Cosmology is one of the best tools to understand the physics that governs the universe at high energies. On one hand, inflation is a very robust mechanism to explain the initial conditions of the universe. On the other hand general relativity provides a solid framework for the formation of cosmic structures at cosmological scales. Nevertheless, there are still important issues that remain without a clear answer. For example, inflation still lacks of a concrete microphysical description, and also there is still no satisfactory mechanism to explain the late time acceleration of the universe. This thesis addresses these two topics. In the first part we discuss the effects of heavy degrees of freedom coupled to inflation. This has been an important topic over the years, because the experimental success might make it possible to detect new degrees of freedom in inflation. In chapter two we discuss the case when non relativistic heavy fields are coupled to the inflaton through a non minimal gravitational coupling. Here we find that, for certain geometries, the heavy field can modify the potential for a few e-folds, either stopping inflation, or setting its initial conditions. In chapter 3 we study the dynamics of fluctuations in holographic inspired models of multi-field inflation. We find that the entropy mass $\mu$ (the mass of the fluctuation orthogonal to the trajectory of inflation) satisfies an universal upper bound given by $\mu \leq 3 H / 2$. This bound coincides with the requirement of unitarity of conformal operators living on the boundary of the theory. In the second part of the thesis we study high energy effects on the Cosmic Microwave Background (CMB). In the fourth chapter we study the role of disformal transformation on cosmological backgrounds and its relation to the speed of sound for tensor modes. A speed different from one for tensor modes can arise in several contexts such as Galileons theories, or massive gravity. Nevertheless the speed is very constrained to be one by observations of gravitational wave emission. It has been shown that in inflation a disformal transformation allows the speed for tensor modes, to be set to one without making changes to the curvature power spectrum. We show that on the CMB, after doing the transformation, there is an imprint on the acoustic peaks, and the diffusion damping. This has interesting consequences: for a particular class of theories the transformation can be used to constrain the parameter space in different regimes. In chapter five we study the impact of gravitons with non-vanishing masses on the polarisation of th CMB . We also focus on putative modifications to the speed of the gravitational waves. We find that a change of the graviton speed shifts the acoustic peaks of the B-mode polarization and then could be easily constrained. In all cases when both massless and massive gravitons are present, we find that the B-mode CMB spectrum is characterised by a low $l$ plateau together with a shifted position for the first few peaks compared to a massless graviton spectrum. This shift depends on the mixing between the gravitons in their coupling to matter and could serve as a hint in favour of the existence of multiple gravitons.

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Alfred P. Sloan School of Management. / Bibliography: leaves 83-86. / M.S.

My dissertation focuses upon low inflation. Many developed countries, especially Japan and the Eurozone, have recently experienced prolonged periods of below-target inflation. This has been blamed for many economic ills including worsening the Great Recession and generating a slow recovery, making monetary policy ineffective and leading to lower labor market flexibility. I study what has caused low inflation, its potential effects and how it could be prevented. In Chapter 1, I look at how effective raising the inflation target would be in mitigating the problems of low inflation. Many economists have proposed raising the inflation target to reduce the probability of hitting the zero lower bound (ZLB). It is both widely assumed and a feature of standard models that raising the inflation target does not impact the equilibrium real rate. I demonstrate that once heterogeneity is introduced, raising the inflation target causes the equilibrium real rate to fall in the New Keynesian model. This implies that raising the inflation target will increase the nominal interest rate by less than expected and thus will be less effective in reducing the probability of hitting the ZLB. The channel is that a rise in the inflation target lowers the average markup by price rigidities and a fall in the average markup lowers the equilibrium real rate by household heterogeneity which could come from overlapping generations or idiosyncratic labor shocks. Raising the inflation target from 2% to 4% lowers the equilibrium real rate by 0.38 percentage points in my baseline calibration. I also analyse the optimal inflation level and provide empirical evidence in support of the model mechanism. In Chapter 2, I study to what degree the recent fall in inflation can explain the rise in firm profitability which has been blamed for a rise in inequality. A theoretical relationship between inflation and profitability is known to exist. I investigate the degree to which the recent fall in inflation can explain the rise in firm profitability. My three primary findings are: 1. The negative relationship between inflation and profitability does not hinge upon the Calvo assumption. Raising inflation significantly lowers profitability under all common price rigidities. The relationship can actually be significantly stronger under menu costs. 2. A rise in the degree to which firms discount the future magnifies the effect; a rise in elasticity of substitution can increase or decrease the effect depending upon the price rigidity. 3. The profit share has risen by around 3.5p.p. since the 1990s. In a richer model with firm heterogeneity, the recent fall in inflation is estimated to explain 14% of the rise. This can increase to 29% if firms are allowed to discount the future by more in line with estimates from the finance literature. I also provide empirical evidence for the negative relationship between inflation and firm profits. In Chapter 3, I examine whether behavioral features can help to explain why some countries have persistently experienced low inflation at the zero lower bound. Economists are keen to introduce behavioral assumptions into modern macroeconomic models. A popular framework for doing so is sparse dynamic programming, which assumes that agents partly base their expectations upon a default model which is typically the steady state. This means agents' expectations will be wrong if there are long-run deviations from the default model and assumes agents can compute the default. I introduce an alternative form of sparse dynamic programming which tackles these problems by allowing for long-run updating to the behavioral part of agents' expectations. I apply this to derive a long-run behavioral New Keynesian model. Within this model, fixed interest rates yield indeterminacy and the costs of remaining at the zero lower bound are unbounded. These results are very different to a behavioral New Keynesian model based upon standard sparse dynamic programming, which can yield determinacy under fixed interest rates and bounded costs of the zero lower bound.

