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Esta tesis ofrece una justificación para el uso de la pluralidad como una manera óptima de agregar información en las sociedades compuestas por individuos con intereses comunes pero con información diversa. El motivo de esta tesis es seguir una línea de investigación sobre la elección social que se remonta al matemático y filósofo político francés Jean-Antoine-Nicolas de Caritat, Marqués de Condorcet (1743-1794). En su Essai sur l'application de l'analyse à la probabilité des decisions rendues à la pluralité des voix (1785), Condorcet afirmó que se garantizaría la justicia social si las naciones adoptaran constituciones políticas que facilitaran el juicio correcto del grupo y argumentó que la votación por mayoría sería la herramienta constitucional más probable para alcanzar este objetivo.Siguiendo esta línea de investigación, la primera parte de esta tesis estudia las condiciones bajo las cuales la pluralidad proporciona a la sociedad el método más adecuado para llegar a decisiones de grupo. Aquí, como en el estudio de Condorcet, supondremos que los votantes actúan honradamente.El desarrollo natural de la teoría de votación, que ha introducido los temas de incentivos e interacción estratégica en la toma de decisiones de grupos, ha sido utilizado para cuestionar la suposición de votación honesta. Austen-Smith y Banks (1996) fueron los primeros en observar que la combinación de información privada e intereses comunes en el sistema propuesto por Condorcet podría crear incentivos para los votantes para actuar estratégicamente. Esta observación les condujo a plantear si la votación honesta sería compatible con el comportamiento de equilibrio de Nash en el juego inducido por la mayoría. La segunda parte de esta tesis expone esta problemática estudiando el comportamiento de los votantes en el juego inducido por la pluralidad.El interés en las instituciones del mundo real, para las cuales la votación es un elemento importante, ha hecho plantear desde hace tiempo la cuestión de si los votantes se comportan tal y como pronostican los modelos teóricos. Otra cuestión ha sido cómo tratar la complejidad del entorno estratégico. La segunda parte de esta tesis pide respuestas a estas preguntas. Puesto que la literatura sobre experimentos de votación parece proporcionar respuestas razonables a estas preguntas, la tercera parte de esta tesis utiliza experimentos de laboratorio para verificar las implicaciones de la segunda parte. / This thesis offers a justification for the use of plurality rule as an optimal way to aggregate information for societies composed of individuals with common interests but diverse information. The motivation of this thesis follows a line of research in social choice that dates back to the French mathematician and political philosopher Jean-Antoine-Nicolas de Caritat, Marquis de Condorcet (1743-1794). In his Essai sur l'application de l'analyse à la probabilité des decisions rendues à la pluralité des voix (1785), Condorcet posited that social justice would be secured if nations would adopt political constitutions that facilitate accurate group judgments, and argued that the majority rule would be the most likely constitutional tool to achieve this goal.Following this line of research, the first part of this thesis discusses the conditions under which plurality rule provides the society with the most likely method to reach accurate group judgments. In this part, as in Condorcet's work, it is assumed that voters act honestly. Natural developments in the theory of voting, that brought in the issues of incentives and strategic interaction in group decision making, were used to challenge the assumption of honest voting. Austen-Smith and Banks (1996) were the first to notice that the combination of private information and common interests in the framework proposed by Condorcet might create an incentive for voters to act strategically. This observation led them to ask the question of whether honest voting is compatible with the Nash equilibrium behavior in the game induced by majority rule. The second part of this thesis advances this problematic by studying voters' behavior in the game induced by plurality rule.The interest in real-world institutions, for which voting is an important element, raised for some time the question of whether voters behave as predicted by the theoretical models. Another question was of how to deal with the complexity of the strategic environment. The second part of this thesis calls for answers to these types of questions. Since the literature on voting experiments seems to provide reasonable answers to these questions, the third part of this thesis uses laboratory experiments to test the implications of the second part.

