The astrophysical data of the last two decades have allowed cosmologists to conclude that the present Universe is accelerating. The research carried out to find the origin of this phenomenon has led to the creation of a vast number of dark energy and modified gravity theories, of which the simplest is the ˄CDM model. The latter is, however, plagued with very difficult problems awaiting a solution. The work here presented seeks to contribute to the discussion of the possible explanation for the Cosmos' acceleration and other important questions in modern cosmology using the newest astrophysical observations available. This thesis starts by exploring a dark energy model dubbed thawing quintessence which is characterised by allowing a non constant ratio of pressure to density for dark energy that is however still close to -1 for most of the cosmological evolution, shifting away from this value when the domination of the radiation and matter components fades away. The findings are the most up-to-date constraints for which this model gives a viable theory for dark energy, including a bound on the equation of state at present of w < -0:88. This exact approach was contrasted with the use of an approximate equation-of-state parametrisation for thawing theories. The analysis also includes different parametrisation choices, and comments on the accuracy of the constraints imposed by CMB anisotropies alone. Next, the cosmology of hybrid metric-Palatini gravity is presented. This is a type of Modified Gravity theory in which the Lagrangian density for the gravitational action is a function of the Ricci scalars of both the connection and the metric. The background evolution of two models of this kind is examined explicitly showing the recovery of standard General Relativity at late times. The maximum deviation from the gravitational constant G at early times is constrained using a combination of geometrical data, finding it to be around 1%. A designer scenario, also introduced under the hybrid metric-Palatini formulation, is then used to explore to what extent early modifications of gravity, which become significant after recombination but then decay towards the present, can be constrained by current and future cosmological observations. This model is embedded in the effective field theory description of Horndeski scalar-tensor gravity with an early-time decoupling of the gravitational modification. Applying cosmological data, the constraints on the early-time deviations from General Relativity are obtained. These are dependent on the redshift at which the oscillations in the slip between the gravitational potentials are turned on. For zon = 1000, the deviation from Einstein's theory is ≤ 10-2 with 95% confidence. An explanation of the effect that these divergences have on the CMB power spectrum are discussed, as well as the effect that future 21 cm survey data will have on this study. The last part of this work is a move towards inflation, the early epoch of accelerated expansion undergone by the Universe. Here a parametrisation of the acceleration trajectory is investigated with the aim of measuring the rolling of the inflaton corresponding to the value of the tensor-to-scalar ratio r to be compared with future observations. Considering five ln ε amplitudes and 14 e-foldings, it was found that the posterior distribution of (r,∆Φ) is in very good agreement with Lyth's bound. The analysis included a histogram depiction of the latter result, from which later a minimum constraint on ∆ϕ for each of the bins was found. These outcomes constitute the intermediate step of this project which will be made more accurate by extending it to ~ 50 e-folds, a larger set of cosmological parameters and observational bounds that are restrictive on small scales.

Given the importance of monetary policy in the operation of a successful modern economy and the use of official interest rates as tools in its implementation, this study investigates the implications of changing bank concentration on the operation of the Interest Rate Pass Through (IRPT) of official rates to bank lending and deposit rates. This is an issue made more poignant by growing mergers, acquisitions and bank consolidation exercises around the world that have brought interest to their implications for economic performance. However, with contention high in the industrial organisation theory on the likely relationship between bank concentration and the IRPT, and the outcomes of empirical investigations producing conflicting evidence, the desire to investigate the issue in the African context necessitated a thorough empirical investigation of four African countries (South Africa, Botswana, Nigeria and Zambia). This study not only extended the investigation of the issue to the African context, but it merged different IRPT measurement techniques that had not been jointly applied to this particular issue, namely; Symmetric and Asymmetric Error Correction Models, Mean Adjustment Lags, Ordinary Least Squares estimations and Autoregressive Distributed Lag models. These measures of the IRPT were compared with three firm concentration ratios on two different levels of analysis, one, over the entire period and, another, through eight year rolling windows. The results reveal that bank concentration can sometimes be related to the speed and magnitude of the IRPT but that these relationships are not consistent amongst the countries, over the entire sample period or across the two levels of analysis, suggesting reasons why empirical results have arrived at contrasting conclusions. The results revealed more evidence of a relationship between bank concentration and the magnitude of the IRPT than between bank concentration and the speed of the IRPT. Furthermore, where relationships were identified there was evidence supporting both the structure conduct performance hypothesis and the competing efficient market hypothesis as the true representation of the relationship between bank concentration and the IRPT. The key implication of the result for African countries is that increased bank concentration through bank consolidation programmes should not be automatically regarded as detrimental to the effective implementation of monetary policy through the IRPT. Consequently,banking sector regulation need not stifle bank consolidation and growth to preserve monetary policy effectiveness. Rather, since the relationship cannot be neatly represented by a single theory or hypothesis each country must determine its own interaction between bank concentration and its IRPT before policies regarding the banking sector concentration and effective monetary policy, through the use of official interest rates, are determined.

