In this dissertation, we study data collection and its achievable network capacity in Wireless Sensor Networks (WSNs). Firstly, we investigate the data collection issue in dual-radio multi-channel WSNs under the protocol interference model. We propose a multi-path scheduling algorithm for snapshot data collection, which has a tighter capacity bound than the existing best result, and a novel continuous data collection algorithm with comprehensive capacity analysis. Secondly, considering most existing works for the capacity issue are based on the ideal deterministic network model, we study the data collection problem for practical probabilistic WSNs. We design a cell-based path scheduling algorithm and a zone-based pipeline scheduling algorithm for snapshot and continuous data collection in probabilistic WSNs, respectively. By analysis, we show that the proposed algorithms have competitive capacity performance compared with existing works. Thirdly, most of the existing works studying the data collection capacity issue are for centralized synchronous WSNs. However, wireless networks are more likely to be distributed asynchronous systems. Therefore, we investigate the achievable data collection capacity of realistic distributed asynchronous WSNs and propose a data collection algorithm with fairness consideration. Theoretical analysis of the proposed algorithm shows that its achievable network capacity is order-optimal as centralized and synchronized algorithms do and independent of network size. Finally, for completeness, we study the data aggregation issue for realistic probabilistic WSNs. We propose order-optimal scheduling algorithms for snapshot and continuous data aggregation under the physical interference model.

We create a dynamic network model to replicate more closely the population network structures of interest. Network, Norms and HIV/STI Risk Among Youth (NNAHRAY) is a community relationship survey data set, which provides a rare sample of a human risky-behavior contact network. Combining disease compartmental models with our dynamic network model, we simulate the spread of Human Immunodeficiency Virus (HIV) and Herpes Simplex Type 2 Virus (HSV2) with consideration of HSV2's synergistic impact on HIV's transmission. Our model reproduces HIV prevalence, HSV-2 prevalence, and the contact network close to those observed in NNAHRAY, with HIV annual prevalence closer to the estimated values from the literature than those of any disease spread model based on static networks. The success of fitting our model to the target data shows the importance of considering the data sampling process, contact dynamics, and contact network structures. Our model, under certain conditions, has prevalence prediction results that are insensitive to changes in network size. The analysis of various prevention/intervention strategies targeting different risky groups gives important insights into strategy prioritization and illustrates how our model can be used to assist in making public health policy decisions in practice, both for individual diseases and in the more-recent area of study that considers synergy between two diseases.

La thèse vise à identifier, dans un premier temps, l’influence du timing de versement des dividendes des sociétés françaises cotées sur les cours boursiers. Elle cherche à identifier, dans un deuxième temps, les déterminants du timing de versement des dividendes. La démarche retenue pour argumenter ces propos est la suivante : dans une première partie, nous avons posé notre cadre théorique. Le positionnement de la thèse dans l’ancrage de la théorie politico-contracteulle et la théorie des signaux nous a orienté vers l’étude du contenu informationnel du timing de versement des dividendes dans un premier temps et à identifier ses déterminants dans un deuxième temps. La seconde partie est consacrée à l’étude empirique réalisée auprès de 69 entreprises initiatrices de dividendes cotées à l’indice SBF 120 durant l’année 2007 afin de répondre à notre premier objectif, et portée sur un échantillon de 57 sociétés françaises distributrices d’un dividende annuel durant la période 2003-2009 afin de répondre à notre second objectif. S’agissant de notre premier objectif, le recours à la méthodologie des études d’évènement a révélé que les cours réagissent à la date de versement des dividendes ce qui confirme que le timing de versement des dividendes possède un contenu informationnel. Quant à notre second objectif, les dispositions réglementaires souples sur la fixation de la date de versement du dividende et son emploi en tant que signal émis de la firme vers le marché posent la question du choix de cette date dans le contexte français à système juridique civil connu pour la protection des intérêts des actionnaires minoritaires. Les résultats de la littérature antérieure restent timides en raison de leur focalisation sur la date de versement du premier dividende – et notamment sur la probabilité d’initier un dividende suite à l’introduction en bourse. Les résultats de notre étude empirique confirment l’impact significatif de la présence d’un actionnaire majoritaire, de la profitabilité, de la liquidité et de la durée de versement du dividende précédent sur la fixation de la date de versement de cette année. Cet impact semble se manifester à travers une limitation de la durée entre la date de l’assemblée des actionnaires et la date de paiement effectif des dividendes et une reconnaissance de cette durée comme étant une bonne nouvelle par rapport aux autres signaux émis par l’entreprise au marché boursier. / The purpose of this study is to identify the informational content of the dividend pay date and its determinants. Namely, is there information in the timing of the dividend payments? The empirical evidence indicates that the market reacts at the dividend pay date. Mean excess returns of stock prices on the pay date are significantly positive and are insignificant and negative around the entire population of dividend pay dates. On the other side we are interested in the determinants of the dividend pay date. Our multivariate analysis shows that the ownership structure, the liquidity of the firm, the result, and the previous timing of dividend payment influence the fixing of the dividend pay date. This impact is shown as shorten as the delay between the date of the general meeting and the dividend pay date. This duration is considered as good news and can be a signal employed to attract new investors in the stock market.

