Quantified Interference: Information Theory and Information Flow

The paper investigates which of Shannon’s measures (entropy, conditional entropy, mutual information) is the right one for the task of quantifying information flow in a programming language. We examine earlier relevant contributions from Denning, McLean and Gray and we propose and motivate a specific quantitative definition of information flow. We prove results relating equivalence relations, interference of program variables, independence of random variables and the flow of confidential information. Finally, we show how, in our setting, Shannon’s Perfect Secrecy theorem provides a sufficient condition to determine whether a program leaks confidential information.

Terror Management Theory and Belief in an Afterlife

Research has shown that belief in an afterlife, a form of symbolic immortality, can alleviate the negative emotions associated with one’s mortality (Deschesne et. al, 2003). We found this aspect of TMT particularly interesting, but lacking any substantial research. Therefore, we set out to determine if belief in an afterlife could diminish the effects of mortality salience. As far as we know, our study is the first to use a pre-screening process to determine participants’ prior beliefs. One prediction might be that those who believe in an afterlife will be less affected by the effects of mortality salience.

A few more moments to finance theory: introducing higher moments in investment theory and econometrics

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Exchange rate policies, patterns of specialization and economic development: theory and evidence in developing countries

The objectives of this paper are twofold. First, it intends to provide theoretical elements to analyze the relation between real exchange rates and economic development. Our main hypothesis is very much in line with the Dutch disease literature, and states that competitive currencies contribute to the existence and maintenance of the anufacturing sector in the economy. This, in turn, brings about higher growth rates in the long run, given the existence of increasing returns in the industrial sector, and its importance in generating echnological change and increasing productivity in the overall economy. The second objective of this paper is empirical. It intends to analyze examples of successful exchange rate policies, such as Chile and Indonesia in the eighties, as a benchmark for comparison with countries where currency overvaluation has taken place, such as Brazil. In the latter case, the local currency is being inflated by large capital inflows, due to high domestic interest rates and to a boom in demand and prices of commodities in the international markets. It will be argued that the industrial sector bears most of the burden when the currency appreciates, and that Brazil risks at deindustrialization if there are no changes in the exchange rate regime

A CAPM with higher moments: theory and econometrics

We develop portfolio choice theory taking into consideration the first p~ moments of the underIying assets distribution. A rigorous characterization of the opportunity set and of the efficient portfolios frontier is given, as well as of the solutions to the problem with a general utility function and short sales allowed. The extension of c1assical meanvariance properties, like two-fund separation, is also investigated. A general CAPM is derived, based on the theoretical foundations built, and its empirical consequences and testing are discussed

Foreign funding to an emerging market: the Monetary Premium Theory and the Brazilian Case, 1991 - 1998

We develop a framework to explain the private capital flows between the rest of the world and an emerging economy. The model, based on the monetary premium theory, relates an endogenous supply of foreign capitals to an endogenous differential of interest rates; its estimation uses the econometric techniques initiated by Heckman. Four questions regarding the capital flows phenomenon are explored, including the statistical process that governs the events of default and the impact of the probability of default on the interest rate differential. Using the methodology, we analyse the dynamics of foreign capital movements in Brazil during the 1991- 1998 period.

Isolated capital cities and misgovernance: theory and evidence

Motivated by a novel stylized fact { countries with isolated capital cities display worse quality of governance { we provide a framework of endogenous institutional choice based on the idea that elites are constrained by the threat of rebellion, and that this threat is rendered less e ective by distance from the seat of political power. In established democracies, the threat of insurgencies is not a binding constraint, and the model predicts no correlation between isolated capitals and misgovernance. In contrast, a correlation emerges in equilibrium in the case of autocracies. Causality runs both ways: broader power sharing (associated with better governance) means that any rents have to be shared more broadly, hence the elite has less of an incentive to protect its position by isolating the capital city; conversely, a more isolated capital city allows the elite to appropriate a larger share of output, so the costs of better governance for the elite, in terms of rents that would have to be shared, are larger. We show evidence that this pattern holds true robustly in the data. We also show that isolated capitals are associated with less power sharing, a larger income premium enjoyed by capital city inhabitants, and lower levels of military spending by ruling elites, as predicted by the theory.

Workplace diversity and incentive contracts : theory and evidence

This paper presents a simple theory of the provision of incentives in firms in which the principal optimally chooses both compensation contracts and the composition of the work force. Assuming that individuals display group loyalty, a less diverse (more homogeneous) work force will be more cooperative. Simple comparative statics provide some testable implications relating risk, diversity and incentive pay. I also analyze the case in which workers’ characteristics cannot be readily observed ex ante. The theory then predicts that firms are more likely to prevent workers from interacting with each other when workers are expected to have similar characteristics. This shows a surprising effect of diversity in the workplace: more diverse firms will promote more interactions between workers of different types, i.e. they will be less segregated. I test the main predictions of the model using a cross-sectional sample of corporate boards. I use the proportion of women on boards as a measure of diversity. There are three main empirical findings: (1) a significant negative correlation between firm risk and diversity, (2) a significant positive relationship between performance-based compensation and diversity and (3) a significant positive correlation between the number of board meetings (a measure of interactions among directors) and diversity. The evidence is broadly consistent with the implications of the theory.

Bias and size effects of price-comparison search engines : theory and experimental evidence

We analyze the impact on consumer prices of the size and bias of price comparison search engines. In the context of a model related to Burdett and Judd (1983) and Varian (1980), we develop and test experimentally several theoretical predictions. The experimental results confirm the model’s predictions regarding the impact of the number of firms, and the type of bias of the search engine, but reject the model’s predictions regarding changes in the size of the index. The explanatory power of an econometric model for the price distributions is significantly improved when variables accounting for risk attitudes are introduced.

Portfolio choice with a correlated background risk : theory and evidence

We extend the static portfolio choice problem with a small background risk to the case of small partially correlated background risks. We show that respecting the theories under which risk substitution appears, except for the independence of background risk, it is perfectly rational for the individual to increase his optimal exposure to portfolio risk when risks are partially negatively correlated. Then, we test empirically the hypothesis of risk substitutability using INSEE data on French households. We find that households respond by increasing their stockholdings in response to the increase in future earnings uncertainty. This conclusion is in contradiction with results obtained in other countries. So, in light of these results, our model provides an explanation to account for the lack of empirical consensus on cross-country tests of risk substitution theory that encompasses and criticises all of them.

Transcriptomics and systems biology analysis in identification of specific pathways involved in cacao resistance and susceptibility to witches' broom disease

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)