In Chapter 1 of this thesis we examine two key empirical questions in public economics by exploiting the 2009 Polish tax reforms. First, we estimate the degree of substitution between employment and self-employment tax bases – on the extensive margin. In particular, we quantify the impact of changes in the differential in rates of taxation between the two tax bases on the propensity of taxpayers to declare any positive level of employment or self-employment income. Second, we contribute to the literature on elasticities of taxable income on the intensive margin – the responsiveness of taxable income to changes in marginal tax rates – by providing estimates which are more likely to be robust to changes in year-to-year income dynamics than previous estimates. To identify these effects, we exploit variation in marginal and total tax rates around the 2009 reforms which occurs independently of an individual’s position in the income distribution as a result of joint reporting with a spouse. At the same time, to obtain the extensive-margin responses, we exploit the uniqueness of the 2009 Polish tax reforms, which left the tax schedule un-changed for some types of self-employment while changing the tax schedule for the employed. The baseline estimates of the intensive-margin elasticities are around 0.2-0.3 for the employed and around 0.5-0.7 for the self-employed. The estimates jointly make possible the decomposition of the deadweight losses of the tax reform into intensive and extensive-margin responses, with the contribution of the extensive margin found to be around 7% of the total. In Chapter 2, we examine the optimal non-linear taxation in an environment in which individuals have the option of engaging in either employment or self-employment activity. We build on the estimates from Chapter 1 to calibrate an extension of the classic Mirrleesian model which allows for extensive-margin transitions between employment and self-employment. The results help rationalise the preferential tax treatment of self-employment income versus employment income given in certain tax systems. They also illustrate the ways in which the possibility of extensive-margin transitions between tax bases moderate the incentive to give such preferential treatment. Based on the parameterisation here, the presence of the extensive-margin ap- pears to have a limited impact on the optimal marginal and total tax rates faced by the employed and self-employed. This, together with the earlier decomposition of deadweight losses in Chapter 1 by types of response, points towards a limited role of the extensive margin as a consideration for optimal-tax design, at least as far as the employment and self-employment tax bases are concerned. Chapter 3 turns to a fundamental question in health economics: how do health states change over the life-cycle, and how does the risk of adverse health-shocks change over the life-cycle? Most economic models of individuals’ behaviour over the life-cycle, to the extent to which they incorporate a measure of health risk, assume a simplified unidimensional measure of health. We contribute to this literature by estimating a flexible dynamic factor model of health and health risk over an individual’s life using the rich health data from the Health and Retirement Study (HRS). We find that the many potentially collinear health indicators found in the HRS can broadly be summarized into four underlying factors. Three of these correspond to what may be termed subjective health measures, such as self-reported mobility, while a fourth corresponds to objective measures, including the number of overnight hospital stays, doctor visits and medical spending. The persistence of these underlying factors and the variance of their shocks are estimated as parameters of a vector auto-regressive process. We obtain results about the deterministic evolution of the health factors with age, the level of risk relating to each health measure, as well as heterogeneity by level of education. These are intended as building blocks of an ongoing project concerning the optimal design of disability insurance, given the health risks faced by individuals.

abstract: An exhaustive parameter study involving 133 dynamic crystallization experiments was conducted, to investigate the validity of the planetary embryo bow shock model by testing whether the cooling rates predicted by this model are consistent with the most dominant chondrule texture, porphyritic. Results show that using coarse-grained precursors and heating durations ≤ 5 minutes at peak temperature, porphyritic textures can be reproduced at cooling rates ≤ 600 K/hr, rates consistent with planetary embryo bow shocks. Porphyritic textures were found to be commonly associated with skeletal growth, which compares favorably to features in natural chondrules from Queen Alexandra Range 97008 analyzed, which show similar skeletal features. It is concluded that the experimentally reproduced porphyritic textures are consistent with those of natural chondrules. This work shows heating duration is a major determinant of chondrule texture and the work further constrains this parameter by measuring the rate of chemical dissolution of relict grains. The results provide a robust, independent constraint that porphyritic chondrules were heated at their peak temperatures for ≤ 10 minutes. This is also consistent with heating by bow shocks. The planetary embryo bow shock model therefore remains a viable chondrule mechanism for the formation of the vast majority of chondrules, and the results presented here therefore strongly suggest that large planetary embryos were present and on eccentric orbits during the first few million years of the Solar System’s history. / Dissertation/Thesis / Masters Thesis Geological Sciences 2018

