We introduce an infinite-horizon endogenous growth framework for studying the effects of foreign aid on the economic growth in a recipient country. Aid is used to partially finance the recipient's public investment. We point out that the same rule of aid may have very different outcomes, depending on the recipient's circumstances in terms of development level, domestic investment, efficiency in the use of aid and in public investment, etc. Foreign aid may promote growth in the recipient country, but the global dynamics of equilibrium are complex (because of the non-monotonicity and steady state multiplicity). The economy may converge to a steady state or grow without bounds. Moreover, there are rooms for the divergence and a two-period cycle. We characterize conditions under which each scenario takes place. Our analysis contributes to the debate on the nexus between aid and economic growth and in particular on the conditionality of aid effects.

We build a dynamic general equilibrium model with heterogeneous producers and financial frictions (collateral constraints and incompleteness). First, we provide a characterization to check whether a sequence is an equilibrium or not. Second, we study the effects of financial imperfections on output and land prices. Third, we develop a theory of valuation of land by introducing the notion of endogenous land dividends (or yields) and different concepts of land-price bubbles. Some examples of bubbles are provided in economies with and without short-sales.

We consider an overlapping generations modelà la Diamond (1965) with two additional ingredients: altruism and an asset (or land) bringing non-stationary positive dividends (or fruits). We study the global dynamics of capital stocks and asset values as well as the interplay between them. Asset price bubbles are also investigated.

We consider a multi-sector infinite-horizon general equilibrium model. Asset supply is endogenous. The issues of equilibrium existence, e ciency, and bubble emergence are addressed. We show how di↵erent assets give rise to very di↵erent rational bubbles. We also point out that e cient bubbly equilibria may exist.

The economic implications of oil price shocks have been extensively studied since the 1970s'. Despite this huge literature, no dynamic stochastic general equilibrium model was available that captures two well-known stylized facts: 1) the stagflationary impact of an oil price shock, together with 2) the influence of the energy productivity of capital on the depth and length of this impact. We build, estimate and simulate a New-Keynesian model with capital accumulation, which takes the case of an economy where oil is imported from abroad, and where these stylized facts can be accounted for. Moreover, the Bayesian estimation of the model on the US economy suggests that the output elasticity of oil might have been above 10%, stressing the role of oil use in US growth at this time. Finally, our simulations confirm that an increase in energy efficiency significantly attenuates the effects of an oil shock -a possible explanation of why the third oil shock (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) did not have the same macro-economic impact as the first two ones. JEL Codes : C68, E12, E23, Q43