A Homomorphism Theorem for Bilinear Multipliers

In this paper we prove an abstract homomorphism theorem for bilinear multipliers in the setting of locally compact Abelian (LCA) groups. We also provide some applications. In particular, we obtain a bilinear abstract version of K. de Leeuw's theorem for bilinear multipliers of strong and weak type. We also obtain necessary conditions on bilinear multipliers on non-compact LCA groups, yielding boundedness for the corresponding operators on products of rearrangement invariant spaces. Our investigations extend some existing results in Euclidean spaces to the framework of general LCA groups, and yield new boundedness results for bilinear multipliers in quasi Banach spaces

The role of new technologies in the economic growth of Andalucia

This paper explores the contribution of Information and Communication Technologies (ICT) on economic growth and labor productivity growth of Andalucía during 1995-2004. We find that the contribution of ICT assets to total market GVA growth is quantitatively modest. Anyway the contribution to GVA growth and employment growth within the intensive ICT sectors has experienced a considerable increase in Andalucía. Although our analysis detects that intensive ICT sectors exhibit a high productivity level with respect to that of the non intensive ones, our main conclusion is that the advantages that might emerge from the use of ICT are nor yet observable in the economic dynamics of Andalucía, at least in a similar manner to that of the most developed.Information and Communication Technologies, productivity growth, regional growth

How tight should one's hands be tied? Fear of floating and credibility of exchange regimes.

The literature on exchange regimes has recently observed that officially self-declared free floaters strongly intervene their nominal exchange rates to maintain them within some unannounced bands. In this paper, we provide an explanation for this behavior, labeled by Calvo and Reinhart (2002) as fear of floating. First, we analyze the linkages between the credibility of the exchange regime, the volatility of the exchange rate and the band width of fluctuation. Second, the model is used to understand the reduction in volatility experienced by most ERM countries after their target zones were widened on August 1993. Finally, solving the model for a subgame perfect equilibrium, fear of floating can be viewed as the credible choice of a finite non-zero bandFear of floating, target zones, exchange rate arrangements, credibility

The optimal degree of exchange rate flexibility: A target zone approach

This paper presents a benchmark model that rationalizes the choice of the degree of exchange rate flexibility. We show that the monetary authority may gain efficiency by reducing volatility of both the exchange rate and the interest rate at the same time. Furthermore, the model is consistent with some known stylized facts in the empirical literature on target zones that previous models were not able to generate jointly, namely, the positive relation between the exchange rate and the interest rate differential, the degree of non-linearity of the function linking the exchage rate to fundamentals and the shape of the exchange rate stochastic distribution.Target zones, exchange rate agreements, monetary policy, time consistency.

Growth, fluctuations and technology in the U.S. post-war economy

This paper explores several issues concerning how technology affects growth and fluctuations during several U.S. postwar series. The nature of technology is divided into neutral progress and investment-specific progress. Accounting for several changes in the first and second order moments of these series (the slowdown of productivity in 1974, the moderation of 1984 and the resurgence in productivity after 1994), I find that the contribution of investment-specific progress to growth has increased over time. I also find that neutral progress is crucial in explaining the cyclical component of output (before and after 1984), contrary to results found in related literature. However, the shocks to investment-specific progress have played an increasing role in output and other macroeconomic variables. Finally, I conclude that moderation in the macroeconomic series can be associated with technology. In sum, the quality of technological processes affecting long run growth and fluctuations has changed over the past decades.Productivity growth; Investment-specific technological change; Neutral technological change

On the Choice of an Exchange Regime: Target Zones Revisited

From the classical gold standard up to the current ERM2 arrangement of the European Union, target zones have been a widely used exchange regime in contemporary history. This paper presents a benchmark model that rationalizes the choice of target zones over the rest of regimes: the fixed rate, the free float and the managed float. It is shown that the monetary authority may gain efficiency by reducing volatility of both the exchange rate and the interest rate at the same time. Furthermore, the model is consistent with some known stylised facts in the empirical literature that previous models were not able to produce, namely, the positive relation between the exchange rate and the interest rate differential, the degree of non-linearity of the function linking the exchange rate to fundamentals and the shape of the exchange rate stochastic distribution.Infrastructures, taxes, efficiency, social welfare

Study of sdO models. Pulsation Analysis

We have explored the possibility of driving pulsation modes in models of sdO stars in which the effects of element diffusion, gravitational settling and radiative levitation have been neglected so that the distribution of iron-peak elements remains uniform throughout the evolution. The stability of these models was determined using a non-adiabatic oscillations code. We analysed 27 sdO models from 16 different evolutionary sequences and discovered the first ever sdO models capable of driving high-radial order g-modes. In one model, the driving is by a classical kappa-mechanism due to the opacity bump from iron-peak elements at temperature ~200,000 K. In a second model, the driving result from the combined action of kappa-mechanisms operating in three distinct regions of the star: (i) a carbon-oxygen partial ionization zone at temperature ~2 10^6 K, (ii) a deeper region at temperature ~2 10^7 K, which we attribute to ionization of argon, and (iii) at the transition from radiative to conductive opacity in the core of the star.Comment: 13 pages, 19 figures, accepted for publication in MNRAS, 2009 September 1