Optical Tests of a 3.7-m diameter Liquid Mirror: Behavior under External Perturbations

We have built and tested a 3.7-m diameter liquid mirror that rotates on a ball bearing. We have carried out extensive optical tests. We find that although the ball bearing has a poor quality, the quality of the mirror, with mercury layers 1-mm thick, is surprisingly good. Taken at face values the instantaneous Strehl ratios indicate a mirror, that is not quite diffraction limited but usable for astronomical applications. However, the large coning error of the bearing (1.5 arcseconds P-V) induces an excessive wobble, considerably worsening the time averaged PSF. The most interesting result of the interferometry is that we do not see any evidence of the strong astigmatism that may have been expected from Coriolis forces.Comment: PDF format, 34 pages, 12 figures, (some figures reduced, full size figures in Applied Optics, Vol. 39, No 36, 5651

Spanish Mothers’ Labour Supply and Child Care Demand: A Structural Model

In this paper we present a structural utility discrete choice model to estimate mothers’labour supply and child care demand in Spain. The mothers are assumed to make choices from a finite set of job possibilities and childcare options. Based on data from the Spanish Time Use Survey, we have estimated a mixed logit model. Our results indicate that Spanish mothers show clear preferences for income and pure leisure. Also, in average, mothers present a relative dislike for non-parental modes of care compared to maternal care. Finally, the child’s age is a significant source of preference heterogeneity

Childcare cost and Spanish mother’s labour force participation

In Spain, female labour force participation is among the lowest in Europe. This paper analyzes the extent to which female labour force participation is affected by the cost of formal childcare. Both decisions, labour force participation and formal childcare use, are jointly considered by means of a bi-variate probit model that accounts for the sample selection. Based on data from the Spanish Time Use Survey, the study indicates that Spanish mothers’ labour force participation is very elastic to changes in childcare costs.Childcare costs, female labour participation

Optical Tests of a 2.5-m diameter Liquid Mirror: Behavior under External Perturbations and Scattered Light Measurements

Interferometric tests of a f/1.2 2.5-m diameter liquid mirror show RMS surface deviations about wave/20 and Strehl ratios of order 0.6, showing that it is diffraction limited. The mirror is certainly better than implied by the data because of aberrations introduced by the auxiliary testing optics. We have made detailed studies of the scattered light of the mirror. We have studied the behavior of the mirror under external perturbations. With this article we have reached an important milestone since we now have a good understanding of liquid mirrors.Comment: To appear in Applied Optics. Postscript, 14 double spaced pages, 5 tables 13 figure

Female labour participation and child care choices in Spain

This paper analyzes Spanish families' behaviour relating to child care and employment issues. It estimates a simultaneous equation econometric model to study the effect of child care costs on labour participation decisions and child care choices. Based on data from the Spanish Time Use Survey, our study indicates that female labour force participation is very elastic to changes in prices of day-care services. Also, choice of child care mode is conditional on employment status. In addition, the type of family or its socioeconomic situation, along with the prices of the different options influences in the chosen child care mode.Child care, female labour participation