Informações sobre variabilidade intrapopulacional de vetores biológicos são críticas para o entendimento da transmissão de agentes infecciosos veiculados por esses organismos. Nesse sentido, o presente trabalho caracterizou a variabilidade de fragmento que codifica a subunidade 4 do gene mitocondrial da Nicotinamina Adenina Dinucleotideo Desidrogenase - NADH4 em populações de Aedes aegypti do Brasil e de outros países. Polimorfismos de nucleotídeos únicos foram detectados através da técnica de seqüenciamento genômico. As análises realizadas compreenderam a de variância molecular (AMOVA), clados agrupados (NCA), distribuição de diferenças pareadas. Paralelamente foram examinadas relações evolutivas entre os haplótipos com o emprego dos critérios de parcimônia máxima e verossimilhança máxima. Os resultados mostram que há polimorfismo do fragmento nas populações analisadas, levando à proposição de dois clados geneticamente independentes (monofiléticos). Inferências de caráter histórico suportam a hipótese de que um dos clados inclui seqüências de indivíduos de populações que chegaram às Américas durante os séculos XVII e XVIII pelo tráfico negreiro, e outro, formado por populações introduzidas mais recentemente, se originou de populações asiáticas. Possíveis implicações epidemiológicas da variabilidade genética apresentada pelas populações do Ae. aegypti são também discutidas. / Knowledge about intrapopulacional variation of biological vectors is critical for understanding the dynamics of the transmission of an infectious agent. The major objective of the present study is to characterize the variability of a gene fragment, which codes for the subunit 4 of the mitochondrial gene of the Nicotinamide Adenine Dinucleotide Dehydrogenase - NADH4 among Aedes aegypti populations from Brazil comparing with that of several other countries. Single nucleotide polymorphism was detected employing genomic sequencing techniques. Nucleotide sequences were analyzed using molecular variance (AMOVA), nested clade (NCA) and mismatch distribution methods. Additionally, evolutionary relationships among haplotypes were estimated employing maximum parsimony and maximum likelihood criterions. The results show that the fragment of the mitochondrial gene (NADH4) is polymorphic, and that the populations of Ae. aegypti from Brazil are grouped into two genetically distinct, monophyletic clades Historical inferences support the hypothesis that one clade includes sequences from individuals that may be introduced in the Americas in the 17th and 18th centuries during the slave trade from Africa to America. The second clade consists of sequences of individuals that may be introduced in Brazil more recent, probably from Asian populations. Epidemiological consequences because of the genetic variability among populations of Ae. aegypti in Brazil are discussed.

Investigating secondary contact of historically isolated lineages can provide insight into how selection and drift influence genomic divergence and admixture. Here, we studied the genomic landscape of divergence and introgression following secondary contact between lineages of the Western Diamondback Rattlesnake (Crotalus atrox) to determine whether genomic regions under selection in allopatry also contribute to reproductive isolation during introgression. We used thousands of nuclear loci to study genomic differentiation between two lineages that have experienced recent secondary contact following isolation, and incorporated sampling from a zone of secondary contact to identify loci that are resistant to gene flow in hybrids. Comparisons of patterns of divergence and introgression revealed a positive relationship between allelic differentiation and resistance to introgression across the genome, and greater-than-expected overlap between genes linked to lineage-specific divergence and loci that resist introgression. Genes linked to putatively selected markers were related to prominent aspects of rattlesnake biology that differ between populations of Western Diamondback rattlesnakes (i.e., venom and reproductive phenotypes). We also found evidence for selection against introgression of genes that may contribute to cytonuclear incompatibility, consistent with previously observed biased patterns of nuclear and mitochondrial alleles suggestive of partial reproductive isolation due to cytonuclear incompatibilities. Our results provide a genome-scale perspective on the relationships between divergence and introgression in secondary contact that is relevant for understanding the roles of selection in maintaining partial isolation of lineages, causing admixing lineages to not completely homogenize.