Magister Scientiae - MSc / Aggressive fiscal and monetary policies by governments of countries and central banks in developed markets could somehow push inflation to some very high level in the long run. Due to the decreasing of pension fund benefits and increasing inflation rate, pension companies are selling inflation-linked products to hedge against inflation risk. Such companies are seriously considering the possible effects of inflation volatility on their investment, and some of them tend to include inflationary allowances in the pension payment plan. In this dissertation we study the management of pension funds of the defined contribution type in the presence of inflation-recession. We study how the fund manager maximizes his fund's wealth when the salaries and stocks are affected by inflation. In this regard, we consider the case of a pension company which invests in a stock, inflation-linked bonds and a money market account, while basing its investment on the contribution of the plan member. We use a benchmarking approach and martingale methods to compute an optimal strategy which maximizes the fund wealth. / South Africa

[pt] Este trabalho pretende, por meio de um modelo de equilíbrio geral com dois países, mostrar que o coeficiente de repasse cambial (ERPT) deve ser usado com cautela para orientação da política macroeconômica. Não só as suas condições de identificação são bastante restritivas (aumentando a chance de serem usadas hipóteses erradas na estimação) como ele não consegue relacionar movimentos da taxa de câmbio e preços de importados: dependendo da origem do choque uma apreciação cambial pode estar associada tanto a um aumento como a uma diminuição desses preços e, se a curva de oferta do produtor sofre choques, o coeficiente de ERPT já não é mais identificado sob as hipóteses de mínimos quadrados ordinários (o procedimento de estimação mais comum nesta literatura). Portanto, além de ser de difícil estimação, a valia do coeficiente de ERPT como regra de bolso para a política econômica é bastante questionável. Todavia, este estudo mostra que os erros cometidos pelo uso do coeficiente como regra de bolso podem ser bastante mitigados se a sua estimativa estiver condicionada à origem do choque gerador do movimento cambial. Além disso, a investigação de técnicas alternativas de estimação (via função de resposta ao impulso, por exemplo) pode ser um caminho para resolver o problema de identificação. / [en] This paper uses a two-country model to show that the exchange rate pass-through (ERPT) coefficient must be used with reservation as a guide to macroeconomic policy. Not only its identification conditions are very restrictive (which increases the chances of assuming wrong hypotheses for its estimation) but it also cannot associate movements of exchange rates and import prices: depending on the origin of the shock an exchange rate devaluation is followed by an import prices increase or decrease. Furthermore, if the supply curve is subject to exogenous shocks the ERPT is not identified under the general assumptions of ordinary least squares (the most usual estimation procedure used in the literature). As a result, the ERPT is difficult to estimate and not much valuable as a rule of thumb for economic policy. However, this work shows the errors of using the ERPT as a rule of thumb are mitigated when its estimates are conditional on the source of the economic shock. Also, the investigation of alternative estimation techniques (using impulse-response matching, for instance) may solve the identification problem.

