The interaction of embedded systems with their environments and their resource limitations make it important to take into account properties such as timing, security, and resource consumption in designing such systems. These so-called Extra-Functional Properties (EFPs) capture and describe the quality and characteristics of a system, and they need to be taken into account from early phases of development and throughout the system's lifecycle. An important challenge in this context is to ensure that the EFPs that are defined at early design phases are actually preserved throughout detailed design phases as well as during the execution of the system on its platform. In this thesis, we provide solutions to help with the preservation of EFPs; targeting both system design phases and system execution on the platform. Starting from requirements, which form the constraints of EFPs, we propose an approach for modeling Non-Functional Requirements (NFRs) and evaluating different design alternatives with respect to the satisfaction of the NFRs. Considering the relationship and trade-off among EFPs, an approach for balancing timing versus security properties is introduced. Our approach enables balancing in two ways: in a static way resulting in a fixed set of components in the design model that are analyzed and thus verified to be balanced with respect to the timing and security properties, and also in a dynamic way during the execution of the system through runtime adaptation. Considering the role of the platform in preservation of EFPs and mitigating possible violations of them, an approach is suggested to enrich the platform with necessary mechanisms to enable monitoring and enforcement of timing properties. In the thesis, we also identify and demonstrate the issues related to accuracy in monitoring EFPs, how accuracy can affect the decisions that are made based on the collected information, and propose a technique to tackle this problem. As another contribution, we also show how runtime monitoring information collected about EFPs can be used to fine-tune design models until a desired set of EFPs are achieved. We have also developed a testing framework which enables automatic generation of test cases in order verify the actual behavior of a system against its desired behavior. On a high level, the contributions of the thesis are thus twofold: proposing methods and techniques to 1) improve maintenance of EFPs within their correct range of values during system design, 2) identify and mitigate possible violations of EFPs at runtime. / CHESS / MBAT / ITS-EASY

This thesis examines capital structure theories and debt level determinants to develop a better understanding, and to establish the most appropriate theory to explain the behaviour of firms‟ debt and equity choices. It tests three major capital structure theories (e.g. the trade-off, pecking order and market timing theories) using static and dynamic statistical models and 13 capital structure determinants, based on three major capital structure theories. The study uses 4,598 sample companies from 11 countries and 27 industries over a 20 year period. This method provides a clear insight into firms‟ debt and equity choice behaviours. The static trade-off theory is tested by first searching for similarities and differences between industries, countries and time periods and, second, by observing whether firms change their capital structures towards optimal levels and whether the coefficient signs are the same as the predictions. The "stock price effect‟ on debt levels is used to examine the pecking order and market timing theories. The pecking order theory is likewise tested by confirming whether firms issue debt when they face a financial deficit. Furthermore, these theories are tested using cluster analyses. The sample examines 11 different characteristics, which include firm size, debt level, and bankruptcy probability. As each characteristic is related to one or more capital structure theories, the most appropriate theory can be derived, based on such characteristics. There are five main findings. First, firms which are financial stable issue relatively more debt. Second, they have a preference for moderate debt levels and thus limit their bankruptcy probability. They also try to exploit opportunities from overestimated stock price by issuing stocks to increase cash inflows. Third, the effects from bankruptcy costs are greater than transaction costs in terms of capital structure adjustment. Fourth, during the sample period, firms continuously decrease leverage levels. Fifth, firms‟ characteristics and macro-economic factors affect their capital structure. There are three main conclusions. First, the behaviour of firms appears generally aligned with the trade-off theory, although the pecking order and market timing theories also partially explain the equity issuance condition. Second, the "equity and debt choice modes‟ can likewise be explained by the use of a theoretically combined approach, using the three major capital structure theories. In this approach, firms increase their value by both increasing debt for tax benefits and low adverse selection costs, and by issuing equity when the stock price is high. Third, this second conclusion implies that the trade-off, pecking order and market timing theories can be combined on the assumption that firms maximise their values under conditions of the existence of asymmetric information, tax shields and bankruptcy probability.