Detonation waves are supersonic combustion waves that have a complex three-dimensional cellular structure. There is growing experimental evidence that the cellular structure of detonations promotes their propagation in the presence of losses. In spite of that, the conventional model for the detonation structure, known as the Zeldovich - Von Neumann - Doring (ZND) model, neglects the existence of cellular structure for detonations and assumes the wave to consist of a strong leading planar shock coupled with trailing chemical reactions. Therefore, the influence of cellular structure on the dynamics and extinction limits of detonation waves has been of particular interest. Previous studies have investigated the influence of cellular structure on the dynamics of detonations with mass divergence in the framework of narrow tubes, porous-walled tubes and weak confinement. However, precise quantification of the loss mechanism in these frameworks has been associated with some difficulties. Complex flow in the boundary layers, inherent in thin tubes, or attenuation of the transverse waves in the porous-walled tubes has made the evaluation of the loss mechanism more difficult in such geometries. In this thesis, a novel well-posed problem is formulated for detonations with mass divergence. It is shown that detonations propagating in a channel with a cross-section area increasing exponentially have a constant mass divergence. The detonations were found to propagate at a quasi-steady speed below the ideal Chapman-Jouguet velocity. This permitted to make meaningful comparison with the theoretical models and simulations. The experiments were performed in two mixtures, one displaying characteristic weakly unstable detonations (2C2H2 + 5O2 + 21Ar), and the other displaying highly unstable detonations (C3H8 + 5O2). The dependence of the velocity deficits and limits on the amount of mass divergence for the two mixtures were compared with the predictions of the quasi-one-dimensional ZND model with lateral mass divergence. Since the ZND model neglects the cellular structure of the detonations, such comparison permitted to asses the influence of cellular structure on the dynamics of detonations with mass divergence. Comparisons were also made with the results of simulations of inviscid cellular detonations. These comparisons showed that the velocity deficits and critical rate of mass divergence in the weakly unstable mixture were reasonably well predicted by the quasi-one-dimensional model. For smaller values of mass divergence rate, a good agreement between the experiments and the predictions of the two-dimensional cellular simulations was observed for the weakly unstable mixture. For the highly unstable detonations, the quasi-one-dimensional model significantly over-predicted the effect of mass divergence.Detonations were observed for rates of mass divergence 93% higher than the critical predicted value, displaying more substantial velocity deficits than predicted. Such observations show conclusively that the ZND model cannot capture the dynamics of highly unstable detonations on large scales.

This thesis deals with mutual socio-economic relations core and hinterland on the example of Prague and Central Bohemia. In the introduction relevant theoretical approaches which deal with this topic are presented. Furthermore most important relations between Prague and Central Bohemia are identified and analyzed. These are migration of population from core to hinterland known as suburbanization, commercial suburbanization, commuting to work and changes in land use. The last chapter is a comparative analysis of relation between core and periphery on examples of Vienna and Budapest. In all three regions there are similarities consisting of faster growth of hinterland in terms of population and the spatial differentiation of suburbanization, which depends on the attractiveness of location and traffic accessibility.

This work presents a novel method to model immiscible incompressible fluids in a stable manner. Here, the immiscible behavior of the flow is described by the incompressible Navier-Stokes-Cahn-Hilliard model, which is based on a diffuse interface method. We introduce buoyancy effects in the model through the Boussinesq approximation in a consistent manner. A structure-preserving discretization is used to guarantee the linear stability of the discrete problem and to satisfy the incompressibility of the discrete solution at every point in space by construction. For the solution of the model, we developed the Portable Extensible Toolkit for Isogeometric Analysis with Multi-Field discretizations (PetIGA-MF), a high-performance framework that supports structure-preserving spaces. PetIGA-MF is built on top of PetIGA and the Portable Extensible Toolkit for Scientific Computation (PETSc), sharing all their user-friendly, performance, and flexibility features. Herein, we describe the implementation of our model in PetIGA-MF and the details of the numerical solution. With several numerical tests, we verify the convergence, scalability, and validity of our approach. We use highly-resolved numerical simulations to analyze the merging and rising of droplets. From these simulations, we detailed the energy exchanges in the system to evaluate quantitatively the quality of our simulations. The good agreement of our results when compared against theoretical descriptions of the merging, and the small errors found in the energy analysis, allow us to validate our approach. Additionally, we present the development of an unconditionally energy-stable generalized-alpha method for the Swift-Hohenberg model that offers control over the numerical dissipation. A pattern formation example demonstrates the energy-stability and convergence of our method.

In this thesis, we discuss some of the results that were proven by Fabes and Stroock in 1984. Our main purpose is to give a self-contained presentation of the proof of this results. The first result is on the existence of a “reverse H ̈older inequality” for the Green’s function. We utilize the work of Muckenhoupt on the reverse Ho ̈lder inequality and its connection to the A∞ class to establish a comparability property for the Green’s functions. Additionally, we discuss some of the underlying preliminaries. In that, we prove the Alexandrov-Bakelman-Pucci estimate, give a treatment to the Ap and A∞ classes of Muckenhoupt, and establish two intrinsic lemmas on the behavior of Green’s function.

Most initial public offerings (IPOs) feature share lockup agreements, which prohibit insiders from selling their shares for a specified period of time following the IPO. However, some IPO firms agree to have a much longer lockup period than other IPO firms, and some are willing to lockup a much larger proportion of shares. Thus, the primary research question for this study is: "What are the reasons for the divergence of the lockup agreements?" The two main hypotheses that this dissertation investigates are the signaling hypothesis based on information asymmetry, and the commitment hypothesis based on agency theory. This study uses methods that have not been applied by previous studies in the literature relating to IPO lockups. First, I directly use IPO firms operating performance as a proxy for firm quality. The results show neither a negative nor a strong positive relationship between lockup length and firm operating performance. Thus, based on operating performance, the evidence does not support the agency hypothesis while showing weak support for the signaling hypothesis. I then examine the long-run returns for IPO firms with different lockup lengths. I find that firms with short lockup lengths have much better long-run returns than firms with long lockup lengths. Therefore, the results reject the signaling hypothesis while supporting the agency hypothesis. This dissertation further contributes to the IPO long-run underperformance literature by showing that firms with a high agency problem have much worse long-run returns than those with a low agency problem. Finally, I investigate the short-term stock returns around lockup expiry. Generally, I find that firms with short lockup periods experience better stock returns around lockup expiry than firms with long lockup periods, though the returns are not significantly different from one another. Overall, I conclude that the results reject the signaling hypothesis while partially supporting the agency hypothesis. In addition, I show that firms with high agency problems have much worse stock returns than those with low agency problems around lockup expiry, even though the agency variable is not significant in the regression analysis.

