Theses and Dissertations from UMD
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Item Essays on Production Networks and International Macroeconomics(2024) Silva Uribe, Alvaro Nicolas; Kalemli-Ozcan, Sebnem S; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation includes three chapters on the role of production networks in (international) macroeconomics. In the first chapter, ``Inflation in Disaggregated Small Open Economies," I study the consequences of these production networks for our understanding of inflation in small open economies. I show that the production network alters the elasticity of the consumer price index (CPI) to changes in sectoral technology, factor prices, and import prices. Sectors can import and export directly but also indirectly through domestic intermediate input-output linkages. Indirect exporting dampens the inflationary pressure from domestic forces, such as adverse sectoral technology shocks and increases in factor prices. In contrast, indirect importing increases the inflation sensitivity to import price changes. Computing these CPI elasticities requires knowledge of the production network structure as these do not coincide with typical sufficient statistics used in the literature, such as sectoral sales-to-GDP ratios (Domar weights), factor shares, or imported consumption shares. Using input-output tables, I provide empirical evidence that adjusting CPI elasticities for indirect exports and imports matters quantitatively for small open economies. I then use the model to illustrate the importance of production networks during the recent COVID-19 inflation in Chile and the United Kingdom. In Chapter 2, ``Business Cycle Asymmetry and Input-Output Structure: The Role of Firm-to-Firm Networks" co-authored with Jorge Miranda-Pinto and Eric R. Young, we study the network origins of business cycle asymmetries using cross-country and administrative firm-level data. At the country level, we document that countries with a larger number of non-zero intersectoral linkages (denser networks) display a more negatively skewed cyclical component of output. At the firm level, firms with more suppliers and customers display a more negatively skewed distribution of their output growth. To rationalize these findings, we construct a multisector model with input-output linkages. We show that the relationship between output skewness and network density naturally arises once we consider non-linearities in production. In an economy with low production flexibility, denser production structures imply that relying on more inputs becomes a risk that further amplifies the effects of negative productivity shocks. On the contrary, when firms display high production flexibility, having more inputs to choose from becomes an opportunity to diversify the effects of negative productivity shocks. We calibrate the model using our rich firm-to-firm network Chilean data and show that (i) more connected firms experience larger declines in output in response to a COVID-19 shock, and (ii) the cross-sectional distribution of output growth in the model displays a fatter left tail during downturns. The previous result is shaped by the interplay between production complementarities and network interconnectedness rather than by the asymmetry of the shocks. The size of the shock determines the strength of the relationship between degrees and output decline, highlighting the importance of non-linearities and the limitations of local approximations. In Chapter 3, ``Commodity Prices and Production Networks in Small Open Economies" co-authored with Petre Caraiani, Jorge Miranda-Pinto, and Juan Olaya-Agudelo, we study the role of domestic production networks in the transmission of commodity price fluctuations in small open economies. We provide empirical evidence of strong propagation of commodity price changes to quantities produced in domestic sectors that supply intermediate inputs to commodity sectors (upstream propagation) and muted propagation to sectors using commodities as intermediate inputs (downstream propagation). We develop a small open economy production network model to explain these transmission patterns. We show that the domestic production network is crucial for shaping the propagation of commodity prices. The two key mechanisms that rationalize the evidence are (i) the foreign demand channel and (ii) the input-output substitution channel. These two channels amplify the upstream propagation of commodity price changes by increasing the demand for non-commodity inputs, and, at the same time, they mitigate the downstream cost channel by allowing firms to use relatively cheaper primary inputs in production.Item Hunting Inflationary Fossils in Primordial Inhomogeneities(2023) Bodas, Arushi; Sundrum, Raman; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cosmological observables such as the Cosmic Microwave Background (CMB) allow us to probe the early universe at extremely high energies far beyond the reach of any particle collider on Earth. In the inflationary paradigm, small perturbations in the energy distribution across space can be directly linked to the quantum fluctuations of an "inflaton'' field that drives inflation. Using these perturbations, it is, therefore, possible to learn about physics at energies as high as 10^(13) GeV. In this thesis, we exploit this powerful connection and explore novel mechanisms to hunt for previously unexplored inflationary dynamics. During inflation, particles with masses larger than the inflationary Hubble scale (H) are produced due to an accelerating spacetime. If coupled to the inflaton, these particles could imprint distinct oscillatory features in higher moments of the density perturbations. Since H can be as high as 5*10^(13) GeV, these oscillatory features present a unique opportunity to directly detect very heavy particles with masses ~ H. In Chapter 2, we explore a mechanism that can boost spin-0 particle production by mining the kinetic energy of the inflaton. This leads to an enhancement of the oscillatory features, which can bring heavier particles with masses up to 60H within the reach of observations. In the final part of the thesis, spanning chapters 3 and 4, we explore the viability of gravitational wave backgrounds (GWB) as novel data sources for unexplored inflationary physics. It was recently shown that a GWB from a first-order phase transition must exhibit fluctuations, much like the CMB. Despite the close analogy, it is possible for fluctuations of the GWB to differ significantly in their detailed pattern from those of the CMB, which would imply the existence of a second light field during inflation in addition to the inflaton. Such a GWB could thus unlock a wealth of new information about multi-field inflation. In Chapter 3, we elaborate on this point with an example. We show that there may exist signals that cannot be extracted using standard cosmological probes such as the CMB and galaxy surveys, but can in principle be detected within GWB with upcoming and proposed gravitational wave experiments. Lastly, in Chapter 4, we focus on the detectability of GWB itself. We discuss a