Generalized flows, intrinsic stochasticity, and turbulent transport

The study of passive scalar transport in a turbulent velocity field leads naturally to the notion of generalized flows, which are families of probability distributions on the space of solutions to the associated ordinary differential equations which no longer satisfy the uniqueness theorem for ordinary differential equations. Two most natural regularizations of this problem, namely the regularization via adding small molecular diffusion and the regularization via smoothing out the velocity field, are considered. White-in-time random velocity fields are used as an example to examine the variety of phenomena that take place when the velocity field is not spatially regular. Three different regimes, characterized by their degrees of compressibility, are isolated in the parameter space. In the regime of intermediate compressibility, the two different regularizations give rise to two different scaling behaviors for the structure functions of the passive scalar. Physically, this means that the scaling depends on Prandtl number. In the other two regimes, the two different regularizations give rise to the same generalized flows even though the sense of convergence can be very different. The “one force, one solution” principle is established for the scalar field in the weakly compressible regime, and for the difference of the scalar in the strongly compressible regime, which is the regime of inverse cascade. Existence and uniqueness of an invariant measure are also proved in these regimes when the transport equation is suitably forced. Finally incomplete self similarity in the sense of Barenblatt and Chorin is established.

Flows of knowledge from universities and federal laboratories: Modeling the flow of patent citations over time and across institutional and geographic boundaries

The extent to which new technological knowledge flows across institutional and national boundaries is a question of great importance for public policy and the modeling of economic growth. In this paper we develop a model of the process generating subsequent citations to patents as a lens for viewing knowledge diffusion. We find that the probability of patent citation over time after a patent is granted fits well to a double-exponential function that can be interpreted as the mixture of diffusion and obsolescense functions. The results indicate that diffusion is geographically localized. Controlling for other factors, within-country citations are more numerous and come more quickly than those that cross country boundaries.

An evolutionary approach to the delineation of functional areas based on travel-to-work flows

This paper presents a new approach to the delineation of local labor markets based on evolutionary computation. The aim of the exercise is the division of a given territory into functional regions based on travel-to-work flows. Such regions are defined so that a high degree of inter-regional separation and of intra-regional integration in both cases in terms of commuting flows is guaranteed. Additional requirements include the absence of overlap between delineated regions and the exhaustive coverage of the whole territory. The procedure is based on the maximization of a fitness function that measures aggregate intra-region interaction under constraints of inter-region separation and minimum size. In the experimentation stage, two variations of the fitness function are used, and the process is also applied as a final stage for the optimization of the results from one of the most successful existing methods, which are used by the British authorities for the delineation of travel-to-work areas (TTWAs). The empirical exercise is conducted using real data for a sufficiently large territory that is considered to be representative given the density and variety of travel-to-work patterns that it embraces. The paper includes the quantitative comparison with alternative traditional methods, the assessment of the performance of the set of operators which has been specifically designed to handle the regionalization problem and the evaluation of the convergence process. The robustness of the solutions, something crucial in a research and policy-making context, is also discussed in the paper.

International Capital Flows and Monetary Policy Spillovers

This dissertation examines the drivers and implications of international capital flows. The overarching motivation is the observation that countries not at the centre of global financial markets are subject to considerable spillovers from centre countries, notably from their monetary policy. I present new empirical evidence on the determinants of the observed patterns of international capital flows and monetary policy spillovers, and study their effect on both financial markets and the real economy. In Chapter 2 I provide evidence on the determinants of a puzzling negative correlation observed between productivity growth and net capital inflows to developing and emerging market economies (EMEs) since 1980. By disaggregating net capital inflows into their gross components, I show that this negative correlation is explained by capital outflows related to purchases of very liquid assets from the fastest growing countries. My results suggest a desire for international portfolio diversification in liquid assets by fast growing countries is driving much of the original puzzle. In the reminder of my dissertation I pivot to study the foreign characteristics that drive international capital flows and monetary policy spillovers, with a particular focus on the role of unconventional monetary policy in the United States (U.S.). In Chapter 3 I show that a significant portion of the heterogeneity in EMEs' asset price adjustment following the quantitative easing operations by the Federal Reserve (the Fed) during 2008-2014 can be explained by the degree of bilateral capital market frictions between these countries and the U.S. This is true even after accounting for capital controls, exchange rate regimes, and domestic monetary policies. Chapter 4, co-authored with Michal Ksawery Popiel, studies unconventional monetary policy in a small open economy, looking specifically at the case of Canada since the global financial crisis. We quantify the effect Canadian unconventional monetary policy shocks had on the real economy, while carefully controlling for and quantifying spillovers from U.S. unconventional monetary policy. Our results indicate that the Bank of Canada's unconventional monetary policy increased Canadian output significantly from 2009-2010, but that spillovers from the Fed's policy were even more important for increasing Canadian output after 2008.

EU Policies on Mixed Migration Flows in the Mediterranean Sea. EU Centre Singapore Background Brief No. 13, February 2015

The tragic deaths of over 300 people off the coast of Lampedusa in 2013 and many other incidents involving migrants from Middle East and North Africa (MENA) crossing the Mediterranean in order to seek refuge in Europe has led to a European Union (EU) level debate on asylum policies and how to deal with irregular migration. However, no concrete policy has been agreed since the tragic events at Lampedusa in 2013 and continuous crossings that have resulted in many more deaths. This background brief provides an overview of the existing EU policies on asylum seekers and in addressing irregular migration and some of the actions which the relevant Member States take when confronted with continuous flows of irregular migrants. This brief concludes that the EU should delink the rescue of irregular migrants from security concerns, provide a legal basis which offers protection to irregular migrants, and create a transparent working environment in which member states are better able to support each other when dealing with such events.

Squaring the cycle: capital flows, financial cycles, and macro-prudential policy in the euro area. Bruegel Working Paper 2015/14, November 2015

• Before the financial and economic crisis, monetary policy unification and interest rate convergence resulted in the divergence of euroarea countries’ financial cycles. This divergence is deeply rooted in the financial integration spurred by currency union and strongly correlated with intra-euro area capital flows. Macro-prudential policy will need to deal with potentially divergent financial cycles, while catering for potential cross-border spillovers from domestic policies, which domestic authorities have little incentive to internalise. • The current framework is unfit to deal effectively with these challenges. The European Central Bank should be responsible for consistent and coherent application of macro-prudential policy, with appropriate divergences catering for national differences in financial conditions. The close link between domestic financial cycles and intra-euro area capital flows raises the question of whether macro-prudential policy in the euro area can be compatible with free flows of capital. Financial cycle divergence had its counterpart in the build-up of macroeconomic imbalances, so effective implementation of the Macroeconomic Imbalance Procedure would support and strengthen macro-prudential policy.

Analysis of developments in EU capital flows in the global context. Bruegel Final study Bruegel N° 2015.2574, November 2015

Free movement of capital, which is one of the four fundamental economic freedoms of the European Union, can enhance welfare if it leads to better allocation of financial and productive resources. However, it can also be a source of vulnerability, with far-reaching spillovers. Monitoring and assessing capital flows is therefore crucial for policymakers, market participants and analysts.