Background. Fluid simulation is an area of ongoing research. In recent years, simulators have become more realistic and stable, partly by employing the condition of having divergence-free velocity fields. A divergence-free velocity field is a strict constraint that requires a high level of correctness in a simulation. Another recent development is in the subject of performance optimization, where asynchronous time integration is used. Asynchronous time integration means integrating different parts of a fluid with varying time step sizes. Doing so leads to overall larger time step sizes, which improves performance. This thesis combines the divergence-free velocity field condition with asynchronous time stepping in a particle-based simulator. Objectives. This thesis aims to achieve a performance speedup by implementing asynchronous time integration into an existing particle-based simulator that assures the velocity field is divergence-free. Methods. With an open source simulator employing a divergence-free velocity field as a starting point, asynchronous time integration is implemented. This is achieved by dividing the fluid into three regions, each with their own time step sizes. Introducing asynchronous time integration means significantly lowering the stability of a simulation. This is countered by implementing additional steps to increase stability. Results. Roughly a 40\% speedup is achieved in two out of three scenes, with similar visual results as the original synchronous simulation. In the third scene, there is no performance speedup as the performance is similar to that of the original simulation. The two first scenes could be sped up further with more aggressive settings for asynchronous time integration. This is however not possible due to stability issues, which are also the cause for the third scene not resulting in any speedup. Conclusions. Asynchronous simulation is shown to be a valid option even alongside a divergence solver. However, occasional unrealistic behavior resembling explosions among the particles do occur. Besides from being undesirable behavior, these explosions also decrease performance and prevent more aggressive performance settings from being used. Analysis of their cause, attempted solutions and potential future solutions are provided in the discussion chapter.

Anomaly detection generally refers to algorithmic procedures aimed at identifying relatively rare events in data sets that differ substantially from the majority of the data set to which they belong. In the context of data series generated by sensors mounted on mobile devices for non-destructive inspection and monitoring, anomalies typically identify defects to be detected, therefore defining the main task of this class of devices. In this case, a useful way of operationally defining anomalies is to look at their information content with respect to the background data, which is typically noisy and therefore easily masking the relevant events if unfiltered. In this thesis, a Kullback-Leibler (KL) Divergence filter is proposed to detect signals with relatively high information content, namely anomalies, within data series. The data is generated by using the model of a broad class of proximity sensors that apply to devices commonly used in engineering practice. This includes, for example, sensory devices mounted on mobile robotic devices for the non-destructive inspection of hazardous or other environments that may not be accessible to humans for direct inspection. The raw sensory data generated by this class of sensors is often challenging to analyze due to the prevalence of noise over the signal content that reveals the presence of relevant features, as for example damage in gas pipelines. The proposed filter is built to detect the difference of information content between the data series collected by the sensor and a baseline data series, with the advantage of not requiring the design of a threshold. Moreover, differing from the traditional filters which need the prior knowledge or distribution assumptions about the data, this KL Divergence filter is model free and suitable for all kinds of raw sensory data. Of course, it is also compatible with classical signal distribution assumptions, such as Gaussian approximation, for instance. Also, the robustness and sensitivity of the KL Divergence filter are discussed under different scenarios with various signal to noise ratios of data generated by a simulator reproducing very realistic scenarios and based on models of real sensors provided by manufacturers or widely accepted in the literature.

Triggered by the negative economic and social consequences of the 2008/09 global financial crisis, critical questions about how financial markets operate and how they benefit society have received renewed attention. In response to these questions, new investment strategies whose objectives go beyond pure financial return have emerged. Impact investing, a concept which closely co-exists with investment strategies such as socially responsible investing and responsible investing, is the latest attempt to combine financial return with a contribution to the sustainable development of society. Although still in the early days of its development, impact investing is a maturing field to the extent that it has developed into a global phenomenon with an emerging global support structure. While impact investing still occupies a tiny niche in South Africa's investment market, there is, at least compared to other developing countries on the African continent, a large community of South African impact investors who are looking to invest locally and beyond. This research investigates how far the understanding and practice of impact investing in South Africa is influenced by global efforts to build the field and to what extent context specific factors are shaping the way in which it is currently evolving. In other words, how both global convergence and local divergence mechanisms interplay to form what is the South African impact investing market. The research findings suggest that while the international movement towards the standardisation of impact investing practices has reached South Africa, context specific factors such as, among others, the social, racial and political legacy of apartheid and the existence of a sophisticated financial system are central to the way in which the field is taking shape.