This paper studies the triggers and the agglomeration of M&A activity within clusters constituted by time, market and industry. Based on almost 500,000 individual transactions, we find that industry factors play a significant role in triggering activity and that M&A agglomerates strongly across related industries. While clustering in time turns out to be insignificant, stock-market effects can be either an attracting or a repelling force, depending on the type of deal examined. This supports the view that merger waves are largely driven by industry shocks.

We estimate the macroeconomic performance in terms of inflation and GDP growth of Sweden in relations to oil price shocks, focusing on the differences across two periods, pre and post 2008. By using a Vector Error Correction model and linear hypothesis testing we can see short term and long term correlations between the nominal oil price and three dependent variables, GDP, CPI and GDP deflator. Our hypothesis is that the effects of oil price shocks are indifferent across our estimation period and this would be in line with previous literature.  We find that the macroeconomic factors of GDP and inflation responds differently post 2008 and by using impulse response functions (IRFs) we can see how the dependent variables responds to an oil price shock. They show that oil shocks have permanent effects in GDP and GDP deflator but transitory effects in CPI, we found short run causality for GDP and CPI but not for GDP deflator.

Esta tese é composta de três ensaios que avaliam os impactos de choques monetários sobre a economia brasileira. Sob um arcabouço de economia fechada, no primeiro ensaio, intitulado \"Choques antecipados de política monetária: uma investigação para a economia brasileira\", apresentamos o conceito de news shock em política monetária, ao mesmo tempo em que apontamos que tais choques não são tão relevantes para economia nacional quando outros choques antecipados são considerados. No segundo ensaio, intitulado \"Mudanças exógenas e antecipadas na meta de inflação e impactos sobre a economia brasileira\", estudamos como alterações nas percepções dos agentes econômicos em relação à meta de inflação futura do Banco Central explicam flutuações no produto, na inflação e também nas taxas longas de juros. No terceiro ensaio, intitulado \"Forward Guidance do Fed e impactos sobre países emergentes: o caso brasileiro\", avaliamos como sinalizações antecipadas da política monetária norte-americana geram impactos sobre as variáveis endógenas domésticas, em um arcabouço no qual o Brasil é a pequena economia aberta e também tem choque na meta de inflação / This thesis consists of three papers assessing the impact of monetary shocks on the Brazilian economy. Under a closed economy framework, in the first paper, entitled \"Anticipated monetary policy shocks: an investigation for the Brazilian economy\", we present the concept of news shock in monetary policy, at the same time that we point out that such shocks are not as relevant for national economy when other anticipated shocks are considered. The second paper \"Exogenous and anticipated changes to the inflation target and effects on the Brazilian economy\" assesses how changes to perceptions of economic agents regarding future changes to the inflation target explain changes in output, inflation and long-term market interest rates. The third paper, \"Forward Guidance by the Fed and effects on emerging economies: the case of Brazil\" assesses how anticipated changes to U.S. monetary policy affect the domestic endogenous variables, applying a small open economy framework. Brazil is the SOE and also has news shocks at the inflation target

