Nifedipine, in a 5mg sublingual acute administration, causes a significant fall in the systolic, diastolic and mean arterial pressure in a mixed group of pregnant hypertensives. A concurrent, significant rise in the pulse rate was seen. The utero-placental blood flow index, which is a measure of utero-placental blood flow, was not significantly reduced following the administration of Nifedipine or a placebo. The utero-placental blood flow index was found to be a consistent measure of utero-placental blood flow in resting patients. In the absence of serious side-effects it can be concluded that Nifedipine is a safe therapy in the acute treatment of hypertensive states in pregnancy.

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Thesis advisor: Jaromir Nosal / This dissertation comprises three self-contained essays that investigate the determination and transmission of exchange rate fluctuations, as well as the impact of import quality on consumers’ gains from globalization. In the first chapter, “Decomposing the (In)Sensitivity of CPI to Exchange Rate", I examine the role of domestic frictions – distribution costs, variable markups and nominal rigidities – in explaining the low sensitivity of domestic prices to exchange rate fluctuations. I begin by modeling what the sensitivity of CPI to exchange rates is expected to be, given the presence of insensitivity in border prices and domestic frictions. Distribution costs, such as transportation and wholesaling costs, introduce a wedge between the retail price, on one side, and the border price of imports and the domestic producers’ costs, on the other. Similarly, domestic firms do not fully adjust their price to changes in their own cost because of changes in the desired markup or because prices are sticky. These frictions introduce wedges between the change in domestic producers’ costs and border prices following an exchange rate shock, and the response of domestic consumption retail prices. Using firm and transaction data from Chile, I document that domestic frictions account for 60% of the overall insensitivity of domestic CPI. Moreover, the presence of domestic frictions also impacts the sensitivity of domestic CPI: contrary to previous literature, most of the sensitivity arises from the direct consumption of imported final goods, rather than through the costs associated to imported inputs in the production of domestic goods. This is because domestic frictions dampen the response of domestically produced goods more significantly. In addition, I quantify a rich heterogeneity in the sensitivity across products, which stems from the interaction of domestic frictions and import exposure. These heterogeneities are relevant for the overall (in)sensitivity, as sectors with higher import exposure face also larger frictions. Overall, my results showcase the importance of domestic frictions and their heterogeneity in studying the response of domestic prices to exchange rate fluctuations, with implications for monetary policy in open economy and redistribution dynamics. In the second chapter, “Strategic Behavior and Exchange Rate Dynamics", joint work with L. Pollio, I examine the impact of heterogeneous investors with different degrees of price impact on exchange rate behavior. The huge trading volume in the currency markets, about $6 trillions per day, is highly concentrated among the market-making desks of few large financial institutions. However, models of exchange rate determination assume that investors take the equilibrium price as given, ignoring the presence of a few large investors who recognize the price impact of their decisions and can exert pressure on market prices. We incorporate heterogeneity in price impact, following of Kyle (1989), into a two-country, dynamic monetary model of exchange rate determination. Our theory of exchange rate determination with heterogeneity in price impact reveals that market structure is a key determinant of exchange rate dynamics. Strategic investors recognize their price impact, which leads them to trade less on any information and reduce the information loading factor of the exchange rate (price informativeness). The presence of strategic investors explains the weak explanatory power of macroeconomics variables in predicting exchange rates (exchange rate disconnect puzzle) and the excess volatility of the exchange rate relative to fundamentals (excess volatility puzzle). We also provide empirical evidence that supports our theoretical predictions by using trading volume concentration data from the NY Fed FXC Reports for 18 currencies from 2005 to 2019. We extend our theoretical framework to include another dimension of heterogeneity among investors, information heterogeneity, that provides similar qualitative predictions in terms of exchange rate dynamics. We demonstrate that both dimensions of heterogeneity are quantitatively relevant in explaining the disconnect of exchange rates and their excess volatility. In the third chapter, “The Quality of US Imports and the Consumption Gains from Globalization", joint work with D. Lashkari, I examine the role of quality improvement in shaping the gains from trade. The existing empirical literature indicates that globalization has offered consumers around the world access to a wider variety of products at cheaper prices. However, since the available data typically lacks detailed information on product characteristics, we may underestimate the value of imports for consumers if the quality of goods within each product rises over time. To overcome this limitation, we propose a novel methodology to estimate demand elasticity and infer unobserved quality using only data on prices and market shares. Our approach builds on the standard framework that models product quality as residual demand. This framework requires estimating price elasticities and the standard approach assumes CES demand and imposes uncorrelated supply and demand shocks. However, the latter assumption is untenable if we associate demand shocks with quality and generates an upward bias in the estimates of price elasticities. Our strategy circumvents this problem by restricting the dynamics of product quality to a Markov process. We apply our new methodology to the US customs data (1989-2006), and find that quality improvements contribute the most to the gains from trade in the US. Quality improvements have lowered the price of US imports relative to the CPI by 17%, with Chinese products contributing the most. In comparison, import prices have fallen by around 11% relative to the CPI and increasing variety has contributed an additional 4%. These findings demonstrate that accounting for quality is essential to better understand and measure the effects of international trade. / Thesis (PhD) — Boston College, 2023. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

In this research, a new zeroth-order (non-gradient based) topology optimization methodology for compliance minimization was developed. It is called the Element Exchange Method (EEM). The principal operation in this method is to convert the less effective solid elements into void elements and the more effective void elements into solid elements while maintaining the overall volume fraction constant. The methodology can be integrated with existing FEA codes to determine the stiffness or other structural characteristics of each candidate design during the optimization process. This thesis provides details of the EEM algorithm, the element exchange strategy, checkerboard control, and the convergence criteria. The results for several two- and three-dimensional benchmark problems are presented with comparisons to those found using other stochastic and gradient-based approaches. Although EEM is not as efficient as some gradient-based methods, it is found to be significantly more efficient than many other non-gradient methods reported in the literature such as GA and PSO.

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