Orientador: Eduardo Strachman / Banca: André Luiz Correa / Banca: Marcos Roberto Vasconcelos / Resumo: Dentre os vários trabalhos publicados sobre o Regime de Metas de Inflação (RMI), poucos procuram comparar o desenho do arranjo institucional escolhido pelos países que usam este regime com os resultados e impactos sobre as principais variáveis macroeconômicas. Deste modo, o objetivo central desse trabalho consistiu em identificar, analisar e comparar o desenho institucional do quadro de metas de inflação com os resultados obtidos pelos países que usam o Regime de Metas de Inflação, com ênfase no desempenho brasileiro em relação aos seus pares emergentes e da América do Sul que usam esse regime de política monetária. Foi realizada uma breve apresentação dos principais fundamentos teóricos e empíricos do RMI e das principais críticas feitas a este regime. Em seguida, foram identificados os diversos formatos que o regime pode assumir e as escolhas feitas pelos países na formatação do arranjo em relação a quatro elementos fundamentais: o nível da meta, o tipo da meta, o índice de preços oficial usado e o horizonte alvo. A combinação desses elementos determina o grau de rigidez do arranjo institucional. Foram comparados os resultados obtidos por países desenvolvidos e emergentes em relação ao nível e volatilidade da inflação e cumprimento da meta. Também foi comparado o desempenho do Brasil em relação às principais variáveis macroeconômicas com o desempenho de outros países que usam este regime há pelo menos uma década e encontram-se no mesmo estágio de desenvolvimento - emergente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Among several works published about Inflation Targeting regime (IT), a few of them attempt to compare the design of the institutional settlement chosen by countries which use this strategy with results and impacts over the main macroeconomic variables. Therefore, the main purpose of this study consists of identifying, analyzing and comparing the institutional design from the inflation targeting table with the results obtained by countries that apply the Inflation Targeting Regime, focused on Brazil's performance compared with its emerging counterparts in South America which use this monetary policy. A brief presentation of the main theoretical and empirical foundations on IT and the primary critics to this system. Secondly, the various formats this system may assume were identified, as well as the choices made by countries for the settings of the system related with four essential elements: target level, target type, the official price index and the target perspective. The combination of these elements determines the level of rigidity for the institutional design. Results obtained by emerging and developed countries were compared in relation with the level and volatility of inflation and target achievement. In addition, in relation with the main macroeconomic variables, Brazil's performance was compared to other countries that apply this system for at least ten years and which are currently in the same development stage (emerging). The obtained data indicate significant diffe... (Complete abstract click electronic access below) / Mestre