Understanding basic antiviral mechanisms in vertebrates is essential for developing methods to enhance antiviral responses and promote human and animal health. In fish these antiviral mechanisms are poorly understood, but are important to understand because of the devastating impact of viral diseases on aquaculture. Therefore, the antiviral responses of a rainbow trout macrophage-like cell line, RTS11, and two non-immune cell lines, the rainbow trout fibroblast RTG-2 and Chinook salmon embryo CHSE-214 were studied. Three antiviral responses were first characterized using the viral mimic, synthetic double-stranded RNA (poly IC), and then their induction was investigated using Chum salmon reovirus (CSV). The responses were: 1) apoptosis, which is programmed cell death and a primitive antiviral defense; 2) homotypic aggregation (HA), which is clustering of like immune cells; and 3) expression of Mxs, which are antiviral proteins belonging to GTPase super-family. Some of these antiviral mechanisms were investigated using a novel continuous cell line, PBLE, developed from a peripheral blood leukocyte preparation of the American eel, <em>Anguilla rostrata</em>. <br> <br> RTS11 was exceptionally susceptible to apoptosis. The cells died at lower concentrations of poly IC and other agents, including the translation inhibitor, cycloheximide (CHX), and fungal metabolite, gliotoxin. Death was predominantly by apoptosis, as judged by DNA ladders, nuclear fragmentation, and protection by caspase inhibitors. By contrast, the other two cell lines died most commonly by necrosis, when death did occur. Co-treating RTS11 with CHX greatly sensitized the cells to poly IC. Based on the protection afforded by inhibitors of dsRNA-dependent protein kinase (PKR), RTS11 apoptosis induced by poly IC with CHX co-treatment but not gliotoxin was mediated by PKR. As macrophages are likely among the first cells to contact viruses during an infection in vivo and are mobile, the sensitivity of RTS11 to dsRNA killing could reflect a protective mechanism by which virus spread is limited by the early death of these first responders. <br><br> HA of RTS11 was induced by poly IC. HA required divalent cations and was blocked by CHX and by PKR inhibitors. This suggested that HA induction was PKR-mediated and involved the synthesis of new cell surface molecule(s), possibly galectins. As an antiviral mechanism, HA induction by dsRNA could be interpreted as an initial protective response, allowing cell localization at the site of infection, but once translation becomes inhibited, apoptosis ensues. <br><br> Mx was induced by poly IC in RTS11 and RTG-2 as judged by RT-PCR. Western blotting revealed constitutive Mx expression more consistantly in RTS11, but induction by poly IC in both cell lines. Medium conditioned by cells previously exposed to poly IC and assumed to contain interferon also induced Mx transcripts in RTS11 but not RTG-2. In RTS11, poly IC activated PKR activity, and PKR inhibitors blocked <em>Mx</em> induction, which is the first demonstration of PKR mediating Mx expression. <br><br> The dsRNA virus, CSV, also induced apoptosis, HA, and Mx expression, but in some cases contrasting with poly IC experiments. CSV induced apoptosis in RTG-2 and CHSE-214 but not in RTS11, and HA induction by CSV in RTS11 was not dependent on PKR. Mx induction was sustained in RTG-2 and transitory in RTS11; however, both cell lines supported CSV replication. <br><br> The novel cell line, PBLE, was also characterized in this study. PBLE was derived from an adherent culture of peripheral blood leukocytes from the American eel, <em>Anguilla rostrata</em>. PBLE were found to grow over a wide range of temperatures and fetal bovine serum (FBS) concentrations. This cell line was able to undergo apoptosis in response to gliotoxin. PBLE was also susceptible to a number of viruses, including CSV; however, CSV infection did not lead to apoptosis. <br><br> This study suggests that antiviral responses are likely numerous and overlapping and depend on cell type and virus. Understanding them should lead to novel methods for protecting fish from viral diseases. More specifically, using cell lines such as PBLE may aid in the understanding of species specific and perhaps even cell type specific antiviral mechanisms.

