Bulges

We model the evolution of the galactic bulge and of the bulges of a selected sample of external spiral galaxies, via the multiphase multizone evolution model. We address a few questions concerning the role of the bulges within galactic evolution schemes and the properties of bulge stellar populations. We provide solutions to the problems of chemical abundances and spectral indices, the two main observational constraints to bulge structure.Comment: 15 pages, 10 figures, to be published in MNRA

Calcium Triplet Synthesis

We present theoretical equivalent widths for the sum of the two strongest lines of the Calcium Triplet, CaT index, in the near-IR, using evolutionary techniques and the most recent models and observational data for this feature in individual stars. We compute the CaT index for Single Stellar Populations (instantaneous burst, standard Salpeter-type IMF) at four metallicities, Z=0.004, 0.008, 0.02 (solar) and 0.05, and ranging in age from very young bursts of star formation (few Myr) to old stellar populations, up to 17 gyr, representative of globular clusters, elliptical galaxies and bulges of spirals. The interpretation of the observed equivalent widths of CaT in different stellar systems is discussed. Composite-population models are also computed as a tool to interpret the CaT detections in star-forming regions, in order to disantangle between the component due to Red Supergiants stars, RSG, and the underlying, older, population. CaT is found to be an excellent metallicity-indicator for populations older than 1 Gyr, practically independent of the age. We discuss its application to remove the age- metallicity degeneracy, characteristic of all studies of galaxy evolution based on the usual integrated indices (both broad band colors and narrow band indices). The application of the models computed here to the analysis of a sample of elliptical galaxies will be discussed in a forthcoming paper (Gorgas et al. 1998).Comment: 17 pages, 7 figures, to be published in A&

Adaptation to Health States: A Micro-Econometric Approach

Health care funding decisions in the UK are based on valuations of the general public. However, it has been shown that there is a disparity between a hypothetical valuation of the impact of a specific condition on health and the effect of that health state by someone who experiences it. This paper examines the issue of adaptation to health states, which partially may explain the discrepancy between hypothetical and experienced health state valuations. We use the British Cohort Study (BCS70) which is a longitudinal dataset that tracks a sample of British individuals since their birth in 1970. We use four BCS70 waves containing information on self-assessed health (SAH), morbidity as well as a number of socio-economic characteristics. To estimate the issue of adaptation, we implement a dynamic ordered probit model that controls for (health) state dependence. The empirical specification controls for morbidity and also includes a variable for the duration of the illness. We find that, for most chronic conditions, duration has a positive impact on self-assessed health, while for some conditions-such as diabetes- this does not occur. We interpret our results as evidence in support of the hypothesis that adaptation to chronic diseases exists and may explain at least in part the differences between general public and patients’ health state valuations