Lo, Kai Lisa. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 43-46). / Abstract also in Chinese. / Chapter 1. --- Introduction --- p.7 / Chapter 2. --- Literature Review --- p.10 / Chapter 3. --- Measuring the Labor Share with US Data --- p.14 / Chapter 3.1 --- Definition and Measurement --- p.14 / Chapter 3.2 --- Some Crude Evidence --- p.16 / Chapter 4. --- A Theoretical Relationship between Labor Share and Inflation in an Open Economy --- p.19 / Chapter 4.1 --- A Static Closed-economy Pricing Model --- p.20 / Chapter 4.2 --- Dynamic Model Based on Quadratic Adjustment Costs --- p.22 / Chapter 4.3 --- An Open-economy Dynamic Pricing Model --- p.30 / Chapter 5. --- An Empirical Investigation --- p.34 / Chapter 5.1 --- Data --- p.34 / Chapter 5.2 --- Estimation Results --- p.36 / Chapter 5.2.1 --- General Findings --- p.37 / Chapter 5.2.2 --- The Role of Adjustment Costs --- p.39 / Chapter 5.2.3 --- Predicting U.S. Inflation --- p.40 / Chapter 6. --- Conclusions --- p.42 / References --- p.43 / Figures and Tables --- p.47 / Data Appendix --- p.56

<p>Flera ekonomiska studier har genom åren genomförts med syftet att undersöka</p><p>om det föreligger en koppling mellan centralbankernas oberoende och</p><p>prisstegringstakten. Tack vare nobelpristagare Kydland&Prescotts och andra</p><p>ekonomers arbete kring tidsinkonsistensproblematiken har regeringar i ett flertal</p><p>länder valt att låta sina centralbanker bli mer oberoende och utifrån givna riktlinjer</p><p>bedriva en självständig penningpolitik. Uppsatsen beskriver hur den</p><p>makroekonomiska teorin ser på sambandet mellan CB:s oberoende och</p><p>inflationsutvecklingen i ett land. Utifrån resultatet av de tidigare studierna i ämnet</p><p>samt av den egna undersökningen kan konstateras att ett ökat centralbanksoberoende</p><p>sänker och stabiliserar inflationsnivån i ekonomin. Det framgick</p><p>däremot inte att ett ökat centralbanksoberoende skulle kunna öka risken för större</p><p>variationer i de reala variablerna såsom arbetslöshet m.fl.</p>

<p>Inkomstklyftor hindrar en ekonomis utveckling på flera sätt. Senare studier fokuserar på</p><p>inflation och demokratins påverkan på inkomstklyftor. Resultaten är dock inte självklara och</p><p>skiljer sig beroende på studien som genomförts. Denna uppsats bidrar till forskningen kring</p><p>inflationen och demokratins påverkan på inkomstklyftor genom att fokusera på effekter i</p><p>Latinamerika under åren 1976-1993. Detta eftersom Latinamerika har en historia med höga</p><p>inkomstklyftor och har drabbats länge av hög och i vissa fall hyperinflation samtidigt som</p><p>många av länderna blev demokratiska under perioden. Resultaten ger ytterligare belägg för att</p><p>detta samband in te är självklara. Uppsatsen finner att inflation är en icke linjär funktion samt</p><p>att det finns tillräckligt med statistiskt belägg för att demokrati har en negativ påverkan på</p><p>inkomstklyftor. Hög- samt hyperinflation har en positiv påverkan på inkomstklyftor och</p><p>hyperinflation har större effekt än höginflation. Uppsatsen finner dessutom att</p><p>interaktionstermen mellan demokrati och hög- respektive hyperinflation är signifikant skiljt</p><p>från noll och påverkar inkomstklyftorna positivt.</p>

Thesis (Ph. D.)--Ohio State University, 1983. / Includes vita. Includes bibliographical references (leaves 62-65). Available online via OhioLINK's ETD Center.

Thesis (Ph. D.)--Ohio State University, 1984. / Includes vita. Includes bibliographical references (leaves 100-104). Available online via OhioLINK's ETD Center.

Flera ekonomiska studier har genom åren genomförts med syftet att undersöka om det föreligger en koppling mellan centralbankernas oberoende och prisstegringstakten. Tack vare nobelpristagare Kydland&amp;Prescotts och andra ekonomers arbete kring tidsinkonsistensproblematiken har regeringar i ett flertal länder valt att låta sina centralbanker bli mer oberoende och utifrån givna riktlinjer bedriva en självständig penningpolitik. Uppsatsen beskriver hur den makroekonomiska teorin ser på sambandet mellan CB:s oberoende och inflationsutvecklingen i ett land. Utifrån resultatet av de tidigare studierna i ämnet samt av den egna undersökningen kan konstateras att ett ökat centralbanksoberoende sänker och stabiliserar inflationsnivån i ekonomin. Det framgick däremot inte att ett ökat centralbanksoberoende skulle kunna öka risken för större variationer i de reala variablerna såsom arbetslöshet m.fl.