Anthropogenic activities are fundamentally altering the chemistry of the world’s oceans. Many of these modifications could have a significant impact on the health of marine organisms. Yet, despite being proposed as one of the most significant threats that marine ecosystems face, to date very little is known about the impact of anthropogenic climate change, and ocean acidification in particular, on host defence. The aims of this thesis are to investigate the impact of environmental stressors on the invertebrate immune response, providing empirical data on how anthropogenically induced stressors will impact the invertebrate immune system and how this will impact organism condition and subsequent physiological trade-offs. Exposure to reduced seawater pH and increased temperature significantly reduced the immune response in the blue mussel, Mytilus edulis. This reduction in immune response could indicate stress-induced immune dysfunction. However, the immune system protects an organism from infectious disease, ensuring survival, and should therefore be evaluated functionally rather than immunologically. By subsequently exposing mussels to a bacterial challenge this study demonstrated that an earlier study which measured a reduction in host defence represented a trade-off of immune system maintenance costs, with mussels maintaining a capacity to up-regulate immune defence when required. However, whilst this immune plasticity ensures mussels are able to survive a pathogen exposure, such a strategy appears to be physiologically costly. This cost is seen as a reduction in reproductive investment, an altered energy metabolism and an altered fatty acid composition in organisms exposed to low pH. Therefore the overarching picture that emerges is, without measuring physiological processes functionally, and in neglecting any physiological trade-offs, it is possible that many studies may misinterpret the complex physiological responses of marine organisms to ocean acidification.

Previous studies of the relationship between egg size and the embryonic development time showed a positive correlation between the two variables at interspecies level, thus offering the idea that the evolution of the latter could be a limiting factor for enlarging the size of eggs during evolution. Some research into interspecies and intraspecific level of reptiles doesn't confirm this correlation. At the same time, the relationship between the development time and egg size is influenced by many factors, such as shifts in ontogenetic stages of the embryo at the time of ablation of eggs, due to temperature and humidity, the presence of embryonic diapause during embryogenesis or synchronization of hatching time, of which the authors of previous studies took no account or filtered out inaccurately. I think that most of these factors can be well controlled in intraspecific studies, but, variation in egg size within species also tends to be small, which prevents a reliable test for correlation. The solution can be to compare closely related species with high variability in the size of the eggs, in our case the geckos of the genus Paroedura and family Eublepharidae. I eliminated temperature effects by comparing the time of incubation in two equal constant temperatures. The results show that, in this...

Tests of the static trade-off theory that posits that firms move towards the optimum capital structure necessitate a joint hypothesis test - whether firms adjust toward target leverage, and whether the proxy used for target leverage is the true target leverage. Prior studies use the time-series mean leverage for each firm, the industry median leverage, an estimated cross-sectional leverage, and a tobit estimated leverage using the factors suggested by the static trade-off theory as proxies for the target leverage. In this dissertation, I examine whether these proxies are equivalent and test the consistency of the proxies with the theorized behavior of the true target leverage. My results indicate that the four proxies we examine have significantly different distributions and this holds across most industries. Further, the industry median leverage is the proxy which best exhibits behavior consistent with the true target leverage. Firm value is higher for firms closer to the industry median and lower for firms away from the industry median. A robustness check using Kmeans cluster analysis confirms the superiority of the industry median leverage over the other proxies of target leverage. This study complements the previous studies on the pecking order theory and the trade-off theory. The main purpose of this study is to investigate three issues that are not considered in the previous studies. The adequacy of the specification and the assumptions of the models used in testing the trade-off and the pecking order theory. The second issue examined in this study is the validity to putting the pecking order and the trade-off theories in a horse race. The final issue examined in this study is the factors driving firms to issue (repurchase) debt or equity or combination of both and simultaneously the factors affecting the size of issue (repurchase)

No description available.

