hanoi où l’incidence est faible. La susceptibilité à la dengue de cette population estudiantine est donc plus forte que dans le reste de la population de Hanoi.La dernière partie de cette thèse s’est intéressée aux relations entre les épidémies successives de dengue à Hanoi de 2011 à 2014. L’épidémiologie de la dengue à Hanoi est très saisonnière avec de très faibles incidences en hiver. Une question majeure dans une telle situation est de savoir si les virus de dengue persistent localement entre chaque épidémie. Si non, alors les cas de dengue observés en hiver correspondraient à des cas d’importation qui pourraient démarrer une nouvelle épidémie chaque été lorsque les conditions climatiques locales deviennent à nouveau favorables pour la transmission de la dengue. Nous avons utilisé une approche de phylogénie moléculaire de virus échantillonnés à Hanoi ainsi que dans d’autres localités en Asie du sud-est d’où les virus de dengue pourraient migrer. L’idée d’une telle approche consiste à comparer les distances phylogénétiques entre des virus circulants dans une localité une année donnée et des virus circulants soit la même année dans d’autres localités, soit durant les années précédentes dans la même localité. Nos résultats suggèrent que, chaque année, les épidémies de dengue à Hanoi démarrent à partir des virus de dengue importés depuis Ho Chi Minh ville. Ce schéma semble être le cas pour les 4 sérotypes de dengue. / While high dengue transmission has been documented in the southern part of Vietnam since the late seventies, the disease started to emerge in the northern part of the country 15 years ago only. In northern Vietnam, annual incidences are consistently increasing from year to year and progressively spreading from Hanoi to the surrounding rural areas. Very little is known on the causes of this recent emergence.The research carried out in this PhD revolves around the spatial and temporal determinants of dengue epidemiological transmission in a context of emergence and the results are organized in 3 parts. The first one focuses on a single epidemic of dengue that occurred during the autumn of 2013 on the small island of Cat Ba, off the coast of Vietnam in Ha Long bay. Cat Ba island is characterized by a population of a small size mostly living from sea farming and tourism. Dengue transmission on this island has been historically rare until the major epidemics that stroke the island in 2013. The population of Cat Ba has this specificity that a large proportion of it lives of floating villages off the island coast. We were interested in investigating whether the epidemics had different behavior on the island and the floating villages. To achieve this aim, we focused on the identification of spatio-temporal clusters of cases. Our results show a higher dengue incidence on the floating villages than on the island despite lower mosquito densities. Dengue cases were also highly clustered in space and time suggesting importation of infected mosquitoes rather than a local complete transmission cycle.The second part focuses on the environmental determinants of dengue transmission in the province of Hanoi. This study is based on the use of 31,906 geospatialized cases of dengue from 2008 to 2013 and applies GIS techniques coupled with modern machine learning techniques in order to quantify in detail the influences of each environmental covariate on dengue risk. Our results showed a strong influence of population density on dengue incidence as previously reported in other parts of the world. Dengue incidence increased with tree coverage for low levels of tree coverage and then reached very low levels for tree coverage above a given threshold. This pattern is consistent with the current knowledge of the dengue vector ecology. Finally we showed a strong association of dengue incidence with academic residential areas. Such areas are populated with students coming from locations around Hanoi with low dengue incidence. The susceptibility of this student population to dengue infection is thus higher than the rest of the Hanoian population.The final part looked at the relationships between the successive epidemics in Hanoi from 2011 to 2014. Dengue epidemiology in Hanoi is very seasonal with very few cases documented in winter. A major question in such situations is whether viruses actually persist locally between epidemics. If not, then observed cases during the winter would correspond to imported cases igniting new epidemics every summer when the local climatic conditions are favorable again for local dengue transmission. To do so, we used phylogenetic analyses of virus sampled in Hanoi combined with virus sampled in other locations in Southeast Asia from where dengue viruses could migrate. The rationale behind this method is to compare the phylogenetic distances between sequences circulating in a given location in a given year and sequences circulating either the same year in other locations or previous years in the same location. Our results suggest that every year dengue epidemics in Hanoi are started from viruses imported from Ho Chi Minh city. This seems to be the case for the 4 dengue serotypes.