This study examines the impact of negative compensation shocks on individual performance over time. To do so, performance data over a two year time period were obtained for individuals who remained with their organization after experiencing a reduction in compensation. Using both equity theory and the unfolding model of turnover as theoretical perspectives, the study examines whether the magnitude of the shock matters, whether the individual's pay level affects their reaction to a negative shock, and whether or not the impact of a negative compensation shock dissipates over time. Additionally, this study proposes an extension to the unfolding model of turnover by suggesting that a logical outcome in response to a negative shock may be to stay with an organization but to reduce one's performance in response to a dissatisfying situation. Based on equity theory, it was predicted that individuals would decrease their performance (inputs) in response to a decrease in compensation (outputs). To examine these questions, the study used an interrupted time series with a nonequivalent no-treatment control group method of design. Data on 292 individuals were analyzed. The findings were contrary to expectations in that negative compensations shocks caused performance to increase rather than decrease. The contradictory findings may be due to the fact that pay was highly linked to individual performance for the individuals participating in this study. Some of the study's findings do show consistency with expectations. First, the results show that in response to a negative compensation shock, individuals at high pay levels change their performance less than individuals at lower pay levels. Thus, high pay seems to be an insulating factor as it relates to negative compensation shocks. Second, the effects of negative compensation shocks on performance tend to dissipate time. Third, the study shows that the magnitude of the shock matters such that the larger the shock, the larger the resulting performance impact. The practical implications of these findings provide important new insights into contingencies that may affect the outcomes of pay for performance programs, particularly in the case of individuals whose performance in tightly linked to their compensation.

<div>Understanding the fundamental physics involved in the high strain rate deformation of high explosives (HE) is critical for developing more efficient, reliable, and safer energetic materials. When HE are impacted at high velocities, several thermo-mechanical processes are activated, which are responsible for the ignition of these materials. These processes occur at different time and length scales, some of them inaccessible by experimentation. Therefore, computational modeling is an excellent alternative to study multiscale phenomena responsible for the ignition and initiation of HE. This thesis aims to develop a continuum model of HMX to study the anisotropic behavior of HE at the mesoscale, including fracture evolution and plastic deformation. This thesis focus on three types of simulations. First, we investigate dynamic fracture and hotspot formation in HMX particles embedded in Sylgard binder undergoing high strain rate compression and harmonic excitation. We use the phase field damage model (PFDM) to simulate dynamic fracture. Also, we implement a thermal model to capture temperature increase due to fracture dissipation and friction at both cracks and debonded HMX/Sylgard interface. In our simulations, we observe that crack patterns are strongly dominated by initial defects such as pre-existing cracks and interface debonding. Regions with initial debonding between HMX particles and the polymer are critical sites where cracks nucleate and propagate. Heating due to friction generates in these regions too and caused the formation of critical hotspots. We also run simulations of a HMX particle under high-frequency harmonic excitation. As expected, higher frequencies and larger amplitudes lead to an increase in the damage growth rate. The simulations suggest that the intensity of the thermal localization can be controlled more readily by modifying the bonding properties between the particle and the binder rather than reducing the content of bulk defects in the particle. </div><div><br></div><div>Second, we present simulations of shock compression in HMX single crystals. For this purpose, we implemented a constitutive model that simulates the elastoplastic anisotropic response of this type of material. The continuum model includes a rate-dependent crystal plasticity model and the Mie-Gruneisen equation of state to obtain the pressure due to shock. Temperature evolves in the material due to plastic dissipation, shock, and thermo-elastic coupling. The model is calibrated with non-reactive atomistic simulations to make sure the model obeys the Rankine-Hugoniot jump conditions. We compare finite element (FE) and molecular dynamic (MD) simulations to study the formation of hot spots during the collapse of nano-size void in a HMX energetic crystal. The FE simulations captured the transition from viscoelastic collapse for relatively weak shocks to a hydrodynamic regime for strong shocks. The overall temperature distributions and the rate of pore collapse are similar to MD simulations. We observe that the void collapse rate and temperature field are strongly dependent on the plasticity model, and we quantify these effects. We also studied the collapse of a micron size void in HMX impacted at different crystal orientations and impact velocities. The simulation results of void collapse are in good agreement with a gas gun void collapse experiment. While the void size and crystal orientation do not affect the area ratio rate, they strongly affect the void collapse regime and temperature. Also, increased plastic activity when the crystal is impacted on the plane (110) renders higher temperature fields.</div><div><br></div><div>Finally, we studied shock compression and dynamic fracture in polycrystalline HMX using the same model implemented for shocks in single crystals. The goal of this study is to understand the role of crystal anisotropy and how it affects other hotspot formation mechanisms such as frictional heating. To simulate fracture, we used a phase field damage model implemented for large deformations. We first perform simulations of sustained shocks in polycrystalline HMX, where the grains are perfectly bonded to understand the effect of plastic deformation and hotspot formation due to plastic heating. Then, we simulate shocks in polycrystalline HMX with dynamic fracture. Simulations capture fracture evolution and frictional heating at cracks. In the polycrystalline case, we study heat generation due to shock and plastic deformation. A heterogeneous temperature field forms when the shock wave travels in the material. Temperature increases more in crystals that showed a higher magnitude of accumulated slip. When weak grain boundaries are included in the simulations, frictional heating becomes the dominant hotspot formation mechanism. As the crystals' interfaces break and crack surface sliding occurs, temperature increases due to friction at cracks. Hotspots tend to form at cracks oriented 45 deg from the shock direction. For this case, crystal anisotropy does not play an important role in temperature generation due to plastic dissipation. However, the random orientation of the crystals creates heterogeneous deformation and stress fields that cause the formation of a higher number of hotspots than the case where all the grains are oriented in the same direction.</div>

