This paper integrates a traditional Dornbusch overshooting model with a macro-economic model of hysteresis in foreign trade. We apply an approach which allows an aggregation of heterogeneous agents and which results in a continuous macroeconomic hysteresis-loop. In our model, short-run exchange rate overshooting generates a persistent current account effect, which feeds back into the exchange rate process and ultimately results in changes of the long-run equilibrium exchange rate. Monetary shocks can lead to hysteresis in both foreign trade and exchange rate processes, invalidating the long-run neutrality of money hypothesis and the purchasing power parity assumption of the conventional overshooting model.

The choice between private and government provision of a productive public good like infrastructure (public capital) is examined in the context of an endogenously growing open economy. The accumulation of public capital need not require government provision, in contrast to the standard assumption in the literature. Even with an efficient government, the relative costs and benefits of government and private provision depend crucially on the economy's underlying structural conditions and borrowing constraints in international capital markets. Countries with limited substitution possibilities and large production externalities may benefit from governments encouraging private provision of public capital through targeted investment subsidies. By contrast, countries with flexible substitution possibilities and relatively smaller externalities may benefit either from governments directly providing public capital or from regulation of private providers. The transitional dynamics also are shown to depend on the underlying elasticity of substitution and the size of the production externality.

I present an environment for which both outside and inside money are essential as means of payment. The key model feature is that there is imperfect monitoring of issuers of inside money. I use a random-matching model of money where some agents have private trading histories and others have trading histories that can be publicly observed only after a lag. I show via an example that for lags that are neither too long nor too short, there exist allocations that use both types of money that cannot be duplicated when only one type is used. Inside money provides liquidity that increases the frequency of trades, but incentive constraints restrict the amount of output that can be traded. Outside money is immune to such constraints and can trade for higher levels of output.

Over the past two million years human body mass first increased and later declined, peaking about 50,000 years ago. This paper sets up a model of natural selection among body types to explain this pattern. Population, technology, and average body mass evolve endogenously and interdependently in such a way that a takeoff in technological progress generates rising population density and resource depletion. This in turn makes large bodies less useful in food procurement, while keeping their metabolism requirements high. The result is a shift in reproductive advantage from big to small bodies and an endogenous reversal of the time trend in body mass.

We consider an economy in which people choose between a random-matching sector and organized markets absent double-coincidence problems. Merchants in the organized markets issue bills of exchange. Pareto-ranked multiple equilibria exist with the extent of the market and circulation of private liabilities endogenously determined. If trade frictions are moderate, bills circulate as a general medium of exchange, and the level of specialization is higher relative to barter. In this case, higher inside liquidity is accompanied by more specialization. When all transactions take place in the organized markets, trading risk vanishes and the economy achieves complete specialization.

We study the constant discount rate present value model for stock pricing in a stochastic setting where the exogenous dividend stream is modeled as a random walk with innovations drawn from the family of stable distributions. We derive an exact analytical solution for the fundamental stock price. We evaluate the ability of the model fundamentals and the dividends-driven intrinsic bubbles to explain the observed variation in annual U.S. stock prices. We compare results obtained in this setting with those from the traditional model where all stochastic processes are driven by Gaussian shocks.

We consider an overlapping generations model with environment and an elastic labor supply. In this framework, consumers have to choose between consumption, environmental quality, and leisure. We show the existence of both deterministic cycles and indeterminacy. In contrast to previous results, the emergence of endogenous fluctuations does not require a high emission rate of pollution.