When simulating air flows in an urban environment, for e.g. pollutant dispersion investigations, today's main tool is advanced computational fluid dynamics simulations. These simulations take a lot of time and resources to perform, even for small geometries. In some situations, one would like to be able to run approximate simulations, possibly with large geometries, without such a significant investment. The model described in this thesis is a graph network model which have streets and intersections of an urban environment modeled as connections and nodes in a graph. The model uses a pressured pipe model, based on the Darcy-Weisbach equation, to simulate air flow in the network. Such a model requires only rough measurements of the urban geometry and an estimated Darcy's friction factor, to be able to solve the system. Furthermore, using the same rough geometrical parameters, together with shear velocity, the model solves atmospheric exchange rates of the streets. Intersections play a major role when investigating urban dispersion. The way this model deals with dispersion in any complex intersections, represented by single nodes, is by using wind direction variance together with a distribution parameter based on computational fluid dynamics intersection simulations made in Comsol Multiphysics - also present in this paper. Using the simple model described above, I have simulated urban air flows in a complex urban geometry of a part of Paris. This specific geometry has already been investigated by computational fluid dynamics simulations as well as wind tunnel experiments. By comparing the computational fluid dynamics simulation with my model, I have validated its accuracy. 40% and 45% of all streets reach a relative and absolute error below 25% respectively. Directions of the street velocities have been simulated with approximately 90% accuracy - with distinct error indications. Atmospheric exchange rates of the streets are within an order of magnitude accurate, however, showing a systematic error by overestimating the vast majority of the exchange rates. The model could become even better by covering error sources discussed in the discussion section. Excess theory for simulating each of the above-described flows is presented, which might change the results. For example, slightly altering the modeling of the atmospheric exchange rate might fix the overestimation offset we have seen. Potential error sources could be the varying building heights and the streets angle relative the overlaying wind direction. The pressured pipe simulated flows have shown tendencies to be bad at picking up the effects of high/low buildings following low/high buildings, as well as accurately capture the behavior of streets close to perpendicular to the wind direction. Main streets with plenty of exits have been modeled with intersections at each exit, which results in strong flow variation along a street that should have a flow close to constant. Solving main streets like this separately could improve this behavior drastically.

A caracterização das flutuações dos resíduos da proteína em torno do seu estado nativo é essencial para estudar mudanças conformacionais, interação proteína-proteína e interação proteína-ligante. Tal caracterização pode ser capturada pelo modelo de rede gaussiana (GNM). Este modelo tem sido modificado e novas propostas têm surgido nos últimos anos. Nesta Tese, apresentamos um estudo sobre como melhorar o GNM e exploramos o seu desempenho em predizer os fatores-B experimentais. Modelos de redes elásticas são construídos a partir das coordenadas experimentais dos levando em consideração pares de átomos de C? distantes entre si até um dado raio de corte Rc . Estes modelos descrevem as interações entre os atómos por molas com a mesma constante de força. Desenvolvemos um método baseado em simulações numéricas com um campo de forças simplificado para atribuir pesos a estas constantes de mola. Este método considera o tempo em que dois átomos de C? permanecem conectados na rede durante o desenovelamento parcial, estabelecendo assim uma forma de medir a intensidade de cada ligação. Examinamos dois diferentes campos de forças simplificados e exploramos o cálculo desses pesos a partir do desenovelamento das estruturas nativas. Nós comparamos o seu desempenho na predição dos fatores-B com outros modelos de rede elástica. Avaliamos tal desempenho utilizando o coeficiente de correlação entre os fatores-B preditos e experimentais. Mostramos como o nosso modelo pode descrever melhor os fatores-B / The characterization of the fluctuations in protein residues around its native state is essential to study conformational changes, protein binding interaction and protein-protein interaction. Such characterization can be captured by simple elastic network models as the Gaussian Network Model (GNM). This model has been modified and new proposals have emerged in recent years. In this Thesis we propose an extended version of GNM, namely wGNM. Elastic network models are built on the experimental C? coordinates,and they only take the pairs of C? atoms within a given cutoff distance Rc into account. These models describe the interactions by elastic springs with the same force constant to predicted the experimental B-factors, providing insights into the structure-function properties of proteins. We have developed a method based on numerical simulations with a simple coarse-grained force field, to attribute weights to these spring constants. This method considers the time that two C? atoms remain connected in the network during partial unfolding, establishing a means of measuring the strength of each link. We examined two different coarse-grained force fields and explored the computation of these weights by unfolding native structures. We compare the B-factors predicted by different elastic network models with the experimental ones employing the correlation coefficient between these two quantities. We show that wGNM performs better and consequently provides better evaluation of the B-factors

This thesis describes a new dynamic network model for imbibition which is based on a physically realistic description of the complex dynamics of corner film flow, swelling and snap-off. The model shows that film flow is a capillary driven non-linear diffusive process and that the competition between snapoff and frontal displacements is rate dependent and results in rate dependent relative permeabilities and residual saturations. In contrast to previously published models in which length scales for snap-off are either specified a priori or calculated assuming steady-state film flow and constant film conductivities, in the present model, snap-off arises as a natural consequence of the fully transient nature of film flow and swelling. The network model is used to analyse the complex interaction between displacement rate, contact angle, aspect ratio and pore and throat shape on relative permeability and residual saturation. Computed relative permeabilities and residual saturations are compared with laboratory measurements reported in the literature. It is concluded that the magnitude of the rate effect on imbibition relative permeabilities and residual saturations for a particular rock microstructure and wettability condition depends largely on the pore-throat aspect ratio. Higher aspect ratios result in stronger rate effects than do smaller aspect ratios.