cosmological mechanism that can enhance the strength of the gravitational wave signal from phase transitions, thereby increasing their detection prospects significantly.Item Polymer Capsules Exhibiting Emergent Properties Due to Internal Chemical Reactions(2018) DeMella, Kerry; Raghavan, Srinivasa R.; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Life is an “emergent” property – i.e., one exhibited by living systems due to interactions between their parts, but not shown by any of the parts on their own. Such emergent behavior is seen at various length scales, down to that of a single cell. In a single eukaryotic cell, there exist internal compartments called organelles, such as the nucleus and mitochondria. While the organelles each have distinct functions, it is the overall cell that has the property of life – i.e., the whole is greater than the sum of the parts. Inspired by these attributes of living cells, this dissertation attempts to create millimeter-scale polymer capsules that exhibit emergent properties. To achieve these properties, I use the lumen of the capsule as the site for a chemical reaction, which in turn bestows a specific behavior to the overall capsule. Three studies are described in this vein in this dissertation. First, in chapter 3, I design capsules that rapidly inflate and then burst, ejecting their core contents. These capsules have a core of catalytic silver (Ag) particles and a crosslinked polymer shell. When a fuel (hydrogen peroxide, H2O2) is added to water, a catalytic reaction generates gas (O2) in the capsule. The gas causes the capsule to inflate over time until the shell finally ruptures. The inflation extent and duration, as well as the rupture intensity can be tuned by altering the core and shell composition. Also, instead of a catalytic reaction, capsule inflation can be achieved by combining reactants, one in the capsule and the other in the solution, that together generate a different gas (e.g., CO2). In chapter 4, I describe a second emergent property of capsules having a design similar to those in chapter 3. The capsules here contain both the catalytic Ag particles as well as a solute (dye). I monitor the release of dye in the presence of the O2-generating reaction (“active release”) or by diffusion alone (“passive release”). Active dye release is shown to be much faster than passive release, i.e., the dye is “pumped” out due to the reaction. More interestingly, when the dye is Rhodamine 6G (R6G), it gets released in a series of pulses, i.e., dye releases for a few seconds, then it stops, and then resumes. The number and duration of the pulses can be tuned. The reason for pulsed release is attributed to the binding interaction of R6G to Ag particles. Finally, in chapter 5, I show the use of an external trigger (temperature) to induce emergent behavior in capsules. For this, I first coat individual capsules with an impermeable shell made of wax. This is done by briefly immersing a cold capsule in molten wax so that a wax layer solidifies around the capsule. This layer is impermeable when the capsule is placed in water, but when heated, the wax melts and the contents can diffuse out. I construct multicompartment capsules (MCCs) that have one or two wax-coated inner compartments. The MCCs are used to conduct cascade reactions such as the iodine clock reaction. Also, an MCC with H2O2 in a compartment and Ag particles in the lumen is used to demonstrate thermally triggered capsule inflation.Item GENERALIZED NATURAL INFLATION AND THE QUEST FOR COSMIC SYMMETRY BREAKING PATTERNS(2018) Riquelme, Simon; Chacko, Zackaria; Wentworth, Richard; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)We present a two-field model that generalizes Natural Inflation, in which the inflaton is the pseudo-Goldstone boson of an approximate symmetry that is spontaneously broken, and the radial mode is dynamical. Within this model, which we designate as ``Generalized Natural Inflation'', we analyze how the dynamics fundamentally depends on the mass of the radial mode and determine the size of the non-Gaussianities arising from such a scenario. We also motivate ongoing research within the coset construction formalism, that aims to clarify how the spontaneous symmetry breaking pattern of spacetime, gauge, and internal symmetries may allow us to get a deeper understanding, and an actual algebraic classification in the spirit of the so-called ``zoology of condensed matter'', of different possible ``cosmic states'', some of which may be quite relevant for model-independent statements about different phases in the evolution of our universe. The outcome of these investigations will be reported elsewhere.Item Debt and Inflation During a Period of Financial Repression(2012) Sbrancia, Maria Belen; Reinhart, Carmen M; Vegh, Carlos A; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The large accumulation of public debt which took place as a consequence of the recent financial crisis, poses the question of how governments are going to reduce their debts. In this dissertation I look at prior episodes where most advanced economies were highly indebted to understand the possible courses of action that may be available to governments in the future. Chapter 1, written with Carmen M. Reinhart, documents the role played by financial repression and inflation in reducing government debt after the end of World War II. This mechanism represents a more subtle and gradual form of debt restructuring. Evidence on the evolution and distribution of several measures of real interest rates show that during the period 1945-1980 interest rates were markedly more negative than what they were both in the period before World War II and after 1980. When looking at the real interest rate on the portfolio of domestic debt, real interest rates were negative half of the time for the 12 countries in the sample. A negative real interest rate on the portfolio of domestic debt represents a saving on interest payments for the government. In this case, savings on interest payments averaged 2 to 3 percent of GDP. The chapter also documents the series of defaults, restructurings and conversions that took place after the end World War I and the Great Depression. Chapter 2 builds on the results of the first chapter. It provides a conceptual framework to understand the different ways through which inflation can affect the value of government debt, and also how to think of financial repression as a restructuring mechanism. Several econometric exercises are performed to disentangle the relative contribution of financial repression and unanticipated inflation. The results point to financial repression combined with inflation (i.e., a nonmarket interest rate combined with inflation) as a relatively more important factor explaining the debt reduction in the post-World War II period. Finally, the question of how investors were affected during this period is explored. It is shown that the equity premium almost doubled during this period. This result suggests that the presence of financial repression, during the period 1945-1980, could help explain to some extent the equity premium puzzle.