Hosts have two main strategies for coping with infections: resistance and tolerance. Resistance is aimed at preventing or eliminating parasites, whereas the goal of tolerance is to maintain performance regardless of parasite burden. The balance between resistance and tolerance within a host may mediate host competence, or the propensity of a host to infect other hosts or vectors. Hosts with high tolerance and low resistance to an infection, for instance, may be highly competent and possess the greatest potential to act as superspreaders. These superspreading hosts will contribute disproportionately to transmission, thus posing the greatest risk to other hosts within a population or community. Understanding the drivers of heterogeneity in host competence therefore has broad implications for the management of infectious diseases in nature. Host tolerance is typically quantified as the slope of the relationship between host performance and parasite burden. The majority of host tolerance studies have been conducted at the level of genotypes, populations and species. Individual hosts often exhibit variation in competence, with some individuals contributing more or less to transmission than the population/species average. Despite the clear importance of understanding tolerance at the individual-level, such studies are rare and may be particularly challenging in field contexts due to the need for repeated performance-burden measurements. I used the house sparrow (HOSP) – West Nile virus (WNV) system to investigate differences among two alternative approaches to estimating individual tolerance: the scope and position methods. The scope method estimates tolerance traditionally as the slope of multiple performance-burden measurements over time within an individual; alternatively, the position method required only one measurement for each individual, thus characterizing tolerance via among-individual variation in host defense. We found strong relationships between scope and position estimates of individual tolerance, suggesting that the position method may be an appropriate proxy to use in field studies. I also compared tolerance estimates derived from different metrics of performance. There were weak correlations among these estimates of tolerance, implying that tolerance estimated by measuring a single trait may not be indicative of tolerance at the level of the whole individual or their contribution to disease processes. Understanding the physiological mediators of host competence may help to pinpoint at-risk and risky individuals (or genotypes, populations and species) within natural communities, thus facilitating the development of more targeted disease management strategies. Cytokines and glucocorticoids have been identified as potent mediators of host defense. Pro-inflammatory cytokines may act to promote resistance, whereas anti-inflammatory cytokines and glucocorticoids tend to mediate host tolerance. I investigated the dynamics of pro-inflammatory cytokine IFN-γ, anti-inflammatory cytokine IL-10, and the major avian glucocorticoid, corticosterone (CORT), following WNV exposure in HOSP. I then assessed the influence of these three mediators on resistance and tolerance to WNV infection. I found unusual dynamics for the three mediators across the infection period: IFN-γ expression was not induced by WNV exposure, IL-10 expression was dampened by WNV exposure, and CORT levels were higher in unexposed individuals. Despite the unique response of HOSP to WNV exposure seen here, we did find that constitutive expression of IFN-γ and IL-10 mediate resistance and tolerance to WNV, respectively. Unexpectedly, we also found evidence for protective (pro-resistance) effects of CORT, which contrasts with previous evidence for the role of CORT in mediating WNV infections. Combined, the results of this study suggest that hosts with constitutively high IL-10 and low IFN-γ expression may have high potential to act as superspreaders of disease, thus becoming critical targets in designing WNV-control strategies in passerines. The methods by which we quantify host tolerance may greatly affect the conclusions we are able to draw from such studies. To date, a variety of definitions and techniques have been used to study tolerance in animals. In chapter three, I briefly summarize past plant and animal tolerance research, highlighting discrepancies among researchers in their motivations, definitions and techniques for studying tolerance. For instance, I discuss biases in the literature regarding the use of range versus point tolerance, vigor, and laboratory versus field studies. In particular, I expound upon the nature of the performance metrics used in the majority of tolerance estimations in the literature, and discuss the ecological implications of these metrics. To conclude, I offer suggestions for overcoming the challenges associated with studying tolerance and encourage a unified way forward in the field, emphasizing the selection of system-specific and ecologically relevant tolerance metrics. My thesis research has employed physiological and behavioral methods in an ecological context to better understand the heterogeneities that exist in host competence. By combining empirical data in the HOSP-WNV system with conceptual and methodological strategies for assessing host defenses, this research has broadened our knowledge of host responses in the WNV system in a manner that may be applicable to understanding and managing disease dynamics in diverse natural communities.