Este trabalho teve como finalidade testar a validade da teoria sobre flutuações na estrutura a termo da taxa de juros – a Hipótese das Expectativas – que estabelece em linhas gerais, que a taxa de juros de longo prazo é formado como uma média das taxas de juros de curto prazo esperadas para o futuro mais um prêmio de risco invariente no tempo; desde a adoção do sistema de Metas para Inflação, com base na estrutura elaborada por Campbell e Shiller (1987, 1991). Apesar de problemas potencias, este exercício possui relevância na medida em que as análises em sua maioria corroboram com os fundamentos pelo que se conclui de forma favorável a validade do modelo. As Evidencias empíricas sugerem que a adoção da estrutura de Metas para Inflação tem apresentado um efeito amortecedor de choques na taxa de juros sobre a estrutura a termo. Com base nos resultados obtidos fica evidente que existe algum grau de antecipação das ações de política monetária pelos participantes de mercado e que, portanto, mudanças na meta para a taxa de juros de curto prazo podem ser previstas e são incorporadas as taxas de juros de mercado, ao menos parcialmente. / The aim of this study was to test the expectation theory of term structure of interest rate to the Brazilian economy under the model developed by Campbell and Shiller (19987, 1991). The Expectation Hypothesis (EH) of term structure of interest rate define that the long-term rate is determined by market’s expectation for the shortterm rate plus a constant risk premium. I found that the forecasting decline with the increasing of maturity spectrum but, a causality test granger provide ambiguous results in some test. Under the Inflation Targeting structure the result show that the agents foresee, at least partially, the monetary policy’s decisions. In general way the results support EH theory for Brazilian data.

O objetivo desta tese será o de contribuir com o desenvolvimento do Sistema de Metas para a Inflação no Brasil. Implantado em 1999, o atual regime monetário brasileiro vem conseguindo manter a evolução dos preços e as expectativas de inflação dos agentes econômicos em conformidade com as metas estabelecidas na maior parte do tempo. Entretanto, existem diversas questões que apresentam espaço para a investigação, tanto teórica, quanto aplicada à realidade brasileira, contexto no qual este trabalho buscou sua justificativa. Primeiramente, é realizado um capítulo teórico que trata dos principais elementos que fundamentam o Regime de Metas de Inflação. Na seqüência, discute-se o papel de regras sub-ótimas no regime e são estimadas funções de reação para o Banco Central do Brasil e para o mercado futuro de juros local. Os resultados permitem observar que há um comportamento compatível com uma Regra de Taylor, tanto por parte da autoridade monetária brasileira, quanto do mercado de juros, sendo esse muito sensível a surpresas nas decisões do Comitê de Política Monetária (COPOM). O terceiro capítulo discute um dos temas mais importantes numa economia sob um sistema de metas: a taxa natural de juros. Seu comportamento é estimado por meio de um modelo macroeconômico simplificado e seus resultados confrontados com outras medidas comumente encontradas na literatura, como filtros estatísticos e uma medida de juros real implícita nas decisões do COPOM, que refutam a idéia de excesso de conservadorismo na condução da política monetária no período avaliado. Por fim, é apresentado um trabalho que discute o papel das instituições como elemento contributivo na condução da política monetária. Mais especificamente, é verificada a existência de ganhos econômicos com a independência dos bancos centrais que adotam o regime de metas. / This thesis aims to contribute to the development for Inflation Targeting System in Brazil. Implanted in 1999, the current Brazilian Monetary Structure has been able to maintain the price evolution and the expectations of the economic agent’s inflation in accordance with the established goals most of the time. However, there are several issues to be argued about, not only theoretical matters but also the ones applied to the Brazilian reality, context in which this work is based. First, a theoretical chapter on the main elements, which base the Inflation Targeting System, was written. Then, the role of sub-optimal rules in the system is discussed and the reaction functions are estimated for the Brazilian Central Bank and for the domestic interest future market. The results allow us to observe that there is a compatible behavior with Taylor’s Rule on the Brazilian monetary authority’s side, and the interest market as well, being this very sensitive to surprises in the Committee for Monetary Policy (COPOM) decisions. The third chapter discusses one of the most important issues in an economy under a goal structure: the natural interest rate. Its behavior is estimated through a simplified macroeconomic model and the results are confronted with other measures – commonly found in the literature-, such as statistical filters and a real interest measurement implicit in COPOM’s decisions, which refute the idea of excess of conservatism in the monetary policy management in the studied period. Finally, a work that discusses the role of the institutions as a contributive element in the monetary policy management is presented. More specifically, the existence of economic earnings from independence of central banks that adopt the Inflation Targeting System is verified.