Thesis advisor: Ryan A. Chahrour / The dissertation studies the primary sources of business-cycle fluctuations and their interaction with uncertainty and financial frictions. In my work, I examine the degree to which changes in uncertainty and financial conditions can be independent drivers of economic fluctuations; I study the sources of boom-bust cycles and whether they are linkedto credit market sentiments; and I ask how financial frictions affect economic fluctuations in terms of prices and quantities. In "Financial and Uncertainty Shocks", I separately identify financial and uncertainty shocks using a novel SVAR procedure and discuss their distinct monetary policy implications. The procedure relies on the qualitatively different responses of corporate cash holdings: after a financial shock, firms draw down their cash reserves as they lose access to external finance, while uncertainty shocks drive up cash holdings for precautionary reasons. Although both financial and uncertainty shocks are contractionary, my results show that the former are inflationary while the latter generate deflation. I rationalize this pattern in a New-Keynesian model: after a financial shock, firms increase prices to raise current liquidity; after an uncertainty shock, firms cut prices in response to falling demand. These distinct channels have stark monetary policy implications: conditional on uncertainty shocks the divine coincidence applies, while in case of financial shocks the central bank can stabilize inflation only at the cost of more unstable output fluctuations. In "What are the Sources of Boom-Bust Cycles?", joint with Vito Cormun, we provide a synthesis of two major views on economic fluctuations. One view maintains that expansions and recessions arise from the interchange of positive and negative persistent exogenous shocks to fundamentals. This is the conventional view that gave rise to the profusion of shocks used in modern dynamic stochastic general equilibrium models. In contrast, a second view, which we call the endogenous cycles view, holds that business cycle fluctuations are due to forces that are internal to the economy and that endogenously favor recurrent periods of boom followed by a bust. In this environment, cycles can occur after small perturbations of the long run equilibrium. We find empirical evidence pointing at the coexistence of both views. In particular, we find that the cyclical behaviour of economic aggregates is due in part to strong internal mechanisms that generate boom-bust phenomena in response to small changes in expectations, and in part to the interchange of positive and negative persistent fundamental shocks. Motivated by our findings, we build a theory that unifies the dominant paradigm with the endogenous cycles approach. Our theory suggests that recessions and expansions are intimately related phenomena, and that understanding the nature of an expansion, whether it is driven by fundamentals or by beliefs, is a first order issue for policy makers whose mandate is to limit the occurrance of inefficient economic fluctuations. In "COVID-19 and Credit Constraints'', joint with Pierluigi Balduzzi, Emanuele Brancati, and Fabio Schiantarelli, we investigate the economic effects of the COVID-19 pandemic and the role played by credit constraints in the transmission mechanism, using a novel survey of expectations and plans of Italian firms, taken just before and after the outbreak. Most firms revise downward their expectations for sales, orders, employment, and investment, while prices are expected to increase at a faster rate, with geographical and sectoral heterogeneity in the size of the effects. Credit constraints amplify the effects on factor demand and sales of the COVID-19 generated shocks. Credit-constrained firms also expect to charge higher prices, relative to unconstrained firms. The search for and availability of liquidity is a key determinant of firms' plans. Finally, both supply and demand shocks play a role in shaping firms' expectations and plans, with supply shocks being slightly more important in the aggregate. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