<p>Background: The Uppsala and Network Models of Internationalization belong to the Nordic School and were created based on Swedish companies. Is that possible to apply these models to a Brazilian context? Brazilian companies are becoming more international and expanding to foreign markets, and this study is going to exam if the Nordic schools models can be used to explain the internationalization process of a Brazilian company. </p><p>Purpose: The purpose of this thesis is to exam if the proposition, that states that the Uppsala and the Network Models combined can explain the internationalization process of a Brazilian company, is correct. </p><p>Method: To collect material for this thesis an interview with the case company was done and also secondary data was used from the company. </p><p>Results: It is possible to state that the combination of the two models is able to explain the internationalization process of the studies Brazilian company. It is also possible to state that where the Uppsala Models lacks explanation value, the Network Model can be applied.</p>

<p>Svenska Lantchips is a Swedish SME sized snack manufacturer. Being a small, medium sized, family-owned business with branches throughout the world, they make an interesting company for a case study. The case study I have conducted focuses on the internationalisation process of this family owned company – how they, despite their size, find ways to keep up an unique business structure, designed for internationalisation.The aim of this essay is to compare Svenska Lantchips’ internationalisation process with traditional internationalisation theories and see if these are compatible with this company. The theories used are The Uppsala Model, The Network Model, and The Born Global Theory, with The Born Global Theory representing the younger generation of models.After undertaking an in-depth interview with Michael Hansen, business developer at Svenska Lantchips, I collated a substantial amount of material, which I have used as the basis of this essay. Theories of storytelling have been used to interpret the information I got from Michael Hansen. Michael Hansen was chosen not only for his role as a business developer, but he is also the co-founder of the company, together with his wife, and brother in law. Previous research was studied to get information about attitudes within this research field today. The result from this thesis is that Svenska Lantchips have forged their own distinctive route out on the global market. Despite being a relatively small, family-owned company, with a low dependency on sophisticated technologies, they have managed to expand and internationalise at an impressive rate. By opening factories on foreign markets, sometimes even before exporting to them, they have produced a unique competitive advantage. Their internationalisation process at times more closely resembles that of a high-tech, innovative company, than a small, family-owned firm. The driving force behind them is their personal determination, and the philosophy that the world is one big market; they refuse to see cultural and geographical differences as an obstacle.</p>

Background: The Uppsala and Network Models of Internationalization belong to the Nordic School and were created based on Swedish companies. Is that possible to apply these models to a Brazilian context? Brazilian companies are becoming more international and expanding to foreign markets, and this study is going to exam if the Nordic schools models can be used to explain the internationalization process of a Brazilian company. Purpose: The purpose of this thesis is to exam if the proposition, that states that the Uppsala and the Network Models combined can explain the internationalization process of a Brazilian company, is correct. Method: To collect material for this thesis an interview with the case company was done and also secondary data was used from the company. Results: It is possible to state that the combination of the two models is able to explain the internationalization process of the studies Brazilian company. It is also possible to state that where the Uppsala Models lacks explanation value, the Network Model can be applied.

Svenska Lantchips is a Swedish SME sized snack manufacturer. Being a small, medium sized, family-owned business with branches throughout the world, they make an interesting company for a case study. The case study I have conducted focuses on the internationalisation process of this family owned company – how they, despite their size, find ways to keep up an unique business structure, designed for internationalisation.The aim of this essay is to compare Svenska Lantchips’ internationalisation process with traditional internationalisation theories and see if these are compatible with this company. The theories used are The Uppsala Model, The Network Model, and The Born Global Theory, with The Born Global Theory representing the younger generation of models.After undertaking an in-depth interview with Michael Hansen, business developer at Svenska Lantchips, I collated a substantial amount of material, which I have used as the basis of this essay. Theories of storytelling have been used to interpret the information I got from Michael Hansen. Michael Hansen was chosen not only for his role as a business developer, but he is also the co-founder of the company, together with his wife, and brother in law. Previous research was studied to get information about attitudes within this research field today. The result from this thesis is that Svenska Lantchips have forged their own distinctive route out on the global market. Despite being a relatively small, family-owned company, with a low dependency on sophisticated technologies, they have managed to expand and internationalise at an impressive rate. By opening factories on foreign markets, sometimes even before exporting to them, they have produced a unique competitive advantage. Their internationalisation process at times more closely resembles that of a high-tech, innovative company, than a small, family-owned firm. The driving force behind them is their personal determination, and the philosophy that the world is one big market; they refuse to see cultural and geographical differences as an obstacle.