O objetivo deste trabalho é estudar a interação entre as autoridades fiscal e monetária no Brasil, de forma a mensurar o nível de dominância fiscal existente na economia brasileira. Para alcançar este objetivo, utiliza-se um modelo de equilíbrio geral dinâmico e estocástico desenvolvido para uma economia com rigidez de preços e com tendência inflacionária, cujos parâmetros de interesses são estimados por inferência bayesiana. Conclui-se que o nível de dominância fiscal na economia brasileira é baixa, em patamar comparado ao da economia norte-americana e canadense. Este resultado tem impacto direto na condução de políticas que visam a redução da inflação, sugerindo que esta atividade deva passar pelo encolhimento das metas inflacionárias, que impactaria diretamente na expectativa dos agentes sobre a inflação futura. / The purpose of this dissertartion is to analyse the interaction between fiscal and monetary authorities in Brazil, in a way that we can be able to measure the level of fiscal dominance occurring in brazilian economy. To attain this purpose, we make use of a dynamic stochastic general equilibrium model with sticky prices and non-zero trend inflation, whose parameters are estimated by bayesian inference. We conclude that the level of the fiscal dominance in Brazil is low, in scale compared to american e canadian economies. This result has consequence in policy conduction that aims to decrease inflation, suggesting that may be necessary straiten the inflation target to reduce the inflation and affect the agent’s expectation about the future inflation.

As modificações geradas no âmbito das decisões de políticas econômicas nacionais das últimas décadas atentaram para o papel da estabilidade macroeconômica no desempenho das economias de mercado. O controle da inflação constitui-se no objetivo primordial das autoridades monetárias que, a partir dos anos 1990, encontraram na adoção de metas de inflação um modo mais eficiente para atingir a estabilidade de preços. Segundo a literatura convencional contemporânea, os resultados do regime de metas de inflação em economias avançadas e emergentes garantem, diretamente, uma redução dos níveis e da volatilidade das taxas de inflação, uma ancoragem das expectativas inflacionárias e menores custos da desinflação em termos do produto. Entretanto, acredita-se que a intensidade e os impactos desses efeitos podem ser diferenciados ou comprometidos quando aplicados à realidade dos países emergentes. Fundamentadas nas visões críticas das implicações do regime de metas de inflação à evolução das economias emergentes, as discussões teóricas visaram expor as definições gerais do regime de metas de inflação e as questões estruturais da dinâmica macroeconômica dos mercados emergentes. Constatou-se que a preponderância dos mecanismos de transmissão da taxa de câmbio sobre a inflação, os desequilíbrios ficais, financeiros e externos, e as características de vulnerabilidade e instabilidade macroeconômicas dos países emergentes podem dificultar o funcionamento do regime de metas de inflação. Essencialmente, a avaliação empírica dos efeitos de metas de inflação sobre o desempenho macroeconômico dos países emergentes evidenciou que, além deste regime não apresentar relevância estatística na explicação das taxas de inflação, de crescimento do produto e de juros, os movimentos da economia internacional parecem definir as condições de estabilidade macroeconômica nessas economias. Portanto, concluiu-se que a implementação de metas de inflação não melhorou nem piorou o desempenho macroeconômico dos países emergentes que adotaram este regime a partir dos anos 1990. Tal resultado contribui no debate atual sobre a dimensão das políticas de estabilidade de preços e, em especial, os efeitos de metas de inflação em economias emergentes. / The modifications generated in the scope of national economy policy decisions in the last decades had attempted for the role of macroeconomic stability in the performance of market economies. The control of inflation consisted in the monetary authorities’ primary objective that, from the 1990 years, had found in the adoption of inflation target a more efficient way to reach the price stability. According to conventional literature contemporary, the results of inflation targeting in the advanced and emerging economies guarantee directly a reduction of the level and the volatility in the inflation rates, an anchorage inflationary expectations and lesser costs of disinflation at the product. However, one gives credit that the intensity and the impacts of effects can be differentiated or biased when applied to reality of emerging countries. Based in the critical views of inflation target implications to emerging economies evolution, the theoretical quarrels had aimed at to display the inflation target general definitions and the structural matters of emerging market macroeconomic dynamic. One evidenced that the predominance of the exchange pass through inflation, the external, financial and fiscal disturbs, and the macroeconomic vulnerability and instability characteristics of emerging countries can difficult inflation target working. Essentially, the empirical evaluation of the inflation targeting effects on the macroeconomic performance of emerging countries demonstrated that, beyond this regime not to present statistics relevance in the inflation rates, growth product and interest rates explanation, the movements of the international economy seem to define the conditions of macroeconomic stability in these economies. Therefore, one concluded that the implementation of inflation target did not improve nor got worse the macroeconomic performance of the inflation targeting emergent countries from 1990s. Such result contributes in the current debate on the prices stability policies and, in special, the effect of inflation target in emergent economies.