The real estate industry is one of the oldest sectors in the world, having existed almost as long as humans have roamed around the earth. Despite the social system in place, the ownership of land and buildings has always been a great source of prosperity to their owner. In addition to creating profit, the real estate sector also contributes to the health of the economy and to the well-being of people by providing necessities such as properties to organizations and individuals and by facilitating economic activities. This panel data study fills a knowledge gap by examining the development of large Swedish real estate companies’ capital structures between the years 2009 and 2017. The research tries to comprehend how the structures have changed during the business cycle following the financial crisis. The sample, consisting of 901 large stock companies, also tries to explain why these changes have occurred by analyzing which factors determine the development of the capital structure. Variables Return of Equity (ROE), Return of Assets (ROA), Assets, Number of Employees, Cost of Debt, Debt Coverage ratio (ICR), Interest Rates, and Stock Index are statistically tested in order to identify relationships between leverage and the given variables. The findings concerning the development of leverage ratios indicate that the Swedish firms, regardless of the amount of debt they possess, are deleveraging. Although the growth trend changes are subtle, they give evidence against the common belief that firms are packing up more debt. Relationships between the variables were all significant except for the relationships between Leverage/Interest Rates and Leverage/Stock Index which yielded conflicting results. Positive relationships were identified between Leverage/Assets, Leverage/ROE, Leverage/ICR, and Leverage/Interest Rates. The associations between the variables Leverage/Employees, Leverage/ROA, Leverage/Cost of Debt, and Leverage/Stock Index were negative. Although most results are in line with the previous research, some surprises were also discovered. Considering the fact that the Swedish market is relatively poorly understood, the area of real estate capital structure determinants still requires further research to understand what truly drives firms to change their debt and equity composition.

Social Hymenoptera (wasps, ants, bees) possess a unique mode of reproduction. Typically, males produce the total amount of their spermatozoa during the nymphal phase solely from the energy reserves acquired during the larval phase. When the adult male hatches, the testes regress and the spermatozoa are then stored in their seminal vesicles. Mating takes place during a mating flight in which hundreds of males and females from surrounding colonies participate only once in their life. Sperm cells are transmitted during mating and are stored in the queen's spermatheca for the rest of its life (which can last several decades depending on the species). After mating, the male dies and the queen founds a new colony from the sperm received during the nuptial flight. She will never re-mate again and will use parsimoniously the spermatozoa to fertilize her eggs. Several factors are likely to dammage sperm cells, among them nutritional deficiencies during development, pathogens transmitted during mating or the immune defenses of the female that hosts sperm. Yet these sperm cells are extremly valuable because they are not renewable, and the queen will use them throughout her whole life to maintain a sufficient working force ensuring all the functions of the colony. The reproductive success of both males and females is highly dependent on the protection and maintain of spermatozoa.In this work we studied different factors that can affect the quantity, quality and protection of sperm in ants. The focus was made at three different stages: during the production of sperm cells, during their transmission at the time of mating and during their storage in the queen’s spermatheca. First, we showed that the investment in somatic development and in sperm quality take precedence over the production of large quantities of sperm cells. Second, we tested the presence and activity of two major components of the immune system (phenoloxidase system and antibacterial substances) in the sexual organs of virgin and mated ants, and we show that sperm protection uses specific systems which response is variable over time. In addition, we studed the temporal variations of these immune responses in the general insect system before and after mating. Finally, we examine the bacterial abundances and communities present in the reproductive organs at these same periods. We show the presence of some bacterial groups from the sperm storage organs that could play a role in the maintenance of spermatozoa. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