Sensor networks are dense wireless networks constituting of small and low-cost sensors that collect and disseminate sensory data. They have gained great attention in recent years due to their ability to offer economical and effective solutions in a variety of fields; and their profound suitability to address mission critical problems that are common in health, transportation, and military applications. “Sensor networks” is a technology that is seen to change the world, and as such their deployment is expected to see a rapid growth. Effective security strategy is essential for any sensor network in order to maintain trustful and reliable functionality, protect sensory information, and ensure network component authenticity. Security models and protocols that are typically used in other types of networks, such as wired networks, are not suitable for sensor networks due to their specific hardware specifications. This thesis highlights some of the research done so far in the area of security of wireless sensor networks and proposes a solution to detect Byzantine behaviour - a challenging security threat that many sensor networks face. The proposed solution’s use of cryptography is kept at a minimum to ensure maximum secure bandwidth. Under this solution, a sensor network continues to work normally until an attack is suspected. Once an attack is suspected, a cryptography scheme is enabled to authenticate suspected nodes and to allow the identification of potential external attacks. If an attack seems to persist after the cryptography scheme has been enabled, the same mechanism is used to identify and isolate potentially compromised nodes. The goal is to introduce a degree of intelligence into such networks and consequently improve reliability of data collection, accuracy of aggregated data, and prolong network lifetime.

In humans, noroviruses (NVs) cause acute epidemic and viral gastroenteritis. NVs do not only infect humans; viruseshave also been found in pigs, cows, sheep, mice and dogs. The focus in this project has been on the murine norovirus(MNV). MNV is a member of the viral family Caliciviridae and it consists of a single-stranded, positive sense RNAgenome. The genome includes three open reading frames (ORFs), ORF1 encodes for a polyprotein that consists of theprecursor to the 6-7 non-structural (NS) proteins. The polyprotein is cleaved by the NS6 protease. The NS6 isresponsible for all the cleaving in ORF1 and that makes it an attractive target for antiviral drugs. The NS6 proteinstructure has been determined at 1.66 Å resolution using X-ray diffraction techniques. Surprisingly, the electrondensity map revealed density for a peptide bound in the active site. The peptide had a length of 7 residues andoriginated from the C-terminus of another chain in an adjacent asymmetric unit. The active site triad was composed ofthe conserved residues; histidine 30, aspargine 54 and cysteine 139, however in the structure the cysteine 139 ismutated to an alanine to inactivate the protease. Activity assays were performed to probe the importance of the residuein position 109 in the β-ribbon located close to the active site. The three full-length constructs with the mutations;I109A, I109S and I109T were found to have less activity than the full-length wt (1-183). A truncated protease, lacking9 residues in the C-terminus, also had less activity. This indicates that the terminal residues are also important foractivity.

Understanding basic antiviral mechanisms in vertebrates is essential for developing methods to enhance antiviral responses and promote human and animal health. In fish these antiviral mechanisms are poorly understood, but are important to understand because of the devastating impact of viral diseases on aquaculture. Therefore, the antiviral responses of a rainbow trout macrophage-like cell line, RTS11, and two non-immune cell lines, the rainbow trout fibroblast RTG-2 and Chinook salmon embryo CHSE-214 were studied. Three antiviral responses were first characterized using the viral mimic, synthetic double-stranded RNA (poly IC), and then their induction was investigated using Chum salmon reovirus (CSV). The responses were: 1) apoptosis, which is programmed cell death and a primitive antiviral defense; 2) homotypic aggregation (HA), which is clustering of like immune cells; and 3) expression of Mxs, which are antiviral proteins belonging to GTPase super-family. Some of these antiviral mechanisms were investigated using a novel continuous cell line, PBLE, developed from a peripheral blood leukocyte preparation of the American eel, <em>Anguilla rostrata</em>. <br> <br> RTS11 was exceptionally susceptible to apoptosis. The cells died at lower concentrations of poly IC and other agents, including the translation inhibitor, cycloheximide (CHX), and fungal metabolite, gliotoxin. Death was predominantly by apoptosis, as judged by DNA ladders, nuclear fragmentation, and protection by caspase inhibitors. By contrast, the other two cell lines died most commonly by necrosis, when death did occur. Co-treating RTS11 with CHX greatly sensitized the cells to poly IC. Based on the protection afforded by inhibitors of dsRNA-dependent protein kinase (PKR), RTS11 apoptosis induced by poly IC with CHX co-treatment but not gliotoxin was mediated by PKR. As macrophages are likely among the first cells to contact viruses during an infection in vivo and are mobile, the sensitivity of RTS11 to dsRNA killing could reflect a protective mechanism by which virus spread is limited by the early death of these first responders. <br><br> HA of RTS11 was induced by poly IC. HA required divalent cations and was blocked by CHX and by PKR inhibitors. This suggested that HA induction was PKR-mediated and involved the synthesis of new cell surface molecule(s), possibly galectins. As an antiviral mechanism, HA induction by dsRNA could be interpreted as an initial protective response, allowing cell localization at the site of infection, but once translation becomes inhibited, apoptosis ensues. <br><br> Mx was induced by poly IC in RTS11 and RTG-2 as judged