Stellar Populations in Normal Galaxies

I describe very briefly the new libraries of empirical spectra of stars covering wide ranges of values of the atmospheric parameters Teff, log g, [Fe/H], as well as spectral type, that have become available in the recent past, among them the HNGSL, MILES, UVES-POP, and Indo-US libraries. I show the results of using the HNGSL to build population synthesis models. These libraries are complementary in spectral resolution and wavelength coverage, and will prove extremely useful to describe spectral features expected in galaxy spectra from the NUV to the NIR.Comment: 6 pages, 4 figures, in Proceedings of the IAU Symposium No. 222 "The Interplay Among Black Holes, Stars, and ISM in Galactic Nuclei", eds. T. Storchi-Bergmann, L.C. Ho, and H.R. Schmitt, Cambridge: Cambridge University Press, 121-12

On TP-AGB stars and the mass of galaxies

Recent calculations of evolutionary tracks of TP-AGB stars of different mass and metallicity by Marigo et al. (2007) have been incorporated in the Bruzual & Charlot evolutionary population synthesis models. The mass of the stellar population in HUDF galaxies at z from 1 to 3 determined from fits to the spectro-photometric data of these galaxies is 50 to 80% lower than the mass determined from the BC03 models. The ages inferred for these populations are, with exceptions, 40 to 60% of the BC03 estimates.Comment: 7 pages, 4 figures, in Proceedings of the IAU Symposium No. 241 "Stellar populations as building blocks of galaxies", eds. A. Vazdekis and R. Peletier, Cambridge: Cambridge University Press, in pres

Coordinating short- and long-run public investment rules

Modelling the accumulation rule evolving public investment is an issue of utmost interest among economists and politicians. The present paper extends the Barro (1990) model of productive government expenditure by considering a time-adapted rule for the public investment/output ratio. The rule allows a particular target on the public investment ratio to be achievable in the long-run. Additionally, throughout the transition, the government may adjust its period-by-period public investment/output ratio in response to the current productivity of public capital relative to its long-run level. The degree of this response depends on a short-run policy instrument, which is decided by the fiscal authority simultaneously to the long-run target ratio. That way, the government problem could be interpreted as a coordination problem between short- and long-term policies. In comparison with a constant-ratio rule, and under alternative taxing scenarios, important welfare improvements are found when coordinating the short- and the long-run policy instruments in an optimal way.Public investment rule, policy coordination, transitional dynamics, Endogenous growth