A compreensão da dinâmica populacional é fundamental para a conservação da biodiversidade, uma vez que as espécies são perdidas através de processos que ameaçam suas populações. Portanto, compreender como as condições ambientais determinam a dinâmica populacional é essencial, especialmente tendo em conta o cenário de mudanças climáticas. Um parâmetro populacional importante é a reprodução, que não só contribui para o tamanho da população, mas também pode afetar a condição corporal e a probabilidade de sobrevivência. Devido aos altos custos energéticos, a reprodução é freqüentemente associada com a disponibilidade de alimentos em ambientes tropicais, que por sua vez é altamente correlacionada com as condições climáticas, especialmente a precipitação. Além disso, o estudo de processos de populações ou comunidades requer dados de boa qualidade, que para vários grupos de animais depende da compreensão das interações entre os métodos de captura, condições climáticas e as características morfológicas e comportamentais de indivíduos e espécies. Através de um conjunto de dados de captura e recaptura de pequenos mamíferos em uma reserva de Mata Atlântica, compreendendo três grades de 2ha amostrados por quase dois anos, esta tese tem como objetivos contribuir com o entendimento: (1) de como as condições ambientais afetam a dinâmica de populações, especialmente a sobrevivência e reprodução, mais especificamente, como as condições climáticas afetam a demanda conflitante (trade-off) entre a sobrevivência e reprodução e quais são as gatilhos ambientais do início da reprodução, (2) de como o tipo de armadilha, características individuais e as condições climáticas interagem para determinar o sucesso de captura, visando a definição de diretrizes de protocolos de captura eficientes para a amostragem de pequenos mamíferos. No primeiro capítulo, mostramos que a precipitação afetou negativamente as taxas de sobrevivência, positivamente a freqüência de fêmeas reprodutivas e não afetou a condição corporal, o que sugere a existência de uma demanda conflitante entre sobrevivência e reprodução em populações de roedores. No segundo capítulo, corroboramos que a reprodução de marsupiais da Mata Atlântica é sazonal e sincrônica, ocorrendo no período quente e úmido, e seu gatilho é o fotoperíodo. Também apresentamos evidências de semelparidade em marsupiais de pequeno porte. No terceiro capítulo, mostramos que a eficiência de diferentes métodos de captura foi influenciada pelas condições climáticas, dependeu da idade e do sexo dos indivíduos e foi condicionada às variáveis quantificadas (número de espécies, de indivíduos ou de recapturas). Os resultados destacam a importância de armadilhas de queda para os estudos de comunidades e a utilização conjunta de armadilhas de queda e Sherman para estudos populacionais. / The understanding of population dynamics is central for biodiversity conservation, since species are lost through processes that threat their populations. Understanding how environmental conditions determine population dynamics is thus essential, especially given the climate change scenario. One important population parameter is reproduction, which not only contributes to population size, but can also affect body condition and survival probability. Given its high energetic costs, reproduction is frequently associated with food availability in tropical environments, which in turn is highly correlated to weather conditions, especially rainfall. However, studying population or community processes requires good-quality data, which for several animal groups depends on understanding the interactions among trapping methods, weather conditions and morphological and behavioral characteristics of individuals and species. Through a capture-recapture dataset on small mammals in an Atlantic Forest reserve, comprising three 2ha grids sampled for almost two years, this thesis aim at understanding: (1) how environmental conditions affect population dynamics, especially survival and reproduction; more specifically, how weather conditions affect the trade-off between survival and reproduction, and which are the environmental triggers for reproduction; (2) how the type of trap, individual traits and weather conditions interacts to determine capture success, aiming at defining guidelines for efficient protocols for small mammal sampling. In the first chapter, we show that rainfall negatively affected survival rates, positively affected the frequency of reproductive females and did not affect body condition, suggesting the existence of a trade-off between survival and reproduction in rodent populations. In the second chapter, we corroborated that reproduction of Atlantic Forest marsupials is seasonal and synchronous, occurring in the warm-wet season, and triggered by photoperiod cues. We also bring evidence for semelparity in small-sized marsupials. In the third chapter, we show that the efficiency of different trap methods was influenced by weather condition, depended on the age and sex of individuals, and was contingent on the quantified variables (number of species, of individuals or of recaptures). Results highlight the importance of Pitfalls for community studies and the joint use of Pitfall and Sherman traps for population studies.

In wireless networks, the exponentially increasing demands for wireless services are encountered by the scarcity of the available radio resources. More bandwidth is required for not only accommodating the increasing number of users, but also to meet the requirements of the new services such as TV on demand, wireless gaming, and mobile Internet. Non-orthogonal multiple access (NOMA) has attracted a great attention recently due to its superior spectral efficiency (SE) over orthogonal multiple access and could play a vital role in improving the capacity of future networks. In particular, power based NOMA multiplexes the users in power domain via superposition coding (SC) and allows them to access the whole spectrum simultaneously while using successive interference cancellation (SIC) at the receiver side for signal detection. Since NOMA exploits the power domain for multiple access, power allocation is vital to achieve superior SE with NOMA. Resource allocation and its optimization are general methods used to further improve the NOMA based networks performance. In this thesis, the resource allocation in the downlink NOMA system is considered and optimized for different objective functions such as the sum rate and the energy efficiency (EE). In addition, the combination of NOMA and multiple antenna is considered using linear and non-linear precoders. In all the considered cases, suboptimal power allocation schemes are proposed and compared to the numerically obtained optimal one. Results confirm that NOMA outperforms OFDMA. It also support the effectiveness of the proposed schemes as compared to the existing ones and to the optimal one. The results also reveal that using multiple antennas with NOMA can significantly enhance the overall performance. Furthermore, a NOMA-multicell scenario is considered to test the proposed schemes under the effect of intercell interference (ICI). The results prove that the proposed methods effective as compared to the optimal one at a much lower complexity.