by RT-PCR. Western blotting revealed constitutive Mx expression more consistantly in RTS11, but induction by poly IC in both cell lines. Medium conditioned by cells previously exposed to poly IC and assumed to contain interferon also induced Mx transcripts in RTS11 but not RTG-2. In RTS11, poly IC activated PKR activity, and PKR inhibitors blocked <em>Mx</em> induction, which is the first demonstration of PKR mediating Mx expression. <br><br> The dsRNA virus, CSV, also induced apoptosis, HA, and Mx expression, but in some cases contrasting with poly IC experiments. CSV induced apoptosis in RTG-2 and CHSE-214 but not in RTS11, and HA induction by CSV in RTS11 was not dependent on PKR. Mx induction was sustained in RTG-2 and transitory in RTS11; however, both cell lines supported CSV replication. <br><br> The novel cell line, PBLE, was also characterized in this study. PBLE was derived from an adherent culture of peripheral blood leukocytes from the American eel, <em>Anguilla rostrata</em>. PBLE were found to grow over a wide range of temperatures and fetal bovine serum (FBS) concentrations. This cell line was able to undergo apoptosis in response to gliotoxin. PBLE was also susceptible to a number of viruses, including CSV; however, CSV infection did not lead to apoptosis. <br><br> This study suggests that antiviral responses are likely numerous and overlapping and depend on cell type and virus. Understanding them should lead to novel methods for protecting fish from viral diseases. More specifically, using cell lines such as PBLE may aid in the understanding of species specific and perhaps even cell type specific antiviral mechanisms.

Sensor networks are dense wireless networks constituting of small and low-cost sensors that collect and disseminate sensory data. They have gained great attention in recent years due to their ability to offer economical and effective solutions in a variety of fields; and their profound suitability to address mission critical problems that are common in health, transportation, and military applications. “Sensor networks” is a technology that is seen to change the world, and as such their deployment is expected to see a rapid growth. Effective security strategy is essential for any sensor network in order to maintain trustful and reliable functionality, protect sensory information, and ensure network component authenticity. Security models and protocols that are typically used in other types of networks, such as wired networks, are not suitable for sensor networks due to their specific hardware specifications. This thesis highlights some of the research done so far in the area of security of wireless sensor networks and proposes a solution to detect Byzantine behaviour - a challenging security threat that many sensor networks face. The proposed solution’s use of cryptography is kept at a minimum to ensure maximum secure bandwidth. Under this solution, a sensor network continues to work normally until an attack is suspected. Once an attack is suspected, a cryptography scheme is enabled to authenticate suspected nodes and to allow the identification of potential external attacks. If an attack seems to persist after the cryptography scheme has been enabled, the same mechanism is used to identify and isolate potentially compromised nodes. The goal is to introduce a degree of intelligence into such networks and consequently improve reliability of data collection, accuracy of aggregated data, and prolong network lifetime.

Despite the growing number of mobile devices equipped with multiple networking interfaces, they are not using multiple available networks in parallel. The simple network selection techniques only allow for single network to be used at a time and switching between different networks interrupts all existing connections. This work presents system that improves network connectivity in presence of multiple network adapters, not only through better network handovers, smarter network selection and failure detection, but also through increased bandwidth offered to the device over aggregated channels. The biggest challenge such a system has to face is the heterogeneity of networks in mobile environment. Different wireless technologies, and even different networks of the same type offer inconsistent link parameters like available bandwidth, latency or packet loss. The wireless nature of these networks also means, that most of the parameters fluctuate in unpredictable way. Given the intended practicality of designed system, all that complexity has to be hidden from both client-side applications and from the remote servers. These factors combined make the task of designing and implementing an efficient solution difficult. The system incorporates client-side software, as well as network proxy that assists in splitting data traffic, tunnelling it over a number of available network interfaces, and reassembling it on the remote side. These operations are transparent to both applications running on the client, as well as any network servers those applications communicate with. This property allows the system to meet one of the most important requirements, which is the practicality of the solution, and being able to deploy it in real life scenarios, using network protocols available today and on existing devices. This work also studies the most critical cost associated with increased data processing and parallel interface usage - the increase in energy usage, which needs to remain within reasonable values for this kind of solution being usable on mobile devices with limited battery life. The properties of designed and deployed system are evaluated using multiple experiments in different scenarios. Collected results confirm that our approach can provide applications with increased bandwidth when multiple networks are available. We also discover that even though per-second energy usage increases when multiple interfaces are used in parallel, the use of multi-interface connectivity can actually reduce the total energy cost associated with performing specific tasks - effectively saving energy.