Made available in DSpace on 2008-05-13T13:48:25Z (GMT). No. of bitstreams: 1 2233.pdf: 464094 bytes, checksum: 6304ee0a64680524e3112ddd267fc553 (MD5) Previous issue date: 2007-05-31 / The bill of the Senate of no. 317 of 2003, that establishes the operational autonomy of the Central Bank of Brazil, is a great step towards an institutional modernization of the country. Being that approved autonomy, a crucial subject that proceed is how the institutional drawing of the Central Bank of Brazil will be. Which areas will be linked to BACEN and which areas will be out? Who will determine the goal? Who will be the members of COPOM? Those are just some subjects that appear when it is spoken in autonomy of the central bank. Several examples of autonomous central banks exist in the world and that study will analyze how those central banks operate, so that hereafter we can try to draw an institutional arrangement that adapts to the Brazilian needs. / O projeto de lei do Senado de Nº 317 de 2003, que estabelece a autonomia operacional do Banco Central do Brasil, é um grande passo em direção a uma modernização institucional do país. Sendo essa autonomia aprovada, uma questão crucial que se segue é como será o desenho institucional do Banco Central do Brasil. Quais áreas estarão ligadas ao BACEN e quais áreas estarão fora? Quem determinará a meta? Quem serão os membros do COPOM? Essas são apenas algumas questões que surgem quando se fala em autonomia do canco central. Existem diversos exemplos de bancos centrais autônomos no mundo e esse estudo irá analisar como esses cancos centrais operam, para que futuramente se possa tentar desenhar um arranjo institucional que se adapte as necessidades brasileiras.

Submitted by Fernando Antônio de Barros Júnior (fernando.junior@fgvmail.br) on 2014-03-17T14:31:41Z No. of bitstreams: 1 Dissertacao_final.pdf: 416302 bytes, checksum: 42bb00304953a814c57d6ada5116013d (MD5) / Approved for entry into archive by ÁUREA CORRÊA DA FONSECA CORRÊA DA FONSECA (aurea.fonseca@fgv.br) on 2014-04-04T19:26:45Z (GMT) No. of bitstreams: 1 Dissertacao_final.pdf: 416302 bytes, checksum: 42bb00304953a814c57d6ada5116013d (MD5) / Approved for entry into archive by Maria Almeida (maria.socorro@fgv.br) on 2014-04-09T14:53:57Z (GMT) No. of bitstreams: 1 Dissertacao_final.pdf: 416302 bytes, checksum: 42bb00304953a814c57d6ada5116013d (MD5) / Made available in DSpace on 2014-04-09T14:54:18Z (GMT). No. of bitstreams: 1 Dissertacao_final.pdf: 416302 bytes, checksum: 42bb00304953a814c57d6ada5116013d (MD5) Previous issue date: 2014-03-12 / I study optima in a random-matching model of outside money. The examples in this paper show a conflict between private and collective interests. While the planner worry about the extensive and intensive margin effects of trades in a steady state, people want the exhaust the gains from trades immediately, i.e., once in a meeting, consumers prefer spend more for a better output than take the risk of saving money and wait for good meetings in the future. Thus, the conflict can force the planner to choose allocations with a more disperse money distribution, mainly if people are im- patient. When the patient rate is low enough, the planner uses a expansionary policy to generate a better distribution of money for future trades.