Chapter 1- How well-off or worse-off a country can be by joining a currency union in the presence of structural heterogeneity and idiosyncratic shocks? In light of the proposed creation of a currency union for the Economic Community of the West African States (ECOWAS), we develop a three-region DSGE model to explore the question. We divide the ECOWAS into three regions-Nigeria, the existing WAEMU (West-African Economic Monetary Union), and the rest. Considering two monetary regimes (monetary union and monetary independence), we assess the heterogeneity in the responses to country-specific productivity and terms-of-trade shocks in these two regimes, as well as the costs related to the loss of monetary independence. Our results indicate that shocks hitting a given region generate cross-border spillover effects, whose sign and magnitude depend not only on the nature of the disturbance but also on its origin and on the monetary policy regime considered. Moreover, the propagation of shocks across regions is magnified under the monetary union regime. Shocks hitting Nigeria's economy tend to have a more destabilizing effect on the other regions, especially when they are inside the union. Our results also suggest that the proposed monetary union for the ECOWAS region can potentially lead to welfare improvement for all the members, but the magnitude of the welfare gain is relatively small. Chapter 2- In this chapter, we develop a multi-region New-Keynesian Dynamic Stochastic General Equilibrium (DSGE) of the West-African countries to provide a quantitative analysis of intergovernmental fiscal transfers in the context of the proposed creation of a monetary union. We assess the potential role of fiscal transfers in the stabilization of business cycle fluctuations in the projected monetary union in the presence of idiosyncratic shocks. Starting from a baseline scenario with no fiscal transfers among the regions, we analyze the dynamic and welfare impacts of full and partial fiscal equalization schemes with nominal tax revenue sharing within the union. We consider adverse productivity and term-of-trade shocks. Our simulation results suggest that the transfer mechanism is an efficient stabilizing tool. However, the stabilization property of the fiscal transfer system hinges upon the full or partial nature of the compensation system. Moreover, the ability of the transfer system to absorb the negative effects of idiosyncratic shocks depends not only on the type of shock but also on the size of the region directly affected. Chapter 3- We analyze in this chapter the macroeconomics effects of fiscal policy shocks in the Economic Community of West African States (ECOWAS). To that end, we use a Global Vector Autoregression (GVAR) model, which allows us to assess both the within country and the cross borders spillover effects of the fiscal shocks. For the dynamic analysis, we consider negative country-specific public spending and revenue shocks affecting Nigeria as well as regional public spending and revenue shocks affecting two groups of countries in the area, namely the West African Economic and Monetary Union (WAEMU) and the Rest of ECOWAS (RECOWAS). We provide evidence of considerable cross-country heterogeneity in fiscal spillovers; for instance, spillovers are high for fiscal shocks affecting Nigeria, while the cross-border spillover effects on Nigeria are weak for shocks affecting WAEMU and RECOWAS. Our results also suggest that fiscal policy is very relevant in stimulating real output in each of the ECOWAS countries but limited for the cross-country output stimulation.

Identifying factors that affect the flow of mutual fund capital and betweenmutualfund types hasthe potential, among others,to relief fund management and investors from unnecessary administrative costs. This study investigated the role media reported weather shocks have on socially responsible and conventional mutual trust funds’capital flow.The study also has compared the magnitude of influence media reported weather shocks has on capital flow between socially responsible-and convectional mutualtrustfunds.It gives conclusionafter empirically studying all accessible socially responsible mutual trust fundswith relevant accessible financial data, originated, and actively traded in the Swedish financial market with the Swedish currency (Kronor) as well as taking conventional mutual trustfundswith similar maturity. And, the study result shows that media reported weather shocks has statistically significant role in the flow of capital, on bothsocially responsible-and conventional mutual funds in Sweden. It also shows that there is no significant difference in the role media reported weather shocks play between the two fundtypes. The result is concurrent with Hirshleifer &amp; Shumway (2003)’s study which indicate that weather affecting investors mood and behavior. The result is interesting as it implicates to the psychological and emotional factorsplaying a significant role in affecting the flow of investment capital in general, in contrast to the rational economic behavior characterized by fund return and risk performance.