Metalloporphyrin aggregation is critical for triplet-triplet annihilation (TTA) to occur. In order to maximize the efficiency of TTA, to use as a mechanism of photon upconversion in dye-sensitized solar cells, it is important to understand the phenomenon of absorber aggregation. The aggregation of ZnTPP in polymer films was investigated by fluorescence anisotropy and total internal reflection fluorescence microscopy (TIRFM). Single molecule spectroscopy (SMS) and spectromicroscopy were the techniques used to study single molecules and multimolecular aggregates of ZnTPP/ZnTPPS in polymer films/adsorbed on glass substrates.<p> Fluorescence anisotropy measurements consistently showed depolarized emission from films most concentrated with ZnTPP. This observation was likely a result of energy transfer in and among porphyrin aggregates. Fluorescence intensity decays were also obtained and they illustrated a pattern of decreased fluorescence lifetime (i.e. faster decays) as the concentration of porphyrin in the film increased. These results are consistent with the formation of aggregates, and their increased presence in more concentrated films. The formation of these aggregates quenches the fluorophores fluorescence, resulting in the observed shorter fluorescence lifetimes. <p> TIRFM was performed to study the structure of these polymer films doped with ZnTPP. It was determined that these films consisted of discrete domains and thus lacked homogeneity, and the presence of aggregates was clearly visible. Time-resolved TIRFM measurements were also performed but no interesting results were collected.<p> SMS and spectromicroscopy were the final techniques employed to study porphyrin aggregation. Preliminary measurements were performed with polymer films doped with ZnTPP, and the single step decay time trajectories collected indicated that single molecules were being studied. Furthermore, emission spectra of these molecules were collected and they were similar to those obtained for a bulk measurement, but the bands were slightly shifted in comparison. These measurements were repeated with ZnTPPS adsorbed to glass substrates. Two different patterns of decay trajectories were measured: (i) single step decays corresponding to single ZnTPPS molecules and (ii) multi step/complex decays representative of multimolecular aggregates. Emission spectra were also collected for the multimolecular aggregates, and they were consistent with those of an ensemble measurement but slightly blue-shifted. Such a shift is common when studying aggregates on such a highly polar surface. Thus, these results demonstrate that ZnTPPS aggregates form even at concentrations as low as 10-8 M, and can be studied using SMS despite their weak fluorescence emission.

The issue of energy shortage has arisen in recent years. All countries must discuss the manner to reduce energy consumption, and smart grid is a better one of the solutions. According to related researches, energy consumption can be effectively reduced using energy management information of smart grids. By using smart grids, electricity suppliers can learn about the current energy consumption of neighborhoods, and control the electrical energy generation and price of electrical energy. Users can learn the current price of electrical energy and obtain energy management information from smart meters for energy management and device control. However, electricity consumptions of users may divulge the privacy information of users. Therefore, privacy of users and communication security of smart grid become crucial security issues. In this thesis, we propose a provably secure power usage data aggregation scheme for smart grids. Electricity suppliers can learn about the current power usage of neighborhoods without knowing the individual electricity consumption of each user, and use the current power usage of neighborhoods to arrange energy distribution. Therefore, electricity suppliers cannot use the data to reveal lifestyles of each user. In our scheme, the transmission information is encrypted and signed to prevent theft or tampering of data. Finally, we also provide formal proofs for our scheme in this thesis.